Mmse journal vol 9 iss 1

Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

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Mechanics, Materials Science & Engineering Journal

April 2017

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

Mechanics, Materials Sciences & Engineering Journal, Austria, Sankt Lorenzen, 2017 Volume 9, Issue 1

Mechanics, Materials Science & Engineering Journal (MMSE Journal) is journal that deals in peerreviewed, open access publishing, focusing on wide range of subject areas, including economics, business, social sciences, engineering etc.

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Editor-in-Chief Mr. Peter Zisser Dr. Zheng Li, University of Bridgeport, USA Prof. Kravets Victor, Ukraine Ph.D., Shuming Chen, College of Automotive Engineering, China Dr. Yang Yu, University of Technology Sydney, Australia Prof. Amelia Carolina Sparavigna, Politecnico di Torino, Italy ISSN 2412-5954

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

CONTENT Carbon Nanotubes as Future Energy Storage System. V. Vasu, D. Silambarasan ................... 8 Synthesis and Characterization studies of ZnFe2O4 nanoparticles. R.C. Sripriya, Ezhil Arasi S. Madhavan J. Victor Antony Raj M. ............................................................................................... 13 Synthesis of Nd3+doped TiO2 nanoparticles and Its Optical Behaviour. Ezhil Arasi S. Victor Antony Raj M, Madhavan J. .............................................................................................................. 18 Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites. T. Sakthivel, K. Jagannathan. .................................................................... 22 Structural and Photoluminescence Studies of (Cu, Al) Co-doped ZnO Nanoparticles. P. Swapna, S. Venkatramana Reddy. ...................................................................... 27 Synthesis of Pure Hydroxyapatite (Ca10 (PO4)6 (OH)2 ) by the Sol –Gel Method and the Doxycycline Loaded in Presence of Gelatin for the Application of Drug Delivery. B. Shalini, A. Ruban Kumar, A. Mary Saral. ...................................................................................................... 32 Low Temperature Ferromagnetism and Optical Properties of Fe Doped ZnO Nanoparticles Synthesized by Sol-Gel Method. B. Sathya, V. Porkalai, D. Benny Anburaj, G. Nedunchezhian. ............................................................................................................................ 38 Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method. D.V. Sridevi, V. Ramesh, T. Sakthivel, K.Geetha, V. Ratchagar, K. Jagannathan, K. Rajarajan, K. Ramachadran ......................................................................................................... 44 Effect OF Ni Concentration on Structural and Optical Properties of ZnS Nanoparticles. B. Sreenivasulu, S. Venkatramana Reddy, P. Venkateswara Reddy. ...................... 49 Synthesis and Characterization of ZnO/NiO and Its Photocatalytic Activity. V. Karthikeyan, A. Padmanaban, T. Dhanasekaran, S. Praveen Kumar, G. Gnanamoorthy, V. Narayanan. ........... 55 Structural, Optical and Antimicrobial Activity of Copper and Zinc Doped Hydroxyapatite Nanopowders using Sol-Gel Method. A. Mariappan, P. Pandi, N. Balasubramanian, R. Rajeshwara Palanichamy, K. Neyvasagam. ................................................................................. 59 Synthesis of Bismuth Stannate Nanoparticles with High Photocatalytic Activity under the Visible Light Irradiation. G. Gnanamoorthy, T. Dhanasekaran, A. Padmanaban, S. Praveen Kumar, S. Munusamy, A. Stephen, V.Narayanan. .......................................................................................... 64 Preparation and Optical Studies of Layered Double Hydroxides for Photo Catalytic Degradation of Organic Dyes. T. Dhanasekaran, A. Padmanaban, G. Gnanamoorthy, R. Manigandan, S. Praveen Kumar, S. Munusamy, A. Stephen, V. Narayanan. ................................... 70 Photocatalytic Activity of Biosynthesized Silver Nanoparticle from Leaf Extract of Justicia Adhatoda. Latha D. C. Arulvasu, P. Prabu, V. Narayanan. ............................................................ 75 Visible Light Photocatalytic Property of Ag/TiO2 Composite. A. Padmanaban, T. Dhanasekaran, S. Praveen Kumar, G. Gnanamoorthy, S. Munusamy, A. Stephen, V. Narayanan. .................................................................................................................................. .80 Design and Simulation of Cantilever Based MEMS Bimorph Piezoelectric Energy Harvester. G.K.S. Prakash Raju, P. Ashok Kumar, Vanaja Aravapalli, K. Srinivasa Rao. ............ 85 Investigation of spinel structure ZnFe1.8La0.2O4 Nanoparticles Synthesized by PEG assisted Wet Chemical Method. M. Shoba, S. Kaleemulla. ........................................................... 91 Microhardness of Hydroxyapatite Doped ZrO2 using Sol-Gel Method. S. Helen, A. Ruban Kumar. ............................................................................................................................................... 96

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

Enhanced Photocatalytic Activity of Rare Earth Metal (Nd and Gd) doped ZnO Nanostructures. P. Logamani, R. Rajeswari, G. Poongodi. ......................................................... 100 Structural and Electrical Properties of CaMnO3 Prepared by Sol-Gel Method. K. R. Nandan, A. Ruban Kumar. ............................................................................................................................. 105 Study on Cobalt Ferrite Nanoparticles Synthesized by Co-Precipitation Technique for Photo-Fenton Application. P. Annie Vinosha, G. Immaculate Nancy Mary, K. Mahalakshmi, L. Ansel Mely, S. Jerome Das. ............................................................................................................. 110 On Feature Image Recognition of Melanoma using Nanotechnology Applications. D. Naveen Raju, S.Shanmugan, M. Anto Bennet. ............................................................................................. 116 Structural and Magnetic Properties of Cr Doped SnO2 Nanopowders Prepared by Solid State Reaction. M. Kuppan, S. Harinath Babu, S. Kaleemulla, N. MadhusudhanaRao, C. Krishnamoorthi, G. VenugopalRao, I. Omkaram, D. SreekanthaReddy, K.Venkata Subba Reddy. ................................................................................................................. 121 Particle Size Effect on the Properties of Cerium Oxide (CeO2) Nanoparticles Synthesized by Hydrothermal Method. G. Jayakumar, A. Albert Irudayaraj, A. Dhayal Raj. ............................ 127 Structural, Optical and Magnetic Properties of Îą-Fe2O3 Nanoparticles. B. Balaraju, M. Kuppan, S. Harinath Babu, S. Kaleemulla, N. Madhusudhana Rao, C. Krishnamoorthi, Girish M. Joshi, G. Venugopal Rao, K. Subbaravamma, I. Omkaram, D. Sreekantha Reddy. ....................... 132 Ferromagnetic and Photoluminescence Properties of Fe doped Indium-Tin-Oxide Nanoparticles Synthesised by Solid State Reaction. Deepannita Chakraborty, N. Madhusudhana Rao, G. Venugopal Rao, S. HainathBabu, S. Kaleemulla, C. Krishnamoorthi. ............................. 137 The Role of Cellulose in the Formulation of Interconnected Macro and Micoporous Biocompatible Hydroxyapatite Scaffolds. J. Anita Lett, M. Sundareswari, K. Ravichandran, Amirdha Sher Gill, J. Joyce Prabhkar. ........................................................................................... 143 Structural, Morphological and Optical Characterization of Eu3+ and Nd3+ Co-Doped Tio2 Nano Particles by Sol Gel Method. P. Sanjay, K. Deepa, M. Victor Antony Raj, S.Senthil. .......................................................................................................................................... 149 Study on the Synthesis, Structural, Optical and Electrical Properties of ZnO and Lanthanum Doped ZnO Nano Particles by Sol-Gel Method. V. Porkalai, D. Benny Anburaj, B. Sathya, G. Nedunchezhian, R. Meenambika. ............................................................................................... 155 Structural and Functional Group Characterization of Nanocomposite Fe3O4/TiO2 and Its Magnetic Property. V. Maria Vinosel, M. Asisi Janifer, S. Anand, S. Pauline. ............................ 161 Optimized Synthesis of Gold Nanoparticles using Green Chemical Process and its Invitro Anticancer Activity Against HepG2 and A549 Cell Lines. S. Rajeshkumar, S. Venkat Kumar, C. Malarkodi, M. Vanaja, K. Paulkumar, G. Annadurai. ............................................................... 167 Phyto-Assisted Synthesis of Silver Nanoparticles using Solanum Nigrum and Antibacterial Activity Against Salmonella Typhi and Staphylococcus Aureus. Venkat Kumar S. Karpagambigai S. Jacquline Rosy P. Rajeshkumar S. .............................................................................................. 173 Temperature Based Investigation on Structure and Optical Properties of Bi2S3 Nanoflowers

by Solvothermal Approach. J. Arumugam, A. Dhayal Raj, A. Albert Irudayaraj, T. Pazhanivel. .................................................................................................................................. 181 Structural, Optical and Magnetic Properties of Cr Doped CdSe Powders Prepared by Solid State Reaction. J. Sivasankar, P. Mallikarjuna, N. Madhusudhana Rao, S. Kaleemulla, M. Rigana Begam, G. Venugopal Rao. ............................................................................................................. 188

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

Structural, Optical and Magnetic Properties of Co doped ZnSe Powders. P. Mallikarjuna, J. Sivasankar, M. Rigana Begam, N. Madhusudhana Rao, S. Kaleemulla, J. Subrahmanyam. ..... 195 Structural, Magnetic Properties of Wide Band Gap Oxide Semiconductors. B. Balaraju, M. Kuppan, S. Harinath Babu, S. Kaleemulla, N. Madhusudhana Rao, C. Krishnamoorthi, Girish M. Joshi, G. Venugopal Rao, K. Subbaravamma, I. Omkaram, D. Sreekantha Reddy. ....................... 201 Preparation and Characterization of Metal Oxide as Nano Particles - Varatika Bhasma. Shebina P. Rasheed, M. Shivashankar. ........................................................................... 206 Design and Simulation of Nano Wire FET. M. Anil Kumar, Y.N.S. Sai Kiran, U. Jagadeesh, M. Durga Prakash. ............................................................................................................................... 211 Modeling and Simulation of Dual Gratings based Ultrathin Amorphous Silicon Solar Cells. S. Saravanan, R.S. Dubey, S. Kalainathan. .......................................................................... 217 Study of Structural and Optical Properties of Zinc-doped Titanium Dioxide Nanoparticles. V.G. Vasavi Dutt, R.S. Dubey. ............................................................................... 222 Temperature Induced Structural and Photoluminescence Properties of Poly Ethylene Glycol (PEG) Capped/Uncapped Cadmium Oxide Nanoparticles (CdO NPs). P. Lokanatha Reddy, S.K. Khadheer Pasha. ..................................................................................................................... 227 Optical Analysis of Ho3+ Ions Doped BaGd2Ti4O12 Ceramics. B. Munisudhakar, C. Nageswara Raju, P. Sreenivasulu Reddy, S. Hemasundara Raju. .................................................. 232 Green Synthesis and Characterization of Sodium Banana Peel Xanthate Carbon Dot (SBPX C-Dot) and Preparation and Utility of Carbon Composite Paste Electrode for Selective Potentiometric Sensing of Hg (II) Ions. M. Muthukumaran, K .Samuel Barnabas, S. Niranjani, K.Venkatachalam, T. Raju. ............................................................................................................. 236 Pulsed Electrodeposited Nickel – Cerium for Hydrogen Production Studies. T. Sivaranjani, T.A. Revathy, K. Dhanapal, V. Narayanan, A. Stephen. ................................................................. 242 Electrochemical Detection of Dopamine at Poly (o-anisidine)/Silver Nanocomposite Modified Glassy Carbon Electrode. D. Sangamithirai, V. Narayanan, A. Stephen. ................................... 247 Visible Light Induced Photocatalytic Degradation of Methylene Blue using Polyaniline Modified Molybdenum Trioxide. S. Dhanavel, E.A.K. Nivethaa, V. Narayanan, A. Stephen. ... 253 Green Synthesis of Silver Nanoparticles Mediated using Lagerstroemia Speciosa and Photocatalytic Activity Against Azo Dye. V. Sai Saraswathi, K. Santhakumar. ......................... 259 Impedance Analysis of Microwave Processed Lead Nickel Titanate. C. Pavithra, S. RoopasKiran, W. Madhuri. ............................................................................................................. 264 Synthesis, Characterization and DFT Calculations of Thiosemicarbazone 4-Methoxy Benzaldehyde Zinc Chloride. S. Attralarasan, A. Shiny Febena, M. Victor Antony Raj, J. Madhavan. ................................................................................................................................... 270 Spectroscopic Characterization, NLO Properties and DFT Study of Amino Acid Single Crystals of Glycine Nickel Chloride. A. Shiny Febena, M. Victor Antony Raj, J. Madhavan. .... 275 Experimental and Computational Studies on L - Histidinium DipicrateDihydrate.

R. Subaranjani, M. Victor Antony Raj, J. Madhavan. .................................................................... 281 Alkali Fusion Process of Waste Stone Dust to Synthesize Faujasite using Rotaky Kiln. Shinji Onishi, Takaaki Wajima, Toshio Imai, Sano Susumu. .................................................................... 287 Growth, Structural and Optical Behaviour of L-Histidinium perchlorate: A Nonlinear Optical Single Crystal. R. Vincent Femilaa, M. Victor Antony Raj, J. Madhavan. ...................... 293

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

Ab initio Study of Electronic, Structural, Thermal and Mechanical Characterization of Cadmium Chalcogenides. Devi Prasadh PS, B.K. Sarkar. .......................................................... 298 Growth, Structural, Spectral, Opticaland Photoconductivity Studies of Semiorganic Nonlinear Optical Single Crystal: Calcium5-Sulfosalicylate. D. Shalini, S. Kalainathan, D. Jayalakshmi. ............................................................................................................................... 304 Synthesis of Hydroxysodalite From Paper Sludge Ash Using NaOH-LiOH Mixtures. Takaaki Wajima. ........................................................................................................................................... 309 Morphological Changes of α-Lactose Monohydrate (α-LM) Single Crystals Under Different Crystallization Conditions Using Polar Protic and Aprotic Solvents. K. Vinodhini, K. Srinivasan. ................................................................................................................................. 315 Growth Aspects, Structural, Thermal and Optical Properties of an Organic Single Crystal: 4-(Dimethylamino)Pyridinium 4-Amino Benzonate Dihydrate. A. Thirunavukkarsu, T. Sujatha, P.R. Umarani, A. Chitra, R. Mohan Kumar. ................................................................................... 320 Growth Aspects, Structural and Optical Properties of 2-aminopyridinium 2,4 Dinitrophenolate Single Crystal. S. Reena Devi, B. Valarmathi, R. Mohan Kumar. .................. 326

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

Carbon Nanotubes as Future Energy Storage System1 V. Vasu1, D. Silambarasan1 1 – School of Physics, Madurai Kamaraj University, Madurai, India DOI 10.2412/mmse.52.18.599 provided by Seo4U.link

Keywords: carbon nanotubes, metal oxides, hydrogen, storage.

ABSTRACT. Hydrogen is considered to be a clean energy carrier. At present the main drawback in using hydrogen as the fuel is the lack of proper hydrogen storage vehicle, thus on-going research is focused on the development of advance hydrogen storage materials. Many alloys are able to store hydrogen reversibly, but the gravimetric storage density is too low for any practical applications. Theoretical studies have predicted that interaction of hydrogen with carbon nanotubes is by physisorption of hydrogen on the exterior and in the interior surfaces. Hence the CNTs appear to be the ultimate solution due to their chemical stability, large surface area, low density and hollowness. Recent studies indicate that the physisorption on pure CNTs may not be a feasible method of storing hydrogen. Hence, the functionalization of CNTs with metal hydrides is a subject of increasing scientific interest, to improve the hydrogen storage capacities. Lithium borohydride is a complex hydride that is received considerable attention due to its high gravimetric and volumetric hydrogen storage capacities. Our experimental investigation deals with the hydrogenation of SWCNTs functionalized with borane and also we have studied SWCNTs with different metal oxides composite like TiO2, SnO2 and WO3.

SWCNTs functionalization with borane was carried out by drop casting method. SWCNTs-metal oxide composite was prepared by both drop casting method and electron beam evaporation method. These results were discussed in detail in the present work. Studies were carried out with the aim to achieve higher storage capacity of hydrogen. It is found that the maximum storage capacity of 4.77 wt.% was observed for the SWCNTs functionalized with borane. The achieved hydrogen storage capacity in this investigation is close to the U.S. DOE target.

Introduction. Being an efficient energy carrier, hydrogen is believed as the appropriate candidate to meet the energy requirements with the increase in population. It is abundant, environmentally friendly fuel that has the potential to reduce our dependence on fossil fuels, but several significant challenges must be overcome before it can be widely used. The issues are namely, production, storage, transportation, conversion and applications. Hydrogen production and conversion are already technologically viable in the present scenario, but its storage and transportation encounter challenges.

This work focuses on the investigations of hydrogen storage. Solid state storage form of hydrogen is considered to be the most appropriate and promising way than other forms such as gaseous and liquid.

A nano-technological approach to solve the problem of storing hydrogen on materials is one of the main motivations behind this experimental research drive.

Among the nano materials, carbon nano materials are the most and widely investigated candidate for hydrogen storage. CNTs play a major role in the curriculum of hydrogen storage than other forms of carbon nanostructures. Carbon nanotubes (CNTs) are one of the allotropes of carbon with a cylindrical nanostructure. These cylindrical sp2 bonded carbon atoms possess unusual properties, which are valuable for nanotechnology, electronics, optics and other fields of materials science and technology. Generally, SWCNTs offer better adsorption and desorption properties than other type of CNTs because of their maximum surface area. Hence, we have chosen SWCNTs for our investigations. The initial investigations carried out (by various group) in bare CNTs for hydrogen storage suggested that CNTs are not an efficient material to store hydrogen for practical applications [1]. However, it has been shown that the addition of functional molecules, atoms and ions with CNTs 1

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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enhances the binding energy of hydrogen as well as the storage capacity via two processes, namely, (i) providing multiple sites for adsorption, (ii) electron charge transfer between metal and carbon atoms. Hence, this research work is focused on functionalization of SWCNTs, addition of metal, metal hydrides and metal oxides to SWCNTs for hydrogen storage.

Experimental. The preparation of materials involved the methods of drop casting, electron beam evaporation (e-beam) and spin coating. In the drop casting method, the appropriate amount of materials is mixed by grinding and ultrasonicated in 2-proponal for fixed durations. The same procedure is followed for spin coating technique. In the e-beam technique, the appropriate amount of materials is mixed by grinding and made into pellet, which is then evaporated with the e-beam current of 20-30 mA under high vacuum conditions for a fixed duration of time. We have designed a Seiverts’ like hydrogen storage setup for the hydrogenation process of the samples prepared by drop casting and spin coating techniques. In the e-beam technique, samples are evaporated in hydrogen atmosphere, i.e. hydrogen is stored in the composite samples during the preparation of hydrogen storage medium (HSM) itself as one-step process. Various characterization techniques such as AFM, SEM, FTIR, RAMAN, CHNS-elemental are employed to analyze the samples.

Results and discussions. The SWCNTs functionalized with borane system show a maximum hydrogen storage capacity of 4.77 wt.% at 50ºC [2-4]. Here, borane helps to anchor hydrogen molecules onto SWCNTs in the ideal binding energy limits. Fig. 1 (a), 1 (b), 1 (c) and 1 (d) shows TEM image, Raman spectrum of SWCNTs, IR spectrum of SWCNTs functionalized with BH3 and Raman spectra for SWCNTs (C), SWCNTs functionalized with BH3 (CB), hydrogenated SWCNTs functionalized with BH3 (CBH) and dehydrogenated SWCNTs (DCB), respectively. Raman spectrum provides valuable information about the purity and defects in the CNT samples. The D/G intensity ratio of SWCNTs (C) is 0.08, which informs the high purity of SWCNTs and for functionalized sample (CB), it is 0.21 and for the hydrogenated samples, the ratio is increased with the degree of hydrogenation. For the dehydrogenated sample (DCB), the D/G ratio is 0.225. This dehydrogenated sample is again hydrogenated and this step is continued. The change in D/G ratio, from 0.21 (CB) to 0.225 (DCB) is 0.015 (7.1%) after the first cycle. For the second cycle, the difference is 0.02 (~9.5%).

In the third cycle, it changes to 11.6%. There is an increase of 2.1-2.4% in the D/G ratio between two successive cycles. If we take the average of change in D/G ratio of the dehydrogenated SWCNTs after each cycle, it is about ~2.3%. The entire hydrogenation and dehydrogenation cycles are independent events and this effect is not cumulative. The quality of CNTs deteriorates due to dehydrogenation is only about 2.3%. This indicates that the functionalized SWCNTs are restored to the original level after dehydrogenation and this is confirmed by Raman study. Hence, at the end of any number of cycles the change in D/G ratio value and the deterioration in the sample are around ~2.3%. This is the limitation in our method. The expected deviation in storage capacity is within 5% about the mean value. Zhang et al. [1] observed the percentage of change in D/G ratio and it was about 3%. The whole hydrogenation and dehydrogenation experiments are stabilized and repeatable.

The achieved hydrogen storage capacity in this investigation is close to the U.S. DOE target. The same way is applied for all the types of samples and their deterioration level of the samples is estimated.

The composites such as, SWCNTs-SnO2, SWCNTs-WO3 and SWCNTs-TiO2 are prepared by both e-beam and drop casting techniques. The surface morphology of SWCNTs dispersed in SnO2 thin film prepared by e-beam technique is shown in Fig. 2 (a). The 3D AFM image reveals the inclusion of SWCNTs in SnO2 thin film, which resulted in the formation of circular cone protrusions with the SnO2 background. The SWCNTs in the composite may be aggregated due to van der Waals forces to form circular cone protrusions. It is noted from the AFM image that, the SWCNTs are arranged perpendicularly to the plane of the substrate rather than a random arrangement on SnO2 thin film surface. Similar kind of occurrence of circular cone protrusion of CNTs on SnO2 thin film background was obtained by Wisitsoraat et al. [5] and the corresponding 3D AFM image is presented in Fig. 2 (b). They pointed out the possible reason for this effect is that, the CNTs self-organized themselves while they are moving towards the substrates in line with the material evaporation trajectory, which MMSE Journal. Open Access www.mmse.xyz

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is almost perpendicular to the substrate. Similar morphologies for SWCNTs-WO3 and SWCNTs-TiO2 composites are obtained.

Fig. 1. TEM image (a) and Raman spectrum of SWCNTs (b), IR spectrum of SWCNTs functionalized BH3 (c) and Raman spectra for all the functionalized, hydrogenated and dehydrogenated samples (d).

Fig. 2. 3D AFM image of SWCNTs-SnO2 composite prepared by e-beam technique of our sample (a) and (b) 3D AFM image of CNTs-SnO2 composite prepared in e-beam technique by Wisitsoraat et al.

[5].

Fig. 3. SEM images of SnO2 (a), WO3 (b), TiO2 (c) and SWCNTs-SnO2 (d), SWCNTs-WO3 (e) and SWCNTs-TiO2 (f) composites prepared by drop casting method.

The composite, SWCNTs-SnO2 prepared by e-beam technique exhibit a hydrogen storage capacity of 2.4 wt.% [6]. SnO2 alone shows a hydrogen uptake of 0.6 wt.%. The same composite prepared by drop casting technique show a storage capacity of 1.1 wt.% at 100ºC. Hydrogen uptake of SWCNTsMMSE Journal. Open Access www.mmse.xyz

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WO3 composite prepared by e-beam technique is found to be 2.7 wt.%. Here, WO3 shows a hydrogen uptake of 0.5 wt.%. The composite, SWCNTs-WO3 prepared by drop casting method show a storage capacity of 0.9 wt.% at 100ºC [7]. The amount of hydrogen uptake by the composite, SWCNTsTiO2 prepared by e-beam technique is found to be 3.2 wt.%. TiO2 alone shows a hydrogen storage capacity of 1.4 wt.%. The same composite, made by drop casting method shows a storage capacity of 1.3 wt.% [8]. Fig. 3 presents the SEM images of SnO2 (a), WO3 (b), TiO2 (c) nanoparticles and SWCNTs-SnO2 (d), SWCNTs-WO3 (e) and SWCNTs-TiO2 (f) composites prepared by drop casting method. The results are summarized in the table 1. These results indicate that the deposition of SWCNTs with metal oxide materials (SnO2, WO3 and TiO2) is possible using e-beam technique without any significant structural decomposition of SWCNTs. The tubular nature of SWCNTs after coating is examined using Raman spectrum. The hydrogen uptake exhibited by these composite materials confirm the synergistic effect exist between CNTs and metal oxides. The hydrogen adsorption in composite samples (SWCNTs-SnO2, SWCNTs-WO3 and SWCNTs-TiO2) prepared by e-beam technique possess weak chemical binding. During the evaporation of material in hydrogen ambient, one can expect the incorporation of hydrogen in atomic form on the composite, which will then result in the strong binding of hydrogen with the composite. But, the obtained range of the binding energy belongs to weak chemical bonding on the composite samples. One of the possible reasons for this kind of adsorption is that, during the process of incorporation of hydrogen, initially the H atoms have lower coverage on the substrate (along with the composite). As the time of evaporation increases, the coverage of H atoms on the substrate also increases (i.e. the available H atoms start to incorporate on the neighboring sites on composite and this process continues upto higher coverage). This may lead to the formation of hydrogen molecules upon higher coverage. During the course of desorption, the adsorbed H2 molecules get desorbed molecularly.

Table 1. Hydrogenation and dehydrogenation parameters of different materials.

System

Preparation method

SWCNT-BH3

Drop casting

Hydrogen storage capacity (wt.%) 4.77

Desorption temp. range (°C) 90-125

SWCNT-SnO2

e-beam Drop casting

2.40 1.10

200-350 170-210

0.36-0.49 0.35-0.38

SWCNT-WO3

e-beam Drop casting

2.70 0.90

175-305 175-215

0.35-0.45 0.35-0.38

SWCNT-TiO2

e-beam Drop casting

3.20 1.30

120-215 160-205

0.31-0.38 0.34-0.37

Bind. energy range (eV) 0.28-0.31

On the other hand, the hydrogenation of composite samples (SWCNTs-SnO2, SWCNTs-WO3 and SWCNTs-TiO2) prepared by drop casting technique is attributed to the mechanism of spillover.

During hydrogenation, the metal oxide nanoparticles may dissociate the hydrogen molecule and migrate the hydrogen atoms to the nearest vacant sites on CNTs. More amount of hydrogen can occupy on the adsorption sites offered by CNTs in this way. During the course of desorption, the adsorbed hydrogen atoms were supposed to recombine into molecular hydrogen (reverse spillover) and get desorbed from the samples [9]. The average binding energy of hydrogen released from most of the samples lie in the recommended range of 0.2-0.4 eV. Thus, the attached hydrogen has weak chemical binding on the samples and importantly all the hydrogenated systems maintain their stability at room temperature. In this binding energy limits, the interaction between the host material and hydrogen molecules are primarily due to the combination of electrostatic, inductive and MMSE Journal. Open Access www.mmse.xyz

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covalent charge transfer mechanisms [10]. Nikitin et al. [11] hydrogenated the SWCNT films using atomic hydrogen. They observed the hydrogen desorption in the temperature range between 200 and 300°C and noted that the chemisorbed hydrogen (C-H) desorbs from the surface of SWCNT. Here, the desorption temperature ranges of our systems lie around the desorption temp erature range reported by Nikitin et al. [11]. Hence, one can emphasize that the stored hydrogen associated with CNTs may have the attachment on its surface.

Summary. Among the hydrogen storage materials investigated in this thesis work, SWCNTs functionalized with BH3 turn out to be a good HSM with the maximum hydrogen storage capacity and the lower desorption temperature. The binding energy of hydrogen also exists in the ideal limits.

The material exhibits excellent reproducibility and lesser deterioration level of only 2.4%. The HSM based on SWCNTs-metal oxide composites shows considerable (but not poor) performance. The preliminary investigation of hydrogen storage in SWCNTs-water soluble polymer composite shows interesting results. Hydrogen uptake of the materials investigated here are depends on the nature of interaction between materials and hydrogen, preparation method as well as the method of hydrogenation. Hence, enhanced performance towards the hydrogen adsorption and desorption of these materials can be achieved by modifying the above stated factors.

Acknowledgements. Madurai Kamaraj University is gratefully acknowledged for academic and financial support through University Stipendiary Research Fellowship (USRF) and UGC for the award of BSR fellowship.

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[3] D. Silambarasan, V. Vasu, V.J. Surya and K. Iyakutti, IEEE Trans. Nanotechnol. 11, 1047-1053 (2012).

[4] D. Silambarasan, V. Vasu, K. Iyakutti, V.J. Surya and T.R. Ravindran, Phys. E 60, 75-79 (2014).

[5] A. Wisitsoraat, C. Tuantranont and P. Singjai, J. Electroceram. 17, 45-49 (2006).

[6] D. Silambarasan, V.J. Surya, V. Vasu and K. Iyakutti, Int. J. Hydrogen Energy 38, 14654-14660 (2013).

[7] D. Silambarasan, V.J. Surya, V. Vasu and K. Iyakutti, ACS Appl. Mater. Interfaces 5, 1141911426 (2013).

[8] D. Silambarasan, V.J. Surya, K. Iyakutti and V. Vasu, Int. J. Hydrogen Energy 39, 391-397 (2014).

[9] Y. W. Li, F. H. Yang and R. T. Yang, J. Phys. Chem. C 111, 3405-3411 (2007).

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Cite the paper V. Vasu, D. Silambarasan (2017). Carbon Nanotubes as Future Energy Storage System. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.52.18.599

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Synthesis and Characterization studies of ZnFe2O4 nanoparticles 2

R.C. Sripriya1, a, Ezhil Arasi S. 1, Madhavan J. 1, Victor Antony Raj M. 1 1 – Department of Physics, Loyola College, Chennai-34, India a – vicvad2003@yahoo.co.in DOI 10.2412/mmse.81.85.882 provided by Seo4U.link

Keywords: microwave irradiation method, conventional heating method, ZnFe2O4 nanoparticles,XRD, HR- TEM, PL.

ABSTRACT. In this work, ZnFe2O4 nanoparticles were synthesized by a simple microwave irradiation method (MIM) using glycine as the fuel. For the comparative study purpose it was also prepared by conventional heating (CHM) method.

The powders were characterized by X-ray diffraction, Transmission electron microscopy and Photoluminescence spectroscopy analysis. XRD Results revealed cubic spinel unit cell structure with an average size of 7 - 21nm. High Resolution Transmission electron microscope (HR- TEM) image shows that sphere like ZnFe2O4 nanoparticles showing particle sizes in the range of 7 – 10 nm. The calculated Eg values of the samples are 2.11 eV and 1.98 eV for ZnFe2O4MIM and ZnFe2O4-CHM, respectively. Photoluminescence emission spectra were analyzed.

Introduction. Nowadays, spinel type magnetic metal oxide nanoparticles (NPs) have attracted significant attention in many areas such as ceramics, semiconductors, sensors and catalytic materials, etc. Among them, spinel ferrites with the general formula M2+ (Fe2)3+O4 have high stability, greater activity and good reusability and environmentally friendly materials for industrial and technological applications [1, 2]. Over the spinel ferrites, zinc ferrites (ZnFe2O4) have been studied for many applications such as catalysts, sensors and photo-catalysts, which belongs to the space group Fd3m.

Spinel ZnFe2O4 NPs exists unique properties such as structural, morphological, opto-electrical, magnetic and photocatalytic activities than that of their same bulk materials, due to their smaller particle size and higher surface area. In this manuscript as prepared spinel ZnFe2O4 nanostructures were investigated for structural, morphological, optical properties and characterizations have been carried out using powderXRD, HR-TEM, UV-Vis DRS and PL spectra and the obtained results are presented here.

Preparation methods of spinel ZnFe2O4 nanostructures by microwave irradiation (MIM) and conventional heating (CHM) techniques. Stoichiometric amounts of metal nitrates and glycine were dissolved separately in a beaker with 20 ml of de-ionized water and stirred for 15 minutes to obtain clear solution. The obtained clear solution was transferred into a silica crucible and it was placed in a domestic microwave-oven (850 W, 2.45 GHz) for 15 minutes. When the precursor solution reached the point of spontaneous combustion, it was vaporized and instantly became solid powders. The obtained solid powders were washed well with water and ethanol several times and dried at 80 ºC for 1 h and labeled as ZnFe2O4-MIM and then used for further characterizations. In the next separate experiment, conventional heating method (CHM), the same reaction mixture was taken in the silica crucible and treated in an air furnace at 500 °C for 2 h at a heating rate of 5°C/min and cooled at the same rate; it became solid powders. The obtained solid powders were washed well with water and ethanol several times and dried at 80 ºC for 1 hr and labeled as ZnFe2O4-CHM and then used for further characterizations.

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Results and discussion XRD analysis. The structural analysis of the samples was investigated by powder X-ray diffraction (XRD) in the range of 2θ between 20º and 80º. From the XRD patterns Fig. 1 (a, b), it can be observed that all the reflection peaks of spinel ZnFe2O4 phase matches well with the standard JCPDS card No. 22-1012 [3]. The diffraction peaks at 2θ values of 29.92, 35.28, 36.92, 42.88, 53.16, 56.72, 62.24 and 73.64 correspond to (220), (311), (222), (400), (422), (511), (440) and (533) planes, respectively which can be readily assigned to a cubic phase of spinel ZnFe2O4. It is observed that, there is no additional peak for both the samples indicates that single-phase cubic structure with Fd3m space group. The intensity of main diffraction peak at the (311) plane was considered as a measure of its degree of crystallinity. Further observation revealed that both the samples had sharp peaks indicates good crystallinity, but the diffraction peaks of the sample ZnFe2O4-MIM were slightly broadened than ZnFe2O4-CHM, due to the smaller crystallite size.

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Fig. 1. Powder XRD pattern of spinel ZnFe2O4 NPs: (a) ZnFe2O4-MIM and (b) ZnFe2O4-CHM. Transmission electron microscopy (TEM) studies. In order to confirm the morphology and particle size of the samples, high resolution transmission electron microscopy (HR-TEM) studies are carried out. Fig. 2a, c shows the HR-TEM images of spinel ZnFe2O4 sample prepared by MIM route, which confirm the formation of nanoparticles (NPs) like morphology with smaller size. The obtained particles are nearly spherical in shape with a uniform size distribution for sample ZnFe2O4-MIM. The average size diameter of single ZnFe2O4-MIM is found to be in the range of 17-20 nm. It may be due to the fact that spinel ZnFe2O4 was prepared within a short reaction time of 10 min by means of a domestic microwave oven operated at 2.45 GHz (850W). The presence of spinel ZnFe2O4 nanoparticles (NPs) like with higher grain size for the sample ZnFe2O4-CHM prepared by CHM route is shown in Fig. 2 b, d, which confirmed the formation of NPs like morphology with diameter ranges 22-25 nm in size. Moreover, the NPs prepared under MIM route were of narrower distribution than those prepared by CHM approach. It is concluded that the temperature is a key factor in the controlled synthesis of nano-sized materials. The crystalline nature of the samples was confirmed by selected area electron diffraction (SAED) pattern. The SAED pattern of the spinel ZnFe2O4-MIM and ZnFe2O4-CHM is shown in the Fig. 2a, b (insets), respectively. The SAED pattern implies that the prepared samples are good crystalline materials with higher crystalline in nature.

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0.248 nm

0.263 nm

Fig. 2. HR-TEM images of spinel ZnFe2O4 NPs: (a, c) ZnFe2O4-MIM and (b, d) ZnFe2O4-CHM, inset of Fig. 2a and 2b shows the SAED patterns of ZnFe2O4-MIM and ZnFe2O4-CHM samples, respectively.

Photoluminescence (PL) spectroscopy. Room temperature photoluminescence (PL) spectroscopy gives the information about the band gap with the relative active position of sub band gap and defect states of the metal oxide semiconductors and it is an important tool for investigating the electronic and optical properties of the semiconducting materials. Fig. 3 a, b demonstrates the room temperature PL spectra recorded at Îťex = 345 nm of ZnFe2O4 samples prepared with two different methods namely MIM and CHM, respectively. A small band is observed at 365 nm is attributed to the near band-edge (NBE) emission of spinel ZnFe2O4 [4, 5]. Both the samples show a sharp peak at 428 nm may be ascribed to the oxygen vacancies. These defects arise from the donor levels near the conduction band edge of the oxide. The maximum emission is shifted to lower energies as the particle size is increased, which might be related to the quantum confinement effect [6].

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Fig. 3. PL spectra of spinel ZnFe2O4 NPs: (a) ZnFe2O4-MIM and (b) ZnFe2O4-CHM. UV-Visible diffuse reflectance spectroscopy (DRS) analysis. The optical band gap and the electronic structures of the metal oxide semiconductor materials were determined by UV-Visible MMSE Journal. Open Access www.mmse.xyz

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absorption/reflectance/transmittance analysis. UV-Visible diffuse reflectance spectroscopy (DRS) studies play a vital role in estimating the band gap energy (Eg) of the metal oxide semiconductors.

The plots of (F (R)hʋ)2 versus hʋ for both samples are shown in Fig. 4. The optical band gap was calculated using Tauc relation. The direct band gap (Eg) value of the sample ZnFe2O4-MIM was observed to be 2.11 eV and it is decreased with increasing the higher crystallite size of the sample ZnFe2O4-CHM (1.98 eV). The observed higher Eg value of the sample ZnFe2O4-MIM is due to smaller particle size. Interestingly, the band gap energy decreased with increasing the crystallite size of the samples, which obey the quantum confinement effect. However, the band gap values of the samples was observed to be 2.11 eV and 1.98 eV for ZnFe2O4-MIM and ZnFe2O4-CHM, respectively, which are blue shifted, when compared with bulk ZnFe2O4 nanoparticles (1.9 eV). It can be attributed to the quantum confinement effect in ZnFe2O4 nanoparticles.

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Fig. 4. UV-Vis. absorption spectra of spinel ZnFe2O4 NPs: (a) ZnFe2O4-MIM and (b) ZnFe2O4CHM. Summary. Nanostructured spinel ZnFe2O4 NPs have been successfully synthesized by a facile, lowcost microwave irradiation route using glycine as the fuel. For the comparative studies, it was also prepared by conventional heating method. It was found that the structural, morphological, optical and magnetic properties are sensitively dependent on the preparation methods and temperature. Powder XRD and HR-TEM analysis showed the nanoparticle-like morphology with agglomeration, which may be due to the magnetic interaction among the particles. UV-Vis DRS and PL spectrum analysis have been used to calculate the band gap energy and defects states of the materials.

References [1] M. Sertkol, Y. Koseoglu, A. Baykal, H. Kavasa, A. C. Basaran, J. Magn. Magn. Mater. 321 (2009) 157–162. DOI /10.1016/j.jmmm.2008.08.083.

[2] M. Sertkol, Y. Koseoglu, A. Baykal, H. Kavas, A. Bozkurt, M. S. Toprak, J. Alloys Compds 486 (2009) 325–329. DOI 10.1016/j.jallcom.2009.06.128.

[3] A. Manikandan, M. Durka, S. Arul Antony, Adv. Sci. Eng. Med. 7 (2015) 33-46. DOI: 10.1166/asem.2015.1654.

[4] A. Manikandan, N. C. S. Selvam, L. John Kennedy, R. Thinesh Kumar, J. Judith Vijaya, J. Nanosci. Nanotech. 13 (2013) 2595-2603. DOI: 10.1166/jnn.2013.7357.

[5] N. C. S. Selvam, A. Manikandan, L. John Kennedy, J. Judith Vijaya, J. Colloid Int. Sci. 389 (2013) 91-98. DOI 10.1016/j.jcis.2012.09.014

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[6] A. V. Dijken, E.A. Meulenkamp, D. V. Ilbergh, A. Meijerink, J. Lumin. 90 (2000)123. DOI 10.1016/S0022-2313 (99)00599-2.

Cite the paper R. C. Sripriya, Ezhil Arasi S., Madhavan J., Victor Antony Raj M. (2017). Synthesis and Characterization studies of ZnFe2O4 nanoparticles. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.81.85.882

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Synthesis of Nd3+doped TiO2 nanoparticles and Its Optical Behaviour3 Ezhil Arasi S.1,a, Victor Antony Raj M1, Madhavan J. 1 1 – Department of Physics, Loyola College, Chennai-34, India a – jmadhavang@gmail.com DOI 10.2412/mmse.21.46.481 provided by Seo4U.link

Keywords: sol-gel method, optical studies, energy transfer.

ABSTRACT. Pure and Rare earth ion doped TiO2 nanoparticles were synthesized by Sol-gel method. The synthesized TiO2 nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, UV–Vis spectroscopy and photoluminescence emission spectra. From the UV-visible measurement, the absorption edge of Nd3+-TiO2 was shifted to a higher wavelength side with decreasing band gap. Photoluminescence emission studies reveal the energy transfer mechanism of Nd3+ doped TiO2 nanoparticles explain.

Introduction. In the recent years, remarkable progress has been achieved in synthesis and characterization of titanium dioxide (TiO2) nanostructures due to their unique physical and chemical properties leading to extensive use as sensing materials, photo catalyst, H2 storage and electrode materials [1]. Compounds doped with rare earth ions have received considerable interest in both fundamental and application studies due to their significant technological importance and are used as high performance luminescent devices, solar cells, solid-state lasers, time-resolved fluorescence labels for biological detection and other functional applications. As a host material, TiO2 is considered as a promising semiconductor with outstanding optical properties [2]. Due to wide band gaps, TiO2 is an important applicant for UV light absorption and is almost transparent for infrared (IR) and visible light. It is a known fact that when dopants are added to a semiconductor they introduce band gap states inside the band gap and these mid-states act as luminescent centers or nonradiative traps.

Because of the effective emission in the visible and near IR region, doping of TiO2 with rare earth elements has attracted much attention [3].

Synthesis of TiO2 nanoparticles. Pure and doped TiO2 samples were synthesized by a sol-gel method. 5ml of Titanium (IV) isopropoxide was added drop wise under vigorous stirring into 30ml of isopropanol. This mixture was added drop wise into 30ml of distilled water under stirring. The final pH was adjusted with an aqueous solution of ammonia. The mixture was left for 24 hours at room temperature to complete the hydrolysis. The precipitate was dried at 100˚C for 1 hour and the resultant white powder was milled. The obtained samples were centrifuged in distilled water and ethanol three times in order to remove any impurities and further calcinated at 400˚C for 3hours.

The metal ion doped TiO2 nanoparticles were synthesized using the same technique as described above. The Nd compound of Nd2O3 was used as a dopant source.

Result and Discussion: X-Ray Diffraction Study. The synthesized TiO2 nanoparticles were characterized by a X-ray Diffractometer with monochromatic CuK (=1.5406 Å) and taken over the 2 range 20 – 70 by 3

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step scanning with a step size of 0.05ď‚°. The strongest peak for the anatase (101) phase of TiO2 was used to determine the average size of the metal oxide nanocrystallites using Scherer’s equation, đ??žđ?œ†

D =đ?›˝ đ?‘?đ?‘œđ?‘ đ?œƒ where D – crystallite size; K is the constant of 0.9; Îť is the wavelength of X-Ray; β is the full width at half- maximum (FWHM) of the selected peak and θ is the Bragg’s angle of the diffraction of the peak.

Fig. 1. XRD patterns of pure and Nd3+ doped TiO2 nanoparticle.

Fig. 1 shows XRD pattern of pure and Nd3+ doped TiO2 nano particles respectively. The diffraction peaks corresponding to 2θ values are identified as (1 0 1), (1 1 2), (2 0 0), (1 0 5), (1 2 1), (2 0 4) and (1 1 6) and it matches well with the diffraction pattern of bulk anatase Titania peaks. XRD patterns are matched with the standard XRD pattern of TiO2 (JCPDS file No: 21-1272).

The peaks at 2θ correspond to the (1 0 1), (0 0 4), (2 0 0), (1 0 5), (2 1 3) and (2 1 3) planes of TiO2:Nd3+ nanoparticles. The average crystalline sizes of pure and doped TiO2 nano particles were in the range of 15 - 25 nm.

UV characterization. UV-Vis absorption Spectra was recorded by using Varian Cary 5E spectrophotometer. The UV-Vis spectral analysis was carried out between 200 nm and 800 nm.

Fig. 2. UV-Vis absorption spectrum of pure and Nd3+: TiO2 nanoparticles.

The plot between the absorption coefficient and wavelength is as shown in Fig. 2 for pure and doped TiO2 nanoparticles. The knee edge at 360 nm in the spectrum shows a shift compared to its bulk MMSE Journal. Open Access www.mmse.xyz

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counterpart which is nearly 50 nm, due to the weak quantum effect occurred during the growth process.

The absorption spectra of Nd3+. TiO2 nanoparticle reveals sharp absorption edge observed at 395nm. The presence of Neodymium had shifted the absorption edge by 35nm from the undoped TiO2.

FT-Raman analysis. Fig. 3 shows the FT-Raman spectra of pure and doped TiO2 nanoparticles synthesized via sol-gel method in the range of 100–800 cm−1. The FT-Raman spectrum was recorded using BRUKER IFS–66V spectrometer.

Fig. 3. FT-Raman spectrum of the pure and Nd3+: TiO2nanoparticles.

The Raman spectrum of the pure TiO2 shows peaks at 143.6 cm-1, 194.2 cm-1, 395.5 cm-1, 515.7 cm-1 and 638.7 cm-1, which can be assigned to the anatase phase [4]. The spectra of Nd3+:TiO2 nanocrystals are similar to that of anatase but being slightly shifted as a result of crystal structure modification via doping. The Raman spectrum of Neodymium trivalent ion doped TiO2 (Fig. 4.14) shows peaks at 144.76 cm-1, 147.76 cm-1, 398.68 cm-1, 517.93 cm-1 and 639.24 cm-1.Thus from the Raman studies we can confirm that the anatase phase was not altered by the presence of trivalent lanthanide dopants.

Photoluminescence (PL). The photoluminescence spectrum of pure TiO2 nanoparticles was recorded in the spectral range of 490-550nm. The peak positioned at 515 nm of the pure TiO2 is due to the radiative annihilation of the exciton after excitation at 330 nm.

4 The PL spectra of 4F3/2 IJ belonging to f-f transition of the trivalent Nd ion in TiO2: Nd nanoparticles are shown in Fig. For the excitation wavelength of 350nm, Two main PL peaks were found at 1095nm and 1366nm. In the prominent transitions are 4F3/2 4I11/2 and 4F3/2 4I13/2 lying at 1095 nm and 1366nm is due to the f-f transitions of Nd3+ [5, 6].

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Fig. 4.Photoluminescence spectrum of pure and Nd3+ TiO2 nanoparticles.

Summary. The successfully prepared TiO2, Nd3+ doped TiO2 samples were subjected to various optical studies. From XRD results, it is clear that synthesized pure and doped Titania nanoparticles exhibited the anatase structure. From the optical absorption spectrum, a significant spectral shift in the wavelength is observed as compared to bulk TiO2 crystal. The broadening of absorption edge is the result of absorption of nanocrystallites with distribution of anatase nanoparticles at different size regime. The presence of trivalent lanthanide ions had resulted in shifting of the absorption edge towards the visible region.

References [1] Vijay K. Tomer, Suman Jangra, Ritu Malik, Surender Duhan, Effect of in-situ loading of nano titania particles on structural ordering of mesoporous SBA-15 framework, Colloids and Surfaces A: Physicochem. Eng. Aspects 466 (2015) 160–165. DOI:10.1016/j.colsurfa.2014.11.025 [2] X.Qi et al. / Optical Materials 38 (2014) 193–197. DOI: 10.1016/j.optmat.2014.10.026 [3] A.S. Bhatti et al, Tunability of morphological properties of Nd-doped TiO2 thin films, Mater. Res. Express 3 (2016) 116410. DOI: 10.1088/2053-1591/3/11/116410 [4] Mona Saif, Abdel Mottaleb M. S. A., Titanium dioxide nanomaterial doped with trivalent lanthanide ions of Tb, Eu and Sm: Preparation, characterization and potential applications, Inorganica Chimica Acta, 360 (2007) 2863 – 2874. DOI: 10.1016/j.ica.2006.12.052 [5] Rajesh Pandiyan et al., J. Mater. Chem., 2012, 22, 22424–22432. DOI: 10.1039/c2jm34708c [6] S.Yildirim et al., Structural and luminescence properties of undoped, Nd3+ and Er3+ doped TiO2 nanoparticles synthesized by flame spray pyrolysis method, Ceramics International (2016), DOI: 10.1016/j.ceramint.2016.03.131

Cite the paper Ezhil Arasi S., Victor Antony Raj M, Madhavan J. (2017). Synthesis of Nd3+doped TiO2 nanoparticles and Its Optical Behaviour. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.21.46.481

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Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites4 T. Sakthivel1, K. Jagannathan1,a 1 – Department of Physics, SRM University, Vadapalani campus, Chennai-600026, Tamilnadu, India a – kjagan81@gmail.com DOI 10.2412/mmse.80.76.610 provided by Seo4U.link

Keywords: TiO2 nanoparticle, sol-gel synthesis, band gap tuning, photoanode.

ABSTRACT. Pure and Ni doped titanium dioxide nanoparticles were successfully synthesized by sol-gel method and characterized usingXRD, UV-Visible, FTIR, FESEM and EDS techniques. XRD pattern confirms the formation of tetragonal TiO2. The absorbance spectra of pure and Ni doped TiO2 showed absorption spectrum at ultra-violet region due to electronic transition between bonding and anti-bonding orbital (π-π•). Bandgap energy of Ni doped TiO2 decreased to 2.5 eV when compared to pure TiO2 (3.39 eV). FESEM study reveals agglomerated spherical shaped morphology. The functional groups of the prepared samples were identified using FTIR spectroscopy and the elemental analysis was further supported with EDS analysis.

Introduction. TiO2 is the promising material as semiconductor having high photochemical stability, non-toxicity, high surface area and low cost. TiO2 is used in many applications such as pigments, adsorbents, photo catalytic, sensors, Photovoltaic devices. [1-2]TiO2 exhibit three main phases namely anatase, rutile and brookite [3]. Among them anatase phase is formed at a lower temperature with a band gap of 3.0-3.2 eV, whereas for the rutile it is 3.0 eV[4]. Also, it has proven itself as one of the promising material to replace the toxic and expensive other metal oxides like CdO, SnO2, In2O3 and etc., for opto-electronic applications. Among others, TiO2 is a superior one in opto-electronic applications, especially in conducting electrodes of dye-sensitized solar cells (DSSC). But the limitation towards using metal oxides is absorption spectrum in UV region [5]. Different dopants are used in TiO2 for the absorption of visible light, such as transition metal ion doping (Fe, Co, Ni, Cu, Zn and Zr) has been found to be efficient dopants for improved photostability and bandgap tuning[6].

Experimental Procedure Preparation of TiO2 Nanoparticles.The TiO2 nanoparticles were obtained from 5 ml of titanium (IV) isopropoxide (TTIP) dissolved in 5 ml of ethanol with 20 ml of distilled water added to the above solution. The mixed solution was vigorously stirred for 1 hr in order to form a gel. The gel was dried at 75 °C for 5 hr to remove the water and organic materials. Then, the dried gel was sintered at 450°C for 2 hr in high temperature muffle furnace. Finally the pureTiO2 nanoparticles were obtained by solgel method.

Preparation of nickel doped TiO2 nano particles.The nickel doped TiO2 nano particles were obtained from titanium (IV) isopropoxide (TTIP) and iso-propanol as the starting material. 5 ml of TTIP was added drop wise to 45 ml of iso-propanol for the TiO2 formation. The solution was vigorously stirred for 45 min to form sols. 5% nickel nitrate was mixed drop by drop to the above

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solution with constant stirring for 1 hr to form the gel. After that a similar procedure explained above was followed to obtain Ni/TiO2 nano particles by sol-gel method.

Results and Discussions Structural analysis: X-ray diffraction The Fig.1 shows the XRD pattern of pure and nickel doped TiO2 nanoparticles prepared by sol gel method. The peaks in the diffraction patterns corresponds to anatase phase of TiO2 nanoparticles, the lattice parameters have been calculated and it was found to be a = b=3.7898 Å and c= 9.5148 Å. The obtained lattice parameter values are matched with previous literatures and diffraction pattern was in good agreement with JCPDS files # 21-1272 [7]. The dominant (101) peak shows that the anatase phase was formed in the synthesized materials. Intensity of diffraction peaks in Ni doped TiO2 is low and a slight broadness occurred in diffraction peaks of Ni/TiO2 nanoparticles is due to nickel content.

Fig. 1. XRD pattern of TiO2 and Ni/TiO2 nanoparticles.

The crystallite size of the pure and nickel doped TiO2 nanoparticles are found to be 10 nm. Crystallite size (D) of these samples are estimated by applying the Scherrer’s equation.

Optical studies: UV-Visible spectroscopy. The Fig. 2 (a) shows the optical absorption spectrum of TiO2 and Ni/TiO2 with an absorption maximum at 312 nm and 337 nm respectively. The absorption edges of Ni doped nanoparticles were shifted to the lower energy region (red shift) compared to pure TiO2. The Fig.2 (b) shows the estimated optical band gap energy of prepared nanoparticles using Tauc plot and band gap values are found to be 3.39 eV and 2.5 eV for pure and Ni doped TiO 2 respectively. The reduction in band gap energy of Ni/TiO2 is due to the presence of Ni metal ion which induces metastable states in pure TiO2 for band gap tuning.

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b)

a)

Fig. 2. (a) optical absorption spectra of TiO2 and Ni/TiO2 nano particles. (b) Tauc plot of TiO2 and Ni/TiO2 nano particles.

Elemental analysis: FTIR

Fig. 3. FTIR Spectrum of TiO2 and Ni/TiO2 nanoparticles.

The FTIR spectrum of Pure and nickel doped TiO2 nanoparticles are shown in Fig. 3. The broadband spectrum occurs at 510-780 cm-1 corresponds to metal oxides (TiO2 nanoparticles). It is attributed to the Ti-O bending vibration and shows the formation of metal oxide bonding in the prepared sample.

Whereas, the characteristic peaks at 1619 cm-1 and 3962 cm-1 are associated with the O-H bending vibration of the water molecules absorbed on TiO2 surfaces in pure TiO2 and Ni doped TiO2. The peaks obtained at 3360 cm-1 is due to stretching vibration of O-H groups in the prepared samples.

Morphological analysis: FESEM The morphology of synthesized material is spherical shaped nanoparticles combined with flake shaped morphology with agglomeration in pure TiO2 are shown in Fig. 4. But Ni doped TiO2 nanoparticles exhibit non-uniform distribution compared with those of pure TiO2 and this result suggest that Ni doping can suppress the TiO2 particle growth, as is shown in Fig. 4.

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a)

b)

Fig. 4. FESEM Images of pure TiO2 and Ni/TiO2 nanoparticles.

EDS Analysis. From the Fig. 5. EDS spectrum doping of Ni into TiO2 is confirmed according to the relative atomic and weight percentage of Ni. It is clear from Ni element is present in the doped TiO2 samples and Ni2+ ions are incorporated in Ti4+ lattice sites.

b)

a) Fig. 5. EDAX Spectra for pure TiO2 and Ni/TiO2 nanoparticles.

Summary. In summary TiO2 and Ni/TiO2 nanoparticles were prepared by simple sol-gel method.

The XRD analysis confirms the formation of anatase TiO2 nano particles. The doping of Ni into TiO2 lattice shifts the position of its fundamental absorption edge toward the longer wavelength and reduces its band gap energy, so that it can absorb energy from visible light photons. The existences of functional groups were identified by FTIR analysis. The FESEM analysis shows the mixed morphology of both spherical and flake like morphology with rough surfaces in the prepared samples.

Hence the prepared sample with reduced bandgap energy of Ni doped TiO2 may be useful in photoanode application of DSSC. Acknowledgement: The authors convey their gratitude to the management of SRM University for their motivation and support.

References [1] Siti Nur Fadhilah Zainudin, Masturah Markom, Huda Abdullah, structural behavior of ni-doped TiO2 Nanoparticles and Its photovoltaic performance on dye-sensitized solar Cell (DSSC), Advanced Materials Research Vol. 879 (2014) pp 199-205, doi:10.4028/www.scientific.net/AMR.879.199 [2] R. Elilarassi, G. Chandrasekaran, Synthesis, Structural and optical characterization of Ni-doped ZnO nanoparticles, J. Mater Sci: Mater Electron (2011) 22:751–756, DOI 10.1007/s10854-0100206- 8

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[3] S. Mugundan, B. Rajamannan, G. Viruthagiri, N. Shanmugam, R. Gobi, P. Praveen, Synthesis and characterization of undoped and cobalt-doped TiO2 nanoparticles via sol–gel technique, (2014) Appl Nanosci, DOI 10.1007/s13204-014-0337-y [4] R. Govindaraj, M. Senthilpandian, G.Senthilmurugan, P.Ramasamy, Sumitamukhopadhyay, Synthesis of porous titanium dioxide nanorods/nano particles and their properties for dye sensitized solar cells. J Mater Sci: Mater electron. DOI 10.1007/s10854-015-2731-y.

[5] L.A. Patil, D.N. Suryawanshi, I.G. Pathan, D.M. Patil, Nickel doped spray pyrolyzed nanostructured TiO2 thin films for LPG gas sensing, Sensors and Actuators B 176 (2013)514521, http://dx.doi.org/10.1016/j.snb.2012.08.030.

[6] Dengwei Jing, Yaojun Zhang, Liejin Guo, Study on the synthesis of Ni doped mesoporous TiO2 and its photocatalytic activity for hydrogen evolution in aqueous methanol solution, Chemical Physics Letters 415 (2005) 74–78, doi:10.1016/j.cplett.2005.08.080 [7] K. AshokKumar, J. Manonmani, J. Senthilselvan, Effect on interfacial charge transfer resistance by hybrid co-sensitization in DSSC applications, J Mater Sci: Mater Electron (2014) 25:5296–5301, DOI 10.1007/s10854-014-2304-5.

Cite the paper T. Sakthivel, K. Jagannathan (2017). Structural, Optical, Morphological and Elemental Analysis on Sol-gel Synthesis of Ni Doped TiO2 Nanocrystallites. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.80.76.610

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Structural and Photoluminescence Studies of (Cu, Al) Co-doped ZnO Nanoparticles5 P. Swapna1, S. Venkatramana Reddy1,a 1 – Department of Physics, Sri Venkateswara University, Tirupati – 517 502, A.P, India a – drsvreddy123@gmail.com DOI 10.2412/mmse.77.36.550 provided by Seo4U.link

Keywords: ZnO nano particles, emission spectra, X-ray diffraction and Elemental analysis.

ABSTRACT. Pristine and co-doped ZnO with doping of Cu and Al nano particles have been successfully synthesized by chemical co-precipitation method without using any capping agent and annealed in air ambient at 500 0 C for one hour.

Here, the Al concentration is fixed at 5 mol percent and copper concentration is increasing from 1 to 5 mol percent. The Crystallanity, structure and crystallite size of pure and co-doped ZnO nano particles are determined by X-ray diffraction (XRD) in range from 200 to 800. XRD pattern reveals that the samples possess hexagonal wurtzite structure of ZnO and the estimated particle size of pure and co-doped ZnO nano particles is 20-22nm. Morphological and compositional analysis is done by SEM and EDS. Photoluminescence studies reveals the origin of PL emission in the visible region. PL spectrum shows the blue emission peaks appeared at 435, 448 and 468 nm and green emission peak at 536 nm.

Introduction. ZnO is a promising (II- V) semi conductor with wide direct band gap (3.32 eV) and large binding energy ( 60 MeV). It have attracted a lot of attention due to its significant properties such as room temperature luminescence, good transparency and high electron mobility. Also, it has practical applications in various fields such as solar cells, light emitting diodes, gas sensors, etc.

Preferentially ZnO is in the hexagonal wurtzite structure[1-3]. Electronic structure, optical and electrical properties of the host lattice ZnO can be varied by adding of different type of metal ions such as Ca, Al, Mg, Ni and Fe[4-10]. The magnetic properties of ZnO also tuned by doping of metal ions such as Co, N, Ru and Cu[11-13]. There are different methods for the synthesis of ZnO nano particles such as solution combustion method [14], vapor phase oxidation[15], chemical vapor deposition, sol-gel[16], chemical co-precipitation method[17-19]. Among these methods chemical co-precipitation method is used for the preparation of large quantity of pure and doped ZnO nano particles because it is simple, cost effective and high yield rate. The structural, compositional and optical properties of the synthesized nano particles are presented.

Experimental Procedure. Pristine and co-doped ZnO nano particles have been synthesized using the chemicals Zinc acetate Dehydrate, Potassium Hydroxide, Alluminium Chloride (anhydrous), Copper Acetate Mono Hydrate, which are all highly pure and in analytical grade used in the experiment without any further purification. 0.2 M ZnO nano particles solution has been synthesized by dissolving Zinc acetate in de-ionized water then adding Potassium hydroxide solution drop wise with constant stirring of 10 hrs. To prepare doped ZnO nano particles, the same process is repeated by adding Alluminium chloride and Copper acetate mono hydrate solutions drop wise, keeping alluminium as constant at 5 mol percent and varying the copper concentration from 1 to 5 mol percent under continuous stirring of 10 hrs. After completion of the filtering process the precipitate is washed several times with de-ionized water to remove the un reacted chemical species. Then the product is 5

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dried in an oven at 700 C for 9 hrs. Now grind the precipitate powder with the help of agate motor until the powder become fine particles. Eventually the powders are annealed in the furnace at 5000 C for one hour. The prepared samples are carefully examined by X-ray diffraction, Scanning electron microscopy, Energy dispersive spectroscopy and photoluminescence.

Results and Discussion: Structural Analysis. Fig.1 shows the XRD pattern of pure and co-doped ZnO nanoparticles. All the peaks in the Fig. are well matched with the standard JCPDS card no 36-1451 and possess hexagonal wurtzite structure. Secondary peaks corresponding to copper or alluminium are never found.

Fig. 1. XRD patterns of (a) pure ZnO, (b)Cu-1 mol%, Al-5 mol%, (c) Cu-2 mol%, Al-5 mol%, (d) Cu-3 mol%, Al-5 mol%, co-doped ZnO nano structure.

This may be attributed to the incorporation of Al and Cu ions into the Zn lattice site rather than interstitial. Contrary to the earlier reports[20- 21], this may be attributed to the limitation of the instrument of the XRD characterization, that small amount of impurities cannot be detected. Particle sizes of pristine and (Cu, Al) doped ZnO nano powders are found to be in the range of 20-22 nm. By increasing the concentration of copper content, the particle sizes are decreases and the intensity of the peak (101) is increases. The crystallite size of nano particles can be calculated using the Debye Scherer formula D=0.91λ /βcosθ , where D is the crystallite size, λ is the wavelength of x-rays and θ is the Bragg’s angle of diffraction. The particle sizes calculated from the formula are decreasing by the increasing of copper doping concentration.

Morphological and compositional analysis. The SEM images of all the samples as shown in Fig. 2, the particles are in regular non uniform, semi spherical shape though agglomeration of primary particles. With the increasing of copper doping concentration, the agglomeration of the particles is reduces. EDAX analysis indicate the successful dopant incorporation of alluminium and copper, which is with the coincidence of XRD result. EDS spectra of pure and doped samples are shown in Fig.3 Elemental analysis shows that all the elements are in stoichometric. Pure ZnO contains only zinc and oxygen elements, where as the co doped samples contains zinc, oxygen, alluminium and copper in the appropriate ratios.

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Fig. 2. SEM images of (a) pure ZnO, (b)Cu-1 mol%, Al-5 mol%, (c) Cu-2 mol%, Al-5 mol%, (d) Cu-3 mol%, Al-5 mol% co-doped ZnO nano structures.

Fig. 3. EDS spectra of (a) pure ZnO, (b)Cu-1 mol%, Al-5 mol%, (c) Cu-2 mol%, Al-5 mol%, (d) Cu-3 mol%, Al-5 mol% co-doped ZnO nano structures.

Photoluminescence Studies. The photoluminescence Excitation spectra and Emission spectra of the pure and co-doped ZnO nano particles recorded at room temperature with excitation wave length of 305 nm and measured at monitoring wavelength 467 nm are shown in Fig.4 and Fig. 5. In the emission spectra blue emission peaks appeared at 435 nm, 448 nm, 468 nm and 473 nm, the peak appeared at 492 nm corresponds to blue-green emission, the green emission band appeared from 527-550 nm centered at 536 nm and the band appeared from 583 nm to 624 nm centered at 608 nm, which corresponds to yellow, orange and red emission regions. The peaks appeared in the visible region may be attributed to the origin of defects such as oxygen vacancies and intrinsic defects in ZnO nano materials [22].Copper is a prominent luminescent activator of visible luminescence by constructing the localized states in the band gap of ZnO. The energy interval from zinc interstitial to zinc vacancy is of the order of 473 nm which corresponds to blue emission, also the prominent transitions observed at 468 nm, 448 nm corresponds to blue emission [1]. The green emission observed at 536 nm may be ascribed to the impurity levels corresponds to the singly ionized oxygen vacancy in ZnO nano

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particles [22, 23]. The green emission observed in the spectra confirmed the substitution of Cu in to the ZnO host lattice [23].

Fig. 4. RTPL Excitation and Emission Spectra of a) pure ZnO, (b)Cu-1 mol%, Al-5 mol%, (c) Cu-2 mol%, Al-5 mol%, (d) Cu-3 mol%, Al-5 mol% co-doped ZnO nano structures.

Fig. 5. RTPL Excitation and Emission Spectra of a) pure ZnO, (b)Cu-1 mol%, Al-5 mol%, (c) Cu-2 mol%, Al-5 mol%, (d) Cu-3 mol%, Al-5 mol% co-doped ZnO nano structures.

Summary. Pure and co-doped ZnO nanoparticles have been synthesized at room temperature with out using any capping agent. XRD pattern reveals that all the samples possess hexagonal wurtzite structure with out any secondary phases.SEM images shows the agglomeration of the particles, and EDS data indicate the incorporation of dopant elements Al, Cu into the ZnO nanoparticles. PL studies shows the defect related peaks in the visible region.

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References [1] Mohua Chakraborty Preetilata Mahapatra, R. Thangavel, Thin Solid Filims, 2016 [2] C. X. Xu, X. W. Sun, X H Zhang, L Ke and S J Chua Nanotechnology, IOP Publishing Ltd, 2004 [3] Tamil Many K. Thandavan, Siti Meriam Abdul Gani, Chiow San Wong and Roslan Md. Nor, PLoS One v.10 (3); 2015, doi: 10.1371/journal.pone.0121756.

[4] X. Qu, S. LĂź, D. Jia, S. Zhou, Q. Meng Mater. Sci. Semicond. Process., 2013.

[5] V. Devi, M. Kumar, D.K. Shukla, R.J. Choudhary, D.M. Phase, R. Kumar, B.C. Joshi Superlattice.

Microst., 2015 [6] B. Santoshkumar, S. Kalyanaraman, R. Vettumperumal, R. Thangavel, I.V. Kityk, S. Velumani, J. Alloys Compd., 2015 [7] R. Thangavel, M.T.Yaseen, Y.C.Chang, C.Hsu, K.Yeh, M.K.Wu, J.Phys. Chem. Solids, 2013 [8] P. Kumar, H.K. Malik, A. Ghosh, R. Thangavel, K. Asokan, Appl. Phys. Lett., 2013 [9] R. Thangavel, Y.-C. Chang, Thin Solid Films, 2012 [10] D. Karmakar, S.K. Mandal, R.M. Kadam, P.L. Paulose, A.K. Rajarajan, T.K. Nath, A.K. Das, I. Dasgupta, G.P. Das, Phys. Rev. B, 2007 [11] S. Kumar, C.L. Chen, C.L. Dong, Y.K. Ho, J.F. Lee, T.S. Chan, R. Thangavel, T.K. Chen, B.H. Mok, S.M. Rao, M.K. Wu, J. Mater. Sci., 2012 [12] S. Kumar, P. Kaur, C.L. Chen, R. Thangavel, C.L. Dong, Y.K. Ho, J.F. Lee, T.S. Chan, T.K. Chen, B.H. Mok, S.M. Rao, M.K. Wu, J. Alloys Compd., 2014 [13] H.L. Liu, J.H. Yang, Y.J. Zhang, Y.X. Wang, M.B. Wei, D.D. Wang, L.Y. Zhao, J.H. Lang, M. Gao, J. Mater. Sci. Mater. Electron., 2009 [14] C. Karunakaran, V. Rajeswari, P. Gomathisankar, Superlattices Microstruct. 2011 [15] J. Q. Hu, Q. Li, N.B. Wong, C. S. Lee, S.T. Lee, Chem. Mater. 2002 [16] J. Yang, L. Feia, H. Liua, Y. Liu, M. Gaoa, Y. Zha nga, L. Yanga, J. Alloys Compd. 2011 [17] B. Sankara Reddy, S. Venkatramana Reddy, P. Venkateswara Reddy, N. Koteeswara Reddy, Optoelectron. Adv. Mat. 2012 [18] R. Chauhan, A. Kumar, R. P. Chaudhary, Arch. Appl. Sci. Res. 2010 [19] Q. Pan, K. Huang, S. Ni, F. Yang, S. Lin, D. He, J. Phys Appl. Phys. 2007 [20] Napaporn Thaweesaenga, Sineenart Supankitb, Wicharn Techidheeraa and Wisanu Pecharapa, Energy Procedia, 2013 [21]R.Elilarassi, G.Chandrasekaran, J Mater sci:Mater Electron, springer science+Business media, 2010, DOI 10.1007/s10854-009-0041-y.

Cite the paper P. Swapna, S. Venkatramana Reddy (2017). Structural and Photoluminescence Studies of (Cu, Al) Co-doped ZnO Nanoparticles. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.77.36.550

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Synthesis of Pure Hydroxyapatite (Ca10 (PO4)6 (OH)2 ) by the Sol –Gel Method and the Doxycycline Loaded in Presence of Gelatin for the Application of Drug Delivery6 B. Shalini1, A. Ruban Kumar1, A. Mary Saral1 1 – School of Advanced sciences, VIT University, Vellore 632014, India a – arubankumarvit@gmail.com DOI 10.2412/mmse.89.93.112 provided by Seo4U.link

Keywords: hydroxyapatite, sol gel process, PXRD, FT-IR, SEM, drug loading and releasing.

ABSTRACT. Hydroxyapatite (HAp) is the most widely accepted biomaterial for the repair and reconstruction of bone tissue defects. The current study is based on HAp was synthesized using sol - gel method. The drug was loaded in presence of gelatin with pure HAp. Precursors like calcium nitrate tetrahydrate and diammonium hydrogen orthophosphate were used and ammonia solution was added to maintain the pH value at 10.5 throughout the reaction. The synthesized HAp and drug loaded HAp with gelatin were characterized using PXRD, FTIR, SEM, Drug loading, drug release studies.

Results show that the average crystallite size for prepared HAp and drug loaded HAp with polymer are ~ 30 to 300 nm respectively was calculated using PXRD and morphology of pure HAp and drug loaded HAp with polymer was found using SEM. Drug loading and release percentage was calculated. Keeping the above points in the present study was aimed to produce the biocompatibility and bioactivity of HAp.

Introduction. Hydroxyapatite (HAp) has been extensively investigated and used in bone clinical application for more than four decades. The increasing interest in HAp is due to its similar chemical composition to that of inorganic component of natural bone [1-2]. Doxycycline is most widely used for bacterial bone infections which are most frequently found in infected bone or a patient with osteomyelities. The present study describes the synthesis and characterization of DOX loaded hydroxyapatite nanoparticles in presence of gelatin intended to be used as drug delivery system. The associations of doxycycline with hydroxyapatite nanoparticles and the nature of interfacial process occurring as a result of coupling between doxycycline molecule and hydroxyapatite surface and the orientation of the DOX on the hydroxyapatite surface are also investigated[3]. The hydroxyapatite/gelatin combined is an ideal vehicle for the delivery of cells, proteins and drugs in the treatment of defective tissues and their regeneration. This kind of composite drug delivery system can release therapeutic molecules in situ to produce an action associated with the osteoconduction. It is used in the prevention and treatment of bone infections [4-5].

Materials and Methods: Materials Preparation. Hydroxyapatite is prepared by using sol-gel process. Calcium nitrate tetrahydrate and diammonium hydrogen orthophosphate were used as a precursor, for pure hydroxyapatite. The molar concentration of calcium nitrate tetrahydrate and diammonium hydrogen orthophosphate is adjusted to have a theoretical value of Ca/P ratio 1:67. The precipitation process is carried out by drop wise addition of diammonium hydrogen orthophosphate into calcium nitrate solution. The process is carried out under continuous stirring at 70°C for 4 hours and an ammonium hydroxide solution was used to adjust pH of 10.5. The white precipitate is formed and washed with

6

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7-8 times with double distilled water and finally with ethanol and dried in a hot air oven till it gets dry.

10Ca (NO3)2.4H2O +6 (NH4)2HPO4 +8NH4OH

Ca10 (OH) 2 (PO4)6 +20NH4NO3+46H2O (1)

Drug loading. In order to load drug on hydroxyapatite, doxycycline powder was dissolved in double distilled water. The concentration of DOX is kept constant (10mg/ml). HAp particles were added to the drug solutions at different ratios (1:1, 1:2, 1:4, 2:1, 4:1) and stirred using magnetically stirred for 60 min at 50°C. Then the solution was left undisturbed overnight. The suspension was then centrifuged (2500 rpm for 15 min) and the supernatant and precipitate were separated. The amount of drug loaded in HAp was determined by finding the difference in DOX concentration in the aqueous solution before and after loading. The percentage of drug loading is calculated using,

% of drug loading =

đ??´âˆ’đ??ľ đ??´

đ?‘‹ 100

(2)

where A is initial concentration, B is final concentration The maximum loading was found to be 87.41 % for 4:1 ratio.

Doxycycline loaded HAp with gelatin. Aqueous solution of 10% gelatin content was prepared using double distilled water at 37°C. After that the gelatin was dispersed in 200ml of vegetable oil in a beaker in order to produce emulsion. Then the DOX loaded HAp with gelatin in a beaker is made of continuous stirring at 200 rpm and repeat the same procedure as the above, then the amount of drug loading can be calculated using the above equation (2). The maximum loading was found to be 70.34%.

Results and discussion Powder X-ray diffraction (PXRD). PXRD pattern indicates that all the synthesized samples are composed of pure apatite phase. The sharp peaks confirm they were highly crystalline. Fig. 1 shows that the intensity of diffracted X-rays as a function of 2θ. The presence of characteristic HAp peaks is represented in the Fig. 1 confirms the hexagonal structure of HAp. PXRD spectrum of pure HAp (a), DOX loaded HAp (b), DOX loaded HAp with gelatin (c) has shown peaks characteristics of pure HAp and confirmed with JCPDS [3]. A comparison between powder X-ray diffraction patterns of a, b and c did not show any major differences in the diffraction patterns even after loading doxycycline is shown in Fig. The average crystallite size was determined using Scherer formula around 40 nm, 100 and 300 nm.

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Fig. 1. PXRD: a) Pure Hydroxyapatite b) DOX loaded hydroxyapatite c) DOX loaded HAp with gelatin.

Fourier transform of infrared analysis of doxycycline loaded HAp with gelatin. The spectra were recorded over the range of 500 - 4000cm-1. The FTIR spectrum of pure HAp, doxycycline loaded with HAp, drug loaded HAp with gelatin is shown in Fig. 2 and the characteristic absorption peaks are shown in table 1. The drug loaded HAp showed peaks similar to pure HAp hence it confirmed that the drugs exist along with HAp [6].

Fig. 2. FTIR: a) Pure Hap, b) DOX loaded hydroxyapatite, c) DOX loaded HAp with gelatin, d) after release.

Drug release percentage. The release profiles of doxycycline from DOX loaded with pure HAp, DOX loaded HAp with gelatin is shown in the Fig. 3. It is clear that DOX loaded with pure HAp shows initial burst release within 24 hours maximum of 45-50% of drug were released and most of the remaining drug was released during 150 hours with a slightly lower rate [8]. The fast release of DOX is due to the fact that the physical interaction between doxycycline and HAp is not that much stronger. The doxycycline release from HAp with gelatin shows that a maximum of 20% release during 24 hours and the remaining percentage of release was released during 150 hours and with these

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two combinations the release rate of the drug is significantly slowed down hence it attains sustained release.

Table 1. IR characteristic absorption.

S.No

Peak position (cm-1)

Assignment

1

Around 3200

Absorbed peak of water (bending vibration of O-H (strong)

2

3414, 3535, 3484

N-H stretching

3

1633.71, 1629.95, 1664, 1633.71

N-H Bending

3

1737, 1726, 1753.2

C =O Stretching

4

1400-1600

C=C Stretching

4

1411, 19, 42

-C-H Bending vibration

5

1325, 11, 30, 69

-C-H bending vibration

6

1024, 1089, 1039, 1016, 962

ϒ3 Vibration mode of phosphate group ϒ1 vibration mode of phosphate group

7

ϒ4 bending mode of phosphate group

630, 601, 599, 563

Fig. 3. Drug release: a) DOX loaded hydroxyapatite b) DOX loaded HAp with gelatin.

Scanning Electron Microscope. Fig. 3 a) shows the morphology of synthesised HAp and shows rod like morphology. b) shows that the drug loaded HAp shows some morphological changes when compared to that of pure HAp. It is found that drug loaded HAp particles are aggregated into large clusters and also formed of separate units gathered into a whole which consists of aggregated beads of approximately 100nm to 300nm. Fig. 3c shows that the drug loaded HAp with gelatin shows that the drug loaded HAp is coated with gelatin [7] hence the pores are filled with drug particles.

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Fig. 4. SEM: a) Pure hydroxyapatite, b) DOX loaded hydroxyapatite, c) DOX loaded HAp with gelatin.

Summary. HAp synthesized by sol-gel method and the synthesized HAp, drug loaded HAp, drug loaded HAp with gelatin were characterized using PXRD, FTIR, SEM, Drug loading, drug releasing.

Results show that the prepared HAp and drug loaded HAp with polymer are ~ 30 to 300 nm respectively and morphology of pure HAp and drug loaded HAp with polymer was found using SEM. Drug loading and release % were calculated as 87.41 %, 75.73% and 76.22%, 44.23% respectively and in-vitro drug release of doxycycline from these methods has done for the period of 150 hours.

The release percentage shows slow and sustained for these days.

Acknowledgement. The authors are very much grateful to the VIT University for providing support and excellent research facilities.

References [1] Zhou, H., & Lee, J. (2011). Nanoscale hydroxyapatite particles for bone tissue ngineering. Acta biomaterialia, 7 (7), 2769-2781. 10.1016/j.actbio.2011.03.019 [2] Agrawal, K., Singh, G., Puri, D., & Prakash, S. (2011).Synthesis and characterization of hydroxyapatite powder by sol-gel method for biomedical application. Journal of Minerals and Materials Characterization and Engineering, 10 (08), 727. 10.4236/jmmce.2011.108057 [3] Venkatasubbu, G. D., Ramasamy, S., Ramakrishnan, V., & Kumar, J. (2011). Hydroxyapatitealginate nanocomposite as drug delivery matrix for sustained release of ciprofloxacin. Journal of biomedical nanotechnology, 7 (6), 759-767. 10.1166/jbn.2011.1350 [4] Ragel, C. V., & Vallet–Regí, M. (2000). In vitro bioactivity and gentamicin release from glass– polymer–antibiotic composites. Journal of biomedical materials research, 51 (3), 424-429.

10.1002/1097-4636 (20000905)51:3, 424: AID-JBM17>3.0.CO;2-E [5] Varde, N. K., & Pack, D. W. (2004). Microspheres for controlled release drug delivery. Expert Opinion on Biological Therapy, 4 (1), 35-51. 10.1517/14712598.4.1.35 [6] Kumar, N. A., & Kumar, S. K. (2009). Hydroxyapatite ciprofloxacin mini pellets for one-implant delivery: preparation, characterization, in-vitro drug adsorption and dissolution studies. International Journal of Drug Development and Research.

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[7] Padmanabhan, V. P., Kulandaivelu, R., Vadivel, S., & Rasumani, S. Synthesis of HydroxyapatiteNanorods with the Effect of Non-Ionic Surfactant as a Drug Carrier for the Treatment of Bone Infections. ISSN (Online) 2347-3207 [8] Raj, M. S., Arkin, V. H., & Jagannath, M. (2013). Nanocomposites based on polymer and hydroxyapatite for drug delivery application. Indian Journal of Science and Technology, 6 (5S), 46534658.

Cite the paper B. Shalini, A. Ruban Kumar, A. Mary Saral (2017). Synthesis of Pure Hydroxyapatite (Ca10 (PO4)6 (OH)2 ) by the Sol –Gel Method and the Doxycycline Loaded in Presence of Gelatin for the Application of Drug Delivery. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.89.93.112

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Low Temperature Ferromagnetism and Optical Properties of Fe Doped ZnO Nanoparticles Synthesized by Sol-Gel Method7 B. Sathya1, V. Porkalai1, D. Benny Anburaj1,a, G. Nedunchezhian1 1 – PG and Research Department of Physics, Thiru.Vi. Ka. Government Arts College, Thiruvarur, Tamil Nadu, India a – bennyanburaj@gmail.com DOI 10.2412/mmse.64.30.685 provided by Seo4U.link

Keywords: nanoparticles, zinc oxide, SEM, optical properties, photoluminescence.

ABSTRACT. In this present investigation, pure and Fe doped Zinc oxide nanoparticles were successfully synthesized by sol gel method.The structural and optical properties were examined by using X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), Ultraviolet spectroscopy and Photoluminescence (PL) techniques.The structural characterization of XRD analysis confirmed the phase purity of the samples and crystallite size can be decreased with increasing doping concentrations.SEM image show that nanoparticles in spherical shape.The optical band gap calculated through UV-visible spectroscopy is found to be increasing from 3.48 to 3.57eV. TEM analysis depicted the crystallinity of nanoparticles prepared and chemical composition conformed the EDAX analysis. The PL spectra reveal that, Fe doped ZnO exhibit a decrease in intensity of the band edge emission peak while the intensity of the deep level emission peak increases.The enhancement of low temperature ferromagnetism in ZnO: Fe was achieved.

Introduction. Recently, the diluted magnetic semiconductors (DMSs) have attracted much attention because new functions can be added and the functions can be tuned in these materials by transporting and controlling various types of spin states [1]. Zinc Oxide is one of the most important II-VI group elements with wide band gap (3.37eV) and large exciton binding energy (60 meV) at room temperature. It is a low cost and environmental friendly n-type semiconductor [2]. The undoped ZnO nanoparticles have only diamagnetic nature. Transition metal doping of ZnO has become an active research field ever since it was predicted to improve the optical and electronic properties of the oxide materials and particularly, leads to room temperature ferromagnetism [3]. By suitably adding transition metals such as Fe, Ag, Co, Cr and Al are an important class of semiconductor, one can tailor its physical, chemical and magnetic properties. The particles are transparent to visible light but they absorb UV light. ZnO has properties and versatile applications in transparent electronics, electrical and optical switching devices, chemicals gas sesors, laser diodes, solar cells, electrostatic dissipative coatings, varistors, luminescencesand spin based devices [4]. Fe doped ZnO nanoparticles have been prepared by the various method like, sol-gel method [5], co- precipitation method [6], solid state reaction method [7].

Experimental Method.The host precursor zinc acetate dihydrate (Zn (CH3COO)2.2H2O) was dissolved in deionized water to obtain an aqueous solution, which was used as the starting solution (0.2 M). Ferricnitrides (FeNO3) were used dopant precursors for 1%, 3%, 5%, 7% respectively. The pH value of the starting solution was maintained at 9 by adding the required amount of NH 4OH solution. After, Tri-ethanolamine (C6H15NO3) is added as surfactant to control size and morphology of nanoparticles.The resultant mixture was heated to 700C and magnetically stirred for 2hrs. After completing the stirring process the precipitate was separated carefully by filtration and washed several 7

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times with a mixture of ethanol and water kept in the ratio of 1:3. The final product was irradiated with microwave oven for 30 min. Finally the powder calcinated at 500 0C for 2hrs.

Result and Discussion Structural Studies. Fig.1 shows that doped ZnO nanoparticles have a polycrystalline structure with three orientations along (100), (002) and (101) diffraction planes.These patterns have been compared with standard JCPDS 89-0510.

Fig. 1. XRD patterns of Fe doped ZnO nanoparticles.

It shows a decrease in crystallite size from 14nm to 11nm as the doping concentration increases.

However, the crystallite size shows a decreasing trend, which consequently increased the dislocation density. The crystallite sizes of the synthesized powders are estimated from X-ray lines broadening using Scherer’s equation [8, 9], D= 0.9λ ∕ βcosθ where β is full width at half maximum (FWHM), θ is diffraction angle and λ is wavelength of X-rays.

Morphological Studies. Fig. 2 shows the SEM micrograph exhibiting the morphology of assynthesized by ZnO nanoparticles. The surface contains spherical structure without any isolated grains or larger agglomerates with nano crystallites revealing the polycrystalline nature as observed from the XRD result [10].

The typical EDAXspectrum of Fe doped ZnOwith 1%, 3%, 5%, 7% Fe elemental compositional and calcined at 500oC is shown in Fig. 2.

TEM studies

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Table 1. Values of crystallite size and dislocation density from XRD of ZnO samples.

Sample

Crystallite size (nm)

Dislocation density -3 -2 (δX10 ) (nm)

Pure ZnO

14.47

4.77

1%

13.54

5.45

3%

12.06

6.87

5%

11.44

7.64

7%

11.04

8.20

Fig. 2. SEM and EDAX image of Fedoped ZnO nanoparticles.

Fig. 3. TEM and SAED image of Pure and Fe doped ZnO nanoparticles.

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Fig. 3 shows the plane-view TEM images of ZnO nanoparticles. There are no aggregates or secondary phases at the inter grain boundaries.The grain size reduction observed is in good agreement with the morphological and structural results revealed by the SEM and XRD studiesand the selected area electron diffraction (SAED) patterns for the ZnOsnanoparticles.The other rings assinged to (002), (100) are also confirming the formation of monophase ZnO nanoparticles with hexagonal structure.

UV-Studies. Fig. 4 shows the optical absorption spectra of as prepared Fe doped ZnO nanoparticles in the visible range. It can be seen that when the doping concentration is increased and band gap can be increased.

Fig. 4. UV-vis spectrum and Tauo plot of Fe doped ZnO nanoparticles Fig. 5 shows the optical band gap of the Fe doped ZnO nanoparticles estimated by extrapolation of the linear portion of (Tauc's plot) using the relation a αhν = A (hν-Eg)n, where α is the absorption coefficient, hν the photon energy and Eg is the optical band gap .

The optical bandgap values of as prepared by nanoparticles have been given in table.2 Table2.Optical band gap of Fe doped ZnO Nanoparticles Sample

Band gap (eV)

Pure ZnO

3.48

1%

3.51

3%

3.52

5%

3.55

7%

3.57

PL Studies. Fig.5 shows the room temperature photoluminescence (PL) spectra ofZnO nanoparticles.

In the room temperature PL spectra of Fe doped ZnO, a dominant peak at about 389 and 390 nmhas been observed. The peak in the UVregion corresponds to the near band edge emission (NBE), because this peak is located close to theband gap energy (~3.3 eV), of ZnO material/crystals at room temperature.

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Fig. 5. PL spectra of Fe doped ZnO nanoparticles The origin of the peak around 415 nm could be ascribed due to the transition occurring from Zn interstitials to the valance band [11].

Summary.Fe doped ZnO nanoparticles were prepared by sol-gel techniques. Structural analysis indicates that the Fe doped ZnO nanoparticles crystallized in hexagonal wurtzite structure and the crystallite size decreases as the doping concentration is increased. From the optical band gap of the ZnO:Fe shows an increase with the doping level increases. The transmittance range of Fe doped Zinc oxide nanoparticles in the visible range is about 85%.PL spectra shows that the emission range in 389-391nm.SEM and TEM images indicate that the nanoparticles have spherical shapes of ZnO nanostructures.

References [1] B. Sankara Reddy, S. Venkatramana Reddy, Room Temperature ferromagnetism of co-doped (Al, Ag) ZnO nanostructures, nanoscience nanotechnology; An International Journal, 3 (3), 2013, 4955.

[2] K. Ravichandran, A. Anbazhagan, M. Beneto, N. Dineshbabu, C. Ravidhas, Enhancement of the Hackee’s quality factor of sol-gel spin coated ZnO thin films by Mo doping, Materials science in semiconductor processing 41, 2016, 150-154.

[3] J. El Ghoul, M. Kraini, O.M. Lemine, sol-gel synthesis structural, optical and magnetic properties of Co-doped ZnO nanoparticles, J.MaterSci:Mater Electron 26, 2015, 2614-2621.

[4] S.B. Rana, P. Singh, A.K. Sharma, A.W. Carbonari, R. Dogra, Synthesis and characterization of pure and doped ZnO nanoparticles, J. optoelectronics and advanced materials 12, 2010, 257-261.

[5] I.Kazeminezhad, S. Saadatmand, RaminYousefi, Effect of transition metal elements on the structural and optical properties of ZnO nanoparticles, Bull.Mater. Sci. 39, 2016, 719-724.

[6] B. Sankara Reddy, S. Venkatramana Reddy, N. Kotesswara Reddy, J. PramodaKumari, Synthesis, structural, Optical properties and antibacterial activity of Co-doped (Ag, Co) ZnO nanoparticles, Res. J. Mater. Sci. 1, 2013, 11-20.

[7] I.Kartharinalpunithavathy, J. Prince Richard, S. JohnsonJeyakumar, M. Jothibas, P. Praveen, Photodegradation of methylviolet dye using ZnOnanorods, J. Mater. Sci:Mater.Electron, Doi.10.1007/s 10854-016-5823-4, 2016, 1-8.

[8] K. Ravichandran, K. Saravanakumar, R. Chandramohan, V. Nandhakumar, Influence of simultaneous doping of Cd and F on certain physical properties of ZnOnanopowderssynthesized via a simple soft chemical route, Appl. Surf. Sci.261, 2012, 405-410.

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[9] G. Nedunchezhian, D. Benny Anburaj, B.Gokulakumar, S.JohnsonJeyakumar, Microwave assisted study on biomaterial nano hydroxyapatite crystal (Helix pomatia) in simulated bodyfluid, Inter.J. Recent scientific Res. 6, 2015, 7793-7797 [10] V.Porkalai, D. BennyAnburaj, B. Sathya, G. Nedunchezhian, Effect of calcinations on the structure and morphological properties of Ag and In co-doped ZnO nanoparticles, J.Mater.Sci: Mater.Electron, Doi 10.1007/s 10854-016-5826-1, 2016, 1-8.

[11] B. Sathya, D. BennyAnburaj, V. Porkalai, G.Nedunchezhian, Ramanscattering and photoluminescence properties of Ag doped ZnO nanoparticles synthesized by sol-gel method, J.Mater.Sci:Mater. Electron. Doi 10.1007/s 10854-016-6278-3, (2017).

Cite the paper B. Sathya, V. Porkalai, D. Benny Anburaj, G. Nedunchezhian (2017). Low Temperature Ferromagnetism and Optical Properties of Fe Doped ZnO Nanoparticles Synthesized by Sol-Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.64.30.685

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Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method8 D.V. Sridevi1, V. Ramesh2,a, T. Sakthivel2, K.Geetha1, V. Ratchagar2, K. Jagannathan2, K. Rajarajan3, K. Ramachadran2 1 – Department of Chemistry, SRM University, Vadapalani, Chennai, 6000026, Tamilnadu, India 2 – Department of Physics, SRM University, Vadapalani, Chennai, 6000026, Tamilnadu, India 3 – Department of Physics, Rajeswari Vedachalam Governmen Arts College, Chengalpet - 603001, Tamilnadu, India a – ramesh.v@vdp.srmuniv.ac.in DOI 10.2412/mmse.99.9.726 provided by Seo4U.link

Keywords: nanoparticles, PXRD, sol-gel method, UV-Vis studies, FT-IR, FE-SEM, EDAX.

ABSTRACT. A TiO2 nanoparticle doped with cobalt was synthesized by sol-gel technique employed at room temperature with appropriate reactants. In the present case, we used titanium tetra isoprotoxide (TTIP) and 2–propanol as a common starting material and the obtained products were calcined at 450 ˚ C. From the Powder XRD data the particle size was calculated by Scherrer method. The FE-SEM analysis shows the morphology of cobalt doped TiO 2 nanoparticles. The various functional groups of the samples were identified by Fourier transform spectroscopy (FT-IR). The UV-Vis-NIR spectra of cobalt doped TiO2 material shows two absorption peaks in the visible region related to d-d transitions of Co2+ in TiO2 lattice. Compared to un-doped TiO2 nanoparticles, the cobalt doped material show a red shift in the band gap.

1. Introduction. Titanium dioxide or titania (TiO2) is the potential material as semiconductor having high photochemical stability, moderate thermal stability and low cost. Well – disband TiO2 nanoparticle with very tiny (nm) sizes are hopeful many applications such as pigments, catalytic and adsornents. The Cobalt doped TiO2 nanocrystals have consumed great attention due to its enhanced photocatalystic activity [1]. Earlier researchers noticed the photocatalytic splitting of water on a TiO2 electrode under ultraviolet light, many synthesis methods for preparing TiO2 nanoparticles and their applications in the environmental and energy fields mainly hydrogen storage, water splitting and photovoltaics have been investigated [2]. In recent days, the fine nanoparticles of TiO2 have attracted a great deal of attention, because of their unique properties as a superior semiconducting material, such as luminous material, solar cell and photocatalyst for photolysis of water and organic compounds and for bactericidal action [3]. In the present paper, the Co-doped TiO2 nanoparticles have consumed great interest due to its superior photocatalytic activity. In this paper, we report the preparation of Co doped TiO2 nanoparticles by a sol-gel mode.

2. Experimental procedure 2.1. Preparation of cobalt-doped TiO2. All the starting materials were of analytical reagent, 90 ml of 2 – propanol was taken as primary precursor and 10 ml titanium (IV) isopropoxide (TTIP) was added into drop wise with vigorouly stirred for an hr in order to form solutions. Aqueous solution of cobalt nitrate of desired concentration (5%) was poured slowly drop by drop to that mixture with continued stirring. After aging a day, the solvents were transformed into gel form. The collected gel were dried at 85˚C for 24 hr to remove the water and other organic compounds. After that, the dried 8

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gel was sintered at 450˚C for 8 hr in high temperature programmable furnace. Finally, the Co-doped TiO2 nanoparticle were obtained.

3. RESULTS AND DISCUSSION 3.1. Powder X-Ray diffraction studies (PXRD). X-ray diffraction pattern of pure tio2 and co-doped TiO2 were carried out by powder x-ray diffractometer (bruker-d8 advance) using Cu-kα1 radiation.

Fig.1 shows pure and co-doped TiO2 nanocrystals (ncys) calcined at 450˚c for 8 hr. From the (powder x-ray) diffraction patterns shows pure and co-doped TiO2 are in anatase phase . From the XRD patterns shows in the present study are indistinguishable with earlier report [4]. For pure and co doped TiO2 Ncrys, the diffraction peaks occurring at 25.42˚, 38.28˚, 48.32˚, 53.90˚, 54.84˚, 63.60˚, 68.96˚ and 70.30˚ have been assigned to the lattice planes (101), (004), (200), (105), (211), (204), (116), (220) and (215) respectively. These lattice planes are attributed to the signals of pure tetragonal anatase phase of TiO2with a space group i41/ and (jcpds file no. 78-2486). From the XRD data, the avaerage Ncys size was calculted by debye- scherrer formula: d = kλ/βcosθ, where d is the crystalline size, k isthe shape factor, λ is the wavelength in nm, β is the full width at half maximum, θ is the reflection angle and the results were presented in table.1

Fig. 1. PXRD pattern of Pure TiO2 and Co-doped TiO2.

Table.1. Crystalline size for the pure and Co-doped TiO2 Samples

Crystalline Size (nm)

Pure TiO2

16.21

5% Co-doped TiO2

20.589

3.2. FT-IR studies. Fig.2 shows the FT-IR spectrum of pure and co-doped TiO2 ncys calcined at 450˚c for 8 hr. From the spectrum there are two prominent peaks present between 400 and 600 cm-1 [5]. The presence of band at 2854 cm-1 was due to the C-H bond of the organic compound [6]. There are two prominent absorption bands present at 3421 and 1645 cm-1 in the materials can be recognized MMSE Journal. Open Access www.mmse.xyz

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as the stretching and bending vibrations of h2o molecules. From the Fig. 2 shows the intensity of two bands in Co is weakened compared with pure TiO2. The peaks in between 2915 and 2869 cm-1 are assigned to C-H stretching vibrations of alkenes groups. A broad absorption band between 500 and 1000 cm-1 is attributed to the vibration of ti-o-ti association in tio2 ncys [7].

100

% Transmittance

80

Co-dopedTiO2 Pure TiO2

60

40

20

0 4000

3500

3000

2500

2000

1500

1000

500

-1

Wavenumber (cm )

Fig. 2. FT-IR spectrum of CO-doped TiO2 3.3. Optical absorption studies. Fig. 3 shows the optical absorption spectrum of pure and Co-doped TiO2 NCYS calcined at 450˚c for 8 hr. The optical properties and calculated the energy band gap of pure and co doped tio2 ncys by UV–VIS-NIR absorption spectroscopy as shown in Fig. 3. The absorbance can vary depending upon the particle size, oxygen deficiency, purity of the material, etc.

The relation connecting the absorption coefficient (α) of semiconductors, the incident photon energy (hγ) and optical band gap (eg), from the TAC’S relation the calculated optical energy band gap of synthesized pure and co-doped TiO2 NCYS are found to be 3.25 ev and 3.39 ev. In this results were coincides the earlier reported the value 3.23 ev for pure anatase phase tio2 [8-9].

Fig. 3. UV-Vis-NIR spectrum of Co-doped TiO2.

3.4. EDAX studies. The elemental analysis of pure and Co-doped TiO2 NCys were analyzed by using electron diffraction X-ray analysis (EDAX). The spectrum shows, the strong X-ray peaks associated with Ti Kα and O Kα were found in the EDAX spectrum Fig.4a. Fig.4b shows depicted the successful doping of Co into TiO2 NCys.

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Fig. 4a. EDAX spectra for pure TiO2

Fig. 4b. EDAX spectra for Co-doped TiO2

3.5. FE-SEM studies. Scanning electron microscope (SEM) images of pure and Co-doped TiO2 NCys synthesized by sol gel method and calcined at 450˚C for 8 hr are shown in Fig.5a and Fig.5b It is clearly shows very closely packed spherical and bubbles shaped nanocrystals (NCys).

Fig. 5a. SEM image of pure TiO2 nanoparticles

Fig. 5b SEM image of Co-doped TiO2 nanoparticles

Summary. The Pure TiO2 and Co-doped TiO2 nanocrystals have been synthesized by sol gel method at room temperature. The synthesized materials were calcined at 450˚C for getting anatase phase.

From the PXRD data the synthesized material shows a space group I41. The calcined samples were characterized by the techniques like PXRD, FT-IR, Optical absorption, FESEM and EDAX. From the results of PXRD patterns, it is confirmed that the TiO2 was in anatase phase with crystalline size in the range of 16.21 to 20.58 nm. The presents of functional groups were identified by FT-IR analysis. The UV cut of wavelength and optical band energy gap of the undoped and doped materials are have the values between 3.25 and 3.39 eV. The SEM with EDAX images confirmed the spherical and bubbles morphology of the products.

Acknowledgement. The authors are grateful to the management of SRM University for their constant support and encouragement.

References

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[1] Yang X, Cao C, Hohn K, Ericksaon L, Maghrang R, Hamal D, Klabunde K, J Catal 252 (2007) 296, DOI: 10.1016/j.jcat.2007.09.014.

[2] Guo-Bin Shan and George P Demopoulos, The synthesis of aqueous-dispersible anatase TiO2nanoplatelets, Nanotechnology 72 (2007) 1687 DOI: 10.1088/0957-4484/21/2/025604.

[3] Tadao Sugimoto, Xingping Zhou, Atsushi Muramatsu, Synthesis of uniform anatase TiO2 nanoparticles by gel–sol method, 259 (2003) 43, DOI: 10.1016/S0021-9797 (03)00036-5.

[4] K. Karthik, S. Kesava Pandian, K. Suresh Kumar, N. Victor Jaya, Influence of dopant level on structural, optical and magnetic properties of Co-doped anatase TiO2 nanoparticles, 256 (2010)4757, DOI: 10.1016/j.apsusc.2010.02.085.

[5] Biswajit Choudhury, Amarjyoti Choudhury, Luminescence characteristics of cobalt doped TiO2nanoparticles, Journal of Luminescence, 132 (2012) 178. DOI: 10.1016/j.jlumin. 2011.08.020.

[6] Santi Maensiri, Paveena Laokul, Jutharatana Klinkaewnarong, A simple synthesis and roomtemperature magnetic behavior of Co-doped anatase TiO2 nanoparticles, DOI: 10.1016/j.jmmm.2005.10.005.

[7] Liu, Xiu-Hua HE, Xiao-Bo FU, Yi-Bei, Effects of Doping Cobalt on the Structures and Performances of TiO2 Photocatalyst, Acta Chimica Sinica 2008 -14.

[8] Alamgir, Wasi Khan, Shabbir Ahmad, M. Mehedi Hassan, A.H. Naqvi Structural phase analysis, band gap tuning and fluorescence properties of Co doped TiO2 nanoparticles, Optical materials 38 (2014) 278. DOI: 10.1016/j.optmat.2014.10.054.

[9] Marta I. Litter, Heterogeneous photocatalysis Transition metal ions in photocatalytic systems, Applied Catalysis B: Environmental 23 (1999) 89, DOI: 10.1016/S0926-3373 (99)00069-7.

Cite the paper D.V. Sridevi, V. Ramesh, T. Sakthivel, K.Geetha, V. Ratchagar, K. Jagannathan, K. Rajarajan, K. Ramachadran (2017). Synthesis, Structural and Optical Properties of Co Doped TiO2 Nanocrystals by Sol-Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.99.9.726

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Effect Of Ni Concentration on Structural and Optical Properties of ZnS Nanoparticles9 B. Sreenivasulu1, S. Venkatramana Reddy1,a, P. Venkateswara Reddy1 1 – Department of Physics, Sri Venkateswara University, Tirupati-517502, A.P. India a – drsvreddy123@gmail.com DOI 10.2412/mmse.0.1.664 provided by Seo4U.link

Keywords. SEM, morphology, Raman studies, PL, DRS, absorption.

ABSTRACT. Ni (1, 5 mol %) doped ZnS nano particles are synthesized by chemical Co-Precipitation method. The prepared samples are characterized byXRD, Raman Spectroscopy, Photo luminescence (PL), Optical absorption, Diffused reflectance (DRS) and Scanning electron microscope (SEM). XRD Analysis confirms the Cubic blended Structure for Ni doped ZnS and no impurity peaks are presented in XRD pattern. The average particle sizes of Ni doped nanoparticles are in the range of 2-3 nm. Raman spectra show the Vibrational modes that represent the structure of ZnS. The PL spectra exhibit emission peaks in both UV and visible regions and these results are good agreement with the absorption spectra and DRS. The optical band gap of ZnS decrease with increase of Ni concentration. SEM micro graphs reveal that the surface morphology of Ni doped ZnS nanoparticles a re spherical in shape.

Introduction. Research on nano sized semiconductors stimulated great interest in the recent past due to their unique properties and potential applications in diverse areas such as photo catalysis , solar cells, display panels, etc. [1–4]. These materials show unusual luminescence properties induced by the quantum size effect. Efforts have been made in realizing luminescence tuneable materials simply by changing the particle size and size distribution and great progress has been achieved [5–9]. They not only give luminescence in various regions but also can add to the excellent properties of ZnS. In doped ZnS nano crystals, impurity ions occupy the ZnS lattice site and behave as a trap site for electrons and holes. The electrons are ex cited from the ZnS valence band to conduction band by absorbing the energy equal to or greater than their band gap energy.

Subsequent relaxation of these photo excited electrons to some surface states or levels is followed by radiative decay, enabling luminescence in the visible region. However, two different kinds of ions simultaneously present in a host material produce fluorescence, which is completely different from the emission due to a single ion and this property is very beneficial for white light generation [10–12]. In this work, the PL properties of the ZnS doped with Ni were investigated in an air atmosphere.

Experimental details: All the chemicals used are of Analytical Reagent grade (Sigma Aldrich chemicals), such as Zinc acetate [Zn (CH3COO)2.2H2O], sodium sulfide (Na2S) and nickel chloride (NiCl2.6H2O) are used as source materials for Zn, S and Ni respectively, with double distilled water as solvent. Pure and Ni-doped ZnS nano particles have been synthesized using the soft chemical approach, known as chemical co-precipitation technique [13-15] by mixing nickel chloride of 1, 5 mol % with zinc acetate aqueous solution. Sodium sulfide aqueous solution was also added to this solution drop-by-drop followed by PVP to prevent agglomeration of the particles. The precipitates so formed are washed and dried to remove the last adherent. The Pure 9

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and Ni (1, 5 mol %) doped ZnS nano particles obtained, are finally crushed to the powder form for further investigations.

Results and discussion: XRD analysis:

(111)

2500

Pure ZnS

160

180

1 mol% Ni;ZnS

120 100

(220)

80

(311)

60 40

5 mol% Ni;ZnS

140

1500 (220) 1000

(311)

500

20 0 20

(111)

160

2000

Intensity(a.u)

Intensity (a.u)

140

(111)

Intensity (a.u)

180

120 100

(220)

80

(311)

60 40 20

30

40

50

60

70

80

0 20

30

40

60

70

80

2ď ą (Theta)

2ď ą (Theta)

a)

50

b)

0 20

30

40

50

60

70

80

2ď ą (Theta)

c)

Fig. 1. XRD patterns (a) pure (b) 1 mol% and (c) 5 mol% Ni doped ZnS nano particles.

The XRD spectra of pure ZnS and as prepared ZnS sample at different dopant concentrations (1, 5 mol %) are shown in Fig.1. The XRD spectra shows three major peaks at 2θ = 28.65°, 48.16° and 56.55° for the miller planes (111), (220) and (311) of Ni doped ZnS nano particles respectively. The indexed plane values of ZnS agree well with the JCPDS file No: 80 -0020 for all samples. The diffraction peaks indicate the nano size of the synthesized particles. The full width at half maximum (FWHM) of the diffraction peaks are slightly increased by the addition of capping agent. This may be due to the reduction of particles size. The averaged crystallite sizes of D is calculated from the FWHM of the diffraction peaks using the Debye–Scherrer equation,

đ??ˇ=

0.91 đ?œ† đ?›˝ cos đ?œƒ

Raman Analysis. The Raman spectra of ZnS poly types have been described by Schneider and Kirby [16]. Nilsen et al. [17] reported the one- and two-phonon Raman spectra of bulk cubic ZnS. The Raman Spectra for pure and Ni doped ZnS nano particles are recorded in the frequency range 200-500 nm as shown in Fig. 2. The Raman spectra of undoped nano particles exhibit strong peaks at 270 and 350 cm-1. Ni doped ZnS nanoparticles exhibits the transverse optical (TO) and longitudinal optical (LO) zone center phonons near 262 cm -1, 342 cm-1, 273 cm-1 and 351cm1 .The TO and LO mode positions are slightly changed for Ni doped ZnS.

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24000

24000 24000

Pure ZnS

22000

22000

20000

14000 350

270

12000 10000 250

300

350

400 -1

Wave number (cm )

450

500

Intensity

16000

18000 16000 14000

18000 16000

12000

10000

10000 250

300

350

400

450

500

Wave number (cm-1)

a)

b)

8000 200

351

273

14000

12000

8000 200

5 mol% Ni; ZnS

22000

342

20000

18000

Intensity

Intensity

20000

8000 200

1 mol% Ni; ZnS

262

250

300

350

400

450

500

Wave number (cm -1)

c)

Fig. 2. Raman Spectra of (a) pure (b) 1 mol% and (c) 5 mol% Ni doped ZnS nano particles.

Morphological studies.

a)

b)

c)

Fig. 3. SEM and EDX of (a) pure (b) 1 mol% and (c) 5 mol% Ni doped ZnS nano particles.

SEM and EDAX analysis.

Fig.3 shows SEM images of different doping concentrations (1, 5 mol %) PVP capped ZnS nano particles and the corresponding EDX spectrum. The spectra demonstrate the presence of various elements in the prepared ZnS nano samles. The peaks corresponding to the elements Zn, Ni and S confirm the presence of the nanoparticles in the polymer matrix. Thus chemical precipitation method is very effective as no loss of elements occurrs during the synthesis.

Optical Properties.

PL Spectra.

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120000 100000 80000 60000

539

609

40000

5 mol % Ni; ZnS

8000 6000 4000 2000

20000 500

600

700

0 400

800

619

140000

0 400

450

160000

539

618

638

2000

10000

1 mol % Ni; ZnS

438

Intensity (a.u)

417

4000

437

Intensity (a.u.)

8000 6000

467

467

180000

438

Pure ZnS

418

200000

466 10000

Intensity (a.u.)

12000

0

450

500

550

600

650

700

400

500

Wavelength (nm)

Wavelength (nm)

a)

600

700

800

Wavelength (nm)

b)

c)

Fig. 4. PL Spectra of (a) pure (b) 1 mol% and (c) 5 mol% Ni doped ZnS nano particles.

Pure and Ni doped ZnS nano particles are shown in Fig.4. It can be observed that PL emission spectra of doped ZnS have sharp intensity and symmetric with four dominant peaks at 419 nm , 438 nm and 467nm corresponding to blue emission and the peak at 539 nm identified as green emission. The emission peak at 467 nm is attributed to sulfur vacancies. Borse et al. [18] and Lu et al. [19] have reported the peak in the range 450 – 460 nm and have been assigned to sulfur vacancies i.e., to the recombination of electrons at sulfur vacancy with holes in the valence band.

The origin of emission peak observed at 539 nm does not result from impurity states related with dopant, but originated from native defect state.

Optical absorption and UV-Visible spectra. Absorption shoulder for pure ZnS and 1, 5 mol % Ni doped ZnS nano particles peaks are centered at 320 nm. The absorption peak positions are compared, the capped particles are significantly shifted to blue region.The relation between reflectance R and absorption coefficient ι as given by Kubelka–Munk method [20] is

đ??š(đ?‘…) =

(1−đ?‘…)2 2đ?‘…

=

� �

where F (R) is the Kubelka–Munk function, S is the scattering coefficient.

The band gap for undoped ZnS came out to be 3.7 eV which is quite higher as compared to its bulk counterpart (3.54 eV). The band gap of 1 mol % Ni doped ZnS has decreased whereas for 5 mol % Ni, it has increased slightly. According to the Burstein–Moss shift [21-22], at high doping content, the Fermi level shifts into the conduction band.

8000

1.6

Pure ZnS

7000

1.4

1 mol% Ni;ZnS

6000

3 mol% Ni;ZnS

1.2 1.0 0.8

4000 3000

0.6

2000

0.4

1000 0

0.2 0.0 200

Pure ZnS 1 mol% Ni; ZnS 5 mol% Ni; ZnS

5000

(ď Ąhď ľ)2

Absorbance (a.u)

1.8

300

400

500

600

700

800

-1000 1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

hď ľ (eV)

Wavelength (nm)

a)

b)

Fig. 5. UV-Visible and Band gap Spectra of (a) pure, (b) 1 mol% and (c) 5 mol% Ni doped ZnS nano particles.

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Summary. In the present work, Ni doped ZnS nanoparticles have been synthesized successfully through chemical co-precipitation method using PVP as the capping agent. Structural analysis indicates that the Ni doped ZnS nanoparticles crystallize in a cubic structure without forming other secondary phases. The substitution of Ni ions at Zn sites is also confirmed by XRD and Raman studies. Raman studies show the quantum confinement effects in ZnS nan oparticles.. It is found that the undoped sample exhibits PL emission peaks at 466 nm but Ni 2+ doped ZnS sample exhibits PL emission covering the whole visible region with multiple peaks at 438 , 450, 467 and 539 nm.This research is supposed to have positive impact on nano technology in fetures.

References [1] G.Y. Ni, J. Yin, Z.X. Hong, Mater. Res. Bull. 2004. DOI 10.1016/j.materresbull.2004.01.011 [2]D .Moore, C. Ronning, C. M. Zhong, L. Wang, Chem. Phys. Lett. 2004. DOI 10.1016/j.cplett.2003.12.063 [3] D. Moore, C. Ronning, C.M. Zhong, L. Wang, Chem. Phys. Lett. 2004. DOI 10.1016/j.tsf.2006.07.035 [4] S. Lee, D. Song, D. Kim, J. Lee, S. Kim, J.Y. Paric, Y.D. Choi, Mater. Lett. 2004. DOI 10.1016/S0167-577X (03)00483-X [5] J. Mu, D. Gu, Z. Xu, Mater. Res. Bull. 2006. DOI 10.1016/j.materresbull.2005.06.014 [6] S. Wageh, Z.S. Ling, X. Rong, J. Cryst. Growth 2003.DOI 10.1016/S0022-0248 (03)01258-2 [7] N. Kumbhojkar, V.V. Nikesh, A. Kshirsagar, S. Mahamuni, J. Appl. Phys.2000. DOI 10.1063/1.1321027 [8] H. Tang, G. Xu, L. 10.1016/j.actamat.2003.11.030

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[9] H.Y. Lu, S.Y. Chu, J. Cryst. Growth 2004. DOI 10.1016/j.jcrysgro.2004.02.011 [10] J.Z. Liu, P.X. Yan, G.H. Yue, J.B. Chang, D.M. Qu, R.F. Zhuo, J. Phys. 2006 DOI.10.1088/0022-3727/39/11/006 [11] K. Liu, J.Y. Zhang, 10.1016/j.physb.2006.06.157

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Wu,

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D.

Shen,

Physica

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[12] P. Yang, M. Lu, D. Xu, D. Yuan, C. Song, J. Phys. Chem. Solids 2003. 10.1016/S0022-3697 (02)00278-0 [13] T. Suemasu, K. Yamaguchi, H. Tomioka, F. Hasegawa, Phys. Status Solidi. 2003. DOI 10.1002/pssc.200303374 [14] D.A. Reddy, G. Murali, R.P. Vijayalakshmi, B.K. Reddy, Appl. Phys.2011.DOI 10.1007/s00339-011-6563-1 [15] P.V.B. Lakshmi, K.S. Raj, K. Ramachandran, Cryst. Res. Technol.2010.DOI 10.1002/crat.200800271 [16] J.Schneider, R.D.Kirby, Phys.Rev.1972. DOI 10.1103/PhysRevB.6.1290 [17] W.G.Nilsen, Phys.Rev. 1969. DOI 10.1103/PhysRev.182.838 [18] P.H. Borse, N. Deshmukh, R.F. Shinde, S.K. Date, S.K. Kulkarni, J. Mater. Sci.1999. DOI 10.1023/A:1004709601889 [19] H.Y. Lu, S.Y. Chu, S.S. Tan, J. Cryst. Growth 2004.DOI 10.1016/j.jcrysgro.2004.05.050 [20] C.C. Hu, J.N. Nian, H. Teng, Electrodeposited p-type Cu2O as photocatalyst for H2 evolution from water reduction in the presence of WO3, Sol. Energy Mater.Sol. Cells 2008. DOI 10.1016/j.solmat.2008.03.012 MMSE Journal. Open Access www.mmse.xyz

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[21] H.S. Yoon, K.S. Lee, T.S. Lee, B. Cheong, D.K. Choi, D.H. Kim, W.M. Kim, Properties of fluorine doped ZnO thin films deposited by magnetron sputtering, Sol. Energy Mater. Sol. Cells 2008. DOI 10.1016/j.solmat.2008.05.010 [22] S. Karamat, S. Mahmood, J.J. Lin, Z.Y. Pan, P. Lee, T.L. Tan, S.V. Springham, R.V.Ramanujan, R.S. Rawat, Structural, optical and magnetic properties of (ZnO)1-x (MnO2)x thin films deposited at room temperature, Appl.

Surf.

Sci.2008.DOI 10.1016/j.apsusc.2008.05.318

Cite the paper B. Sreenivasulu, S. Venkatramana Reddy, P. Venkateswara Reddy (2017). Effect OF Ni Concentration on Structural and Optical Properties of ZnS Nanoparticles. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.0.1.664

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Synthesis and Characterization of ZnO/NiO and Its Photocatalytic Activity10 V. Karthikeyan1, A. Padmanaban1, T. Dhanasekaran, S. Praveen Kumar1, G. Gnanamoorthy1, V. Narayanan1,a 1 – Department of Inorganic Chemistry, Guindy Campus, University of Madras, Chennai, India a – vnnara@yahoo.co.in DOI 10.2412/mmse.23.8.292 provided by Seo4U.link

Keywords: ZnO/NiO, photocatalyst, methylene blue.

ABSTRACT. Bimetallic ZnO/NiO was synthesized by a simple one-pot solvothermal method with zinc nitrate hexahydrate and nickel nitrate hexahydrate in ethanol medium. Material was characterized by X-ray diffraction, Field emission scanning electron microscope, UV-Vis and FTIR. The proposed mixed oxide was investigated as a suitable photocatalytic material for the degradation of organic dyes under visible light irradiation. The formation of ZnO/NiO hetero-junction improved the separation rate of photogenerated electrons and holes and therefore yields enhanced photocatalytic efficiency.

Introduction. Nanostructured metal oxide materials fascinated the lot of attention due to their multifunctional activities including optical, magnetic, electrical and catalytic properties. These interesting features increases the wide utility of the materials to many promising applications. Zinc oxide (ZnO) as n–type semiconductor with a direct wide band gap of (Eg = 3.2 eV), has high photosensitivity, photocatalytic activity, quantum efficiency, non-toxicity and low cost [1]. Its extraordinary structural and microstructural benefits further extends their applications to gas sensors, solar cells, light-emitting diodes, field effect transistors, varistors and piezoelectric devices. To date several morphologies such as nanotubes, nanoflowers, nanowires and nanorods of ZnO have developed and studied as the photocatalysts for degradation of organic pollutants. Recent years it has been well established that the coupling of two different semiconductors with different energy levels of photogenerated electron–hole pairs enhanced their functional properties due to their interfacial activity. In particular, the combination of p and n type binary semiconductor oxides could form the p-n junction at the interface and lead to the effective separation of electron-hole pairs. Among various p-type oxides nickel oxide (NiO) is a highly active material with wide band gap (3.6eV to 4.0 eV) and extensively studied for various applications such as catalysis, gas sensing, battery cathodes, magnetic materials, electrochromic films, chemical sensors and photovoltaic devices [2]. In this study, the NiO–ZnO binary composite oxide has been synthesized by one-pot solvothermal synthesis and investigated as the visible light catalyst for photodegradation. The photogenerated electron–hole pairs were effectively separated, which facilitates to enhance their photocatalytic activity.

Experimental Materials Zinc nitrate, nickel nitrate and sodium lauryl sulphate was purchased from SRL. Absolute ethanol was used as a solvent without purification. 2mmol Zn (NO3)2, 6H2O and 2mmol Ni (NO3)2.6H2O were dissolved in 40 mL of ethanol. The mixture was stirred for 15 min and then 0.1g of SDS was added as a surfactant. 1M NaOH was used to adjust pH before the mixture was sealed in a Teflon10

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lined stainless-steel autoclave. The autoclave was heated to 140˚C for 12 h, then cooled to room temperature. The final product was collected by centrifugation and washed with ethanol and deionized water for five times. Then the product was dried and annealed at 450˚C for 3 h.

Instruments. The powder X-ray diffraction (XRD) of the sample were performed on Rich Siefert 3000 diffractometer Cu-Kα1 radiation (λ=1.5406Å). Ultraviolet visible spectral analysis was performed on Perkin Elmer lambda 650. The morphology of the samples was analyzed by FE-SEM using a HITACHI SU6600 filed emission - scanning electron microscopy.

Results and discussion Fig. 1 (a) shows the XRD pattern of ZnO/NiO binary composite. The diffraction peaks at 31.2o, 33.7o, 35.6o, 46.7o, 55.8 o, 67.3o, 68.6o of ZnO were well matched with standard (JCPDS No. 76-0704). In the meantime the ZnO is in good agreement with the hexagonal phase. Moreover, diffraction peaks at 42.5o, 62.2o, are related to the NiO and directly indexed to (JCPDS No. 65-2901). The observed peaks indicates the NiO phase is the face centered cubic structure. And there is no other impurity phase or secondary phase in the XRD pattern. Typical UV- Vis spectrum of ZnO/NiO composite is shown in Fig.1 (b). It exhibit absorption band at 200-400nm indicating the extended UV-vis absorption property of the mixed oxide.

a)

b)

a)

b)

Fig. 1. (a) XRD pattern and (b) UV Vis spectrum of ZnO/NiO. Fig. 2 shows the FT-IR spectrum of ZnO/NiO composite. It shows the absorption the region of 1128 cm-1, 1392 cm-1, 1613 cm-1 and 3442 cm-1. The absorption band at 400 cm-1 to 600 cm-1 corresponds to M-O bond [4]. The band observed at 1128 cm-1 corresponds to C-O stretching vibration. The band appearing at 1392cm-1 attributed to C-H bending vibration. The band at 1613 cm-1 corresponds to the symmetrical of C-O. The band at 3442 cm-1 corresponds to stretching vibration of the –OH group.

The FESEM image and EDS spectrum of ZnO/NiO composite are given in Fig. 3. The FESEM image of ZnO/NiO composite shows undefined coarse morphology. The non-uniform particles are agglomerated and forms irregular shaped particles. Fig. 3 shows the EDS spectrum which confirms the presence of Zn, Ni, O and no other impurity present in the sample.

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Fig. 2. FT-IR spectrum of ZnO/NiO composite.

Fig. 3. FESEM images of ZnO/NiO. Photocatalytic activity. The photocatalytic degradation of methylene blue was studied by taking 100ml double distilled water containing 0.001M of methylene blue and 0.05g of ZnO/NiO. The reaction mixture was irradiated under visible light. For irradiation purpose, 500W Halogen lamp was used in photo reactor chamber. Fig.4 shows the absorption spectrum of methylene blue subsequently the visible light irradiation for different time interval. It can be seen that the intensity of the absorption peaks decreased as the reaction progressed with ZnO/NiO nanocomposite as a catalyst. After 60 min of irradiation, the intensity of the absorption peaks decreased to 30% of the initial methylene blue solution. When the irradiation time was increased to 180 min, the degradation of MB was nearly ~85%. This result shows that the ZnO/NiO exhibit good photocatalytic activity. The surface interface of the combined systems ZnO/NiO significantly influenced on the structure relation properties.

Thereby, the photocatalytic activities has been increased. This p-n hetero-junction forms the negative and positive charges in p-NiO and n-ZnO regions respectively. In the ZnO/NiO composite the photogenerated e-/h+ pairs form at the interface. The photogenerated electrons can easily migrate from NiO to ZnO because conduction band-NiO is more negative than the conduction band-ZnO. At the same time, the hole transfer take place in opposite direction from valence band-ZnO to valence bandNiO. So the e-/h+ recombination processes decrease significantly and increase the photocatalytic activity [3, 5].

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Fig. 4. Photocatalytic degradation of Methylene blue under visible light in presence of ZnO/NiO. Summary. ZnO/NiO composite was synthesized by one-pot solvothermal method. The synthesized ZnO/NiO was confirmed by XRD analysis and the material was characterized by various techniques.

The morphologies of the sample found to be aggregated nanoparticles. The photocatalytic results show the ZnO/NiO composite has better degradation efficiency under visible light irradiation towards MB. Hence it can be suggested that the formation of p-n hetero junction enhances the separation rate of photogenerated electrons and holes and therefore yields enhanced photocatalytic efficiency.

References [1] Rujia Zou, Guanjie He, Kaibing Xu, Qian Liu, Zhenyu Zhang and Junqing Hu “ZnO nanorods on reduced graphene sheets with excellent field emission, gas sensor and photocatalytic properties” J. Mater. Chem. A, (2013), 1, 8445–8452. [DOI: 10.1039/c3ta11490b] [2] F.A. Harraz, R.M. Mohamed, A. Shawky, I.A. Ibrahim, “Composition and phase control of Ni/NiO nanoparticles for photocatalytic degradation of EDTA” J. Alloy Compds. 508, 2010, 133 – 140. [DOI:10.1016/j.jallcom.2010.08.027] [3] Minggui Wang, Yimin Hu, Jie Han, Rong Guo, Huixin Xiong and Yadong Yin, “TiO2/NiO hybrid shells: p–n junction photocatalysts with enhanced activity under visible light”, J. Mater. Chem. A, (2015), 3, 20727–20735 [DOI: 10.1039/c5ta05839b] [4] Jianing Li, Fei Zhao, Li Zhang, Mingyue Zhang, Haifeng Jiang, Shu Li and Junfeng Li, “Electrospun Hollow ZnO/NiO Heterostructure with Enhanced Photocatalytic Activity” RSC Adv. [DOI: 10.1039/C5RA08903D] [5] Hadis Derikvandi, Alireza Nezamzadeh-Ejhieh, “Increased photocatalytic activity of NiO and ZnO in photodegradation of a model drug aqueous solution: Effect of coupling, supporting, particles size and calcination temperature” J. Hazard. Mater [DOI:10.1016/j.jhazmat.2016.09.056]

Cite the paper V. Karthikeyan, A. Padmanaban, T. Dhanasekaran, S. Praveen Kumar, G. Gnanamoorthy, V. Narayanan (2017). Synthesis and Characterization of ZnO/NiO and Its Photocatalytic Activity. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.23.8.292

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Structural, Optical and Antimicrobial Activity of Copper and Zinc Doped Hydroxyapatite Nanopowders using Sol-Gel Method11 A. Mariappan1, P. Pandi 2, N. Balasubramanian3, R. Rajeshwara Palanichamy4, K. Neyvasagam2 1 – Madurai Institute of Engineering and Technology, Madurai, T. N. State, India 2 – P.G and Research Department of Physics, The Madura college, Madurai, T. N. State, India 3 – Department of Immunology, School of Biological Sciences, Madurai Kamaraj University, Madurai, T. N.State, India 4 – P.G and Research Department of Physics, N.M.S.S.Vellaichamy Nadar college, Madurai, T. N. State, India DOI 10.2412/mmse.1.46.162 provided by Seo4U.link Keywords: HAp, Cu2+, Zn2+, XRD, E. coli., S. typhi.

ABSTRACT. Antimicrobial materials based on hydroxyapatite nanopowders are functionally attractive in a wide variety of medical applications. The Cu2+ and Zn2+ incorporated HAp nanopowders were synthesized by simple Sol-Gel method.

The structural study, optical study and biological activity of the prepared nanopowders were characterized by X-ray diffraction, UV-Vis absorption spectroscopy and disc diffusion method respectively. The XRD results are demonstrated that the presence of copper and zinc doped hydroxyapatite nanopowders and size of the crystalline was found for pure HAp, 10%, 25% and 50% of Zn2+/ Cu2+ metal ions incorporated HAp respectively. The optical absorption analysis was used to estimate band gap value of pure HAp 3.86eV and Zn2+/ Cu2+ doped HAp 3.77eV (10%), 3.69eV (25%) and 3.30eV (50%) respectively. Antibacterial activity of synthesized nanocomposite against human pathogenic bacteria was tested by disc diffusion method on Muller- Hinton agar medium. The pure HAp powder has excellent antibacterial activity and the antibacterial rate gradually rise with the increase in Copper and Zinc concentrations in the HAp nanopowders.

Introduction. Inorganic antimicrobial materials are made of dense metal ions having biocidal action such as silver, zinc, copper and calcium phosphate [1-5]. Calcium phosphate, synthetic hydroxyapatite (HAp, Ca10 (PO4)6 (OH)2), is one of the most promising material because of its biocompatibility, good cation exchange rate with metals and high affinity for the pathogenic microorganisms [6-8]. In recent years, incorporation of metallic antibacterial agents (such as Cu2+, Zn2+, Ag+ and Ce4+) in bioceramics is mainly implemented because of their antibacterial property, which aids in inhibiting microbial growth at the implant site and their lack of cytotoxicity at low concentrations. HAp is incorporated with metal ions can be synthesized by various methods, among them Sol-Gel technique is a versatile method for the synthesis of ion substituted HAp nanopowders.

Hence, the present work is designed to synthesis Zn2+/Cu2+ metal ions incorporated into HAp nanopowders and to improve the antibacterial efficiency.

Experimental details Preparation of HAp nanopowders. Calcium acetate (Ca (C2H3O2)2, Orthophosphoric acid (H3PO4), Copper oxide (CuO), Zinc oxide (ZnO) were used as starting materials. Ethanol and double distilled water were used as solvents and acetic acid was used as a stabilizing agent. 0.55M solution of calcium acetate was prepared by dissolving the appropriate amount of calcium acetate Ca (C2H3O2)2 salt and it was mixed with 125 ml of solvent (100 ml double distilled water and 25 ml of ethanol). The solution was stirred for 2 hrs under vigorous conditions at room temperature while obtained Ca (OH)2 Sol-Gel solution. A required amount of Zinc oxide and Copper oxide was dissolved in 0.33M of H3PO4 and then add drop by drop in above prepared Sol-Gel solution. Finally, the transparent solution was 11

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formed after stirring for 4 hrs. During the preparation of HAp solution the pH of the solution was maintained at 10.5 by adding aqueous ammonia. Then various proportions of the powders were annealed at 500˚C in a muffle furnace at a constant heating rate under an air atmosphere for about 1 hr and then grained in a mortar and pestle. Finally, pure form of powder of HAp, 10% Zn/Cu-HAp, 25% Zn/Cu-HAp and 50%Zn/Cu-HAp obtained. Antibacterial activity of synthesized nanocomposite against human pathogenic bacteria was tested by disc diffusion method on Muller- Hinton agar medium (MHA) ([g/L]: Beef extract – 3, Casein acid hydrolysate – 17.5, Starch – 1.5 and Agar – 17) (Nagarajan et al., 2014). The human pathogenic bacterium Escherichia coli MTCC 443 and Salmonella typhi MTCC 733 were obtained from Microbial Type Culture Collection (MTCC) Chandigarh, India. The above said two human pathogens were inoculated in 25mL of sterile Nutrient broth and it was incubated at 37 °C for 10 hrs. A 50µL of human pathogens were inoculated on MHA medium, cultures were swabbed with the help of sterile cotton buds. A disc with 120 mg/mL concentration of nanocomposite was used in this study with tetracycline (2 mg/ml) as reference control. Inoculated plates were incubated for 24 hrs at 37 °C. After 24 hrs of incubation, different levels of zone of inhibition (ZOI) were measured using a meter ruler. The experiments were performed in triplicates.

Result and Discussion Structural study. Fig.1 (A) shows the XRD patterns of the synthesized pure form of HAp and Fig.1 (B) shows Zn/Cu metal ions doped HAp with different amount, such as 10% Zn/Cu-HAp, 25%Zn/CuHAp and 50% Zn/Cu-HAp.

(B)

(A)

(d)

Intensity ( arb.units)

Intensity ( arb.units)

(d)

(c)

(b)

(002)

(c)

10

20

(201) (210) (112) (300) (202) (301) (113) (203) (312) (213) (410) (322) (501) 30

40

50

(a) (512)

(101) (111) (200)

(002)

(b)

60

70

(a)

80

25

30

2 Theta (degree)

2 Theta (degree)

Fig. 1. (A) XRD patterns of hydroxyapatite powders prepared under different doping concentrations. a) pure form of HAp, b) 10% Zn/Cu-HAp, c) 25% Zn/Cu-HAp and d)50% Zn/CuHAp; (B) Enlarged XRD patterns of (0 0 2) plane.

It was found that the XRD results confirmed the hexagonal HAp (Space group P63/m, JCPDS file no.09-432) to be the main apatite phase and sharp peaks confirm that they are well crystallized. In the case of doped powders, the sharp and shallow peaks denoted that increased crystallinity as well as crystalline size, owing to the incorporation of Zn and Cu in Zn/Cu-HAp powders. The diffraction peak (0 0 2) plane was selected for local comparison because the plane was separated from other peaks. In particular, for Zn/Cu-HAp (Fig.1 (B)), the diffraction peak position shifted towards smaller angles from the standard XRD pattern for HAp. From the graph, the value of FWHM are decreased MMSE Journal. Open Access www.mmse.xyz

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for the plane (0 0 2) due to increase the Zn and Cu concentrations with respect to increase the crystallinity and peaks gets sharpened. The 50% Zn/Cu-HAp has more new peaks which denoted that peaks correspond to Zn and Cu in HAp sample.

Table 1. Crystalline sizes for Hydroxyapatite powders prepared underdifferent doping concentrations.

Sample name

Crystalline size in nm

HAp

15.88

10% Zn/Cu-HAp

16.05

25% Zn/Cu-HAp

21.21

50% Zn/Cu-HAp

21.52

Optical study. Fig. 2 (A) shows that the optical absorption analysis of synthesized pure form of HAp and Fig. 3 (A) shows that the optical absorption analysis of synthesized various ratios of (Zn/Cu) doped HAp powder samples. According to Lambert–Beer law, absorption coefficient (α) is proportional to absorbance. Thus, the energy intercept of the curve in (αhυ)2 vs hυ plot gives the value of Eg when the tangent line is extrapolated to the zero ordinate. Fig. 2 (B) pure form of HAp composite sample gives the band gap value is 3.86eV [as per literature band gap energy value of HAp is 5.3eV] [8]. Fig. 3 (B) shows the band gap values of the corresponding doped HAp composites were found to be 3.77eV, 3.69eV and 3.30eV for 10%Zn/Cu-HAp, 25%Zn/Cu-HAp and 50%Zn/Cu-HAp respectively, which were smaller than pure HAp (3.86eV). From the UV-Vis absorption analysis, the observed band gap values decrease with increase in doping concentrations. From the absorption spectrum of doped samples, absorption edge is slightly shifted towards the higher wavelength (red shift), as compared to the pure form of HAp. This could be attributed to the uniform doping of Cu2+ and Zn2+ ions in the HAp lattice. The decrease in the band gap with increase in the concentrations of Cu2+ and Zn2+ ions can be explained by the p-d spin-exchange interactions between the band electrons and the localized d electrons of the transition metal ion substituting the host metal ion. There is a strong p-d mixing of O, Cu and Zn ions in HAp lattice. This could also be a possible reason for the narrowing of the band gap.

0.7

(2A)

(2B)

0.6

(h) (eV)2

0.4

2

Absorbance(a.u)

0.5

0.3 0.2 0.1

343nm Eg=3.86eV

0.0 200

300

400

500

1.5

2.0

2.5

Wavelength (nm)

3.0

3.5

4.0

4.5

5.0

Energy (eV)

Fig. 2. (A) UV-Vis absorption spectrum of pure form of HAp and (B) Tauc extrapolation plots for the pure form of HAp sample.

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22

0.8

(c)25% ZnCuHAp

18

(b)10% ZnCuHAp

16

0.7

(d)

(c)25%ZncuHAp (b)10%ZncuHAp

14

0.6

2

(d)

2

0.5 0.4

(c)

0.3 0.2

(3B)

(d)50%ZncuHAp

12 10

(c)

8 6

(b)

4

380nm

0.1

(b)

Eg =3.77 eV

20

Eg =3.30 eV

(d)50% ZnCuHAp

Eg = 3.69 eV

(3A)

0.9

(h) (eV)

Absorbance(a.u)

1.0

2 0

0.0

-2

200

300

400

1.5

500

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

Energy(eV)

Wavelength(nm)

Fig. 3. (a) UV-Vis absorption spectrum of (b)10%Zn/Cu-HAp, (c)25%Zn/Cu-HAp and (d)50%Zn/Cu-HAp and (B) Tauc extrapolation plots for the (b)10%Zn/Cu-HAp, (c)25%Zn/Cu-HAp and (d)50%Zn/Cu-HAp samples.

Fig. 4. Antibacterial activity of human pathogens against nanopowders (zone of inhibition in mm).

Antibacterial activity. Fig.4 shows the bactericidal activity of the Zn2+/Cu2+-HAp composites were evaluated by the inhibition of bacterial growth of S.typhi and E.Coli. Both pathogens are Gramnegative bacteria. It is conclude that HAp doped nanocomposite was checked for antibacterial activity against human pathogens. Among the four compounds, two compounds shows there is no zone of inhibition compared with Tetracycline as a reference control, because doping concentration is low compare to other compounds. The remaining two compounds showed antibacterial activity against E. coli at 50% Zn/Cu-HAp (24 mm) and pure HAp (16 mm) compared with the reference control (Table2). Also the compound 50% Zn/Cu-HAp showed antibacterial activity (26 mm) against S. typhi compared with Tetracycline as a reference control. Results showed good inhibition on two types of bacteria E.Coli and S.typhi.

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Table 2. Antibacterial activity of human pathogens against nanopowders (zone of inhibition in mm).

S. No.

Sample name

Escherichia coli MTCC443

1

50% Zn/Cu-HAp

24

Salmonellatyphi MTCC733 26

2

Pure HAp

16

-

3

Tetracycline

27

36

Summary. The XRD analysis confirmed that sharp and shallow peaks denoted that increased crystallinity as well as crystalline size, owing to the incorporation of Zn and Cu in HAp powders. The optical analysis denoted that the bandgap values of the corresponding doped HAp composites were found to be 3.77eV, 3.69eV and 3.30eV for 10%Zn/Cu-HAp, 25%Zn/Cu-HAp and 50%Zn/Cu-HAp respectively which were smaller than pure HAp (3.86eV). The above results confirmed that uniform doping of Cu2+ and Zn2+ ions in the HAp lattice. The Antibacterial activity of human pathogens reveals that good inhibition on two types of bacteria E.coli and S.typhi.

References [1] Vojislav Stanic, Suzana Dimitrijevic, Jelena Antic-Stankovic, Miodrag Mitric, Bojan Jokic, Ilija B.Plecas, Slavica Raicevic, Synthesis and characterization and antimicrobial activity of copper and zinc-doped hydroxyapatite nanopowders, Applied Surface Science 256, 2010, 60836089.10.1016/j.apsusc.2010.03.124.

[2] J. Husheng, H. Wensheng, W. Liqiao, X. Bingshe, L. Xuguang, The structures and antibacterial properties of nano-SiO2 supported silver/zinc–silver materials, Dent. Mater. 24, 2008, 244–249.

10.1016/j.dental.2007.04.015.

[3] G. Zhou, Y. Li, W. Xiao, L. Zhang, Y. Zuo, J. Xue, J.A. Jansen, Synthesis characterization and antibacterial activities of a novel nanohydroxyapatite/zinc oxide complex, J. Biomed. Mater. Res. A 85, 2008, 929–937. 10.1002/jbm.a.31527.

[4] Y. Zhou, M. Xia, Y. Ye, C. Hu, Antimicrobial ability of Cu2+-montmorillonite, Appl. Clay Sci. 27, 2004, 215–218. 10.1016/j.clay.2004.06.002.

[5] K.C. Carson, J.G. Bartlett, T.J. Tan, T.V. Riley, In vitro susceptibility of methicillinresistant Staphylococcus aureus and methicillin-susceptible Staphylococcus aureus to a New antimicrobial, copper silicate, Antimicrob. Agents Chemother. 51, 2007, 4505–4507. 10.1128/AAC.00771-07.

[6] R.Z. LeGeros, Calcium phosphate-based osteoinductive materials, Chem. Rev.108, 2008, 4742– 4753. 10.1021/cr800427g.

[7] I. Smiˇciklas, A. Onjia, J. Markovi´ c, S. Raiˇcevi´ c, Comparison of hydroxyapatite sorption properties towards cadmium, lead, zinc and strontium ions, Mater.Sci. Forum 494, 2005, 405– 410.10.4028/www.scientific.net/MSF.494.405.

[8] S. Shanmugam and B. Gopal, Copper substituted hydroxyapatite and fluorapatite: synthesis, characterization and antimicrobial properties, Ceram. Int., 2014, 40, 15655– 15662. http://dx.doi.org/10.1016/j.ceramint.2014.07.086.

Cite the paper A. Mariappan, P. Pandi, N. Balasubramanian, R. Rajeshwara Palanichamy, K. Neyvasagam (2017). Structural, Optical and Antimicrobial Activity of Copper and Zinc Doped Hydroxyapatite Nanopowders using Sol-Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.1.46.162

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Synthesis of Bismuth Stannate Nanoparticles with High Photocatalytic Activity under the Visible Light Irradiation12 G. Gnanamoorthy1, T. Dhanasekaran1, A. Padmanaban1, S. Praveen Kumar1, S. Munusamy1, A. Stephen2, V.Narayanan1, a 1 – Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai, India 2 – Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai, India a – vnnara@yahoo.co.in DOI 10.2412/mmse.13.41.415 provided by Seo4U.link

Keywords: bismuth stannate, hydrothermal method, photocatalysis.

ABSTRACT. Malachite Green is one of the most important organic dye, it contains triphenylmethane groups and it has been widely used for many industries. The hazardous dyes were rapidly act on immune and reproductive systems with carcinogenic effect of human health. Different methods were used for the hazardous removal in various industries, such as photocatalysis, biological treatment and adsorption process. The bismuth stannate nanoparticles have special properties of the hydrogen storage, biomolecule detection, gas sensors and catalysis. The bismuth stannate nanoparticles can be used for the degradation of organic pollutants and bismuth stannate is an important ternary oxide semiconductor with a wide band gap material. The composites were synthesized by a hydrothermal method, the obtained product was characterized byXRD, Raman, the morphology structure was confirmed by scanning electron microscopy and optical properties were carried out by DRS-UV-Vis spectroscopy. The excellent photocatalytic performance of the catalyst was evaluated by malachite green under the visible light.

Introduction. Bi2Sn2O7 plays an important role in photocatalytic activity and different temperature stabilities in the hydrothermal reaction processes. Nowadays this pyrochlore structured material have several applications such as solar energy conversion, environmental remediation [1-2], catalysis, gas sensors [3-4] and hydrogen generation [5-6]. Many canvassers were reported to the excellent photocatalytic performance, chemical stability, low cost and non-toxicity of the semiconductors [7- 9]. The Photocatalytic degradation can be assigned for high mobility of photoinduced electrons from band dispersion and its ion separation [10].

Bi2O3 is a p-type semiconductor material and SnO2 is n-type material, were used in a many industries and several applications of Bi- based material. This material is used in anticancer activity, antimicrobial[11], electrical, optical and fast-ion conducting characteristics and as well performance of photocatalysis[12-17]. In this work, we have synthesized materials at higher temperature, which facilitates the formation of nanoflakes with uniform shape and size. Here itaconic acid can act as a surfactant in case of shape and size growth for the bismuth stannate surface. The Bi7Sn0.1O10.7 nanoparticles have excellent photocatalytic performance for the photocatalytic degradation of malachite green dye under visible light irradiation.

Experimental methods.

Synthesis of Bi7 Sn0.1 O10.7 nanoparticles. The Bi7Sn0.1O10.7 nanoparticles were synthesized by hydrothermal method. SnCl2.2H2O (2mM) was dissolved in methanol. Bi (NO3)3.5H2O was 12

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dissolved in dilute nitric acid. The tin solution was added dropwise with continuous stirring for 2 h and small amount of itaconic acid was added to the solution Finally KOH solution was added, after this precursor were transferred to stainless steel teflon autoclave and heated at 170 ºC for 12 h. The obtained product was centrifuged at 12000 rpm immediately to get a residue. The residue is washed with ethanol and dried at a room temperature.

Characterization techniques. The morphology of synthesized samples was characterized using SEM at Hitachi S-3000H, Japan. The crystalline cubic phase of the Bi7Sn0.1O10.7 is evaluated by using Bruker D8 ADVANCE and monochromatic Cu Kα1 radiation (λ = 1.5418 Å). DRS -UV- visible spectroscopy was carried out by Perkin Elmer (lambda 35 India PVT LTD).

Photocatalytic activity. The photocatalytic degradation of Malachite green in an aqueous solution was carried out by using Bi7Sn0.1O10.7 materials at a room temperature. In a typical experiment, bismuth stannate (25 mg) and 100 ml MG (1 × 10−5 M) solution was sonicated for 5 min. and continuously stirred. The solution was equilibrated for 5 min. The mixture is subjected to visible light irradiation. The phodegradation was followed by collecting the solution at equal intervals, which was analysed by using UV- Visible spectroscopy.

Result and discussion.

Structural and morphological analysis using XRD and SEM. The synthesized Bi7Sn0.1O10.7 nanoparticles structural analysis will be carried out by X-ray diffraction and the patterns were shown in Fig. 1. The bismuth stannate nanoparticle diffraction patterns corresponds to the crystalline cubic phase. The peaks at 2θ = 27.6º, 31.9º, 45.8º and 54.3º corresponds to the diffraction planes (111, 200, 220 and 311) were confirmed by JCPDS no - 42-0187. Fig. 2 shows the flakes like morphology of synthesized Bi7Sn0.1O10.7 nanoparticles with uniform size.

Fig. 1. X-Ray diffraction patterns.

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Fig. 2. SEM images of Bi7 Sn0.1 O10.7 nanoparticles.

Raman spectroscopy. Raman spectroscopy studies of the obtained bismuth stannate nanoparticles are shown in the Fig. 3. The peak at 98 cm-1 corresponds to the A1g modes of metallic bismuth and 119, 312 and 445 cm-1 are Bi – O stretching modes of the catalyst. The modes at 147 and 532 cm-1 peak was commonly according due to the O - M - O (M - Bi, Sn) bending modes of the products.

Diffuse reflectance spectroscopy. Fig. 4 shows the diffuse reflectance spectrum of the bismuth stannate nanoparticles with systematic band gaps are observed. Bi7Sn0.1O10.7 optical band gap energy is 3.5 eV. The band gap values are comparable with previous reports.

FT-IR Spectroscopy.

The FT-IR spectrum of as prepared bismuth stannate nanoparticles was shown in Fig. 5: These materials show three peaks at 504, 611 and 1038 cm-1. Band at 504 cm-1 corresponds to the Bi–O vibrations 611 and 1308 cm-1 are attributed to stretching vibration of the M-O (Sn and Bi).

Fig. 3. Raman, DRS UV-Visible and Infrared spectra of synthesized Bi7 Sn0.1O10.7 nanoparticles.

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Fig. 4. Raman, DRS UV-Visible and Infrared spectra of synthesized Bi7 Sn0.1O10.7 nanoparticles.

Fig. 5. Raman, DRS UV-Visible and Infrared spectra of synthesized Bi7 Sn0.1O10.7 nanoparticles.

Photocatalytic activity. The photocatalytic activity of dye under visible light illumination was studied by measuring to the absorbance of the malachite green dye in presence of the (catalyst) bismuth stannate nanoparticles. The degradation was monitored, here time was increase and absorbance decreased in the malachite green concentration. Fig. 6 shows absorbance at different time intervals for the degradation of Malachite Green under visible light irradiation.

The relative concentration with time of the sample was shown in Fig. 7. Steady degradation of the dye with increase in irradiation time is observed. The complete degradation of the dye was observed with in 60 min. of visible light irradiation.

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Fig. 6. Time-dependent absorption spectrum of malachite green dye solution under visible light irradiation.

Fig. 7. Degradation of dye Vs time.

Summary. Bismuth stannate nanoparticles were synthesized by hydrothermal method. The bismuth stannate nanoparticles were characterized by XRD, SEM, FT-IR, Raman and DRS-UV-Vis spectroscopy. The bismuth stannante nanomaterials have a band gap of 3.5 eV. The synthesized materials show excellent photocatalytic activity for the degradation of malachite green.

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Chem. Rev. 114 (2014) 9919–9986.[ DOI:

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[7] Y. Cong, J. Zhang, F. Chen, M. Anpo, J. Phys. Chem. C., 111 (2007) 10618–10623.

[DOI:10.1021/jp0727493] [8] A.K. Chandiran, P. Comte, R. Humphry-Baker, F. Kessler, C. Yi, M.K. Nazeeruddin, M. Gratzel, Adv. Funct. Mater., 23 (2013) 2775–2781. [DOI:10.1002/adfm.201202956] [9] Y. Ao, J. Xu, P. Wang, C. Wang, J. Hou, Y. Li, Colloids Surf. A 487 (2015) 66–74.

[10] X.C. Ma, Y. Dai, L. Yu, B. Huang, Light 5 (2016) 16017. [DOI:10.1038/lsa.2016.17] [11] Mahmoud Abudayyak, Merve [DOI:10.1016/j.chemosphere.2016.11.018]

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Cite the paper G. Gnanamoorthy, T. Dhanasekaran, A. Padmanaban, S. Praveen Kumar, S. Munusamy, A. Stephen, V.Narayanan (2017). Synthesis of Bismuth Stannate Nanoparticles with High Photocatalytic Activity under the Visible Light Irradiation. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.13.41.415

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Preparation and Optical Studies of Layered Double Hydroxides for Photo Catalytic Degradation of Organic Dyes13 T. Dhanasekaran1, A. Padmanaban1, G. Gnanamoorthy1, R. Manigandan1, S. Praveen Kumar1, S. Munusamy1, A. Stephen2, V. Narayanan1,a 1 – Department of Inorganic Chemistry, Guindy Campus, University of Madras, Chennai, India.

2 – Department of Nuclear physics, Guindy Campus, University of Madras, Chennai, India a – vnnara@yahoo.co.in DOI 10.2412/mmse.97.8.19 provided by Seo4U.link

Keywords: layered double hydroxides, optical studies, photocatalytic degradation.

ABSTRACT. Over the past decades metal-oxide played in important role in electrocatalyst and photocatalyst. The MnRu layered double hydroxides are prepared by facile one step hydrothermal method. The prepared sample was characterized by variety of techniques. Such as X-Ray Diffract meter was used to determine the phase purity and Crystal structure of the prepared sample. FT-IR is reveals the present of functional groups and DRS UV spectroscopy used to conclude the band gap energy of the prepared materials. The surface morphology was analyzed by using FESEM microscope. The prepared Mn-Ru are layered double hydroxides was further used to photo catalytic degradation of organic dyes.

Introduction. In recent years, most of research efforts have been put into the design and study of different layered double hydroxides (LDHs) for photocatalysis. LDHs, generally also called anionic clays, are known as host-guest layered materials. Though, these contrasts to cationic clays, LDH materials are quite rare in nature [1]. Most of the LDHs are synthetic materials and their structure shows the naturally arising mineral hydrotalcite. LDHs have emerged as a ground breaking photocatalyst group in the fields of energy and environment because of their multy exceptional properties. The fabrication of visible active layered double hydroxide photocatalysts is currently a subject of particular importance because of their significance in both fundamental research and practical applications. Different groups have reported neat LDHs and modified LDHs for the photocatalytic decoloration of organic pollutants and decomposition of water into hydrogen and oxygen, designing a novel visible active LDH photocatalyst for industrial uses is still a great challenge [2]. Manganese oxides (MnOx) are eminent resourceful, robust and earth abundant photocatalyst [3].

Moreover, manganese oxides are ubiquitous in nature and environmental responsive that deserve their applications in catalysis, renewable energy and environmental remediation. Although manganese oxides available in various oxidation states of manganese (II, III, IV), Mn3O4 (hausmannite) has been found to be an effective and inexpensive catalyst in versatile reactions and we hypothesized that fine MnOx nanostructures can scavenge the photo-generated holes utilizing them to oxidize water.

Ruthenium is one of the versatile noble metals. It has low bulk resistivity and good physical and chemical stability. These properties make ruthenium appropriate for various applications in photocatalyst and semiconductor device technologies. Ru and RuO2consist of 3D structures at the nanoscale and they need a deposition technique that can deliver conformal films on a high aspect ratio framework [4]. Here, Mn-Ru layered double hydroxides synthesized by simple one pot hydrothermal method. The synthesized materials were acts as a very good photocatalyst against Methylene Blue.

13

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The high amount of degradation performs based their wide surface area and electron and hole separation with less activity of recombination.

Experimental.

Materials. MnCl2.4H2O and RuCl3.4H2O were purchased from Aldrich company. Urea and NaOH were purchased from LOBA chemicals. Ethanol and Acetone solvents were purchased from SRL without purification.

Synthesis of Mn-Ru layered double hydroxides. Manganese chloride and Ruthenium chloride was thoroughly dissolved in 100 ml beaker with constant stirring (ratio 1:1). The hydrolyzing agent of 0.1M prepared urea solution was added drop by drop into the metal solution and maintained the base medium using 0.05M NaOH. The mixture of the solution was stirred for 30 min then poured into 100 ml of Teflon steel autoclave. The solution was aged upto 150 oC for 12 h. The product was centrifuged using 4000 rpm, the decanted product was dried an oven at 60 oC. Photocatalytic activity. The photocatalytic activity of the LDH was monitored by the degradation of methylene blue (MB) under irradiation with visible light using a 500 W xenon lamp at room temperature. Typically, a mixture of 50 ml of MB (3.0 mg L-1) solution and 175 mg of catalyst was mixed and vigorously stirred for 30 min in the dark in order to establish an adsorption–desorption equilibrium. The reaction solution was then stirred under visible-light irradiation for several hours.

At given time intervals, ml aliquots were sampled and filtered to remove the catalysts. The filtrate was analyses by measuring the absorbance at 664 nm using a UV-Vis spectrophotometer. A blank reaction was also carried out using the same procedure, but without adding any LDH catalyst.

Results and discussion X-ray diffract meter. Fig. 1a shows the XRD pattern of the prepared Mn-Ru LDH sample. The diffraction peaks indicates the layered material of Manganese and ruthenium was formed as layered material. The cubic structure shows, 2ɵ at 32.0 (111), 37.2 (200), 53.6 (220) corresponding to RuO2 [JCPDS file no # 50-1428]. The cubic structure of the Mn3O4 peaks appeared 2ɵ at 18.03 (101), 2809 (112), 31.0 (200), 36.11 (211), 44.4 (220), 49.9 (204), 50.80 (105), 53.9 (312), 56.30 (303), 580.

(321), 59.9 (224), 64.6 (400) [JCPDS file no # 80-0382]. The well crystalline peaks due to the manganese oxide homogeneously bind with ruthenium oxides particles. This samples exhibits and highly active catalyst against methylene blue photocatalytic degradation under visible light [5].

Fourier Transmission Infrared spectroscopy. The functional groups of the prepared samples revealed from FTIR. Fig. 1b the broad peak and sharp peaks due to –OH stretching and bending vibration of the water molecules at 3404 cm-1 and 1620 cm-1 respectively. The small peak appears at 1434cm-1 indicates the –NH vibration of the present urea. The two sharp intense peaks corresponding to Ru-OH2 and Ru-O appears at 1328 cm-1 and 1256 cm-1 respectively [6]. The Mn-O and Mn-O-Mn stretching vibration peak shows at 600 cm-1 to 1000 cm-1.

Field Emission Scanning Electron Microscope. The prepared Mn-Ru LDH particle size and surface morphology analyzed using FESEM. Fig. 1c clearly tells the rod manganese oxides (Mn3O4) were surrounds on the sphere shape ruthenium oxide. The ruthenium oxides were formed regular sphere shape but manganese oxides formed irregular rod shape. Mn-Ru LDH nuclei well growth in base medium using urea and NaOH. The high surface area and many valence state of manganese oxides, induced to act as a superior catalyst. From FESEM image the particle size is ~ 100-140 nm.

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Fig. 1. (a) XRD pattern of Mn-Ru layered double hydroxides. (b) FTIR spectrum of LDH (c) FESEM image of layered materials (d) EDX spectrum of the LDH sample.

UV-vis spectroscopy. Fig. 2a, indicates the Mn-Ru LDH of the sample analyzed using UV-vis spectroscopy. Finally, in the Mn and Ru hybrid hydroxides, the electronic transitions of the complexes overlay the transitions arising from the inorganic structures. In the UV region, the charge transfer O→M (M = Mn or Ru) of the inorganic layers is superimposed upon the ligand transitions. The absorption band at about 272 nm and 367 nm is according to the direct charge transfer transitions from O2- 2p to Mn2+ 3d. The energy band structures of RuO2-Mn3O4 are generally defined by considering the O 2p orbital as the valence band and the Mn 3d orbital as the conduction band absorption of RuO2-Mn3O4 in the UV-visible region can be ascribed to the photo-excited electron transition from the O-2p level into the Mn-3d level.

Photocatalytic Degradation. The high surface area enables sufficient interaction between the asprepared sphere RuO2-Mn3O4 nanorods and MB dye molecules, thus making the LDH favorable for the rapid degradation of MB dye molecules, which is illustrated in the following sections. MB dye solution is discolored by the as-prepared RuO2-Mn3O4 LDH rapidly, while the color of the MB dye solution shows apparent changes. The results indicate that the layered LDH have much higher oxidation/adsorption ability than general metal oxide nanoparticles. The changes in the UV-Vis spectra demonstrate the discoloration of MB dye solution quantitatively. Fig. 2b shows the successive degradation of MB dye using LDH within 90 min. Fig. 2c&d indicates the efficiency of MB degradation and Percentage of degradation using active prepared LDH layered materials. The possible mechanism of MB dye degradation, the active LDH separates the electron-holes through absorbs the light energy [7]. After electron-holes separation the OH radicals formed, this radical occupy the MB dye sites. Finally, the organic pollutant of MB dye degrades using active prepared LDH layered materials. The degradation percentage reached upto 92%.

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Fig. 2. a) UV-vis spectrum of Mn-Ru LDH, (b) Changes in the UV-Vis absorbance spectra of MB dye after different time intervals at 0-90 min. (c, d) Degradation efficiency of layered LDH materials.

Summary. The Mn-Ru layered double hydroxides prepared via one-pot hydrothermal method. The LDH materials were characterized using many techniques.XRD, FTIR, UV-vis spectroscopy and FESEM carried out for LDH material. The Ru-Mn3O4 LDH have effectively degrades the organic pollutants of MB dye. The degradation performance reached upto 92%.

References [1] T. Baskaran, J. Christopher and A. Sakthivel, RSC Adv., (2015) DOI: 10.1039/c5ra19909c.

[2] T. Dhanasekaran, A. Padmanaban, R. Manigandan, K. Giribabu, S. Praveen Kumar, G. Gnanamoorthy, S. Munusamy, A. Stephen and V. Narayanan. Int. j. App. Eng. Res., (2015) DOI: ISSN 0973-4562, Vol 10, No 91.

[3] P. R. Chowdhury and K.G. Bhattacharyya, RSC Adv., (2016) DOI: 10.1039/C6RA24288J. [4] A. Nakada, T.Nakashima, K. Sekizawa, K. Maeda and O. Ishitani, Chem Sci., (2016) DOI: 10.1039/C6SC00586A. [5] C. H. Choi, S. H. Park and S. I. Woo, Phys. Chem. Chem. Phys., (2012) DOI: 10.1039/C2CP24128E. [6] S. Sambasivam, G. J. Li, J. H. Jeong, B. C. Choi, K. T. Lim, S. S. Kim and T. K. Song, J. Nanopart. Res., (2012) DOI: 10.1039/c4ce02390k.

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[7] M. Zaied, S. Peulon, N. Bellakhal, B. Desmazieres and A. Chausse, Appl. Catal., B, (2011) DOI: org/10.1016/j.apcatb.2010.10.014.

Cite the paper T. Dhanasekaran, A. Padmanaban, G. Gnanamoorthy, R. Manigandan, S. Praveen Kumar, S. Munusamy, A. Stephen, V. Narayanan (2017). Preparation and Optical Studies of Layered Double Hydroxides for Photo Catalytic Degradation of Organic Dyes. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.97.8.19

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Photocatalytic Activity of Biosynthesized Silver Nanoparticle from Leaf Extract of Justicia Adhatoda14 Latha D.1, C. Arulvasu2, P. Prabu2, V. Narayanan3 1 – Department of Inorganic Chemistry, University of Madras, Guindy campus, Chennai, India 2 – Department of Zoology, University of Madras, Guindy campus, Chennai, Tamil nadu, India 3 – Department of Zoology, Pachaiyappa’s college for men, Kanchipuram Tamil nadu, India DOI 10.2412/mmse.81.72.41 provided by Seo4U.link

Keywords: green synthesis, justicia adhatoda, leaf extract, silver nanoparticle.

ABSTRACT. In the present study, we investigate synthesis of silver nanoparticles from leaf extract of Justicia adhatoda.

The synthesized silver nanoparticles showed the Surface Plasmon Resonance peak at 425 nm. The XRD analyzed intense peaks corresponding to (111), (200), (220) and (311) bragg’s reflection based on the face centered cubic structure of silver nanomaterial. In addition, spherical shape topography of nanoparticle was observed by HRSEM and EDAX indicates the presence of silver. Further, biogenic silver nanoparticles are proved its efficient photocatalytic activity against methyl orange dye.

Introduction. Nanoparticles are extremely small in size and high surface to volume ratio, which alter their chemical and physical properties compared to bulk of the same chemical composition [1]. Owing to these beneficial properties, nanomaterial have potential applications in drug delivery, biomedical, electronics, catalysis, photonics, chemical sensing and imaging optics [2]. Various techniques are available to synthesis of nanoparticles like as physical, chemical and biological methods. In green approach, the rate of formation of metal nanoparticles has been faster and eco-friendly compared with other methods [3]. The medicinal plant of J. adhatoda contain bioactive compounds, such as essential oil, quinazoline and alkaloids etc are used for cold and cough etc[4]. Especially, several literature surveys are documented to synthesize of nanoparticles from various parts of plant, Leaf extract of Albizia adianthifolia and which is used for A549 lung cell line activity [5].Gold nanoparticles were synthesized using Acacia nilotica (Babool) leaf extract exhibited remarkable study of its catalytic properties in a reduction reaction. Synthetic organic dyes are widely used in the textile industry. The removal of such kind of non-biodegradable dyes make crucial ecological problem. Numerous techniques are available to remove such kind of dyes, but in recent scenario metal nanoparticle were used to recover this problem. Beside, this work describes biosynthesized silver nanoparticle are treated to degrade the methyl orange by visible illumination.

Materials and methods Synthesis of silver nanoparticles. The J.adhatoda plant is collected from local area at Theni district, Tamilnadu. Approximately weighed 10 g of leaf powder are added with 100 ml of double distilled water and boiled it for 20-25 min further centrifuged at 5000 rpm for 15min then collect the supernatant extract. One ml of aqueous extract was poured into 9 ml of 1×10−3M silver nitrate solution and incubates for 25 min, color change was monitored visually (Fig.1).

Characterization of nanoparticles. The bioreduction of Ag+ ions was monitored by using spectra of synthesized silver nanoparticle were recorded by UV-visible spectrophotometer (Perkin-Elmer 14

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Lamda-45). The X-ray diffraction pattern of powdered nanoparticle was obtained using Enraf Nonius CAD-4 model of XRD with CuKÎą radiation (k=0.154060 nm). The morphological observations of nanoparticle were found by HRSEM with EDX study was carried out on Hitachi-S4800.

Photo catalytic activity. In this study, photo catalytic activity of green synthesized silver nanoparticle was evaluated by degradation of methyl orange dye under light irradiation.

Approximately weighed 10 mg of the silver nanoparticles was mixed with 50 ml of Methyl orange dye solution (10 mg/L). A control was maintained without adding silver nanoparticles. This mixture is kept under magnetically stirrer in dark condition to maintain equilibrium constant. The suspension was then exposed under mercury lamp light irradiation with constant stirring. About 3ml of suspension were taken from the reactor at regular intervals and centrifuged it. The supernatant solution was consequently measured using UV-vis (Perkin-Elmer Lamda-45) spectrophotometer.

Results and discussion Contact time. Biologically synthesize of silver nanoparticles was achieved with the help of bioactive components of leaf extract. About 10 ml of aqueous extract was mixed with 100ml of silver nitrate (1mM) solution were observed visually, the pale yellow color solution became dark brown color due to excitation of Surface Plasmon Resonance vibrations of metal nanoparticles, which indicate formation of silver nanoparticles. The absorbance of SPR peak at 425 nm increases with the escalating time, in proper intervals (Fig.1).These results are correlated with literature of Gliricidia sepium [6].

Effect of temperature. The temperature acts as an important role to affect the synthesis of silver nanoparticles was studied from 30-700 C as shown in Fig.2. The intensity of SPR peak of silver nanoparticle was examined at 425nm in various temperatures. From this observation that the SPR peak sharpness is mounting with increasing of temperature respectively. The recent report were also indicated the formation of nanoparticle is fast and its size is decreases with increasing temperature, in olive leaf extract [7] due to increased level of kinetic energy, while Ag+ ion are rapidly stimulated as the result of decreasing particle size, which are concluded smaller particle and anisotropy distribution are possible at high temperature. Therefore, the temperature is crucial factor for which influence the particle size of nanoparticle.

Fig. 1. Synthesis of silver nanoparticle from J. adhatoda with silver nitrate solution by various time intervals.

Fig. 2. Effect of temperature Fig. 3. Effect of pH silver on silver nanoparticles. nanoparticle.

Effect of pH. Formation of nanoparticles is affected by another significant parameter is pH . The effect of pH on stability of the synthesized silver nanoparticles was studied at different range of pH from 8 to 12.The results showed that the rate of silver nanoparticles synthesis increases with increasing pH up to12. The maximum sharp peaks are obtained at pH 9-12 similarly [8]. The positive MMSE Journal. Open Access www.mmse.xyz

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result for synthesis of silver nanoparticles at pH 10 has given and sharp peaks, it indicates may nanoparticle may be spherical shape. In addition, the intensity of peak increases with increasing pH refers with result of gradual red shift at 423 to 426 nm (Fig.3) [9]. were also reported like as agglomeration of nanoparticles took place at higher pH Biosynthesized nanoparticle size is demonstrating that the alkaline pH is more good turn for the synthesis of silver nanoparticles.

The size and structural morphology of silver nanoparticles, which is clearly indicates spherical shape of silver nanoparticle by HRSEM (Fig. 4). The HRSEM images were illustrated that all silver nanoparticles were well separated and there were no aggregations. The EDAX spectrum has given strong signals in the region of 3 keV, assures the significant presence of silver atoms weight (89.68%) and 10.32% weight of oxygen and potassium are also present in the sample. The strong signal shows due to the excitation of SPR of silver nanoparticle (Fig. 5).

Fig. 4. HRSEM image of AgNps.

Fig. 5. EDX of AgNps.

Fig. 6. XRD pattern of silver nanoparticle.

The crystalline nature of silver nanoparticles was confirmed by XRD pattern as shown in the Fig. 6.

The diffraction peaks at 2 theta angles of XRD pattern of AgNps, which represents four peaks at 38.1°, 44.09°, 64.36° and 77.29°are assigned to the face centered cubic units of silver which can be MMSE Journal. Open Access www.mmse.xyz

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indexed to (111), (200), (220) and (311) respectively. In addition, unassigned peaks at 2θ values of 27.96°, 32.28°, 46.260 and 54.790 due to amorphous and organic compounds are present in biosynthesized silver nanoparticles, apart from this result of XRD [10] were also reported the same.

The XRD patterns were observed sharp peaks, which indicated good crystalline nature of silver nanoparticles.

Photocatalytic degradation. The photocatalytic activity of silver nanoparticle was analyzed by photo degradation of methyl orange dye act as a model.An additional vital application of silver nanoparticle is in the domain of photocatalytic degradation, which has become an ever more effective, ecofriendly with low cost by mean of eliminate toxic organic materials from the ecosystem. Methyl orange is an anionic organic dye which has an azo (N=N) and diethyl amine group and therefore, it is risky for livelihood and has to be degraded from the nature (11). In this study, the degradation activity of synthesized nanomaterial was evaluated against methyl orange. The UV-vis absorbance peak of methyl orange dye at 460 nm is recorded. The result of absorbance peak is gradually decreased with increasing for period of 4.30 hr incubation (Fig.7.)

Fig. 7. UV Spectra indicates photocatalytic degradation of methyl orange with reaction time

Fig. 8. % of dye degradation at exposure time

Percentage of dye degradation was calculated by the following formula: Dye degradation (%) =

đ??ś0 − đ??śđ?‘Ą đ??ś0

Ă— 100

where C0 is the initial concentration of methyl orange, Ct=concentration of dye at t-time.

The concentration is directly proportional to the absorbance of dye degradation. The result showed the percentage of dye degradation was initially low and subsequently increased with increasing exposure time (Fig. 8.)[12]. The degradation is initiated by photons of sunlight strike on the surface of silver nanoparticle, as it should be excitation of conduction electrons on surface of silver nanoparticle as a result of SPR effect. Therefore, this article is designed for degradation of organic dyes under visible light irradiation in the presence of biogenic nanoparticles, which is very stable and efficient photocatalysts.

Summary. In conclusion, we report a simple speedy and efficient biosynthesis of silver nanoparticles using J.adhatoda leaf extract. The stability of nanoparticles are discussed by temperature and pH are characterized by UV-Vis, morphology study of nanoparticles by HRSEM with EDX spectrum andXRD. This green method deals with synthesis of silver nanoparticles can potentially active material and then it applied to photocatalytic activity of degrade against organic dyes were proved.

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Refference [1] S.Iravani, H. Korbekandi, S.V.Mirmohammadi, B.Zolfaghari Synthesis of silver nanoparticles: chemical, physical and biological methods. Research in Pharmaceutical Sciences, (2014). 9, 385– 406.

[2] S. Ahmed, M. Ahmad, B. L.Swami, S. Ikram, A review on plants extract mediated synthesis of silver nanoparticles for antimicrobial applications: A green expertise. Journal of Advanced Research, (2016). doi:10.1016/j.jare.2015.02.007.

[3] Shashi Prabha Dubey, Manu Lahtinen, Mika Sillanp Green synthesis and characterizations of silver and gold nanoparticles using leaf extract of Rosa rugosa Colloids and Surfaces A: Physicochem.

Eng. Aspects, (2010). 364 34–41 [4] Sandeep Dhankhar, Ramanjeet Kaur, S. Ruhil, M. Balhara, Seema Dhankhar, A. K. Chhillar A review on Justicia adhatoda: A potential source of natural medicine African Journal of Plant Science, (2011). Vol. 5 (11), pp. 620-627, 6 [5] R.M. Gengan, K. Anand, A. Phulukdaree, A. Chuturgoon A549 lung cell line activity of biosynthesized silver nanoparticles using Albizia adianthifolia leaf Colloids and Surfaces B: Biointerfaces 105, (2013). 87– 91 [6] R.W. Rout, J.R. Lakkakula, N.S. Kolekar, V.D.Mendhulkar, S.B.Kashid, Phytosynthesis of silver nanoparticle using Gliricidia sepium (Jacq.). Current Nanoscience, 5, (2009). 117-122 [7] Kantrao Saware, Balaji Sawle, Basavraja Salimath, Kamala Jayanthi, Venkataraman Abbaraju biosynthesis and characterization of silver nanoparticles using ficus benghalensis leaf extract, pissn: 2014.s2321-7308 [8] Aparajita Verma, Mohan Singh Mehata Controllable synthesis of silver nanoparticles using Neem leaves and their antimicrobial activity Journal of Radiation Research and Applied Sciences 9, (2016).

109-115.

[9] Ravichandran Veerasamy, Tiah Zi Xin, Subashini Gunasagaran, Terence Foo Wei Xiang, Eddy Fang Chou Yang, Nelson Jeyakumar, Sokkalingam Arumugam Dhanaraj Biosynthesis of silver nanoparticles using mangosteen leaf extract and evaluation of their antimicrobial activities Journal of Saudi Chemical Society, (2011). 15, 113–120 [10] A.M.Awwad, N.M. Salem, A.O. Abdeen AO. Green synthesis of silver nanoparticles using carob leaf extract and its antibacterial activity. Inter J Ind Chem, 2013.1:1-6.

[11] Kaushik Roy, C.K. Sarkar, C.K. Ghosh Photocatalytic activity of biogenic silver anoparticles synthesized using potato (Solanum tuberosum) infusion Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 146 (2015) 286–291 [12] M. Vanaja, K. Paulkumar, M. Baburaja, S. Rajeshkumar, G. Gnanajobitha, C. Malarkodi, M. Sivakavinesan and G. Annadurai, Degradation of Methylene Blue Using Biologically Synthesized Silver Nanoparticles, Bioinorganic Chemistry and Applications Volume 2014.

Cite the paper Latha D., C. Arulvasu, P. Prabu, V. Narayanan (2017). Photocatalytic Activity of Biosynthesized Silver Nanoparticle from Leaf Extract of Justicia Adhatoda. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.81.72.41

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Visible Light Photocatalytic Property of Ag/TiO2 Composite15 A. Padmanaban1, T. Dhanasekaran1, S. Praveen Kumar1, G. Gnanamoorthy1, S. Munusamy1, A. Stephen2, V. Narayanan1,a 1 – Department of Inorganic Chemistry, University of Madras, Chennai, India 2 – Department of Nuclear Physics, University of Madras, Chennai, India a – vnnara@yahoo.co.in DOI 10.2412/mmse.97.67.748 provided by Seo4U.link

Keywords: Ag/TiO2, photo catalyst, methylene blue.

ABSTRACT. Ag/TiO2 composite was synthesized by thermal decomposition method using tetraethyl orthotitanate, silver nitrate and hexamine as a surfactant. The synthesized materials were confirmed by X-ray diffraction. The morphology of the sample was investigated by field emission scanning electron microscope (FE-SEM). The morphology of the Ag/TiO2 composite was found to be the cubic microstructure with complete decoration of Ag nanoparticles over the TiO 2 surface uniformly. The optical property of the photo catalyst was observed from UV-vis spectroscopy. The photocatalytic activity of the Ag/TiO2 composite was investigated by the degradation of a methylene blue under visible light irradiation. The observed results showed that Ag incorporation enhance the visible-light adsorption and improved the photocatalytic efficiency of TiO2 composite significantly under visible light.

Introduction. Recent years we are facing number of environmental issues related to the energy disaster, water pollutions, etc. To overcome this problem the semiconductor materials have been used as a photocatalyst for degradation of organic pollutants, hydrogen production from water splitting and dye sensitized solar cells. Among various semiconductor oxides titanium dioxide (TiO2) is one of the well-known wide band gap n-type semiconductor materials. Since last decade, TiO2 has been widely investigated for photocatalytic degradation of harmful organic pollutants from the waste water due to its nontoxicity, low cost and excellent chemical stability. Because of its limited visible-light absorption nature and low photocatalytic efficiency their practical application is limited and need to be improved. Consequently, the surface modification in TiO2 lattice such as doping of various transition metals, noble metals and combine with narrow band gap semiconductor materials could make it as more sensitive to visible light and improve the photocatalytic efficiency. In general, the noble metals Pt, Pd, Rh, Au and Ag are having superior photocatalytic efficiency but their high cost limit their large scale applications. Recently, TiO2 with noble metals combination have received more attention towards photodegradation. Among them the above noble metals Ag is the less expensive and can be used as visible sensitive material for photocatalytic activity. Since the surface loading of metallic Ag nanoparticles on different semiconductors would be an effective way to improve the photocatalytic activity [1, 2]. Hence, in this work the metallic Ag nanoparticle has been incorporated into TiO2 matrix and used as visible photo catalyst material with improved degradation efficiency.

Here, the Ag nanoparticles are readily available to accept photogenerated electrons from excited semiconductor which facilitates dioxygen reduction and thereby Ag/TiO2 showed an enhanced UVlight photocatalytic activity for the decomposition of organic substances.

Experimental.

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Materials. Analytical reagents of Tetraethyl orthotitanate, Silver nitrate and Hexamine were used as received without further purifications. Ethanol and double distilled water were used as the solvents.

Ag/TiO2 was synthesized by simple thermal decomposition method. Typically, 2.4 ml (0.01 M) of Tetraethyl orthotitanate was dissolved in 30 ml of ethanol and 0.01 M of silver nitrate dissolved in 50 ml of double distilled water and it was slowly added to reaction mixture. 2.5g of hexamine was added to the above mixture and the solution was stirred for 3h in 70 ˚C. The final product was centrifuged and washed with several times by water and ethanol. The synthesized materials was dried in room temperature and calcined at 450 ˚C. Results and Discussion. The crystalline phase of Ag/TiO2 composite are confirmed by XRD pattern as shown in Fig.1. (a). The observed XRD pattern clearly evidences the formation of mixed phase of face centered cubic Ag and rutile TiO2. Typical 2θ˚ values at 38.1˚, 44.3˚, 64.4˚ corresponds to the metallic Ag in the face centered lattice and it is well matched with JCPDS card (No.65-2871).

Similarly, the observed 2θ˚ values are 27.3˚, 36.0˚, 41.1˚, 54.2˚, 56.5˚ and 68.8˚ corresponds to tetragonal phase and can be indexed to the JCPDS card (No. 77-0441). And no other secondary phase is observed in the XRD pattern which confirms that phase purity of the composite.

b)

a)

Fig. 1. (a) Shows the XRD pattern and (b) FTIR spectrum of Ag/TiO2.

The FTIR spectrum of the prepared Ag/TiO2 was shown in Fig.1 (b). The strong absorption band at 400 cm-1 to 700cm-1 corresponds to the Ti-O stretching vibrations [3]. The band appearing at 1610 cm-1 is attributed to the bending vibrations of O-H. The broad absorption at 3464 cm-1 corresponds to the O-H stretching vibrations due to absorption of water molecules from the moisture.

The optical properties of prepared sample were measured using UV-Vis Diffuse reflectance spectroscopy. Fig.2 (a) displays the UV-Vis spectrum of Ag/TiO2 composite. The broad absorption in visible light is attributed to the surface plasmon resonance (SPR) confirming the formation of Ag nanoparticles [4]. The band gap energy can be estimated by following equation. αhυ = A (hυ − Eg)n/2 where α represents the absorption coefficient, υ is the light frequency, Eg is the band gap energy, A is a constant and n depends on the characteristics of the transition in a semiconductor.

The band gap plot of (αhυ)2 vs hυ of Ag/TiO2 shown in Fig. 2. (b), the calculated band gap value for Ag/TiO2 is 2.8eV. MMSE Journal. Open Access www.mmse.xyz

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b)

a)

Fig.2 (a) shows the DRS UV-Vis spectrum, (b) band gap plot of (αhυ)2 vs hv of Ag/TiO2.

The surface morphology of the Ag/TiO2 composite is analyzed by field emission scanning electron microscope. As shown in (Fig. 3), the surface of theTiO2 is found to be cube like morphology and size of the cube is ~100 to 200nm. The small Ag nanoparticles uniformly dispersed on the surface of the TiO2 cubes. The size of the Ag nanoparticles is ~5nm to 10nm. The EDS spectrum confirms the presence of primary elements of Ti, Ag and O without any impurities.

Fig. 3. shows the FESEM images and Edax spectrum of Ag/TiO2.

Photocatalytic activity. The photocatalytic activity of the prepared materials was irradiated under visible light degradation of methylene blue. The photo chamber was designed with a 500 W xenon lamp. The photocatalytic degradation of methylene blue was examined by taking 100ml of reaction mixture containing 0.001M of methylene blue and 0.02g of Ag/TiO2. The prepared solutions were irradiated under visible light for 2 h. The concentration of the solution taken out from reaction mixture at different time intervals. The photocatalytic degradation solution was analyzed by UV-Vis spectroscopy. Fig. 4 shows the UV-Vis absorption spectrum of methylene blue under visible light irradiation time in presence of Ag/TiO2. As shown, the intensity of the methylene blue peak decreases with increasing the time, meantime the 85% of methylene blue degraded in 60 min under visible light degradation. Ag/TiO2 material can absorb and degrade the methylene blue solution in visible light degradation.

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Ag nanoparticles are photoexcited due to the plasmon resonance. Consequently, the photoexcited electrons are migrated from the surface of the Ag nanoparticles to the conduction band of TiO 2. In meantime, due to crystallinity of the Ag nanoparticles, the electron migration is suppressed so as to reduce the recombination of e-/h+ pairs. The electrons which accumulate on the surface of TiO2 are then scavenged by dissolved oxygen molecules in water to yield highly oxidative species such as the superoxide radical anion (O2-.) and hydroxyl radical (.OH), which can degrade the organic dyes effectively[1, 5, 6]. These oxidative species can easily diffuse out of the composite to attack the MB dye.

Fig. 4 shows the UV-Vis absorption spectrum of methylene blue under visible light irradiation time in presence of Ag/TiO2.

Summary. The Ag/TiO2 material was synthesized by simple thermal decomposition method and investigated for MB photodegradation. The Ag/TiO2 composite formation and microstructure was confirmed by XRD pattern and SEM analysis. It was observed that Ag decorated nano/micro cubes of TiO2 microstructure. The estimated band gap value for prepared composite materials is about 2.8eV. The enhanced photocatalytic activity was observed for Ag/TiO2 under visible light towards the degradation of methylene blue, which is mainly due to the surface plasmon resonance based recombination reaction between Ag and TiO2. From this investigation, it can be concluded that Ag/TiO2 composites could be better choice of photocatalyst material for MB degradation.

References [1] Chunyan Su, Lei Liu, Mingyi Zhang, Yue Zhang and Changlu Shao “Fabrication of Ag/TiO2 nanoheterostructures with visible light photocatalytic function via a solvothermal approach” CrystEngComm, (2012), 14, 3989–3999. [DOI: 10.1039/c2ce25161b].

[2] Rui Liu, Ping Wang, Xuefei Wang, Huogen Yu and Jiaguo Yu. “UV and Visible Light Photocatalytic Activity of Simultaneously Deposited and Doped Ag/Ag (I)-TiO2 Photocatalyst” J. Phys.Chem.C, (2012), 116, 17721 – 17728. [DOI:10.1021/jp305774n].

[3] Yanfeng Chen, Weixin Huang, Donglin He, Yue Situ and Hong Huang “Construction of Heterostructured g-C3N4/Ag/TiO2 Microspheres with Enhanced Photocatalysis Performance under Visible-Light Irradiation” ACS Appl. Mater. Interfaces (2014), 6, 14405 – 14414.

[DOI:10.1021/am503674e]

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[4] Di Wang, Zhong-Hua Zhou, Huan Yang, Kai-Bo Shen, Yue Huang and Shirley Shen “Preparation of TiO2 loaded with crystalline nano Ag by a one-step low-temperature hydrothermal method” J. Mater. Chem., (2012), 22, 16306–16311 [DOI: 10.1039/c2jm16217b] [5] Thanh-Dong Pham, Byeong-Kyu Lee and De Pham-Cong, “Advanced removal of toluene in aerosol by adsorption and photocatalytic degradation of silver-doped TiO2/PU under visible light irradiation” RSC Adv. (2016) 6, 25346–25358. [DOI: 10.1039/c5ra23786f] [6] P.V.R.K. Ramacharyulu, J. Praveen Kumar, G.K. Prasad and A. R. Srivastava, “Synthesis, Characterization and Photocatalytic activity of Ag-TiO2 Nanoparticulate film” RSC Adv. [DOI: 10.1039/b000000x]

Cite the paper A. Padmanaban, T. Dhanasekaran, S. Praveen Kumar, G. Gnanamoorthy, S. Munusamy, A. Stephen, V. Narayanan (2017). Visible Light Photocatalytic Property of Ag/TiO 2 Composite. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.97.67.748

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Design and Simulation of Cantilever Based MEMS Bimorph Piezoelectric Energy Harvester16 G.K.S. Prakash Raju1, P. Ashok Kumar1, Vanaja Aravapalli2, K. Srinivasa Rao3,a 1 – M. Tech, KL University, Dept of ECE, Green Fields-522502, India 2 – Tirumala Engineering College, Dept of AS & H, Narasaraopeta-522601, India 3 – Professor & Head of MERG, KL University, Dept of ECE, Green Fields-522502, India a – gorantlaraju02@gmail.com, drksrao@kluniversity.in DOI 10.2412/mmse.16.9.490 provided by Seo4U.link

Keywords: cantilever beam, MEMS, Piezo-electric bimorph, power consumption, proof mass.

ABSTRACT. Piezoelectric generators designed for harvesting vibratory energy are usually based on mechanical resonators, cantilever beams for instance, able to effectively transmit ambient energy to the active materials. In this paper, we have designed and simulated a rectangular piezoelectric energy harvester, which consists of cantilever, proof mass, piezoelectric bimorph with different lead-zirconate-titanate (PZT) materials (PZT-5A, PZT-5H, PZT-5J, PZT-7A, PZT8) using COMSOL Multiphysics, (Finite Element Analysis) FEM Tool. The performance of the device mainly engrossed with the power-optimization by varying the materials and varying the dimensions of the proof mass and dimensions of piezoelectric bimorph. This model describes the consumption of the power dependence with the mechanical acceleration, frequency response and helps in the load behaviour for power optimization. The designed device will be used in aircraft engine and car engine. We observed from the simulated results, a rectangular piezoelectric energy harvester with PZT5H material gives optimal power. Comparable with the conventional devices, MEMS based energy harvesting device is optimized with 33.3% of power.

Introduction. Now-a-days, researchers are mainly concentrating on the reduction in size, area, cost and power consumption of sensors and complementary metal oxide semiconductor (CMOS) electronic circuitry research lines on battery recharge via available power sources. Energy harvesters can be operating as battery rechargers in various environments, such as wireless communication systems, wireless sensors, houses and military applications. The possibility to bypass replacing exhausted batteries is highly attractive for wireless networks [1-2], due to maintenance of battery check and restoration are relevant.

There are several mechanisms for converting vibrational mechanical energy to electrical energy. The most important are electrostatic, electromagnetic and piezoelectric. Among the three mechanisms, piezoelectric transduction principle offers higher power density compared to electrostatic transduction and electromagnetic transduction. A majority of current research has been done on piezoelectric conversion due to the low complexity of its analysis and fabrication. For electrostatic transduction principle, which initially we need to provide the polarization and for electromagnetic transduction principle which are having some limitations in the magnet miniaturization [3]. Marin et al. have discussed about the scaling of output power as a function of effective material volume (v) for different mechanisms. By taking account into some equations for the respective conversion mechanisms, the output power of the electromagnetic mechanism is proportional to v2, while the piezoelectric mechanism is proportional to v3/4. Thus, at smaller scales, the piezoelectric mechanism becomes more attractive as compared to electromagnetics.So, piezoelectric is well suited than electrostatic and electromagnetic transduction principle for MEMS implementation [4]. Piezoelectric 16

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energy harvester generators produces very low power in the range of milliwatts or microwatts due to the mechanical properties. Here, stress is very large, strain is small and piezoelectric materials may work up to hundreds of kilohertz. The mechanical vibrations of the cantilever beam are in the range of 0.1 Hz – 1 kHz . In this paper, the design and simulation of a piezoelectric energy harvester based MEMS sensor has been performed. The simulations should be performed by varying the materials and by varying dimensions of piezoelectric structure components. From all the designs performed, the PZT-5H material energy harvester gives optimal power.

Theory: Piezoelectric Generator. A majority of the energy harvesters has been designed and simulated with piezoelectric materials i, e Lead zirconate titanate (PZT) and Aluminium nitride (ALN) but most of the researchers has been using PZT because of the high piezoelectric coefficent and dielectric constant, it produces optimal power and less will be used Aliminium nitride (ALN) because of the material deposition and compatable with CMOS fabrication process. The materials will be chosen according to the users requirements. The energy flow diagram for the design structure as shown below.

Environment Excitation Energy

Mechanical Vibrational Energy

Mechanical – Electrical Transduction Loss

Mechanical Loss 

Unmatched mechanical impedance



Damping factor

Electrical Energy Output

Electrical Energy Generated



Coupling factor



Piezoelectric coefficient

Electrical Loss 

Unmatched electrical impedance

Fig. 1. Energy flow of piezoelectric generator.

The source excitation is converted into cyclic oscillations through mechanical assembly due to this there is a loss of some energy through unmatched mechanical impedance, damping and backward reflection followed by the cyclic mechanical oscillations are converted into cyclic electrical energy through the piezoelectric effect. Due to this there is a loss of some energy through electromechanical losses of piezoelectric material. Electromechanical coupling factor (k) represents the efficiency of the conversion process from mechanical energy to electrical energy and then followed by generated electrical energy is conditioned through rectification and dc/dc conversion. This step results in some losses due to power consumption by the circuit.

Designing of Device Structure. This model analyses a simple “seismic” energy harvester, which is designed to generate electrical energy from the local variations in acceleration. The cantilever based energy harvester has two ends. One end is fixed with piezoelectric bimorph and other end is connected to vibrating machinery with proof mass. To ensure the same voltage on the external electrodes of the cantilever beam, even though the above and below the stress is of opposite sign with the help of applied load. The below conFig.uration needs, the bimorph has ground electrode inside within it and

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coincident with neutral plane of the beam. The schematic structure of of the piezoelectric energy harvester, dimensions and materials of the designed structure are tabulated as shown below.

Table. 1. Dimensions, Materials of the designed structure Component

Material

Dimensions (mm)

Colour

Anchor or Die

Structural Steel

1×1

Orange

Electrodes

Lead_Zirconate_Titanate (PZT-5A)

21×0.06

Green

Piezoelectric Bimorph

Structural Steel

21×0.04

Orange

Proof or Seismic Mass

Structural Steel

4×1.7

Orange

Proof Mass Piezoelectric Bimorph Bimorph

Electrodes Anchor or Die Fig. 2. Schematic structure of energy harvester.

Principle of operation. For a typical energy harvester, anchor is fixed at one end of cantilever while other end of the cantilever is free to move with proof mass. A input force ( in the form of load) is applied at a one end of cantilever, beam will vibrates up and down due to electrostatic force and a mechanical energy is produced. The produced mechanical energy is converting in to the electrical energy with the piezoelectric principle. A voltage (V) will be measured at the two electrodes of the beam. The power (P) can be calculated as P = V2rms/R = V2/2R

(1)

where V – voltage induced; R – load resistance Results and Analysis. This designed model performs three analysis of the piezoelectric energy harvester are power and DC voltage as a function of frequency, electrical load and acceleration. First, the power output is shown as a function of frequency with a fixed electrical load. Then the DC voltage is shown linear as a function of acceleration and at last the power output is analysed as a function of electrical load. From the analysis of the device, the input mechanical power and output electrical power is plotted and peak voltage is induced across the piezoelectric bomorph (in V) at 77Hz with

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respect to frequency, when the energy harvester is excited by a sinusoidal acceleration with electrical load of 12kΩ.

Fig. 3. Mechanical, electrical power (mW) and peak voltage (V) w.r.t the frequency.

The input mechanical, electrical power and DC voltage is harvested from the device as a function of electrical load resistance at an acceleration of 1 g oscillations at 77 Hz. The peak in energy harvested corresponds to an electrical load of 12kΩ.

Fig. 4. Power harvested from the device as a function of electrical load resistance at an acceleration of 1 g oscillating at 77 Hz. The DC voltage and mechanical/electrical power output versus the magnitude of the mechanical acceleration at a fixed frequency of 77 Hz with a load impedance of 12 kΩ. The voltage increases linearly with the load, while the harvested power increases quadratically.

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Fig. 5. DC voltage, mechanical and electrical power verses acceleration at a fixed frequency of 77 Hz with a load impedance of 12 KΩ.

The simulation results with different materials is shown below.

Table 2. Comparison of energy harvester simulation results with various materials.

Material

PZT-5° PZT-5H PZT-5J PZT-7A PZT-8

Frequency response M.P (mW) 1.3 0.8 1.2 3.4 1.7

E.P (mW) 1.3 0.8 1.2 3.4 1.7

Voltage (Volts) 5.5 4.5 5.3 9 6.5

Load dependence M.P (mW) 1.4 0.8 1.2 2.9 1.7

E.P (mW) 1.4 0.8 1.2 2.6 1.7

Voltage (Volts) 6.2 7 7 8 8

Acceleration dependence M.P (mW) 5 3.6 4.7 9 5.8

E.P (mW) 5 3.6 4.7 8.6 5.8

Voltage (Volts) 10 9.5 10 14 12.5

M.P – Mechanical power in, E.P – Electrical power out.

From the above table, when compared to all other materials PZT-5A (Lead-zirconate-titanate) material gives optimal mechanical and electrical power.

The energy harvester device is mainly depends on two parameters namely, load resistance and acceleration. Based on these parameters power can be calculated. Here we have shown the comparsion between theoritical and simulated results.

Table 3. Theoritical and simulation calculations of the electrical power at 12 KΩ Frequency 60 65 70 72 74 77 80 85 90

Power (mW) Theoretical simulation 0.03 0.04 0.06 0.09 0.20 0.23 0.32 0.37 0.58 0.60 0.86 0.90 0.54 0.58 0.17 0.18 0.06 0.0

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Fig. 6. Comparing theoritical and simulated results of the energy harvester.

Summary. In this paper, the design and simulation of a piezoelectric energy harvester based MEMS sensor has been performed. Here, the design and simulation has been observed by varying the materials and by changing the dimensions of piezoelectric bimorph and dimensions of proof mass of the rectangular cantilever beam. From all the above designs performed, the PZT-5H material energy harvester gives optimal power. The optimal power will be 0.9 mW at 77 Hz References [1] Kim Sang-Gook, Shashank Priya, Isaku Kanno. “Piezoelectric MEMS for Energy Harvesting.”

MRS Bulletin 37.11 (2012): 1039–1050. Web. © Materials Research Society 2012.

[2] Jornet, J.M.; Akyildiz, I.F. Joint energy harvesting and communication analysis for perpetual wireless nanosensor networks in the terahertz band. IEEE Trans. Nanotechnol. 2012, 11, 570–580.

[3] Renato Caliò, Udaya Bhaskar Rongala, Domenico Camboni, Mario Milazzo, Cesare Stefanini, Gianluca de Petris and Calogero Maria Oddo. “Piezoelectric Energy Harvesting Solutions.” Sensors 2012 [4] Bridget Cunningham, Optimizing the Power of a Piezoelectric Energy Harvester, www.comsol.co.in/blogs/optimizing-the-power-of-a-piezoelectric-energy-harvester/

Cite the paper G.K.S. Prakash Raju, P. Ashok Kumar, Vanaja Aravapalli, K. Srinivasa Rao (2017). Design and Simulation of Cantilever Based MEMS Bimorph Piezoelectric Energy Harvester. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.16.9.490

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Investigation of Spinel Structure ZnFe1.8La0.2O4 Nanoparticles Synthesized by PEG Assisted Wet Chemical Method17 M. Shoba1, S. Kaleemulla1,a 1 – Center for Crystal Growth, SAS, VIT University, Vellore, Tamilnadu, India a – skaleemulla@gmail.com DOI 10.2412/mmse.87.32.410 provided by Seo4U.link Keywords: La3+substituted zinc ferrite, a spinel structure, structural and optical properties, PEG, hydrothermal method.

ABSTRACT. Rare-earth substituted zinc ferrite nanoparticles with the chemical formula ZnFe1.8La0.2O4 have been successfully synthesized via a polyethylene glycol (PEG) assisted facile hydrothermal route. The influence of La substituted zinc ferrite nanoparticles was investigated using various techniques. The structure, crystallite size, functional group, optical properties, surface morphology and elemental analysis of synthesized sample were analyzed by Powder Xray diffraction (PXRD), Fourier transform spectroscopy (FTIR), UV–visible spectroscopy, scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The PXRD pattern analysis indicated the formation of a simple cubic spinel structure. Also, using Debye-Scherrer equation, the average crystallite size of the particles was calculated to be about 15.06 nm. FT-IR studies confirmed the tetrahedral and octahedral sites in its cubic spinel structure. UV–visible spectrum of the sample showed absorbance peak in the wavelength range between 200- 800 nm. The optical energy band gap was calculated to be 2.03 eV. Surface morphology analysis by Scanning Electron Microscope (SEM) shows the formation of ununiformed agglomerated nanoparticles. Elemental composition of synthesized sample was obtained from combined SEM–EDX measurements which confirmed the presence of Zn, Fe, La and O ions.

Introduction. At present, magnetic nanomaterials are considered very attractive and exhibit distinct advanced physical and chemical properties due to their small size and enhanced surface to volume ratio in comparison to their bulk counterparts [1]. From the diverse forms of magnetic nanomaterials, transition-metal oxides based ferrites have received considerable attention owing to their interesting magnetic properties, high electrical resistivity, mechanical hardness and excellent chemical stability.

All of these properties apply to many technological applications in various fields of magnetic and optical materials, semiconductors, pigments, catalysts and biomedical applications [2], [3]. Among these ferrite materials, spinel type ZnFe2O4 has gained the significant attention of both researchers and scientific research community because of their potential applications such as spintronics, magnetic resonance imaging (MRI), high-density data storage, photocatalyst, gas sensors, water splitting for hydrogen energy production, electronic devices, transformers and so on [4]. The common structure of as-prepared ferrites is (Zn2+)tet[Fe3+ X3+]OctaO2-4. In this Zn2+ cation occupy the tetrahedral (8a) sites and Fe3+ cations occupy in octahedral (16d) sites with the Fd3̅m space group. The addition of X3+ metal ion can change Fe3+ distribution sites and modifies the ion distribution in spinel structure [5]. The scientific community has interested to study the influence of partial substitution of rare earth ions in different ferrites systems. One of the promising additives La3+ was used to improve the physical and chemical properties of parent ferrite material. We used PEG as a surfactant during the synthesis process, to prevent agglomerations and limit their size. The ZnFe2O4 NPs have been synthesized using various methods, such as sol–gel method, chemical co-precipitation route, high energy ball milling method, electrodeposition technique, microemulsion process and so on [6].

However, all of the above methods encounter the problems like inevitable compound inhomogeneity, 17

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complicated steps, long time process and unavailability of expensive instruments, etc [7]. Among these techniques, to date, PEG assisted facile hydrothermal is the most suitable method for better reproducibility, crystallite size control, nontoxic, homogeneity, low temperature with high pressure closed energy saved system [8]. To the best of our knowledge, there are no other reports published on the synthesis of ZnFe1.8La0.2O4 by the facile hydrothermal route using PEG as a surfactant.

However, the effect of surfactant on La substituted Zn ferrite has not been reported as far as we know.

In the present research, we have successfully synthesized ZnFe1.8La0.2O4 nanoparticles by PEG assisted facile hydrothermal method. Furthermore, the structural, functional group, optical, morphological and elemental analysis were investigated usingXRD, FTIR, UV-VIS, SEM and EDS. Experimental.

Raw Materials. All chemicals (zinc nitrate hexahydrate (Zn (NO3)2·6H2O), Iron (III) nitrate nonahydrate (Fe (NO3)3·9H2O), lanthanum (III) nitrate hexahydrate (La (NO3)3.6H2O), sodium hydroxide [NaOH], Polyethylene glycol and ethanol (CH3CH2OH)) were of reagent grade and were purchased from Alfa Aesar (India) and used without any further treatment. Double distilled water was used for throughout the experiments.

Synthesis procedure. To synthesize nanosized ZnFe1.8La0.2O4, the molar ratio of Zn: Fe: La nitrates were fixed at 1.0:1.8:0.2. 1.0 M of Zn (NO3)2·6H2O, 1.8 M of Fe (NO3)3·9H2O and 0.2 M of lanthanum (III) nitrate hexahydrate (La (NO3)3.6H2O) salts were dissolved in 50 ml of double distilled water separately stirring with vigorous using a magnetic stirrer. Once getting the homogeneous solution, 2.0 M of NaOH was added drop by drop until pH of the solution reached 11 and precipitated the precursor. During the reaction, 5 ml polyethylene glycol (PEG-6000) was added to the solution to assist as a surfactant that covers nanoparticles to prevents agglomeration. The final mixture was transferred to 150 ml Teflon-lined stainless steel autoclave, which was sealed tightly and maintained for 10h at 180° C using hot air oven. Then the autoclave was allowed to cool down to room temperature gradually. The resulting dark brown precipitate was washed three times with distilled water and absolute ethanol and finally dehydrated in hot air oven at 100 C for 24 h. Finally, ZnFe1.8La0.2O4 samples were successfully synthesized by PEG assisted hydrothermal method and the obtained nanoparticles used for further characterizations.

Results and Discussion.

Powder X-ray powder diffraction. Powder X-ray powder diffraction (PXRD) patterns of the prepared sample were obtained at room temperature using a Bruker D8 Advanced XRD diffractometer with CuKα radiation (λ = 1.542 Å) and with step mode of 0.2/min. The PXRD was carried out to confirm the structural formation of ZnFe1.8La2O4 ferrite nanoparticles. From XRD patterns (Fig.1), the well-indexed diffraction peaks can be assigned to the cubic spinel phase of ZnFe2O4 with space group Fd3̅m (227), which was in good agreement with the standard pattern of JCPDS card NO.82-1042. Moreover, there are no other additional peak appears in the XRD pattern, which indicates the high purity of ferrite nanoparticles. The average crystallite size (D) of the ZnFe1.8La2O4 nanoparticles was calculated from the full width at half maximum (FWHM) intensity of the prominent (311) plane reflection using the Debye–Scherrer formula: D= Kλ/β cosθ, Where K is the Scherrer constant (K =0.94), λ is the X-ray wavelength of CuKα radiation; β is the full width at half-maximum intensity (FWHM) in radian and θ is the diffraction angle. The crystallite size of ZnFe1.8La2O4 sample was found to be 15.06 nm. The size of the particles was small due to the doping of La3+ ions into the Fe3+ ions (octahedral B site) of zinc ferrite lattice that suppresses the grain growth during the synthesis procedure [4].

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Fig. 1. XRD Patterns of ZnFe1.8La2O4 sample synthesised by the PEG-assisted hydrothermal method.

FTIR spectral analysis. To confirm the various modes of functional groups existing in the synthesized nanoparticles was recorded using a Shimadzu IRAffinity FTIR Spectrometer in the scan range 4000–400 cm-1. The FTIR spectrum of the ZnFe1.8La0.2O4 is shown in Fig.2. The broad absorption band in the range of 3000-3600 cm-1 is due to stretching vibration of OH. The peaks can be seen at 1737, 1492, 1367, 1247 and 862 cm-1 is resulted from a characteristic peak of PEG [9].

The intensive peak observed at 526 cm-1 for ZnFe1.8La0.2O4 is due to stretching vibration of Zn2+ at the tetrahedral site, ν1 and the band positioned at 420 cm-1 can be assigned to Fe3+ vibration at the octahedral site, ν2 [10].

Fig. 2. FTIR spectrum of ZnFe1.8La2O4 nanoparticles.

UV-Vis-NIR spectral analysis. Diffuse Reflectance UV-Vis-NIR spectra were recorded using a JASCO V-670 spectrophotometer equipped with a JASCO ISN-723 UV-Vis-NIR 60 mm in the wavelength range 200-2500 nm. With the help of UV-Vis-NIR spectra, the influence of La3+on zinc ferrite nanoparticles optical behaviour was investigated. Fig. 3 [a] shows the absorption spectra of the ZnFe1.8La0.2O4. As shown in Fig. 3 [b], the absorption spectra show a wide wavelength range from UV to visible light and the absorption tail extending into the infrared region, predominantly the ferrite nanoparticles illustrated excellent visible light absorption in the range of 200–600 nm. The optical MMSE Journal. Open Access www.mmse.xyz

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absorption coefficient (α) can be evaluated from the reflectance data by using Kubelka Munk function, α = (1−R) 2/2R, where R is the diffuse reflectance. The correlation between α and Eg as expressed by the following Tauc relation, (αhυ) =A (hυ-Eg) n, where A is the constant depends on the transition probability, hυ is an energy of the incident photon, Eg is the optical band gap and n is an index describes the optical absorption process. The optical band gap Eg is calculated to be 2.03 eV. When compared to the pure ZnFe2O4 (Eg =1.90 eV), it is obviously shown that there is an increased band gap value with lanthanum concentration which is evident from the Fig. 3 [b]. The optical band gap value increased with the decrease of crystallite size indicates the result of quantum confinement effects [4].

Fig. 3. (a) Absorption spectrum and (b) optical band gap (Eg) of ZnFe1.8La2O4 nanoparticles.

SEM with EDS analysis. SEM-EDS analyses were performed to observe the surface morphology and elemental composition of the as-synthesized nanoparticles using SEM (ZEISS EV018, Germany) equipped with EDX, (XMax, Oxford Instruments). Fig.4 [a] shows the SEM micrographs of ZnFe1.8La2O4 nanoparticles, which appear agglomerated irregular shape. The strong agglomeration is due to magnetic attraction between the ions and surfactant high surface energy. The chemical composition has been investigated by energy dispersion spectroscopy (EDS) to confirm the elements present in the ZnFe1.8La2O4 nanoparticles. Fig. 4 [b] indicates the EDX spectrum of ZnFe1.8La2O4 nanoparticles. The elemental peaks of Fe, Zn, La and O were detected and no significant peaks were observed for other impurities, which demonstrated that, the high purity of the ferrite nanoparticles [6].

Fig. 4. (a) SEM micrograph and (b) EDS spectrum of ZnFe1.8La2O4 nanoparticles.

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Summary. ZnFe1.8La0.2O4 nanoparticles were successfully synthesized through a PEG surfactant assisted facile hydrothermal route. PXRD patterns established the ZnFe1.8La0.2O4 nanoparticles in the simple cubic spinel structure. By FT-IR studies, we confirmed the presence of tetrahedral and octahedral sites of the spinel ferrite. Using the UV-Vis-NIR absorption spectra data, the energy band gap is found to be 2.03 eV. SEM micrograph of ZnFe1.8La0.2O4 nanoparticle showed the surface of uneven ridges and the EDX spectra clearly showed the presence of Zn, Fe, La and O ions in the ZnFe1.8La0.2O4 structure References [1] Chantharasupawong, P., Philip, R., Endo, T., & Thomas, J. (2012). Enhanced optical limiting in nanosized mixed zinc ferrites. Applied Physics Letters, 100 (22), 221108. DOI: 10.1063/1.4724194.

[2] Philip, J., Gnanaprakash, G., Panneerselvam, G., Antony, M. P., Jayakumar, T., & Raj, B. (2007).

Effect of thermal annealing under vacuum on the crystal structure, size and magnetic properties of ZnFe2O4 nanoparticles. Journal of Applied Physics, 102 (5), 54305-54305. DOI: 10.1063/1.2777168.

[3] Blanco-Gutiérrez, V., Torralvo-Fernández, M. J., & Sáez-Puche, R. (2010). Magnetic behavior of ZnFe2O4 nanoparticles: effects of a solid matrix and the particle size. The Journal of Physical Chemistry C, 114 (4), 1789-1795. DOI: 10.1021/jp908395v.

[4] Tholkappiyan, R., & Vishista, K. (2014). Influence of lanthanum on the optomagnetic properties of zinc ferrite prepared by combustion method. Physica B: Condensed Matter, 448, 177-183. DOI: 10.1016/j.physb.2014.04.022.

[5] Köseoğlu, Y., Bay, M., Tan, M., Baykal, A., Sözeri, H., Topkaya, R., & Akdoğan, N. (2011).

Magnetic and dielectric properties of Mn0.2Ni0.8Fe2O4 nanoparticles synthesized by PEG-assisted hydrothermal method. Journal of Nanoparticle Research, 13 (5), 2235-2244. DOI: 10.1007/s11051010-9982-6.

[6] Rameshbabu, R., Ramesh, R., Kanagesan, S., Karthigeyan, A., & Ponnusamy, S. (2013).

Synthesis of superparamagnetic ZnFe2O4 nanoparticle by surfactant assisted hydrothermal method. Journal of Materials Science: Materials in Electronics, 24 (11), 4279-4283. DOI: 10.1007/s10854-013-1397-6.

[7] Cao, S. W., Zhu, Y. J., Cheng, G. F., & Huang, Y. H. (2009). ZnFe2O4 nanoparticles: microwavehydrothermal ionic liquid synthesis and photocatalytic property over phenol. Journal of Hazardous materials, 171 (1), 431-435. DOI: 10.1016/j.jhazmat.2009.06.019.

[8] Rahman, M. M., Khan, S. B., Faisal, M., Asiri, A. M., & Alamry, K. A. (2012). Highly sensitive formaldehyde chemical sensor based on hydrothermally prepared spinel ZnFe2O4 nanorods. Sensors and Actuators B: Chemical, 171, 932937.DOI:10.1016/j.snb.2012.06.006 [9] Tomasovicova, N., Koneracka, M., Kopcansky, P., Timko, M., & Zavisova, V. (2006). Infrared study of biocompatible magnetic nanoparticles. Meas. Sci. Rev, 6, 32-35.

[10] Köseoğlu, Y., Baykal, A., Toprak, M. S., Gözüak, F., Başaran, A. C., & Aktaş, B. (2008).

Synthesis and characterization of ZnFe2O4 magnetic nanoparticles via a PEG-assisted route. Journal of Alloys and Compounds, 462 (1), 209-213.DOI: 10.1016/j.jallcom.2007.07.121.

Cite the paper M. Shoba, S. Kaleemulla (2017). Investigation of spinel structure ZnFe1.8La0.2O4 Nanoparticles Synthesized

by PEG assisted Wet Chemical Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.87.32.410

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Microhardness of Hydroxyapatite Doped ZrO2 using Sol-Gel Method18 S. Helen1, A. Ruban Kumar1, a 1– Centre for Crystal Growth, VIT University, Vellore, India a – arubankumar@vit.ac.in DOI 10.2412/mmse.48.98.680 provided by Seo4U.link

Keywords: hydroxyapatite, zirconium oxide, sol-gel method, micro-hardness.

ABSTRACT. Calcium Phosphate based bio-ceramics in the form of hydroxyapatite (HA) with high biocompatibility in hard tissues. In this work HA mixed with ZrO2 using Sol-gel method. Calcium nitrate with Di-ammonium hydrogen phosphate used for the formation of HA, which exhibited less mechanical property. To overcome these problems ZrO 2 were used to increase its mechanical strength.XRD and FTIR confirmed the phases and functional groups and its hardness was analysed and confirmed it is a soft material used in various medical applications especially in orthopaedics field.

Introduction. Hydroxyapatite is an inorganic material with minerals present in bone and teeth which have low mechanical property, which does not support for load bearing applications. To sustain these problems, HA incorporates with different composites to increase mechanical strength in the field of implants. The combination of hydroxyapatite with composites improves hardness and fracture toughness .YSZ/HA used to improve wear resistance, strength of HA using co-precipitate method [1]. For load-bearing applications various metals, as alloys were used but using of metals has some drawbacks such as corrosion, negative tissue reactions, the slack of implants and stress due to high stiffness, which used in various medical applications. To prevent the decomposition of HA doped ZrO2 must less than 10% unless specific sintering temperature should apply.ZrO2 has an eminent potential to used in bone implantations which are tougher than Al2O3.And the stable phase of HA produced with some OH- bond. However, while sintering the H2O vapour and decay at 1300°C, which produces secondary phases. ZrO2 has tetragonal or cubic in structure at room temperature.ZrO2 has high mechanical strength and low toxicity for living organisms. The HA synthesized using ZrO2 which can use in various applications in both dentistries and in orthopedics which has the mechanical strength greater than the cortical bone [2].Zirconium oxide is known as ceramic which has a high thermal expansion with high resistance to crack propagation. HA improves bending strength and coatings for medical applications by adding the small amount of ZrO2.The hardness and flexural strength for HA were 5.4GPa and 94MPa; ZrO2 has 14.2GPa and 929MPa [3]. As catalytic ZrO2 has the potential application due to less toxicity, less volatile and more stable at high temperature and eco-friend with environmental.ZrO2 and Al2O3 are bioinert materials with high fracture strength and high toughness. Ceramics such as ZrOCl2 and AlCl3 using a precipitate method using calcium nitrate with di-ammonium hydrogen phosphate to improve both bending strength and disintegration toughness [4]. Composites synthesized using sol-gel with polymers to ceramics in that ZrO2 with PEG used as a plasticizer for medical applications. The polyethylene glycol (PEG) added with Zirconium oxide (ZrO2) which increase the coating ability and films were more homogeneous [5].

HA added with PEG/ZrO2 as the bioactive material used widely in wear resistance in joint applications using the sol-gel method. The aim of this paper is about the micro hardness of HA with inorganic (PEG) and ceramic (ZrO2) combinations using sol-gel method which does not report yet.

18

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Synthesis Method. The precursor’s calcium nitrate tetra hydrate with Diammonium hydrogen phosphate for synthesized HA and Ammonium hydroxide for maintaining the pH. .The HA will form stable at high pH give chemical stability and biological activity. Adding Diammonium hydrogen phosphate into Calcium nitrate maintaining pH form 9-11 using NH4OH. And adding of HA with PEG which increases the ability of HA to sustain in coatings and ZrO2 which is an oxide in form for increase hardness of HA. The pure hydroxyapatite (HA) and doped zirconium oxide with both HA and polyethylene glycol (HPZ).The flow chart for synthesizing HA with PEG and ZrO2 given below.

Fig. 1. Sol-gel method for synthesis of pure HA and adding of ZrO2 +PEG to HA (HPZ).

Results & Discussions: X-ray Diffraction shows the peaks with good crystallinity with sharp peaks for pure hydroxyapatite and doped zirconium oxide with HA shows the broad peak with 2theta values 31.7 for pure and 31.93 for HPZ with hkl value 211, 300, 112 but in HPZ there was a disappearance of peaks shows decomposition of hydroxyapatite Fig. 2.

Table 1. Lattice parameters and Volume for Pure HA and HPZ Sample

aÅ

cÅ

Volume (V) Cm3

Hydroxyapatite (09-0432)

9.418

6.884

528.80

HA

9.418

6.884

528.8

HPZ

9.418

6.882

528.77

The above table gives the lattice parameters and volume of synthesized materials with the JCPDS of hydroxyapatite (09-0432).The obtained HA with JCPDS are same but adding zirconium to HA gives a value same with decrease in c parameter which shows decomposition of HA.

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Fig. 2. XRD graph of pure HA and HPZ. The analysis of functional groups for doped Inorganic with ceramics was shown in Fig. 3.The peaks from 500-1442 indicate the presence of PO43- groups in stretching mode and OH- in the range 30003500 and extra peak at 1300 may due to zirconium oxide compared with HA doped PEG. The peaks range from 1000-1500cm-1 shows PO stretching mode which confirms the presence of HA.

Fig. 3. FTIR analysis for HA +PEG and HA+PEG+ZrO2.

Hardness. Hardness is the ability to determine the surface of the material withstands forces. Vickers’s hardness is the capacity to resist plastic deformation. The hardness increase with the load, if n is greater than two if n less than two it will decrease the hardness. The value with the range 1-1.6 is considered as hard materials and greater than 1.6 are called soft materials. The average hardness of HA 6.77GPa. Using Meyer’s index hardness value for HPZ is 2.66 shows it is soft material due to RISE. Mechanical stability essential for making devices which can be used in implantations.

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Fig. 4. Microhardness for HPZ. Summary. Hydroxyapatite doped with zirconium oxide by adding polyethylene glycol which increases the strength of HA which is a less mechanical strength; XRD shows the decomposition of HA and functional group were confirmed by FTIR. The materials were revealed as a soft material, which can use to increase the ability of coatings and implantations.

Acknowledgement. The authors thank the management of VIT University Vellore for providing the excellent research facilities.

References [1] Sung, Y. M., Shin, Y. K., & Ryu, J. J. (2007). Preparation of hydroxyapatite/ zirconia bio ceramic nano composites for orthopaedic and dental prosthesis applications. Nanotechnology, 18 (6), 065602, DOI 10.1088/0957-4484/18/6/065602.

[2] Matsumoto, T. J., An, S. H., Ishimoto, T., Nakano, T., Matsumoto, T., & Imazato, S. (2011).

Zirconia–hydroxyapatite composite material with micro porous structure. Dental materials, 27 (11), e205-e212, DOI 10.1016/j.dental.2011.07.009.

[3] Chaudhry, A. A., Yan, H., Viola, G., Reece, M. J., Knowles, J. C., Gong, K., Darr, J. A. (2012).

Phase stability and rapid consolidation of hydroxyapatite–zirconia nano-coprecipitates made using continuous hydrothermal flow synthesis. Journal of biomaterials applications, 27 (1), 79-90, DOI 10.1177/0885328212444483.

[4] Mobasherpour I., Hashjin, M. S., Toosi, S. R., & Kamachali, R. D. (2009). Effect of the addition ZrO2–Al2O3 on nanocrystalline hydroxyapatite bending strength and fracture toughness. Ceramics International, 35 (4), 1569-1574, DOI 10.1016/j.ceramint.2008.08.017.

[5] Catauro, M., Bollino, F., & Papale, F. (2014). Biocompatibility improvement of titanium implants by coating with hybrid materials synthesized by sol–gel technique. Journal of Biomedical Materials Research Part A, 102 (12), 4473-4479, DOI: 10.1002/jbm.a.35116.

Cite the paper S. Helen, A. Ruban Kumar (2017). Microhardness of Hydroxyapatite Doped ZrO 2 using Sol-Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.48.98.680

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Enhanced Photocatalytic Activity of Rare Earth Metal (Nd and Gd) doped ZnO Nanostructures19 P. Logamani1, R. Rajeswari2, G. Poongodi3, a 1 – Department of Chemistry, Bharathiyar University, Coimbatore, India 2 – Department of Chemistry, Quaid-e-Millath Govt. College for Women, Chennai, India 3 – Department of Physics, Quaid-e-Millath Govt. College for Women, Chennai, India a – srpoongodi@gmail.com DOI 10.2412/mmse.89.80.76 provided by Seo4U.link

Keywords: ZnO, rare earth dopants, photocatalytic activity, FESEM.

ABSTRACT. Presence of harmful organic pollutants in wastewater effluents causes serious environmental problems and therefore purification of this contaminated water by a cost effective treatment method is one of the most important issue which is in urgent need of scientific research. One such promising treatment technique uses semiconductor photocatalyst for the reduction of recalcitrant pollutants in water. In the present work, rare earth metals (Nd and Gd) doped ZnO nanostructured photocatalyst have been synthesized by wet chemical method. The prepared samples were characterized

by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). The XRD results showed that the prepared samples were well crystalline with hexagonal Wurtzite structure. The results of EDS revealed that rare earth elements were doped into ZnO structure. The effect of rare earth dopant on morphology and photocatalytic degradation properties of the prepared samples were studied and discussed.

The results revealed that the rare earth metal doped ZnO samples showed enhanced visible light photocatalytic activity for the degradation of methylene blue dye than pure nano ZnO photocatalyst.

Introduction. The photocatalytic degradation of organic pollutants such as dyes or pesticides from water using semiconductor materials has recently attracted a lot of attention. Among photocatalysts, Zinc oxide (ZnO) have received much attention owing to its stable structure, wide direct bandgap, nontoxicity, high photocatalytic activity, mild reaction conditions and reasonable cost[1]. However, in practical applications, the photocatalytic activity of ZnO is greatly limited by its wide band-gap (3.37 eV) which makes it poor response towards visible light and rapid recombination rate of photogenerated electron-hole pairs which inhibits its photocatalytic reaction. Hence, various strategies have been adopted to enhance the photocatalytic activity of ZnO. It is well known that doping is an effective method to improve the photocatalytic activities. Recent studies revels that the rare earth (RE) ions doping on ZnO can introduce impurity energy levels in band gap and expanded its visible light response [2-6]. Furthermore RE ions doping can produce traps for photogenerated charge carriers and decreased the electron–hole pairs recombination rate.

Several methods have been adopted to synthesize pure and RE doped ZnO structures, including microwave heating process, hydrothermal method, chemical co precipitation method, chemical vapour synthesis and sol-gel method. In this paper a template free precipitation method was used to prepare RE doped ZnO nanopowders. This method is simple, inexpensive and high yield providing room temperature synthesis of pure and doped ZnO nano powder.

Experimental Details. Pure and RE (Nd and Gd) doped ZnO nano powder were synthesized using wet chemical precipitation method. Initially, 0.25M of ZnCl2 and 2mol% of each doping rare earth 19

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element precursor [((CH3CO2)3 Nd•3H2O) and (Gd (NO3)3•6H2O)] were also dissolved in distilled water. Each of the as obtained solution was dropped into 50ml of 0.1M NaOH solution under magnetic stirring. The precipitated materials were centrifuged and washed with distilled water many times to remove the unwanted ions. The wet samples were dried at 800 for 24h. The dried powders were then calcined at 4000 for 2h.

The crystalline structure of the pure and RE doped ZnO samples were characterised byXRD. The surface morphology and elemental confirmation of the samples were studied using field emission scanning electron microscopy (FE-SEM) equipped with an energy dispersive X-ray (EDS) detector.

Optical transmission spectra were taken using LABINDIA T90+ UV-Vis spectrophotometer in the wavelength range of 300-800 nm.

Photocatalytic activity of the pure and RE doped ZnO photocatalysts was studied by degrading an aqueous solution of methylene blue (MB) ( (1×10-5 M) dye under visible light. Prior to the light irradiation, 50 ml of MB solution with 0.1 g of photocatalysts was continuously stirred using a magnetic stirrer and kept in the dark for 30 minutes in order to reach adsorption equilibrium. The photocatalytic degradation was evaluated by measuring the absorbance of MB solution at 665 nm.

The degradation efficiency of MB was calculated using the relation [7], Degradation (%) = (C0 – Ct)/C0 x 100 = (A0 – At)/A0 x 100 where C0 is the initial concentration, Ct is the concentration after‘t’ min. A0 is the initial absorbance and At is the absorbance after ‘t’ min. reaction of MB solution at the characteristic absorption wavelength of 665 nm.

Result and discussion Structural and morphological studies. Fig. 1 shows X-ray diffraction patterns of RE-doped ZnO samples. All the diffraction peaks were indexed and found to be Wurtzite hexagonal structure (JCPDS No.36-1451). It is evident from the XRD data that no extra peaks related to RE related compounds or precipitates were detected, which illustrates that the RE atoms were incorporated into the ZnO lattice.

Fig. 1. Powder XRD patterns of pure and RE doped ZnO.

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Figs. 2 (a–c) shows the FESEM image of synthesized Pure and RE-doped ZnO samples. It can be seen that the synthesized products were rod shaped and grown in large quantity. The nanorods were 30–80nm diameter and 300–400 nm long. FESEM images reveals that the nanorods are grown in very high density, uniform size and distributed randomly. The incorporation of rare earth ion Gd and Nd in ZnO lattice slightly changes the aspect ratio of nanorods. The EDAX analysis was performed to confirm the presence of RE ions (Gd and Nd) in ZnO thin films. The results reveal that the samples consist of Zn, Gd, Nd and O which confirms the substitution of RE in ZnO.

Fig. 2. (a-c) FE-SEM images of Pure and RE doped ZnO samples with corresponding EDS. 3.2 Optical studies The optical UV –Vis transmittance spectra of pure and RE doped ZnO samples were recorded in the wavelength range 300 – 800 nm are shown in Fig. 3. The optical band gap energy values (Eg) were calculated by extrapolation of the linear part of (αhν)2 versus hν plot as shown in inset of Fig. 3. It is observed that the band gap values of pure, Gd and Nd doped ZnO samples are 3.25eV, 3.16eV and 3.06eV respectively. The reduction in band gap originated from the charge transfer between the ZnO valence band and the RE ion 4f level [8].

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Fig. 3. Optical transmittance spectra of pure and RE doped ZnO samples (Inset: Tauc plot between Eg and (αhν)2).

3.3 Photocatalytic activity The photocatalytic activity of pure and RE doped ZnO samples were investigated using MB degradation under visible light irradiation. It was found that RE doped ZnO samples exhibit enhanced photocatalytic activity than pure ZnO (Fig.4 (a - c)).

Fig. 4. Photocatalytic (a) degradation (b) degradation efficiency and (c) degradation kinetics of MB dye for pure and RE doped ZnO samples Fig. 4 (c) shows the first order reaction kinetic model for photocatalytic degradation of MB dye. The apparent first order reaction rate constant (k), half-life value (t1/2) and linear coefficient (R2) calculated from the kinetic plot for MB dye is given in Table 1. From the table, it was observed that Nd doped ZnO sample showed higher photocatalytic activity than Gd doped ZnO and pure ZnO.

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Table 1 Kinetic parameters of pure and RE doped ZnO samples for MB dye Sample

Rate constant k (min-1)

Half Life Value t1/2

Linear coefficient R2

(min) Pure ZnO

0.0099

69.94

0.960

Gd ZnO

0.0133

52.03

0.979

Nd ZnO

0.0189

36.59

0.966

The defect generated by RE doping in ZnO lattices could became the centres to capture photoinduced electrons, so that the recombination of photoinduced electrons and holes could be effectively inhibited. The trapped electron or hole will be migrated to the catalyst surfaces where it will participate in a redox reaction with the dye molecules, thereby reducing the electron and hole recombination and hence increases the photodegradation efficiency [9-11]. Moreover the reduction in the band gap energy of RE doped ZnO may also attributed to the enhanced photocatalytic activity.

Summary. Pure and RE (Gd and Nd) doped ZnO nanorod samples were synthesised by wet chemical precipitation method. The XRD studies revealed that all the prepared samples exhibit hexagonal wurtzite structure. FE-SEM images revealed that the samples consist of nanorod structure. The optical studies showed reduction in the band gap. The RE doping in ZnO act as electron trapping centres and inhibit electron hole recombination, which leads to the generation of ROS and enhances the photocatalytic activity of ZnO. References [1] M. Ahmad, J. Zhu, J. Mater. Chem., 21 (2011) 599 – 614.

[2] S. Anandan, A. Vinu, K.L.P. Sheeja Lovely, N. Gokulakrishnan, P. Srinivasu, T. Mori, V. Murugesan, V. Sivamurugan, K. Ariga, J. Mol. Catal. A 266 (2007) 149–157.

[3] C.Y. Kao, J.D. Liao, C.W. Chang, R.Y. Wang, Appl. Surf. Sci. 258 (2011) 1813– 1818.

[4] O. Yayapao, T. Thongtem, A. Phuruangrat, S. Thongtem, Materials Letters 90 (2013) 83–86.

[5] C. Karunakaran, P. Gomathisankar, G. Manikandan, Materials Chemistry and Physics 123 (2010) 585–594.

[6] Nina Kaneva, Assya Bojinova, Karolina Papazova, Dimitre Dimitrov, Catal. Today 252 (2015) 113–119.

[7] K. Thongsuriwong, P. Amornpitoksuk, S. Suwanboon, Adv. Powder Technol. 24 (2013) 275-280.

[8] V. Štengl, S. Bakardjieva, N. Murafa, Mater.Chem.Phys.114 (2009) 217–226.

[9] L. Gomathi Devi, N. Kottam, B. Narasimha Murthy, S. Girish Kumar, J. Mol. Catal. A: Chem.

328 (2010) 44–52.

[10] R. Ullah, J. Dutta, Journal of Hazardous Materials 156 (2008) 194–200.

[11] S.M. Lam, J.C. Sin, A.Z. Abdullah, A.R. Mohamed, Mater.Lett.93 (2013)423–426.

Cite the paper P. Logamani, R. Rajeswari, G. Poongodi (2017). Enhanced Photocatalytic Activity of Rare Earth Metal (Nd and Gd) doped ZnO Nanostructures. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.89.80.76

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Structural and Electrical Properties of CaMnO3 Prepared by Sol-Gel Method20 K. R. Nandan1, A. Ruban Kumar1, a 1 – Center for Crystal Growth, School of Advanced Sciences, VIT University, Vellore-632 014, India a – arubankumarvit@gmail.com DOI 10.2412/mmse.59.12.214 provided by Seo4U.link

Keywords: sol-gel, SEM, FT-IR, dielectric properties.

ABSTRACT. The structural and electrical properties of CaMnO3 prepared by a sol-gel technique using citric acid as a chelating agent at 8000C were studied; the phase formation was determined by powderXRD. The surface morphological studies were carried out through SEM and EDX confirmed the chemical compositions of the sample. The various modes of vibrations due to the Mn-O and O-Mn-O stretching bonds were observed by FTIR spectroscopy studies.The electrical properties of the prepared samples were analysed at different temperatures in the frequency ranges from 50Hz to 5MHz.

Introduction. The Manganese oxide based elements with the low-temperature synthesis of ABO3 perovskite type oxides has attracted due to their interesting technological applications in thermoelectric, magnetic and electrical properties have drawn more attention from the past few decades [1]. These compounds show large magnetoresistance properties due to an unusual spin – orbital and charge ordering phenomenon these can be easily altered by temperature, pressure, applied field, doping and also the way of preparation. The manganese based on CaMnO3 compound has a mixed valence system of Mn3+/Mn4+ could induce charge transfer effects and double-exchange interaction it possesses many applications such as solid fuel cells, magnetoresistance switchings, cathode materials and oxygen sensors [2].

The perovskite structure of CaMnO3 is a G-type antiferromagnetic insulator with an additional weak ferromagnetic component in ground state and it belongs to an orthorhombic structure this kind of structure is quite suitable for colossal magnetoresistance, the strong correlation between an electronic system and thermoelectric materials [3]. Recently, CaMnO3 has been one of typical perovskite oxide which shows an excellent dielectric polarisation behaviour being one kind of absorbing agent and a promising thermoelectric material with high Seebeck coefficient low electrical conductivity [4].

CaMnO3 has synthesiszed with various methods namely hydrothermal method, solid state reaction, sol-gel method and so on. To obtain a homogenous compound, uniform particle size, high crystallinity and morphology, the sol-gel method is used to reduce the agglomeration in the prepared compound.

Most of the studies of CaMnO3 have focused mainly on the magnetic and thermal properties; less attention has been paid about structural and electrical properties of the materials. Here in our report the results of structural, morphological, dielectric and impedance studies on CaMnO3. The electrical properties for the synthesised CaMnO3 as a function of frequency varying from 50 Hz to 5 MHz at different temperatures have measured.

Experimental. The perovskite CaMnO3 have synthesized the material by sol-gel method using citric acid as chelating agent. The stoichiometric ratio of Calcium nitrate (Ca (NO3)3.4H2O) and Manganese nitrate (Mn (NO3)3.4H2O), dissolved in the deionized water to form a homogenous solution and citric acid (C6H8O7) solution was added slowly drop by drop to the homogenous solution. All reagents used 20

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were of analytical grade and used without further purification. Then the solution was stirred continuously to ensure homogeneity continuously for 3 h at room temperature. Further the homogenous solution was heated to 800 C with stirring until the gel is formed. The obtained gel was dried overnight in a vacuum oven at 1200 C. It was then pre-sintered at 3000 C in air for 4 h to eliminate the organic constituents present. Finally the precursor was sintered at 8000c for 5 h to obtain the final product. Again the obtained CaMnO3 was ground into fine powder before subjecting it into further characterization.

The phase formation and crystal structure of the synthesized material were confirmed by X-ray diffraction with a range of 2θ from 100 to 800 with a step size of 0.02 s-1 at a scan rate of 2 min-1. The surface morphology and compositions of the samples were investigated by scanning electron microscopy equipped with an energy-dispersive X-ray spectrometer (EDX). The Fourier transform infrared spectroscopy (FT-IR) spectra were obtained by JASCO 400 Infrared spectrometer from 4000cm-1 to 400cm-1. The pellets were made from the synthesized material for electrical measurements with silver paste coating for ohmic contact. The dielectric measurements were carried out by a LCR meter in the frequency range from 50 Hz to 5 MHz for the temperature ranging from 313K to 443K. Results and discussion XRD analysis

Fig. 1. XRD pattern of synthesized CaMnO3.

The XRD pattern for the synthesized material CaMnO3 is shown in Fig.1. The patterns of the synthesized material confirmed the single phase formation and crystal structure orthorhombic with space group Pnma. It is observed that all the diffraction peaks apparently were indexed with hkl values by conformed with standard JCPDS 89-0666. The unit cell parameters are a=5.3010 Å, b= 7.5137 Å and c=5.3130 Å calculated using Powder X software [5].

SEM-EDX analysis. The surface morphology of the CaMnO3 sintered at 8000C is shown in the Fig. 2. From the image, it is evident that the particles have uniformly distributed with uniform size. The morphology of the sample revealed that grains have a well defined spherical structure [4]. From the elemental X-ray diffraction analysis spectra shows the presence of chemical composition and confirm no other impurities present in the prepared material.

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Fig. 2. SEM image and EDX spectra, inset shows percentage of chemical composition of CaMnO3.

FTIR Spectroscopy. Fig. 3 shows the FTIR spectra of the as-prepared CaMnO3 samples prepared in sol-gel method. The bending mode and stretching mode at around 410 and 590 cm-1 is corresponds to the changes in the Mn-O or Mn-O-Mn bonds [6]. This also confirms the formation of single phased compound of synthesized material at 8000C without any impurity in the FT-IR spectrum and also from the previous analysis by XRD spectrum.

Fig. 3. FT-IR Spectra of synthesized CaMnO3.

Dielectric studies. The dielectric constant has been analysed at the frequency ranging from 50 Hz to 5 MHz at the different temperatures ranging from 300 to783 K. From Fig. 4 shows dielectric constant decreases gradually with increase in the frequency in low-frequency region whereas it is almost independent of the frequency in the high-frequency region. The prepared material exhibits high dielectric constant in low frequency which is due to the presence of space charge polarisation present in the prepared material [7-8].

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Fig. 4. Variation of Dielectric constant with frequency for different temperatures.

Summary. Nanocrystalline CaMnO3 material was synthesized by the sol-gel method using citric acid as chelating agents were prepared at 8000C. The single phase formation was confirmed by the XRD analysis. The morphology was analyzed by SEM and chemical composition by EDX. The various modes of vibrations due to the Mn-O and O-Mn-O stretching bonds were observed by FTIR spectroscopy studies. The dielectric constant in these materials confirmed the presence of space charge polarization.

Acknowledgment. The authors would like to thank Dr. S. Kalainathan for providing dielectric facilities and also thank VIT University for their constant encouragement and support.

References [1] Kompany, A., Ghorbani-Moghadam, T., Kafash, S., & Abrishami, M. E. (2014). Frequency dependence of Néel temperature in CaMnO3− δ ceramics: Synthesized by two different methods. Journal of Magnetism and Magnetic Materials, 349, 135-139. DOI: 10.1016/jmmm.201308-015.

[2] Loshkareva, N. N., & Mostovshchikova, E. V. (2012). Electron-doped manganites based on CaMnO3. The Physics of Metals and Metallography, 113 (1), 19-38. DOI: 10.1134/S0031918X12010073.

[3] Li, Y., Hao, S., Wang, F., Liu, X., & Meng, X. (2015). Investigation on relationship among calcination temperature, grain size, Mn valence and resistivity of Ca0.75Er0. 25MnO3− δ powders. Journal of Materials Science: Materials in Electronics, 26 (1), 176-184. DOI: 10.1007/s10854-014-2380-6.

[4] Nandan, K. R., & Kumar, A. R. (2016). Electrical properties of Ca0. 925Ce0. 075Mn1− xFexO3 (x= 0.1–0.3) prepared by sol–gel technique. Journal of Materials Science: Materials in Electronics, 27 (12), 13179-13191. DOI 10.1007/s10854-016-5464-7 [5] C. Dong, PowderX: Windows-95-based program for powder X-ray diffraction data processing. J. Appl. Crystallogr. 32 (4), 838 (1999).

[6] Soleymani, M, Moheb, A, & Joudaki, E. (2009). High surface area nano-sized La0. 6Ca0. 4MnO3 perovskite powder prepared by low temperature pyrolysis of a modified citrate gel. Open Chemistry, 7 (4), 809-817. DOI: 10.2478/s11532-009-0083-2.

[7] Lobo, L. S., & Kumar, A. R. Investigation of structural and electrical properties of ZnMn2O4 synthesized by sol–gel method. Journal of Materials Science: Materials in Electronics, 1-9. DOI 10.1007/s10854-016-4714-z MMSE Journal. Open Access www.mmse.xyz

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[8] Murugesan, G., Nithya, R., Kalainathan, S., & Hussain, S. (2015). High temperature dielectric relaxation anomalies in Ca0.9Nd0.1Ti0.9Al0.1O3−δ single crystals. RSC Advances, 5 (96), 7841478421. DOI 10.1039/C5RA15876A.

Cite the paper K. R. Nandan, A. Ruban Kumar (2017). Structural and Electrical Properties of CaMnO3 Prepared by Sol-Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.59.12.214

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Study on Cobalt Ferrite Nanoparticles Synthesized by Co-Precipitation Technique for Photo-Fenton Application21 P. Annie Vinosha1, G. Immaculate Nancy Mary1, K. Mahalakshmi1, L. Ansel Mely1, S. Jerome Das1,a 1 – Department of Physics, Loyola College, Chennai, India a – annieakash@gmail.com, jerome@loyolacollege.edu DOI 10.2412/mmse.36.49.466 provided by Seo4U.link

Keywords: inverse spinel cobalt ferrite (CoFe2O4), nanomaterials, co-precipitation method, optical properties, weak ferromagnetic nature.

ABSTRACT. Inverse spinel Cobalt ferrite (CoFe2O4) nanoparticles has fascinated colossal attention owing to its remarkable photo fenton activity and extra ordinary amalgamation of its properties specially its optical and magnetic properties are catered as suitable candidates in the field of electronics. Their high electrical resistivity prevents induction of eddy currents and the resultant loss of energy. Ferrites are economically viable and their magnetic and optical properties can be tailored as per the requirement of applications. Nanostructured cobalt ferrite particles were synthesised using scalable and facile co-precipitation technique by maintaining pH 9 by using the precursor solution. The particle size, morphology and reaction rate of the nanoparticles could be well tailored. The prepared CoFe 2O4 nanoparticles were characterized by X-ray diffraction (XRD) revels the crystalline nature of the synthesized product, PL photoluminescence spectra and UV-Vis Spectroscopy (UV-Vis) divulges the optical properties and the spectrum is further used to evaluate the optical constants required for fabrication and Using, VSM, the magnetic behavior of the material have been determined. Degradation of Methylene blue dye using synthesized sample was studied for photocatalytic application.

Introduction. Over last few years, nano sized materials have been extensively studied worldwide, owing to its pro and unique applications to communal at large and to have a deeper perceptive on the exceptional and challenging behavior of materials, hence nanotechnology field is zealously hunted by the researcher community. The inimitable attribute of nanomaterials arises, due to their inimitable physical properties like electrical conductivity, refractive index, optical band gap, magnetic properties and superior mechanical properties such as stringency of the nano sized material are being revealed and inferred progressively by the techno crafts and scientists.

Among diverse nanomaterials, inverse spinel ferrite nanoparticles have become incalculably popular for a spacious variety of applications [1], such as photocatalytic activity, magnetic resonance imaging contrast enhancement, hot gas desulphurization, magnetic refrigerator, superconductors, gas-sensitive materials, flexible recording media, Li-batteries etc. Among spinel ferrites, cobalt ferrite has been the area of concern due to its unique properties such as thermal stability and chemical the particle size dependence of magnetic properties. The dispensation routes to synthesize CoFe2O4 are many such as microemulsion method, co-precipitation, sol-gel, ball milling, ceramic method, hydrothermal method and solvothermal synthesis etc, [2-4]. Among these, co-precipitation is an uncomplicated and economically viable technique to prepare inverse spinel structured ferrite nanoparticles at low temperatures. In this work, we have synthesized cobalt ferrite nanoparticles via the co-precipitation technique to investigate their structural, optical, magnetic property and their degradation efficiency.

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Experimental. Cobalt Nitrate (CoNo3) and ferric Nitrate (FeNo3) of analytically graded Merck chemical were used without further purification. Initially CoNo3 (0.1 M) and FeNo3 (0.2 M) were dissolved in 100 mL of distilled water separately and stirred in order to obtain a lucid solution. Then mineralizer (NaOH) was added drop wise in line to achieve pH 9 under continuous stirring, finally the obtained by precipitate was stirred at 80 °C for 3h. As a result, brown precipitate was centrifuged thrice with double distilled water and twice with ethanol. The obtained product was dried at 80 °C for 24 hours in an oven, followed by calcination at 500 °C to a further period of 5 hours to obtain the final product of CoFe2O4 nanoparticles. The sample thus obtained was characterized.

Results and discussion. Crystalline nature and phase formation of the CoFe2O4 powder were notorious by recording their X-ray diffractograms using Bruker AXS D8 Advance instrument with Cu KÎą radiation (Îť=1.540598 Ă…) in the 2θ range 20 - 70° is shown in Fig. 1. It was confined that all the peaks of CoFe2O4 matches well with the JCPDS No.22-1086. Hence the observed patterns have been clearly endorsed to the presence of spinel structure. The particle size of the co-precipitated products strongly depends on the precipitation medium and molarity of the precursor. The crystallite size was calculated by using the Scherrer formula [5], đ?‘˜đ?œ†

ÎŚ = đ?›˝ cos đ?œƒ

(1)

2200 (311)

Intensity (a.u)

2000 (222)

1800 1600

(422)

1400

(220)

(400)

(511)

(440)

1200 1000 20

30

40

50

60

70

2 Theta (degree)

Fig. 1. XRD pattern of CoFe2O4 nanoparticle.

The crystallite size was found to be around 16 nm. The FTIR spectra recorded the information about the positions occupied by the ions is shown in Fig. 2. The wide band in the region of 3403 cm-1 corresponds to OH group of CoFe2O4 nanoparticles. The peaks at 549 and 451 cm-1 are owed to stretching vibration of M-O bond in octahedral and tetrahedral sites were 451 cm-1 is assigned to be Co-O band and 549 cm-1 is associated to Fe-O band. The band observed around 1379 and 3403 cm-1 frequency are endorsed due to the stretching of H-O-H binding. The particle size and morphology of the cobalt ferrite nanoparticles was investigated by High Resolution Transmission Electron microscope (HRTEM) model Joel/TEM 2100. The arbitrary direction of particles allows for a geometrial measure of the size distribution shown in Fig. 3. The pH had no noticeable sway on the morphology, but it affects the crystalline size, which demonstrates that the CoFe2O4 nanoparticles are cubically spherical with an average grain size of about 9 nm, which is smaller than Scherrer calculation.

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120

Transmittance (%)

110 100 90 80 70 60 50 40 30 3500

3000

2500

2000

1500

1000

500

Wavenumber (cm-1)

Fig. 2. FTIR of CoFe2O4 nanoparticles.

Absorbance (a.u)

Fig. 3. HR-TEM of CoFe2O4 nanoparticle Ultraviolet-visible spectroscopy refers to reflectance spectroscopy or absorption spectroscopy in the visible spectral region (i.e. 200 – 800 nm).

0.9

0.8

300

400

500

600

700

Wavelength (nm)

(hv)2(eV/cm2)

100000

80000

60000

40000 (Eg=2.14 eV)

20000

2

3

4

h (eV)

Fig. 4 Optical absorption spectra of CoFe2O4.

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In this vastness of the electromagnetic spectrum, ions, atoms or molecules undergo electronic transitions from the ground to excited state. UV–vis spectra (Fig.4) for CoFe2O4 sample are recorded in the range 200–800 nm. The absorbance result demonstrated that CoFe2O4 nanoparticles had considerable absorbance in the range of 542 nm wavelength. The band gap energy was estimated from the intercept of hν vs (đ?›źâ„Žđ?‘Ł)2 for direct transitions as shown in Fig. 4. The optical absorption coefficient is calculated by the equation, đ?›źâ„Žđ?‘Ł = đ??´ (â„Žđ?‘Ł − đ??¸đ?‘”)1/2

(2)

where h, Îą, Ď…, đ??¸đ?‘” and A are the Planck constant, light frequency, absorption coefficient, band gap and proportionality constant.

The band gap value was 2.14 eV, the red shift to bulk band gap. The band gap value is influenced by various factors such as presence of impurities, crystalline size and structural parameters [6]. From the emission spectrum shown in Fig.5, a broad visible emission is being hardnosed in the intact PL spectrum, which has been assigned due to the charge convey between Zn 2+ at tetrahedral sites and Fe3+ at octahedral sites which is bounded by O2- ions. The excitation wavelength is at 418 nm for CoFe2O4, which trait to the recombination of holes and electrons in the valence and conduction band [7].

(417)

0.20

80

0.15 0.10

M (emu/g)

Intensity (a.u)

70 60 50 40

0.05 0.00 -0.05 -0.10 -0.15

30

-0.20 20 400

410

420

430

440

-15000-10000 -5000

450

0

5000 10000 15000

H (kOe)

Wavelength (nm)

Fig. 5. PL spectra of CoFe2O4 Fig. 6. Magnetization curve for CoFe2O4.

The magnetic properties of CoFe2O4 particles were pragmatic using a vibrating sample magnetometer (VSM) Lakeshore VSM 7407 with magnetic field 2.5 T at room temperature (303 K). In Fig. 6 hysteresis loops is extremely narrow for the reason that the particles is of small average diameter.

The saturation magnetization (Ms) for synthesized sample was derived from the law of saturation using the following equation: đ??´

đ??ľ

đ?‘€ = đ?‘€đ?‘† (1 − đ??ť − đ??ť 2 ) + đ?œ’đ?‘? đ??ť

(3)

where A is inhomogeneity parameter, Ms is the saturation magnetization, B is the anisotropy and χp is the highest field susceptibility parameter.

The loop indicates a steep ascend of magnetization as the applied field increases. The superior slope of the curve results to the abridged anisotropy. The corecivity (Hc), saturation magnetization (Ms) and

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retentivity (Mr) values of the synthesized sample are 333.76 (emu/g), 0.5656 G and 0.10134 (emu/g) respectively. The squareness value of the hysteresis loop is found to be 0.179 (emu/g).

3.0

T=MB T=0 mins T=30 mins T=60 mins T=90 mins T=100 mins

Absorbance

2.5 2.0 1.5 1.0 0.5 0.0 200

300

400

500

600

700

800

Wavelenght (nm)

Fig. 7. Change in absorption spectra of MB with time in the presence of CoFe2O4 nanoparticles.

The curve indicates the definite ordering of ionic spin states and the sample possesses ferromagnetic in nature and their application is in recording media where low coercivity is required when maintaining high saturation magnetization. Photo-Feton activity for CoFe2O4 nanoparticles was examined by the degradation of MB with the synthesized catalyst under visible light irradiation. In this experiment 50 ml of 10 mg/l of MB aqueous solution was taken in which 50 mg of photo-catalyst was dispersed. Before irradiating, the suspension was kept in the absence of light for 30 minutes to ensure desorption-adsorption equilibrium and then the solution with the catalyst was out in the open visible light before irradiation H2O2 was added. At given time intervals, 3 ml of aliquots were taken and centrifuged. The intensity of MB was determined with the help of UV-vis spectrophotometer.

Hence presence of light with the catalyst the degradation was found to be 99.8% within 100 minutes shown in Fig.7. Hence, it can be proved that CoFe2O4 nanoparticle has a potential photo-Fenton activity.

Summary. In prĂŠcis, inverse spinel CoFe2O4 nanoparticles were successfully synthesized using coprecipitation technique, resulting into favorable magnetic, optical properties and small particle size.

X-ray diffraction revealed the formation of cubic spinel structure CoFe2O4 nanoparticles. In FTIR spectrum, the foremost band at 549 cm-1 corresponds to metal-oxygen, stretching vibrations located at octahedral and tetrahedral positions. The TEM image of CoFe2O4 nanoparticles gives an idea about the distribution of spinel shape nanoparticles. VSM measurements revealed the weak ferromagnetic behavior from which the magnetic parameters were observed. Application of photo-fenton activity proved that the synthesized nanoparticle is an efficient catalyst in degradation of MB. Acknowledgement One of the authors (SJD) is grateful to the management of Loyola College, Chennai - 34 for awarding the project (3LCTOI14PHY002).

References [1] S.Chang, Q.Haoxue, Tuning Magnetic Properties of Magnetic Recording Media Cobalt Ferrite Nano-Particles by Co-Precipitation Method, IEEE Transactions of magnetics 2009 DOI: 10.1016/j.jmmm.2015.08.022 [2]A.K Nikumbh,, R.A Pawar, D.V Nighot, G.S Gugale, M.D Sangale, M.B Khanvilkar, A.V Nagawade, Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt MMSE Journal. Open Access www.mmse.xyz

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ferrites nanoparticles synthesized by the co-precipitation method, J.Magu.Magn.Mater, 2014 DOI: 10.1016/j.jmmm.2016.08.027 [3] A.B Salunkhe, V.M Khot, M.R Phadatare, S.H Pawar, Combustion synthesis of cobalt ferrite nanoparticles – Influence of fuel to oxidizer ratio, J.Alloys comp 2012 DOI: 10.1016/j.jallcom.2011.10.094.

[4] Yuksel Koseoglu, Furkan Alan, Muhammed Tan, Resul Yilgin, Mustafa Ozturk, Low temperature hydrothermal synthesis and characterization of Mn doped cobalt ferrite nanoparticles, Ceram.Int, 2012 DOI:10.1016/j.ceramint.2012.01.001.

[5] Lunhong Ai, Jing Jiang, Influence of annealing temperature on the formation, microstructure and magnetic properties of spinel nanocrystalline cobalt ferrites, Curr. Appl. Phys. 2010 DOI: 10.1016/j.cap.2009.06.007.

[6] G. Pandey, S. Dixit, Growth Mechanism and Optical Properties Determination of CdS Nanostructures, J. Phys. Chem. C, 2011 DOI: 10.1021/jp2015897.

[7] R.B Kale, C.D Lokhande, Influence of air annealing on the structural, optical and electrical properties of chemically deposited CdSe nano-crystallites, Appl Surf, 2004 DOI: 10.1016/j.mssp.2015.06.019.

Cite the paper P. Annie Vinosha, G. Immaculate Nancy Mary, K. Mahalakshmi, L. Ansel Mely, S. Jerome Das (2017). Study on Cobalt Ferrite Nanoparticles Synthesized by Co-Precipitation Technique for Photo-Fenton Application. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.36.49.466

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On Feature Image Recognition of Melanoma using Nanotechnology Applications22 D. Naveen Raju1,a, S.Shanmugan2,b, M. Anto Bennet3,c 1 – Research scholar, Anna University, Chennai, Tamilnadu India 2 – Research Centre of Physics, Vel Tech Multi Tech Dr.Rangarajan Dr.SakunthalaEngineering College, Avadi, Chennai Tamilnadu, India 3 – Electrical Communication Engineering, Vel Tech Rangarajan Sakunthala Engineering College, Avadi, Chennai, Tamilnadu, India a – drnaveenraju@gmail.com b – s.shanmugam1982@gmail.com c – bennetmab@gmail.com DOI 10.2412/mmse.82.25.192 provided by Seo4U.link

Keywords: dermoscopy, ABCD rule, segmentation, feature extraction, classification.

ABSTRACT. Melanoma is energy form of skin cancer and has cancer of Nanotechnology has the potential to improve both the diagnosis and treatment of this disease. Combining nanoparticles with the biological and chemical therapies has immense scope and potential. Dermatologists use the ABCD rule to characterize skin lesions. Image analysis including image acquisition, hair detection, the segmentation methods are thresholding, edge-based, region-based on color images with computerized image analysis. It is the total number of pixels in the largest diameter by a millimeter (mm). It has four parameters classification on ANN for the recognition of malignant melanoma. They have been compared with the results classification obtained by ANN. There is implemented in MATLAB used the dataset which that they consider of 100 dermoscopic images from Hospital Kovai Medical. They have been achieved results shows an acceptable effect rates, an accuracy 95.32%, sensitivity 75% and specificity 96.28%.

Introduction. Melanoma, originated from melanocytes, is the most dangerous type of skin cancer.

Although melanoma represents only a very little portion of skin, it accounts for the vast majority of skin cancer deaths [1] Siegel.et.al.An early stage melanoma can be surgically removed, with a survival rate of 99%. However, metastasized melanoma is difficult to cure. Metastasized melanoma is currently treated by chemotherapy, immunotheray, radiotherapy and targeted therapy.

Nanotechnology has been extensively studied for melanoma treatment and diagnosis, to decrease drug resistance, increase therapeutic efficiency and reduce side effects. we summarize the recent progress on the development of various nanoparticles for melanoma treatment and diagnosis. Several common nanoparticles, including liposome, polymersomes, dendrimers, carbon-based nanoparticles and human albumin, have been used to deliver chemotherapeutic agents and small interfering ribonucleic acids (siRNAs) against signaling molecules have also been tested for the treatment of melanoma. Indeed, several nanoparticle-delivered drugs have been approved by the US Food and Drug Administration and are currently in clinical trials. The application of nanoparticles could produce side effects, which will need to be reduced so that nanoparticle-delivered drugs can be safely applied in the clinical settings Nanoparticles in Melonoma Treatment

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Nanoparticles can be designed to have multiple functions, such as targeting to cancer cells and producing image contrast. Many nanoparticles have been studied for the treatment of melanoma, including liposomes, polymersomes, and inorganic nano particles.liposome is a sphere consisting of a lipid bilayer that contains aqueous core for hydrophilic drugs.Hydrophobic drugs can be contained between the two layers. Liposome is prepared by sonicating a lipid, with a process involving emulsification. Homogeneous nanosized liposomes can be achieved by filtering through a 0.2 ÎźM membrane. Furthermore specific ligands against tumor antigens can be attached to the liposome surface so that the nanoparticles can target cancer cells specifically. [2] Liposomes have been used to carry chemotherapeutic drugs, immunocytokines and siRNA, to increase treatment efficacy for melanoma.Similar structural nanoparticles have been designed, such as the cubosome and niosome, which consist of lipids. Polymersomes are composed of amphiphilic block copolymers, such as polylactic acid and poly (É›-caprolactone), formulated to become nanoparticles.Polymersomes can encapsulate either hydrophilic or hydrophobic drugs.They are more stable and less permeable to small water-soluble molecules than are liposomes.Their surface can also be attached with ligands for targeting cells and controllable release. [3] Polymersomes have been used to deliver Dox for treating melanoma and demonstrated to be preferentially taken up by melanoma cells. The nanoparticles markedly reduced tumor growth in a melanoma xenograft model. Inorganic nanoparticles made from materials such as silica and aluminum have also been applied in melanoma therapy[4]. Silica can be made multiporous (which is then called mesoporous silica) to carry more drugs than as a simple sphere.A layered double hydroxide nanoparticle is made by layering a hydroxyl (-OH) group on inorganic materials, to carry drugs.This has been shown to increase immune response to a deoxyribonucleic acid (DNA) vaccine in a melanoma mouse model the capability of layered double hydroxide to carry enough small molecular drug is still a major problem.

Methodology Clinical diagonosis. One of the widely used methods by dermatologiststo classify The cancerous skin melanoma from normal skin is the ABCD rule[5].It is proved that it can be easily learned a reliablemethod providing.A more objective and reproducible diagnosis of melanoma Asymmetry-one half unlike the other half.Border irregular--scalloped or poorly circumscribed border. Color varied from one area to another; shades of tan and brown; black; sometimes white, red or blue. Diameter larger than 6mm as a rule (diameter of a pencil eraser)Shown in Fig. 1

Fig. 1. ABCD rule of dermoscopy, Fig. 2 (a) Original image (b) Gray scale image (c) Filtered image (d) Contrast enhanced image Fig. 3 (a) Original image (b) Segmented image.

Skin cancer detection methods

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Image acquistion

Image preprocessing

Image segmentation

Feature Extraction

Classification using ANN

Image Acquistion. The first stage of our automated skin lesion analysis system is image acquisition.

This stage is essential for the rest of the system. hence, if the image is not acquired satisfactorily, then the remaining components of the system may not be achievable, or the results will not be reasonable, even with the aid of some form of image enhancement. In order to capture high quality images, the iPhone 5S camera is used, equipped with 8 megapixels and 1.5 pixels Image Preprocessing. Images are often corrupted by impulse noise due to transmission errors, The goal of noise removal is to suppress the noise while preserving image details.A variety of techniques have been proposed to remove impulse noise. Noise is perturbations of the pixel values.. Filters are used to suppress noise, enhance contrast, find edges and locate features. To enhance the quality of images, we can use various filtering techniques which are available in image processing. There are various filters which can remove the noise from images and preserve image details and enhance the quality of image. The common noise which contains the image is impulse noise. The impulse noise is salt and pepper noise (image having the random black and white dots). Medianfilter is the filter that removes most of the noise in image and grey scale image into contrast enhanced image shown Fig. 2.

Image Segmentation. In segmentation methods are Edge based, region based, thresholding.Edge carries a lot of information about the various regions in an image. They provide an outline of the object. An edge is said to be a set of connected pixels that lies on the boundary between two regions that differ in grey value. These pixels on the edge are called edge points.In Fig. 3 Edge points are shown clearly [6]. Edge detection technique is boundary identification where the information of the edge is detected and edge pixels with adjacent neighbour connectivity are tracked..Edge detection technique is a structural technique of the image segmentation process An edge detection operation is basically an operation to perceive important local changes in the intensity level of an image. The variation in intensity level is measured by gradient of the image. Major approaches of segmentation are based on the pixel values [7]. Thresholding technique is based on image space regions i.e. on characteristics of image. It converts a multilevel image into a binary image. In this approach a threshold is applied to the image in order to distinguish the regions in distinct intensities Thresholding technique is used to determine an intensity value called as threshold and then threshold splits the desires classes. The segmentation is done by grouping pixels with intensity greater than the threshold into one class and all other pixels into another class.A region of an image is defined as a connected homogenous subset of the image with respect to some criterion such as gray level or texture. The regions in an image are defined as group of connected pixels with similar properties. In this approach, every pixel is allotted to a particular object or region. On Comparing with edge detection method, segmentation algorithms are relatively simple and more immune to noise. Edge based method partition an image on the basis rapid change in intensity near edgeswhereas region based methods, partition an image regions that are similar according to some predefined criteria. In the region-based segmentation, pixels which are corresponds to a particular object are grouped together and marked.

Region-based segmentation uses appropriate thresholding techniques Feature Extraction. The main step to detect the cancer is selection and extraction of the features; as we know performance of system are more dependent on optimization of features’ selection than the classification method. We implemented feature extraction using Gray level Co-occurrence Matrix.

Gray Level Co-occurrence Matrix (GLCM) is the matrix where the number of rows and columns is equal to number of gray levels (pixel values). The GLCM is a tabulation of how often various combinations of pixel brightness values occur in an image. The Preprocessed image in gray scale is given as input to GLCM. MMSE Journal. Open Access www.mmse.xyz

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Classification. Artificial neural network (ANN) is a machine learning approach that models human brain and consists of a number of artificial neurons. Neuron in ANNs tend to have fewer connections than biological neurons. Each neuron in ANN receives a number of inputs. An activation function is applied to these inputs that results in activation level of neuron (output value of the neuron).

Knowledge about the learning task is given in the form of examples called training examples [8]. An Artificial Neural Network is specified by Neuron model, which is the information processing unit of the NN, an architecture that contain a set of neurons and links connecting neurons. Each link has a weight, alearning algorithm that is used for training the NN by modifying the weights shown in Fig.:4.in order to model a particular learning task correctly on the training examples.The neural network classifier structure consists of Input layer, Hidden layer and Output layer. Hidden layer and Output layer. In this methodology, there is one hidden layer with ten hidden neurons and Output layer with one output neuron. The hidden and output layer adjusts weights value based on the output inClassification

Fig. 4. Neuron diagram.

Result.This section details the results of automatic classification on images that acquired by means of dermoscopy technique. Database consists of 101 dermoscopy images, previously diagnosed, 45 of them are melanomas and 51 are non-melanomas. GLCM features were used for feature extraction and neural network for classification. 5 features are selected and these input fed to neural input layer.Corresponding values of each features are extracted and then compared with the values of database using neural networking. Fig. 5 shows the output of each stages. The proposed method trained with 75% and tested with 25% of the total number of images. At the end of the training process updated weight values are stored. Then the performance value is measured final result is shown

Fig. 5. Classification and detection of melanoma.

Summary. It proves to be a better diagnosis method than the conventional biopsy method. This detection method is very advantageous to patients, because it find result faster than biopsy method.

This detection method will time consuming. This skin cancer detection method differentiated two types of skin cancer (Melanoma and Non-Melanoma) from each other and found the stages of cancer.

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This methodology uses digital image processing technique and artificial neural networks for the classification of cancer image and non-cancer image.

References [1] R. L. Siegel, K. D. Miller and A. Jemal, "Cancer statistics, 2016, " CA: a cancer journal for clinicians, vol. 66, no. 1, pp. 7-30, 2016.

[2] Sawant RR, Torchilin V P. Challenges in development of targeted liposomal therapeutics. Aaps J. 2012; 14 (2):303–315.

[3] Liao J, Wang C, Wang Y, Luo F, Qian Z. Recent advances in formation, properties and applications of polymersomes. Curr Pharm Des. 2012;18 (23):3432–3441 [4] Lloyd-Hughes H, Shiatis AE, Pabari A, Mosahebi A, Seifalian A (2015) Current and Future Nanotechnology Applications in the Management of Melanoma. J Nanomed Nanotechnol 6: 334. doi:10.4172/2157-7439.1000334.

[5] Soltani-Arabshahi, R.; Sweeney, C.; Jones, B.; Florell, S.R.; Hu, N.; Grossman, D. Predictive value of biopsyspecimens suspicious for melanoma: Support for 6-mm criterion in the ABCD rule. J. Am. Acad. Dermatol.2015, 72, 412–418 [6] Leszek A. Nowak, Maciej J. Ogorzaek, Marcin P. Pawowski, Texture Analysis for Dermoscopic Image Processing, Faculty of Physics, Astronomy and Applied Computer Science Jagiellonian University Krakow, Poland, 2014 vol 4, pages 786-799.

[7] Harpreet Kaur Aashdeep Singh (2015) ―A Review on Automatic Diagnosis of Skin Lesion Based on the ABCD Rule & Thresholding Method‖ International Journal of Advanced Research in Computer Science and Software Engineering, Volume 5, Issue 5, May 2015 [8] Aswin.R.B, J. Abdul Jaleel, Sibi Salim ―Implementation of ANN Classifier using MATLAB for Skin Cancer Detection‖ International Journal of Computer Science and Mobile Computing, ICMIC13, December- 2013, pg. 87-94.

Cite the paper D. Naveen Raju, S.Shanmugan, M. Anto Bennet (2017). On Feature Image Recognition of Melanoma using Nanotechnology Applications. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.82.25.192

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Structural and Magnetic Properties of Cr Doped SnO2 Nanopowders Prepared

by Solid State Reaction23 M. Kuppan1, S. Harinath Babu2, S. Kaleemulla1,a, N. MadhusudhanaRao1, C. Krishnamoorthi1, G. VenugopalRao3, I. Omkaram4, D. Sreekantha Reddy5, K.Venkata Subba Reddy6 1 – Thin films Laboratory, Centre for Crystal Growth, VIT University, Vellore, Tamilnadu, India 2 – Department of Physics, Annamacharya Institute of Technology and Sciences, New Boyanapalli, Rajampet, India 3 – Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu, India 4 – Department of Electronics and Radio Engineering, KyungHee University, Yongin-si, Gyeonggi-do 446-701, Republic of Korea 5 – Department of Physics and Sungkyukwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwan – 440746, Republic of Korea 6 – Department of Physics, S.B.V.R. Degree college, Badvel-516227 andhra Pradesh, India a – skaleemulla@gmail.com DOI 10.2412/mmse.9.43.91 provided by Seo4U.link

Keywords: thin film, nano powder, vacuum annealing, Cr doped SnO2 nanopowders.

ABSTRACT. Chromium-doped tin oxide nano powders (Sn1-xCrxO2, x = 0.00, 0.03, 0.05 and 0.07) were prepared using simple low cost solid state reaction and followed by vacuum annealing at 900 oC and studied the effects of Cr dopant concentration on structural and magnetic properties. The X-ray diffraction (XRD) studies confirmed that all the diffracted peaks were polycrystalline rutile structure of SnO2 phase. FT-IR analysis gave additional supports of formation of O-SnO and Cr-Sn-O the system. Magnetic studies revealed that all the powder samples were ferromagnetic at room temperature. Further the saturation magnetization increased with increase of doping concentration.

Introduction. Since the discovery of room temperature ferromagnetism in Mn doped GaP and ZnO

by Deitl et. al. [1] and the discovery of room temperature ferromagnetism in Co doped TiO2 by Mastumoto et al [2], intense research work has been carried out on doping og different semiconductors with different impurities. An extensive research work has been carried out on wide band gap oxide semiconductors such titanium oxide, zinc oxide, copper oxide, tin oxide and gallium nitrate systems [3-9]. These semiconductors possess wide band gap of the order of 3.5 eV, high electrical conductivity, high optical transmittance in visible region and high stability. The discovery of high temperature ferromagnetism in Co doped SnO2 thin films by Ogale et. al. [10] prompted a large number of experimental investigations on pure and transition metal doped tin oxide [11]. Among the other wide band gap oxide, tin oxide is one of the best material due to its wide band gap (3.5 eV), n-type conductivity and high transmittance in visible region of the electromagnetism spectrum and finds many applications such as solar cells, gas sensors, photo detectors etc.[12-14]. Different synthesis methods were adopted for the synthesis of undoped and impurity doped metal oxides.

Among the other synthesis methods, solid state reaction method is the one of the best techniques by which one can get nanoparticle with uniform size. The synthesis of nanoparticles such as indium oxide, tin oxide and indium tin oxide were studied and reported the room temperature ferromagnetic

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properties in these. An effort is made here for the synthesis of Cr doped SnO2 nanoparticles using simple solid state reaction method and studied their structural and magnetic properties [6, 15, 16] Experimental details. Chromium doped tin oxide Sn1-xCrxO2 (x = 0.00, 0.03, 0.05 and 0.07) concentrations were prepared by a solid state reaction followed by vacuum annealing. Commercially available SnO2 and Cr2O3 (M/S Sigma-Aldrich 99.99 % pure) were accurately weighed in required proportions and were mixed and ground thoroughly using an Agate mortar and pestle to convert to very fine powders. The grinding of the mixtures was carried out for 16 hours for all the powder samples. The ground powder samples were loaded into a small one end closed quartz tube of diameter 10 mm and length of 10 cm, which was enclosed in a bigger quartz tube of diameter of 2.5 cm and length of 75 cm with provision to allow unwanted vapors to escape from the reaction chamber and evacuated at 2 × 10−3 mbar using a rotary pump was used for the synthesis of the present samples.

The complete set up was placed in horizontal tubular microprocessor controlled furnace and fired for several hours at different temperatures. The firing temperature and firing periods were optimized at 900 °C and 10 hours. X-ray diffraction (X-ray diffractometer, D8 Advance, BRUKER) was used to establish structural aspects. Energy dispersive analysis spectroscopy (EDS) (OXFORD instrument inca penta FET X3) was used to carry out elemental analysis. Magnetic measurements were carried out using Vibrating sample magnetometer (Lake Shore-7410) Results and discussion Structural properties. Fig.1 shows the XRD pattern of chromium oxide (Cr2O3). The diffraction peaks such as (0 1 2), (1 0 4), (1 1 0), (1 1 3), (0 2 4), (1 1 6), (2 1 4) and (3 0 0) were observed among with (1 0 4) as the most predominant orientation. All these diffraction peaks were exactly coincided with α-crystalline Cr2O3 [JCPDS card: 74-0326]. The other stable phases of chromium (Cr) such as CrO, Cr2O, CrO2 and Cr3O4 were not found in the present X-ray diffraction pattern, indicating the absence of other phases of Chromium.

1200 Cr2O3Powder (104) (116)

(110)

(012)

800

600 (113)

400

(300)

(024)

(214)

Intensity (Counts)

1000

200

0 20

30

40 50 2 (degrees)

60

Fig. 1. XRD profile of bulk Cr2O3.

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SnO2

(110) (101) (211)

(321)

(202)

(310)

(111)

(200)

(112) (301)

1000

(220)

2000

(002)

Intensity (Counts)

3000

0 20

30

40

50

60

70

80

2(degrees)

Fig. 2. XRD profile of bulk SnO2.

Fig. 2 shows the XRD profiles of bulk SnO2. The diffraction peaks were found at diffraction angles of 26.62o (110), 33.89o (101), 37.98 o (200), 39.09 o (111), 42.65 o (210), 51.80 o (211), 54.79 o (220), 57.85 o (002), 61.92 o (310), 64.75 o (112), 65.98 o (301) 71.39 o (202) and 78.73 o (321) were exactly coincided with tetragonal structure of SnO2 [JCPDS No. 411445]. Among the above orientations, (110) was the predominant orientation. No other diffraction peaks related to tin in other phases such as SnO or tin (Sn) metal clusters were identified in XRD within detectable limit of XRD. The same diffraction peaks were observed for the Cr doped SnO2 nanoparticles and no diffraction peaks related to either Cr or Cr2O3 were observed inXRD. All the diffraction peaks were exactly coincided with tin oxide XRD profiles. The crystallite size (G) was calculated by using the Debye-Scherer formula: G = k  / cos, where k is particle geometry dependent constant (for spherical shape k ~1),  is the wavelength of used ( = 1.5406 Å),  is the full width-at-half maximum (FWHM) and  is the diffracted angle, respectively.

The estimated average crystallite size is found to be 47 nm. The same was confirmed by elemental analysis and spectroscopic studies. It confirms the doping of Cr into the SnO2 lattice.

Optical properties. Fig. 3 shows the optical band gaps of the Cr doped SnO2 nanopartticles. The optical bang gap was obtained by plotting (αhυ)2 versus the photon energy (hυ) and by extrapolating of the linear region of the plots to zero absorption ( = 0). The optical band gap of the powder samples decreases from 3.58 eV to 3.63 eV when the Cr doping concentration increased from x = 0.03 to x = 0.07.

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1.08E+013

6.45E+012

2

-1

(h) (cm eV)

2

8.60E+012

4.30E+012

2.15E+012

0.00E+000 2.5

3.0

3.5

4.0

h (eV)

Fig. 3. Optical band gaps of Cr doped SnO2 nanoparticles.

Magnetic properties. Fig.4. shows the magnetic measurements, which were carried out for all the samples including pure SnO2 and Cr2O3. The SnO2 nanoparticles exhibit the weak ferromagnetism at low magnetic fields and converted to paramagnetic at higher applied magnetic fields. The Cr2O3 nanoparticles exhibited antiferromagnetic behaviour. By doping Cr impurity of 3 at.%, 5 at.% and 7 at.%, the nanoparticles exhibited weak ferromagnetism without saturation even at high applied magnetic fields. From this it conclude that the observed ferromagnetism is an intrinsic in nature rather than any impurities as no impurity phase was observed from XRD and other spectroscopic studies.

-3

6.0x10

Cr(3 at.%):SnO2) Cr(5 at.%):SnO2) -3

Cr(7 at.%):SnO2)

Magnetization (emu/g)

4.0x10

-3

2.0x10

0.0

-3

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-3

-4.0x10

-3

-6.0x10

-1.0

-0.5

0.0

0.5

1.0

Applied Field (KOe)

Fig. 4. M-H loops of Cr doped SnO2 nanoparticles at different doping concentrations.

Summary. Chromium doped SnO2 nanoparticle were synthesised using simple solid state reaction method and studies their structural, optical and magnetic properties. The structural studies indicated that the synthesised nanopowders were in rutile structure and particle size was of the order of 47 nm.

From the optical studies, it was found that the optical band gap of the nanoparticle decreased with the increase of doping concentration. From the magnetic studies it was found that the nanoparticles exhibited ferromagnetism at low external magnetic fields the strength of magnetization increased with the increase of doping concentration. It seems that the observed ferromagnetism is an intrinsic in nature.

References [1] T. Dietl, H. Ohno, F. Matsukura, J. Cibert, D. Ferrand, Zener model description of ferromagnetism MMSE Journal. Open Access www.mmse.xyz

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[13] Z. Guo-Zhong, W. Jin-Feng, C. Hong-Cun, S. Wen-Bin, W. Chun-Ming, Q. Peng, Effect of Co 2 O 3 on the microstructure and electrical properties of Ta-doped SnO 2 varistors, Journal of Physics D: Applied Physics, 38 (2005) 1072, DOI: 10.1088/0022-3727/38/7/017.

[14] A. Punnoose, J. Hays, V. Gopal, V. Shutthanandan, Room-temperature ferromagnetism in chemically synthesized Sn (1−x)CoxO2 powders, Applied Physics Letters, 85 (2004) 1559-1561, DOI: 10.1063/1.1786633.

[15] S.H. Babu, S. Kaleemulla, N.M. Rao, G.V. Rao, C. Krishnamoorthi, Microstructure, ferromagnetic and photoluminescence properties of ITO and Cr doped ITO nanoparticles using solid state reaction, Physica B: Condensed Matter, 500 (2016) 126-132, DOI : MMSE Journal. Open Access www.mmse.xyz

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10.1016/j.physb.2016.07.037.

[16] N.S. Krishna, S. Kaleemulla, G. Amarendra, N.M. Rao, C. Krishnamoorthi, M. Kuppan, M.R. Begam, D.S. Reddy, I. Omkaram, Structural, optical and magnetic properties of Fe doped In2O3 powders, Materials Research Bulletin, 61 (2015) 486-491, DOI: 10.1016/j.materresbull.2014.10.065.

Cite the paper M. Kuppan, S. Harinath Babu, S. Kaleemulla, N. MadhusudhanaRao , C. Krishnamoorthi, G. VenugopalRao, I. Omkaram, D. SreekanthaReddy, K.Venkata Subba Reddy (2017). Structural and Magnetic Properties of Cr Doped SnO2 Nanopowders Prepared by Solid State Reaction. Mechanics, Materials Science & Engineering, Vol 9. doi: 10.2412/mmse.9.43.91

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Particle Size Effect on the Properties of Cerium Oxide (CeO2) Nanoparticles Synthesized by Hydrothermal Method 24 G. Jayakumar1,a, A. Albert Irudayaraj1, A. Dhayal Raj1 1 – PG and Research Department of Physics, Sacred Heart College, Tirupattur, India a – gjayaphysics@gmail.com DOI 10.2412/mmse.3.4.481 provided by Seo4U.link

Keywords: hydrothermal, SEM, HRSEM, degradation.

ABSTRACT. The Cerium oxide (CeO2) nanoparticles with different particle sizes were successfully synthesized by hydrothermal method with different reaction time. The synthesized CeO2 nanoparticles were characterized by Powder XRay diffraction (XRD), Scanning Electron Microscopy (SEM), High Resolution Scanning Electron Microscopy (HRSEM), UV-Vis spectroscopy and FTIR spectroscopy. The effects of the particle size on the structural properties of the prepared samples were investigated usingXRD, SEM and HRSEM. The better optical properties exhibited by CeO 2 having smaller particle size has been revealed by UV-Visible study. The Photo-catalytic study showed that the lower particle size CeO2 nanoparticles have higher Photo-catalytic activity for degradation of Methylene Blue. The optical properties of CeO2 nanoparticles improve with reduction in the particle size.

Introduction. Rare earth, which has been called an industrial vitamin and a treasury of new materials, has an increasingly important role in technical progress and the development of traditional industries and it is also widely applied in high-technology industries such as information and biotechnology.

The particle size of materials affects their basic properties such as lattice symmetry, cell parameters, optical and structural characteristics. Generally, phases in bulk form are unstable in bulk material due to high surface energy, however the surface energy decreases rapidly when size reduces to nanoscale level leading to high stability of materials at nanostructure levels [1]. The surface area and particle size of the CeO2nanoparticles have exceptional impact oversensitivity, conductivity and catalytic activity. Cerium oxide nanoparticles have been widely utilized in various advanced technologies such as solid oxide fuel cells, polishing powders, catalytic materials, sunscreen cosmetic materials, gas sensors and solar cells [2]. Cerium oxide nanoparticles were synthesized using various methods such as chemical precipitation, micro-emulsion, reverse micelles, hydrothermal, ball milling, solution combustion, spray pyrolysis and solvothermal method. Among these methods, hydrothermal method has attracted the most extensive attention, because it is comparatively simple and easy to prepare narrow sized CeO2 nanoparticles[3-5].The main objective of this research paper is investigation on the particle size effect on the properties and photo-catalytic degradation of methylene blue of the cerium oxide nanoparticles prepared by hydrothermal method.

Experimental Method Materials. Cerium nitrate (Ce (NO3)2.6H2O; 432.2 g/mole; 99.9% purity) and Sodium hydroxide (NaOH; 40 g/mole; 99.9% purity) were purchased from Sigma Aldrich Chemicals. These chemicals were used without further purification.

Synthesis. In the synthesis process, 0.217g of Cerium nitrate hexahydrate [Ce (NO3)26H2O] and 0.280g of Sodium hydroxide [NaOH] were taken in 5ml and 35ml of distilled water respectively.

Then, these two solutions were mixed and this mixture was stirred at room temperature for 30 min.

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The solution obtained was transferred to a Teflon lined autoclave which was maintained at a constant temperature of 180° C for 12 hours and 24 hours. The autoclave was allowed to cool down naturally and to reach the room temperature. The final product was collected from the autoclave and washed several times with distilled water and ethanol. The product was dried at 80° C for 6 hours. The dried sample was calcinated at 500°C for 2 hrs. In order to obtain the smaller size CeO2 nanoparticles to repeat the same procedure, but keep the reaction time 24 hours instead of 12 hours.

Characterizations. The X-ray diffraction (XRD) patterns of the samples were obtained from a Rigaku X-ray diffractometer with Cu-Kι (Ν = 1.54187Å) radiation in the range of 10 – 90°at room temperature. The morphology of the particles was studied by QUANTA 200 scanning electron microscope (SEM) and FEI QUANTA FEG 200 High resolution scanning electron microscope (HRSEM). The optical transmittances of the samples were studied by Varian Cary 50 UV-Visible spectrophotometer in the range at 180-850 nm. The FTIR spectra were recorded in the range of 4004000 cm-1by PERKIN ELMER SPECTRUM IIFTIR spectrometer.

Results and Discussions XRD analysis. The XRD patterns of CeO2 nanoparticles prepared at (a) 12 hours and (b) 24 hours are shown in Fig.1. The peaks are indexed using JCPDS card no: 34-0394. Both samples of CeO2 nanoparticles have Face Centered Cubic structure with the lattice parameters a = b = c = 5.411 Å and ι = β = γ = 90°. The diffraction peaks found at 28.56°, 33.08°, 47.47°, 56.36°, 59.08°, 69.40°, 76.70°, 79.07° and 88.41° and it suggests the formation of nano sized CeO2. Absence of impurity indicates that pure CeO2 is synthesized by the hydrothermal method. The average crystallite size (D) of CeO2 nanoparticles are calculated by the Debye-Scherer equation

đ??ˇ=

đ?‘˜đ?œ† đ?›˝ đ?‘?đ?‘œđ?‘ đ?œƒ

where Ν is the wavelength of the Cu-Kι radiation, D is the crystallite size, K is a constant and its value is taken as 0.9, θ is the diffraction angle and β is the full-width at half maximum (FWHM).

The average crystallite size is12.8 nm for CeO2 nanoparticles prepared at 12 hours. The average crystallite size is 9.4 nm for the CeO2 nanoparticles prepared at 24 hours.

Fig. 1. XRD patterns of CeO2 nanoparticles prepared at (a) 12 hours and (b) 24 hours.

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UV-Visible analysis. The optical property of synthesized CeO2 was studied by UV-Visible spectrophotometer and results are shown in Fig.2.The UV cutoff wavelength of CeO2nanoparticles prepared at 12 hours is 335 nm while the UV cutoff wavelength of CeO2 nanoparticles prepared at 24 hours is observed at 352 nm. Additionally, UV-Visible spectra showed no other peak related with impurities and defects which confirms that the synthesized nanoparticles are pure CeO2. The band gap energy is 3.70eV for CeO2 nanoparticles prepared at 12 hours whereas the band gap energy is found to be 3.52eV for CeO2nanoparticles prepared at 24 hours. The UV- Visible spectra reveal that the smaller size CeO2 nanoparticles have the better optical properties.

Fig. 2. UV-Vis spectra of CeO2 nanoparticles prepared at (a) 12 hours and (b) 24 hours.

FTIR analysis.

Fig. 3. FTIR spectra of CeO2 nanoparticles prepared at (a) 12 hours and (b) 24 hours.

The FTIR spectra of CeO2 nanoparticles prepared by the hydrothermal method with different reaction time are shown in Fig.3. The bands at 545cm-1and 750 cm-1 are due to the Ce–O stretching vibrations.

The bands at 1379 cm-1 and 1539 cm-1are due to theC-O stretching vibration and the band at 3412 cm-1 is due to O-H vibration of water absorbed from the moisture.

Scanning Electron Microscopy. SEM image of CeO2 nanoparticles prepared with different reaction time are shown in Fig. 4. The SEM image revealed that the CeO2nanoparticles prepared with large size have sphere like structure with average particle size of 110 nm. The HRSEM image revealed that the CeO2 nanoparticles prepared with small size also have sphere like structure with the average particle size of 23 nm.

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a

b

Fig. 4. SEM image of CeO2 nanoparticles prepared at (a) 12 hours and (b) 24 hours.

Photocatalytic analysis. The Photocatalytic activities of the CeO2 nanoparticles under visible-light irradiation have been evaluated using methylene blue (MB). In a typical process, 1mmol of Methylene blue aqueous solution and 0.5 g of catalyst were mixed. Prior to a photocatalytic reaction, the photocatalyst suspension was sonicated to reach adsorption equilibrium with the photocatalyst in darkness. The above solution was photoirradiated using Halogen-lamp as light source under continuous stirring. At various time intervals, the concentrations of MB in the photocatalytic reaction were analyzed by using an UV-Vis spectrometer. The degradation of MB by CeO2 nanoparticles have been investigated comparing the UV-Vis spectra of the original and degraded MB solutions recorded at various time intervals in the wavelength range from 400nm to 800nm respectively as shown in the Fig. 5 (a). The absorption of MB solution at around 661 nm decreases with increased exposure to light irradiation in the presence of CeO2 nanoparticles. Fig. 5 (b) exhibits the amendment in absorption spectra for the photo-catalytic degradation of MB at dissimilar time periods CeO 2 nanoparticles prepared at (I) 12 hours and (II) 24 hours. The results clearly indicate that degradation of MB is increased for the smaller sized CeO2 nanoparticles [6] and also the CeO2 nanoparticles act as effective photocatalyst in degradation of methylene blue from the aqueous medium.

Fig. 5. UV- Vis spectra of the MB degradation under visible light irradiation in the presence of CeO2 nanoparticles (a) prepared at 24 hours, (b) Comparison of Change in absorbance vs irradiation time of the CeO2 nanoparticles prepared at (I) 12 hours and (II) 24 hours.

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Summary. CeO2 nanoparticles were successfully synthesized by hydrothermal method with different reaction time. The prepared CeO2 nanoparticles were analyzed by Powder X-ray diffraction, UVVisible spectroscopy, Fourier transform infrared spectroscopy, Scanning electron microscopy and High resolution scanning electron microscopy. The XRD studies revealed that the CeO2 nanoparticles have face centered cubic structure and have the average grain size of 12.8nm for 12 hours and 9.4nm for 24 hours. From the SEM studies, the average particle size of CeO2 nanoparticles prepared at 24 hours was found to be 23 nm. The UV-visible spectroscopic study indicates that they are legitimately transparent in the entire UV-Vis region and the smaller size CeO2 nanoparticles have band gap energy of 3.52eV. The UV- Visible spectra revealed that the smaller size CeO2nanoparticles have the better optical properties. The Photocatalytic analysis revealed that the smaller size CeO2 nanoparticles are potential photocatalyst for the degradation of methylene blue.

References [1] Reza Zamiri, Hossein Abbastabar Ahangar, Dielectrical Properties of CeO2 Nanoparticles at Different Temperatures, PLOS ONE, 2015, DOI:10.1371/journal.pone.0122989.

[2] V. Sajith, C. B. Sobhan, G. P. Peterson, Experimental Investigations on the Effects of CeO2 Fuel Additives on Biodiesel, Advances in Mechanical Engineering, 2009, doi:10.1155/2010/581407.

[3]Xiaowang Lu, Xiazhang Li, Feng Chen, Chaoying Ni, Zhigang Chen, Hydrothermal synthesis of prism-like mesocrystal CeO2, Journal of Alloys and Compounds, 2008, doi:10.1016/j.jallcom.2008.09.198.

[4] Fei Lu, Fanming Meng, Leini Wang, Yuan Sang, Jingjing Luo, Controlled synthesis and optical properties of CeO2 nanoparticles by aN2H4.H2O-assisted hydrothermal method, Micro & Nano Letters, 2012, doi: 10.1049/mnl.2012.0279.

[5] A. Bonamartini Corradi, F. Bondioli, A.M. Ferrari, T. Manfredini Synthesis and characterization of nanosized ceria powdersby microwave–hydrothermal method, Materials Research Bulletin, 2006, doi:10.1016/j.materresbull.2005.07.044.

[6]Sher Bahadar Khan, M. Faisal, Mohammed M. Rahman, Effect of Particle Size on the Photocatalytic Activity and Sensing Properties of CeO2nanoparticles, Int. J. Electrochem. Sci., 2013.

Cite the paper G. Jayakumar, A. Albert Irudayaraj, A. Dhayal Raj (2017). Particle Size Effect on the Properties of Cerium Oxide (CeO2) Nanoparticles Synthesized by Hydrothermal Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.3.4.481

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Structural, Optical and Magnetic Properties of α-Fe2O3 Nanoparticles25 B. Balaraju1, M. Kuppan1, S. Harinath Babu2, S. Kaleemulla1,a, N. Madhusudhana Rao1, C. Krishnamoorthi1, Girish M. Joshi3, G. Venugopal Rao4, K. Subbaravamma5, I. Omkaram6, D. Sreekantha Reddy7 1 – Thin films Laboratory, Centre for Crystal Growth, VIT University, Vellore-632014, Tamilnadu, India 2 – Department of Physics, Annamacharya Institute of Technology and Sciences, New Boyanapalli, Rajampet-516 126 andhra Pradesh, India 3 – Polymer Nanocomposite Labrotory, Centre for Crystal Growth, VIT University, Vellore-632014, Tamilnadu, India 4 – Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, Tamilnadu, India 5 – Department of Physics, AMET University, Kanthur, Chennai-603112, Tamilnadu, India 6 – Department of Electronics and Radio Engineering, KyungHee University, Yongin-si, Gyeonggi-do 446-701, Republic of Korea 7 – Department of Physics and Sungkyukwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwan – 440746, Republic of Korea a – skaleemulla@gmail.com DOI 10.2412/mmse.22.88.233 provided by Seo4U.link

Keywords: iron oxide, nanoparticles, XRD profile, oxide semiconductors.

ABSTRACT. High purity Iron oxide (α-Fe2O3) powder was grinded for 16 hours using mechanical milling and studied for its physical properties. The micro structures, crystallite size of the nanoparticles were examined using X-ray diffractrometer (XRD). From this it was found that the particles were in rhombohedral structure with average crystallite size of 39 nm. The optical absorbance and reflectance spectra were recorded using UV–Vis-NIR spectrophotometer in the wavelength range of 200 – 2500 nm. From this it was found that the optical band gap of the nanoparticles as 2.08 eV. The magnetic measurements were carried out using vibrating sample magnetometer at 100 K. From the magnetic studies it was found that the magnetic moment of the nanoparticles increased with increase of applied field and saturation was not observed even at high applied magnetic fields.

Introduction. Now-a-days, wide band gap oxide semiconductors, tin oxide, tungsten oxide, nickel oxide, chromium oxide, iron oxide etc. are finding great interest in many potential applications such as magnetic devices, sensors, lithium ion batteries, etc.[1-5]. Moreover much focus in being paid on nanoparticles of these oxide materials as they are best suited for the device applications as the nanoparticle find peculiar properties. More efforts were put for the synthesis of nanoparticles using different physical and chemical methods. Among the various types of nanomaterials, the magnetic materials of iron oxides such as α-Fe2O3 and Fe3O4 are the most popular and promising materials due their many technological applications. Among the other metal oxide materials, α-Fe2O3 finds in many applications such as pigment, electrode material, magnetic materials etc.[6-10]. Further it finds applications in many photovoltaic devices [11-15]. In the present investigation, synthesis of α-Fe2O3 nanoparticles were done using mechanical milling method and subjected to structural, optical and magnetic properties.

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Experimental. The commercially available Îą-Fe2O3 powder was procured from Sigma Aldrich (India). Îą-Fe2O3 nanoparticles were prepared by simple mechanical milling method. The powder was milled using Agate mortar and ground thoroughly for 16 hours using pestle. After that the samples were characterized for structural, optical, magnetic and photoluminescence properties. X-ray diffraction (X-ray diffractometer, D8 Advance, BRUKER) patterns were used to study the structural aspects. The optical reflectance spectra were recorded using UV-VIS spectrophotometer (JASCO-V670) in the wavelength range of 200 nm to 2500 nm and the magnetic studies were studied using vibration sample magnetometer (VSM Lakeshore 7404 ).

Results and discussion.

Structural properties. Fig. 1 shows the X-ray diffraction profile of the Fe2O3 nanoparticles. The diffraction peaks such as (0 1 2), (1 0 4), (1 1 0), (1 1 3), (0 2 4), (1 1 6), (1 2 2), (2 1 4) and (3 0 0) were found in their respective diffraction angles. From this the structure of the nanoparticles was found to be in rhombohedral structure. These are in good agreement with that of standard XRD pattern of Îą-Fe2O3 derived from the JCPDS Card No. 33-664 [16]. No other diffraction peaks related to either FeO or Fe3O4 were found in the profile indicating that the source material is pure from any kind of impurities.

2000

(116)

(122)

(113)

(214) (300)

1000

(024)

(110)

1500

(012)

Intensity (counts)

(104)

Fe2O3

500 20

30

40

50

60

70

2ď ą (degrees)

Fig. 1. XRD profiles of Îą-Fe2O3 nanoparticles.

The crystallite size (G) was calculated by using the Debye-Scherer formula, đ?‘˜đ?œ†

đ??ş = đ?›˝đ?‘?đ?‘œđ?‘ đ?œƒ

(1)

where k - particle geometry dependent constant (for spherical shape k ~1), ď Ź - wavelength of used (ď Ź = 1.5406 Ă…), ď ˘ - full width-at-half maximum (FWHM) and ď ą - the diffracted angle, respectively.

The estimated average crystallite size is found to be 39 nm.

Optical properties. Fig. 2 shows the optical absorbance spectrum of Îą-Fe2O3 nanoparticles. From the optical absorbance and reflectance data, the optical band gap of the nanoparticles was estimated.

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The optical bang gap Eg was obtained by plotting (ÎąhĎ…)2 versus the photon energy (hĎ…) and by extrapolating the linear region (Îą = 0). The optical band gap was estimated using the Tauc equation đ?›źâ„Žđ?œˆ = đ??´ √ (đ??¸đ?‘” − hν)

(2)

where hν – the photon energy, ι – the absorption coefficient and n – either 1/2 for a direct transition or 2 for an indirect transition.

An optical band gap of 2.08 eV was observed for Îą-Fe2O3 nanoparticles. The observed optical band gap is inconsistent with that of published work [9].

1.0

Fe2O3

Absorbance (%)

0.8

0.6

0.4

0.2

0.0 500

1000

1500

2000

Wavelength (nm)

Fig. 2. Optical absorbance spectrum of Îą-Fe2O3 nanoparticles.

Magnetic Properties. Fig.3 shows the magnetization versus magnetic field curve of the Îą-Fe2O3 nanoparticles calibrated at 100 K in the external magnetic field of -10 kOe to +10 kOe. From the Fig. it is clear that the nanoparticle exhibits ferromagnetism. But the strength of magnetization is less. Fig. 4 shows the magnetization versus magnetic field curve of the Fe2O3 nanoparticles calibrated at 100 K in the external magnetic field of -70 kOe to +70 kOe. Here also the magnetic hysteresis measurements for synthesized samples were carried out using vibrating sample magnetometer (VSM) at 100 K. It can be seen that the magnetization increases almost linearly under an applied magnetic field. The saturation in the magnetization could not be observed even under the high magnetic field of 40, 000 Oe. This observation is similar to the earlier study [17] . The linear increase in the magnetization represents the contribution of the Îą-Fe2O3 antiferromagnetic core [18].

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Magnetization (emu/g)

0.2

0.1

0.0

-0.1

-0.2 -10.0k

-5.0k

0.0

5.0k

10.0k

Applied Field (kOe)

Fig. 3. M-H curve of α-Fe2O3 nanoparticles at under low magnetic fields.

Magnetization (emu/g)

1.0

-Fe2O3-100 K

0.5

0.0

-0.5

-1.0 -60.0k

-40.0k

-20.0k

0.0

20.0k

40.0k

60.0k

Applied Field (kOe)

Fig. 4. M-H curve of α-Fe2O3 nanoparticles at under high magnetic fields.

Summary. Nanoparticles of highly purified α-Fe2O3 have been synthesized by solid state method.

The average crystallite size has been found as 39 nm. The optical properties of the sample show that the optical bandgap is at 2.08 eV. The magnetic studies of the sample confirm the ferromagnetic nature of sample with the absence of saturation even at high fields.

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[2] V.M. Aroutiounian, V.M. Arakelyan, G.E. Shahnazaryan, Metal oxide photoelectrodes for hydrogen generation using solar radiation-driven water splitting, Solar Energy, 78 (2005) 581-592, DOI : 10.1016/j.solener.2004.02.002.

[3] X. Lai, G. Shen, P. Xue, B. Yan, H. Wang, P. Li, W. Xia, J. Fang, Ordered mesoporous NiO with thin pore walls and its enhanced sensing performance for formaldehyde, Nanoscale, 7 (2015) 40054012, DOI: 10.1039/C4NR05772D. [4] C. Wang, L. Yin, L. Zhang, D. Xiang, R. Gao, Metal Oxide Gas Sensors: Sensitivity and Influencing Factors, Sensors, 10 (2010) DOI : 10.3390/s100302088.

[5] N. Song, H. Jiang, T. Cui, L. Chang, X. Wang, Synthesis and enhanced gas-sensing properties of mesoporous hierarchical α-Fe2O3 architectures from an eggshell membrane, in: Micro & Nano Letters, Institution of Engineering and Technology, 2012; pp. 943-946; DOI : 10.1049/mnl.2012.0631.

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[6] M. Mohapatra, D. Behera, S. Layek, S. Anand, H.C. Verma, B.K. Mishra, Influence of Ca Ions on Surfactant Directed Nucleation and Growth of Nano Structured Iron Oxides and Their Magnetic Properties, Crystal Growth & Design, 12 (2012) 18-28, DOI : 10.1021/cg201124c.

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[10] L. Wang, L. Gao, Morphology Transformation of Hematite Nanoparticles Through Oriented Aggregation, Journal of the American Ceramic Society, 91 (2008) 3391-3395, DOI : 10.1111/j.15512916.2008.02537.x.

[11] P. Gangopadhyay, S. Gallet, E. Franz, A. Persoons, T. Verbiest, Novel superparamagnetic Core (Shell) nanoparticles for magnetic targeted drug delivery and hyperthermia treatment, IEEE Transactions on Magnetics, 41 (2005) 4194-4196, DOI : 10.1109/TMAG.2005.854805.

[12] E. Katz, I. Willner, A quinone-functionalized electrode in conjunction with hydrophobic magnetic nanoparticles acts as a "Write-Read-Erase" information storage system, Chemical Communications, (2005) 5641-5643, DOI : 10.1039/B511787A. [13] Y.-X.J. Wang, S.M. Hussain, G.P. Krestin, Superparamagnetic iron oxide contrast agents: physicochemical characteristics and applications in MR imaging, European Radiology, 11 (2001) 2319-2331, DOI : 10.1007/s003300100908.

[14] S. Yan, D. Zhang, N. Gu, J. Zheng, A. Ding, Z. Wang, B. Xing, M. Ma, Y. Zhang, Therapeutic Effect of Fe2O3 Nanoparticles Combined with Magnetic Fluid Hyperthermia on Cultured Liver Cancer Cells and Xenograft Liver Cancers, Journal of Nanoscience and Nanotechnology, 5 (2005) 1185-1192, DOI : 10.1166/jnn.2005.219.

[15] M. Zahn, Magnetic Fluid and Nanoparticle Applications to Nanotechnology, Journal of Nanoparticle Research, 3 (2001) 73-78, DOI : 10.1023/A:1011497813424.

[16] J. Chen, L. Xu, W. Li, X. Gou, α-Fe2O3 Nanotubes in Gas Sensor and Lithium-Ion Battery Applications, Advanced Materials, 17 (2005) 582-586, DOI : 10.1002/adma.200401101.

[17] C. Xia, C. Hu, Y. Xiong, N. Wang, Synthesis of α-Fe2O3 hexagons and their magnetic properties, Journal of Alloys and Compounds, 480 (2009) 970-973, DOI : 10.1016/j.jallcom.2009.02.106.

[18] M. Tadić, D. Marković, V. Spasojević, V. Kusigerski, M. Remškar, J. Pirnat, Z. Jagličić, Synthesis and magnetic properties of concentrated α-Fe2O3 nanoparticles in a silica matrix, Journal of Alloys and Compounds, 441 (2007) 291-296, DOI : 10.1016/j.jallcom.2006.09.099.

Cite the paper B. Balaraju, M. Kuppan, S. Harinath Babu, S. Kaleemulla, N. Madhusudhana Rao , C. Krishnamoorthi, Girish M. Joshi, G. Venugopal Rao, K. Subbaravamma, I. Omkaram, D. Sreekantha Reddy (2017). Structural, Optical and Magnetic Properties of α-Fe2O3 Nanoparticles. Mechanics, Materials Science & Engineering, Vol 9. doi: 10.2412/mmse.22.88.233

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Ferromagnetic and Photoluminescence Properties of Fe doped Indium-TinOxide Nanoparticles Synthesised by Solid State Reaction26 Deepannita Chakraborty1, N. Madhusudhana Rao1,a, G. Venugopal Rao2, S. HainathBabu1, S. Kaleemulla1, C. Krishnamoorthi1 1 – Centre for Crystal Growth, School of Advanced Sciences, VIT University, Vellore, Tamilnadu, India 2 – Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu, India a – drnmrao@gmail.com DOI 10.2412/mmse.47.72.37 provided by Seo4U.link

Keywords: Fe and Sn codoped Indium Oxide, Dilute magnetic semiconductors, antiferromagnetism.

ABSTRACT. Iron and tin codoped indium oxide (In0.90Sn0.05Fe0.05)2O3) nanoparticles were synthesized by solid state reaction. The synthesized nanoparticles were studied for their structural, surface, chemical, optical, magnetic and photoluminescence properties using respective characterization techniques. The XRD and FE-SEM images confirmed the nanosize of the particles. Raman studies indicated no structural changes in the indium oxide lattice after addition of Fe and Sn into the lattice. From magnetic studies it was observed that the Sn doped indium oxide nanoparticles were ferromagnetic. The ferromagnetic nature is destroyed after codoping of iron and tin in indium oxide lattice. Two broad emission peaks were observed in photoluminescence spectra.

Introduction. Currently the dilute magnetic semiconducting (DMS) materials are finding increased interest due to their potential as well as practical applications in the field of spintronics as well as exhibiting ferromagnetism at or above room temperature [1-4]. Till now many transition metal doped oxide semiconductors such as ZnO, TiO2, CeO2 and In2O3 were found to be exhibiting ferromagnetism at room temperature[5-7]. Among them, Indium oxides (In2O3) have high density of charge carriers, optical transparency and have low impact on the environment. Previous reports suggest that the decrease in crystal size of these oxides in the range of nanoparticles can lead to the change in their physical, chemical and optical properties [8, 9]. The decrease in crystal size can occur by doping the host lattice with another lattice having less ionic radii than the host. So In2O3 is doped with Sn as ionic radii of Sn is less than In. This leads to the formation of one of the best transparent conductive oxides (TCOs) namely indium-tin oxide (ITO). Generally, it has a lattice parameter of a = 10.118 Å[10]. Consequently, ITO has high optical transparency, high electrical conductivity and high reflectance. ITO in the form of films has been used as transparent electrodes for flat-panel displays, electrochromic windows, solar panels and transparent coatings for solar-energy heat mirrors [11-14]. A large number of articles regarding transition metal doped In2O3 thin films have been published but there are rarely any reports on magnetic and photoluminescence properties of transition metal and tin codoped indium oxide nanoparticles having uniform sized particles [15, 16].

Experimental Details. Commercially available In2O3 (99.999%), SnO2 (99.99%) and Fe2O3 (99.99%) precursor powders were procured from Sigma-Aldrich (made in Germany) and were used as source materials. The ITO (In1.95Sn0.05O3) and (Fe:Sn) codoped In2O3 powder samples were prepared by mixing stoichiometric molar ratio of In2O3, SnO2 and Fe2O3 precursors in Agate mortar and pestle. The mixture was ground for 16 hrs to make it homogeneous fine powder which was then 26

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loaded into a one-end closed quartz tube with 1 cm diameter and 10 cm length. This precursor loaded quartz tube was further enclosed in a large diameter quartz tube (reaction chamber) with 2.5 cm dia and 75 cm length. The synthesis procedure was carried out in an optimised pressure of about 2x10-3 mbar. The whole setup was then heated at low ramping to reach 800 oC by microprocessor controlled furnace and then soaked for 6 hrs until it was cooled back to room temperature. The structural, morphological, optical and magnetic properties of the samples has been studied by using their corresponding measuring instruments at room temperature.

Results and Discussions. Fig. 1 depicts the X-ray diffraction plot of (Fe:Sn) codoped In2O3 powder.

The diffraction peaks in (Fe:Sn) codoped In2O3 profile matches with the JCPDS No. #06-0416 having cubic structure. The lattice constant of (Fe:Sn) codoped In2O3 fine powders is calculated as 10.08 Å.

This is less than the lattice constant of In2O3, as reported in literature as 10.112 Å. The average crystallite size of (Fe:Sn) codoped In2O3 is determined as 41 nm by using the Debye-Scherrer formula.

9000

(Fe:Sn)In2O3

Intensity (Counts)

7500

6000

4500

3000

1500

0 20

30

40

50

60

2 (degrees)

Fig. 1. X-ray diffraction of (Fe:Sn) codoped Indium Oxide nanoparticles.

Fig. 2. FE SEM micrograph of (Fe:Sn)In2O3 nanoparticles.

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Fig. 2. shows the morphology of the (Fe:Sn) codoped In2O3 powders having average particle size of 47 nm. This is greater than the crystallite size which suggests that the particles are multi-grained.

Fig.3. confirms the presence of appropriate ratios of all elements in the EDAX spectra of (Fe:Sn) codoped In2O3 nanoparticles. It has also been confirmed that Fe and Sn ions substitute in the host lattice of In2O3.

The Raman spectra of ITO, (Fe:Sn) codoped In2O3 as well as the precursors were measured. From Fig. 4. the characteristic Raman peaks of In2O3 were observed at 110, 132, 154, 164, 212, 249, 307, 365, 480, 495, 631 cm-1. These peaks perfectly coincide with the reports in the literature[17]. The characteristic Raman peaks of ITO and (Fe:Sn) codoped In2O3 perfectly matches with the peaks of In2O3. This indicates that (Fe:Sn) codoped In2O3 has good lattice order, suggesting that Fe+3ions might have been located at substitutional lattice sites of In+3 as reported earlier by Harinath et.al[18].

Fig. 3. EDAX image of (Fe:Sn) In2O3 nanoparticles.

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1200 1000 800 600 400 200 0 200

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Fig. 4. Raman spectra of In2O3, SnO2, ITO and Fe doped ITO powders.

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The diffuse reflectance spectra for pure In2O3, ITO and Fe doped ITO has been reported earlier by Harinath et.al.[18]. The optical band gap of (Fe:Sn) codoped In2O3 has been determined by plotting tauc’s plot. The (Fe:Sn) codoped In3O3 sample undergoes indirect transition with an optical band gap of 2.82 eV. The ferromagnetic nature of ITO at room temperature has been observed in previous report by Harinath et.al.[18]. This may be attributed to the dopant Sn which might have created carrier mediated mechanism or due to formation of oxygen vacancies at the time of synthesis. It has also been observed in previous report by Harinath et.al[18] that the doping of Fe in the ITO lattice degraded the magnetic property of ITO. The temperature dependent magnetization measurements for (Fe:Sn) codoped In2O3 have been carried out. The formation of antiferromagnetism and the absence of magnetic cluster formation can be suggested from the plots of zero fields cooled (ZFC) and field cooled (FC) datas.

Fig. 5. The photoluminescence plot of ITO and (Fe:Sn) codoped In2O3 nanoparticles.

The photolumiscence (PL) plots for the ITO and (Fe:Sn) codoped In2O3 nanoparticles were recorded at room temperature. Fig.5. depicts the UV emission peak at 330 nm and blue-green emission peak at 465 nm for ITO and (Fe:Sn) codoped In2O3. The UV emission peak is broad in nature. This is caused by the near band edge (NBE) radiative transitions. The blue-green emission peak occurs due to the various crystalline or surface defects.

Summary. Nanoparticles of ITO and (Fe:Sn) codoped In2O3 has been synthesized. The ferromagnetic behavior is observed in ITO at room temperature and it is found to decreasing on codoping of Fe ions with Sn ions in In2O3 lattice. The optical band gap energy of (Fe:Sn) codoped In2O3 is found to be 2.82 eV. The emission peaks has been observed at 329 nm and 466 nm on an excitation wavelength at 300 nm indicating the occurrence of surface defects.

Acknowledgements. The authors are highly thankful to the UGC-DAE-CSR, IGCAR, Kalpakkam 603102, Tamilnadu, India, for providing financial (Grant No: CSR-KN/CRS-72/2015-16/809) support to carry out the present work. The authors also thank VIT-SIF for providingXRD, Raman, UV-Vis-NIR and Photoluminescence facilities.

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[2] S.A. Wolf, D.D. Awschalom, R.A. Buhrman, J.M. Daughton, S. von Molnár, M.L. Roukes, A.Y. Chtchelkanova, D.M. Treger, Spintronics: A Spin-Based Electronics Vision for the Future, Science, 294 (2001) 1488, DOI: 10.1126/science.1065389.

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[5] R. Singhal, A. Samariya, S. Kumar, Y. Xing, D. Jain, U. Deshpande, T. Shripathi, E. Saitovitch, C. Chen, On the longevity of H-mediated ferromagnetism in Co doped: A study of electronic and magnetic interplay, Solid State Communications, 150 (2010) 1154-1157, DOI: 10.1016/j.ssc.2010.03.018.

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Cite the paper Deepannita Chakraborty, N. Madhusudhana Rao, G. Venugopal Rao, S. HainathBabu, S. Kaleemulla, C. Krishnamoorthi (2017). Ferromagnetic and Photoluminescence Properties of Fe doped Indium-Tin-Oxide Nanoparticles Synthesised by Solid State Reaction. Mechanics, Materials Science & Engineering, Vol 9. doi: 10.2412/mmse.47.72.37

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The Role of Cellulose in the Formulation of Interconnected Macro and Micoporous Biocompatible Hydroxyapatite Scaffolds 27 J. Anita Lett1, M. Sundareswari1, K. Ravichandran2, Amirdha Sher Gill1, J. Joyce Prabhkar3 1 – Department of Physics, Sathyabama University, Chennai, India 2 – Department of Analytical Chemistry, University of Madras, Chennai, India 3 – Department of General Surgery, Madras Medical College, Chennai, India DOI 10.2412/mmse.62.43.650 provided by Seo4U.link

Keywords: bone tissue engineering, pure hydroxyapatite scaffolds, cellulose, porosity.

ABSTRACT. In bone tissue engineering, ceramics are widely used as implant material to enhance bone growth formation or as drug release vehicle. In the existing work porous Hydroxyapatite scaffolds were prepared by polymeric replication method using Cellulose as a binding agent. The influence of binder on various sintering temperature were evaluated. The Hydroxyapatite scaffold sintered at 1150°C was characterized for phase purity, structural analysis and porosity measurements. Hence, it is possible to produce Hydroxyapatite scaffolds with highly inter connecting macro and micro pores with an apparent density of 0.944g/cm3 corresponding to 75% porosity.

Introduction. Tissue engineering is a field where cells, bone/ scaffolds and signals/factors are mutually joined with the endeavour to re-establish, preserve and improve tissue and organ utility.

Various scaffold resources have been investigated worldwide with both positive and negative outcomes. Factors for the failure of scaffolds include undesired scaffold degradation commodities affecting cellular functions, unaffected responses elicited by the scaffold materials themselves, lack of cell adhesion appropriate to non-suitable surface properties, controversies in the degradation rate of the scaffold and the growth rate of the fresh tissue, or mechanical mismatches connecting scaffolds and the tissue at the implantation location. Calcium phosphates are amongst the most widely used resources for bone tissue regeneration. They can be man-made as gels, pastes and solid blocks or even as porous matrices, with orthopaedics and dentistry being their main areas of relevance.

Hydroxyapatite (HAP) are the most frequently used calcium phosphates, owed to their Stoichiometric ratio (Ca/P) ratios close to that of natural bone and also for their stability when in contact with physiological environment. HAP is a major constituent of bone resource and is resorbed after a long time in the body, due to its biocompatibility [1-4]. The porous network or interconnected pores in HAP structure permit the tissue to penetrate, which further enhances the implant tissue attachment (Itoh et al). Several methods have been investigated to achieve the required porous scaffolds for instance, Sopyan et al has studied with pore-creating volatile particles, ceramic foaming methods and polymeric sponge process [5]. The polymeric sponge technique, which offers great flexibility, is particularly of interest due to its greater advantages such as opportunity to control the pore size, for several required complex shapes and straightforward process (Tian and Tian 2001).The polymeric sponge technique involves covering of open-cell polymeric foam with ceramic slurry followed by flaming out of polymeric foam in the course of sintering process which yields a duplication of the original polymer foam in the ceramic foam structure. However, the properties of the Hydroxyapatite scaffold prepared through the polymeric sponge technique are highly depend on the slurry properties together with homogeneity, rheology and dispersion (Zhang et al 2006). Monmaturapoj has reported 27

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the dispersant on the rheological behaviour of concentrated hydroxyapatite suspensions [6]. In this study, porous hydroxyapatite scaffolds were obtained using the polymer replication method, using cellulose as a binding agent and the morphology and its physio-chemical properties were studied.

These scaffolds can be used as matrices for bone tissue engineering or as specific release vehicles [7].

Also, they may be functionalized with molecules such as collagen, chitosan, etc, in order to enhance their biological responses [8].

Material and Methodology.

Sample Preparation. The Hydroxyapatite powder with an average crystallite size of approximately 40 nm, was prepared according to our previous work by sol-gel [9].The template used to prepare scaffolds were polyurethane sponges with an average pore size of 400 microns. The Cellulose, used as a binder was made into a homogenous mixture by mixing for 2 hr with water at 50 ºC. To fabricate scaffolds, a ceramic slurry containing 6 g of Hydroxyapatite powder, binder, tensioactive agent (A40 V Dispex provided from BASF) and water [6] were blended again for 2 hours to disperse thoroughly.

The polyurethane sponges were dipped in the slurries and the excess slurry was removed and dried at room temperature for 2 days, followed by drying in the hot air furnace at 110 ºC until its completely dried. The polyurethane sponge used as template was removed by heating in a muffle furnace at 600oC for 2 hrs, followed by the densification of scaffold by sintering at 1150 oC for 4 hours. Now, these prepared scaffolds were cut into cubes for further characterization.

Physio-Chemical Characterization. The microstructure of the hydroxyapatite scaffolds was characterized using scanning electron microscopy (FESEM: Supra VP35 Carl Zeiss, Germany) and the macro porous structure using optical stereo zoom microscope. The phase purity of the Hydroxyapatite scaffolds were determined by X-ray diffraction using a X’pertPro, Philips, The Netherlands with CuKα radiation over the 2θ range of 10°–80° with a step size of 0.05°. The functional group analysis of HAP scaffolds was carried out in the spectral range from 4000 to 650 cm−1 using a single beam Fourier transform infrared spectrometer (Agilent, Cary 630). The porosity and density measurements of the scaffolds were calculated by simple displacement techniques [8-9].

A scaffold of weight ‘W’ was immersed in a graduated cylinder containing a known volume (V1) of water until no air bubble emerged from the scaffold. The total volume of the water and scaffold was then recorded as V2. The volume difference (V2 – V1) was the volume of the skeleton of the scaffold.

The scaffold was removed and the residual water was measured as V3.

The apparent density of the scaffold (ρ), was evaluated using,



W V2  V3

(1)

The porosity of the open pores in the scaffold (ε), was evaluated using,



V1  V3 V2  V3

(2)

Results and Discussions. The nano-HAP powder used for fabricating scaffolds processed an elongated cylindrical shape with the crystallite size of 40 nm. The scaffolds were approximately 10 mm x 10 mm x 10 mm in size. The morphology of the fabricated Hydroxyapatite is shown in Fig.1, 2. It is found that the scaffolds replicated the pores in the sponges with a pore size of approximately 500 microns. Thus, highly porous Hydroxyapatite scaffolds were produced using the polymer MMSE Journal. Open Access www.mmse.xyz

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replication method as seen in Fig. 2.With SEM observations (Fig. 2), pore diameters ranging from 400 to 500 μm were observed. On the other hand, micropores (Fig. 3) of size lesser than micron were also visualised in the pore walls and wall struts. The microstructures of the scaffolds (Fig. 2) could be observed that the scaffold had a compact structure and that the pores were evenly distributed. The open as well as interconnected pore network was an essential factor for the scaffold to permit cell growth and the transportation of nutrients and metabolic waste. Gotz et al.[13] has reported that pore sizes around 300 µm were suggested for implants due to improved new bone and capillary formation.

Hollister et al[14] conducted in vivo studies on HAP scaffolds with pore diameters ranging between 400 µm and 1200 µm and inferred no significant difference in bone growth for scaffolds of all pore sizes.

Fig. 1. Macro pores of Scaffold.

2µm Fig. 2 Micro pores of Scaffold.

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Fig. 3. XRD pattern of Sintered Scaffold.

The XRD patterns of the scaffolds prepared is shown in Fig. 3. All of the peaks matched with the JCPDS pattern 09-0432 for HAP, which suggested that no other phases were present, as shown in Fig. 3. All of the peaks were attributed to the HAP phase and no additional peaks were observed. The results indicated that the HAP did not decompose after sintering. The characteristic peaks at two theta 31.7° corresponding to 211 diffraction became narrower and sharper for sintering temperature 1150°C. These data confirms that the major phase as Hydroxyapatite and absence of impurity such as calcium phosphates and calcium oxide are clearly identified [22] .

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Fig. 4. FTIR pattern of Sintered Scaffold.

The FT-IR spectra of the synthesized HAP scaffold prepared using cellulose as a binding agent is shown in Fig.4. In the FTIR spectra, the bands at 3570 and 630 cm-1[15] were recognized to the hydroxyl stretching bands and bending bands of HAP, respectively. The broad absorption band from 3600 to 3300 cm-1[15] indicated the existence of the bending mode of absorbed water[16]. The bands at 1093 and 1041 cm-1 were assigned antisymmetric ʋ3 [PO43− ] P-O stretching mode and the ʋ1 P-O symmetric stretching mode was detected at 962 cm-1 [15, 17-18]. The bands at 603 and 569 cm-1 were attributed to components of the triply degenerate ʋ4 O-P-O bending modes.

The Scaffold prepared using cellulose showed high porosity of 75% with apparent density of 0.944 g/cm3. The mechanical properties are strongly subjective by apparent density [18]. In trabecular bone, the apparent density ranges from 0.14g/cm3 to 1.10g/cm3 [18]. Porosity is based on the presence of MMSE Journal. Open Access www.mmse.xyz

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open pores. It was found that mechanical properties varied with binders used. Moreover, a few studies [19, 20] have reported that the decomposition of HAP would reduce its mechanical properties. Hence, a symmetry is to be maintained between the porosity and apparent density for precise purposes, since higher mechanical strength corresponds to higher density, while a high porosity provides a surrounding favourable for living organism[21].

Summary. In this work, porous scaffolds were prepared using a polymeric sponge template method using cellulose as a binding agent. A well defined elongated cylindrical HAP crystals with negligible agglomeration was used to fabricate these scaffolds. The FESEM results exposed that the porous Hydroxyapatite scaffolds acquired macro pores and micro pores that emerges to be interconnected with a homogenous porous network (Fig. 3).The scaffolds comprises pure crystalline Hydroxyapatite phase and no additional phase were produced through the spongy technique as confirmed by XRD and FTIR. The scaffold prepared with cellulose in spite of high porosity (75%) appeared to report an apparent density of 0.944 g/cm3 comparable with trabecular bone (0.14 g/cm3 to 1.10 g/cm3).

Thus, it is possible to produce porous scaffolds with varied porosity and density. Such scaffolds can find its application for tissue engineering in non load bearing applications or even as a vehicle for the delivery of biological molecules. Currently, studies are being performed in order to incorporate collagen type I in these porous constructs, to improve their potential applications.

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[19] Li, S., Izui, H., Okano, M. &Watanabe, T. The effects of sintering temperature andpressure on the sintering behavior of hydroxyapatite powder prepared by spark plasma sintering. J. Biomech.

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[20] Khalil, K. A., Won Kim, S. & Kim, H. Y. Consolidation andmechanical properties of nanostructured hydroxyapatite- (ZrO2 1 3 mol% Y2O3) bioceramics by highfrequency induction heat sintering. Mat. Sci. Eng. A-Struct. 456, 368–372 (2007).

[21] Gu, Y.W., Loh, N. H., Khor, K. A., Tor, S. B. & Cheang, P. Spark plasma sintering of hydroxyapatite powders. Biomaterials 23, 37–43 (2002).

Cite the paper J. Anita Lett, M. Sundareswari, K. Ravichandran, Amirdha Sher Gill, J. Joyce Prabhkar (2017). The Role of Cellulose in the Formulation of Interconnected Macro and Micoporous Biocompatible Hydroxyapatite Scaffolds. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.62.43.650

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Structural, Morphological and Optical Characterization of Eu3+ and Nd3+ CoDoped Tio2 Nano Particles by Sol Gel Method28 P. Sanjay1, K. Deepa2, M. Victor Antony Raj2, S.Senthil1, a 1 – Department of Physics, Government Arts College for Men (Autonomous), Chennai, India 2 – Department of Physics, Loyola College, Chennai, India a – ssatoms@yahoo.co.in DOI 10.2412/mmse.77.97.901 provided by Seo4U.link

Keywords: co-doped TiO2 nanoparticles, XRD, UV-Vis, HRTEM, FTIR. ABSTRACT. Semiconductor nano crystals have been widely studied for their fundamental properties. The Eu 3+ and Nd3+ doped titanium dioxide nano powder was successfully synthesized by sol-gel method. The morphological and structural properties of as-prepared samples were characterized by X-ray diffraction (XRD), High Resolution Transmission Electron Microscope (HRTEM). The Powder X- ray diffraction is carried out in order to examine the phase formation and substitution of Eu3+ and Nd3+ doped in TiO2 matrix. The UV-Vis spectral analysis was carried out between 200 nm and 1200 nm. The band gap of the Eu3+ and Nd3+ doped Tio2 nanoparticles was calculated. The functional groups of the synthesized compound have been identified by FTIR spectral analysis. The strong PL intensity confirms a blue shift.

Introduction. Titanium dioxide (TiO2) nanomaterials are used in a wide range of applications such as photo catalysis, sensor devices, paints and dye-sensitized solar cells. The material properties of TiO2 nanoparticles depend upon the parameters like crystal structure, nanoparticle size and morphology. However, these parameters are depending on the method of synthesize [1]. Titanium dioxide exists in three main crystallographic forms of anatase, rutile and brookite [2]. Among the various polymorphs listed above, anatase type has been selectively used for photocatalytic applications and various other applications [3]. Sol–gel method was often employed to prepare TiO2 because of its simplicity and low equipment requirement. The conventional sol–gel process usually involved uncontrollable fast hydrolysis and condensation and therefore could result in formation of amorphous TiO2 [4]. Sometimes, the high temperature would seriously affect the particle size and surface area and even could result in a collapse of the mesoporous structure. Therefore, it is necessary to synthesize nanocrystalline anatase under mixed conditions. Many researchers have tried to prepare nanostructure anatase TiO2 in well crystalline form.Some researchers have reported that they could improve the absorption and photocatalytic activity via dye sensitizing, surface deposition with metal or doping with metal, nonmetal, or their oxides. Many nonmetal ions have been successfully doped the intensity of photoluminescence (PL) of TiO2 doped with Sm3+ ions was reported to show specific dependence on the oxygen content in the surrounding atmosphere and similar effects have been seen in case of Eu3+ doped titania and also in the intrinsic emission of porous TiO2[5-7]. This motivates further work to elaborate photoluminescent gas sensing materials based on lanthanide doped TiO2. It is very necessary for researchers to explore the theory and the experimental results on such field. In the present work, we have synthesized anatase phase of Nd3+ and Eu3+ co-doped TiO2 nanoparticles by sol–gel method and they were analyzed for structural and optical properties.

EXPERIMENTAL DETAILS

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Synthesis procedure. Pure Titanium dioxide nanocrystals were prepared using the sol - gel method.

Titanium isopropoxide (TIP) was used as the precursor for Titania sol preparation. The sol corresponds to the overall volume ratio of Ti [OCH (CH3)2]4: C3H8O: CH3COOH: Distilled H2O = 5:30:4.4:30. Ti [OCH (CH3)2]4 was first dissolved in isopropanol and distilled water to form titania sol and then stirred for 1h at room temperature. The pH of sol was adjusted to 2-3 by adding 1-2 drops of ammonia with stirring in room temperature for 12h. The prepared sol was left to stand for the formation of gel and dried at 100°C for an hour in a furnace to remove the solvents. The obtained gel was milled into powders and calcined at 400°C for 4h to keep anatine TiO2 phase. Europium and neodymium co-doped TiO2 was synthesized using the same procedure as the reference sample.

RESULT AND DISCUSSION XRD Analysis. The XRD pattern of the Nd3+ and Eu3+ co-doped TiO2 nanoparticles are shown in Fig.1. The Strong and sharp peaks of the pattern confirmed the crystalline structure of the samples.

All theme main diffraction peaks at 25.38 (101), 37.96 (002), 48.04 (042), 55.94 (361) and 63.20 (211) coincide with the JCPDS values (PDF Card No: 21-1272) which correspond to crystal structure of anatase. The variation in intensity of the diffraction peaks indicates the crystallinity behavior due to lattice distortion. When Nd3+ and Eu3+ ions are incorporated into the periodic crystal lattice of TiO2, a strain is induced into the system, resulting in the alteration of the lattice periodicity.

Furthermore, after doping, the diffraction peaks got broadened suggesting a systematic decrease in the crystallite size. The crystallite size of the co-doped nanoparticle were estimated from the most intense peak based on Scherer equation D = kλ/βcosθ where k is the shape factor taken as 0.9, λ is the wavelength, β is full width at half maximum and θ is the diffraction angle. Average crystallite size in co-doped Tio2 matrix was calculated as 25.50 nm.

Fig. 1. XRD pattern of Nd3+ and Eu3+ co-doped TiO2 nanoparticles.

Optical Properties. The synthesized Nd3+ and Eu3+ co-doped TiO2 nanoparticles were analyzed by UV-Vis absorption spectroscopy as seen in Fig. 2 (a). The absorbance of the nanoparticles exhibits a sharp decrease in the visible region (380 nm); co-doping of Nd3+ and Eu3+ can have significant influence on the absorption of light. The cut-off wavelength has been enlarged to the visible regions by doping. The cut-off wavelength shifted from 380nm by increasing with Nd3+ and Eu3+ content.

The result shows that the range of light absorption of doped TiO2 is wider than undoped TiO2 nanoparticles, also optical band-gap measurements of the prepared sample were carried out. The band gap for Nd3+ and Eu3+ co-doped TiO2 nanoparticles was calculated using the formula: αhv = C (hv-Eg)1/2

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where α is absorption coefficient, C is a constant, hv is energy of photons and Eg is the energy band gap.

By plotting (αhv)2 versus ‘hv’ the value of the band gap was found to be 3.02 eV for co-doped TiO2 nanoparticles . Fig. 2 (b) shows the band gap plot of the Nd3+ and Eu3+ co-doped TiO2 nanoparticles.

As the Nd3+ and Eu3+ doping ratio is increasing the band gap values decreased. These band gap and absorbance spectra supported each other. These results prove that doping can reduce the wideness of forbidden band of TiO2 nanoparticle.

Fig. 2. (a) UV-vis absorption spectra of the Nd3+ and Eu3+ co-doped TiO2 nanoparticles.

Fig. 2. (b)Optical band gap (Eg) spectra of the Nd3+ and Eu3+ co-doped TiO2 nanoparticles.

HRTEM Analysis HRTEM allows the direct imaging of nanoparticles and provides authentic information on the distribution, size and morphology of the nanocrystalline. The morphology of the synthesized products was investigated by HRTEM analysis. Fig.3 shows the HRTEM images of Nd3+ and Eu3+ co- doped TiO2. From the Fig., it is observed that most of the particles are almost spherical in shape with uniform size distribution. However, on Nd3+ and Eu3+ co-doping the size of the particles is increased in spherical morphology.

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Fig. 3. HRTEM image of the Nd3+ and Eu3+ co-doped TiO2 nanoparticles.

Photoluminescence (PL) The PL spectra of Nd3+and Eu3+ co-doped TiO2 nanoparticle are shown Fig.4. PL emission spectra have been widely used to investigate the efficiency of charge carrier trapping and migration and to understand the fact of electron-hole pairs in semiconductors. As shown in Fig., three emission peaks are observed for Nd3+and Eu3+ co-doped TiO2. Among the three peaks one is large intense positioned at 380 nm. The peak at 380 nm is band edge luminescence of TiO2 nanoparticle and other two less intense peaks are positioned at 363 and 424 nm respectively. These emission bands originated from charge recombination at the shallow-trap surface state. This surface state originated from the oxygen vacancies which act as radioactive centers. However, in Nd3+and Eu3+ co-doping the above stated three peaks are largely blue shifted to 363, 380 and 424 nm as a result of doping.

Fig. 4. PL spectra of the Nd3+ and Eu3+co-doped Tio2nanoparticles.

Fourier Transform Infrared Spectroscopy (FT-IR). FTIR spectroscopy is used to identify and characterize the organic species present in the Nd3+ and Eu3+ co-doped TiO2 nanostructured materials.

The FTIR spectra of the as prepared Nd3+ and Eu3+ co-doped TiO2 nanoparticles is shown in Fig.5.The two weak absorption bands around 2043 cm-1 and 2984 cm-1 are due to C–H symmetric stretching of organic residue. The weak peak that appeared at 1124 cm −1 and 1082 cm −1 in Nd3+ and Eu3+ codoped sample is associated to the asymmetric stretching vibration modes of Ti–O networks. The peaks observed at 3600–3000 cm-1 is assigned to -OH of water absorbed from the molecular precursors. The band at 3000–2750 cm-1 may be due to symmetrical stretching vibration of –CH2 MMSE Journal. Open Access www.mmse.xyz

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groups. The peaks 1530–1260cm-1 indicates asymmetrical and symmetrical CH3 deformation vibrations from titanium-isopropoxide.and C–C–O stretching vibration is positioned at 1130– 820cm- 1 from ethylene glycol. Thus the FTIR spectra confirm the presence of functional groups and their mode of vibrations.

Fig. 5. FTIR spectra of the Nd3+ and Eu3+ co-doped Tio2nanoparticles.

Summary We have successfully synthesized the Nd3+ and Eu3+ co-doped TiO2 nanoparticles by solgel method at room temperature. The XRD pattern depicted the structure and grain size of the Nd3+ and Eu3+ co-doped TiO2 nanoparticles. The UV-DRS spectra of Nd3+ and Eu3+ co-doped TiO2 nanoparticles showed an absorption peak at 380 nm in the UV region. In the co-doped TiO2, considerable blue shift was obtained for all the samples due to quantum confinement effect. The band gaps were found to be 3.02 eV on increased doping concentration doping band gap energy has been decreased. The various functional groups present in the material have been determined by FTIR analysis. The morphology of the products revealed spherical structure of Nd3+ and Eu3+ co-doped TiO2 nanoparticles which characterized using High Resolution Transmission Electron Microscopy (HRTEM). The PL emission spectra revealed the structural modification of the TiO2 matrix with doping by Nd3+ and Eu3+ ions, as well as the change in the charge transfer pairs on the surface of TiO2.

References [1] M. Stefan, C. Leostean, O. Pana, D. Toloman, A. Popa, I. Perhaita, M. Senil, O. Marincas and L. Barbu-Tudoran, “Magnetic recoverable Fe3O4-TiO2:Eu composite nanoparticles withenhanced photocatalytic activity”, Applied Surface Science, 390, pp248–259, (2016), Doi:org/10.1016/j.apsusc.2016.08.084.

[2] Hai Liu, Lixin Yu, Weifan Chen and Yingyi Li, “The Progress of TiO2 Nanocrystals Doped with Rare Earth Ions”, Journal of Nanomaterials, pp 9, 2012, Doi:10.1155/2012/235879.

[3]S.Sarah, Watson, Donia Beydoun, A.Jason Scott, Rose Amal, “The effect of preparation method on the photoactivity of crystalline titanium dioxide particles”, Chemical Engineering Journal, 95, pp 213–220. (2003), Doi: 10.1016/S1385-8947 (03)00107-4.

[4] Shumaila Islam, Noriah Bidin, Saira Riaz, Shahzad Naseem, Mohd. Marsin Sanagi, “Low temperature sol-gel based erbium doped mullite nanoparticles, Structural and optical properties”, Journal of the Taiwan Institute of Chemical Engineers, pp 1–8, (2016), Doi.org/10.1016/j.jtice.2016.10.031.

[5] Joanna Reszczy´nskaa, Tomasz Grzyb, Zhishun Wei, Marek Klein, Ewa Kowalsk, Bunsho Ohtani, “Adriana Zaleska-Medynska, Photocatalytic activity and luminescence properties of RE3+– MMSE Journal. Open Access www.mmse.xyz

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TiO2 nanocrystals prepared by sol–gel and hydrothermal methods”, Applied Catalysis B, Environmental, 181 pp 825–837, (2016), Doi.org/10.1016/j.apcatb.2015.09.00.

[6] Xiaofei Wu, Zui Ding, Ningning Song, Lin Li, Wei Wang, “Effect of the rare-earth substitution on the structural, magnetic and adsorption properties in cobalt ferrite nanoparticles”, Ceramics International, (2015), doi.org/10.1016/j.ceramint.2015.11.100.

[7] Dandan Liu, Yiming Liu, Zhansheng Wu, Fei Tian, Bang-Ce Ye, Xiaoqing Chen, “Enhancement of photodegradation of Ce, N and P tri-doped TiO2 AC by microwave radiation with visible light response for naphthalene”, Journal of the Taiwan Institute of Chemical Engineers, pp 1–8, (2016), Doi.org/10.1016/j.jtice.2016.10.002.

Cite the paper P. Sanjay, K. Deepa, M. Victor Antony Raj, S.Senthil (2017). Structural, Morphological and Optical Characterization of Eu3+ and Nd3+ Co-Doped Tio2 Nano Particles by Sol Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.77.97.901

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Study on the Synthesis, Structural, Optical and Electrical Properties of ZnO and Lanthanum Doped ZnO Nano Particles by Sol-Gel Method29 V. Porkalai1, D. Benny Anburaj1,a, B. Sathya1, G. Nedunchezhian1, R. Meenambika2 1 – PG, Research Department of Physics, Thiru. Vi. Ka. Government Arts College, Thiruvarur, Tamil Nadu, India 2 – Marthandam College of Engineering & Technology, Kanyakumari District, India a – bennyanburaj@rediffmail.com DOI 10.2412/mmse.77.37.393 provided by Seo4U.link

Keywords: lanthanum, photo luminescence, morphology, nanoparticles.

ABSTRACT. In this study, pure and lanthanum doped ZnO nano particles have been succaessfully synthesized by solgel method using the mixture of Zinc acetate dihydrate and ethanol solution. The powders were calcination at 600°C for 2h. The effect of lanthanum incorporation on the structure, morphology, optical and electrical conductivity were examined

by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray Absorption (EDAX), Fourier transform infrared spectroscopy (FTIR), UV and Photo Luminescence (PL) Characterization. The average particle size of the synthesized ZnO nanoparticles is calculated using the Scherrer formula and is found to be of less than 20 nm.

Luminescence as well as conductivity properties were found to be enhanced for the La doped ZnO nanoparticles.

Introduction. Synthesize and study of nanostructured materials have become a major attractive interdisciplinary area of research over the past few decades. Recently rare earth ion doped II-IV semiconductor nano particles have received much attention because such doping can modify and improve optical properties of II-VI semiconductor nanoparticles by large amount [1-4]. Zinc Oxide is a transparent electro conductive and piezo electric material. Zinc Oxide is an excellent ultraviolet absorber and antibacterial agent. ZnO is one of the metal oxides which attracts due to its direct band gap energy of 3.37eV and large excitation binding energy of 60 meV at room temperature which provides excitonic emission more efficiently even at high temperature. ZnO is particularly important because of their unique optical/electronic properties and promising applications in various fields such as photonic catalysis [5], light emitting diodes [6], field emission, gas sensors [7], fluorescent materials and solar cells [8].

Doping with rare earth elements leads to many interesting properties of ZnO. Usually, semiconducting nanoparticles are known to exhibit exotic physico-chemical properties due to quantum confinement effect. Especially, doped luminescent nanoparticles are predicted to show improved optical properties, viz., luminescence efficiency and delay time and band edge emission with respect to particle size variation. ZnO nanoparticles at different Lanthanum (La) doping concentration varied from 0.1 to 0.3 mole % have been synthesized via sol–gel route and characterization of the sample byXRD, SEM, EDAX and FTIR analysis. UV and Photo Luminance (PL).

Experimental Procedure. Zinc Oxide nanoparticle were synthesized by dissolving Zinc acetate (Zn (CH3COO)2 2H2O) in distilled water by continuous stirring for half an hour. Lanthanum chloride (LaCl3) taken at appropriate proportion of 0.1M, 0.2M and 0.3M respectively was added drop by drop and mixed thoroughly. TEA (Triethylamine) was added as surfactant to control the morphology and 29

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size of nanoparticles. Suitable amount of NH4OH solution was added to maintain the PH level at10.The whole setup is maintained at a temperature of 80oc for 2 hours. The colloidal precipitate obtained was cooled and washed several times with ethanol and acetone to remove theorganic impurities present, if any. The solution is then preheated in microwave oven for 30 mins for the evaporation of the solvent. The product was then calcinated to 600 °C for 2 hours.

Results and Discussions: Structural Analysis. Fig. 1 shows the XRD pattern of pure and La-doped ZnO (0.1, 0.2 and 0.3 mol%) calcined at 600 °C. The strong intensities of diffraction peaks (100), (002), (101), (102), (110), (103), (112) and (201) can be indexed to the hexagonal wurtzite structure of ZnO (JCPDS# 79-0208) [13].

Fig. 1. XRD pattern of pure and Lnthanum doped ZnO nanoparticles.

The average crystalline size can be determined through FWHM of X-ray diffraction peak by using Debye-Scherer, s equation as

D

0.9  cos 

where λ is the wavelength of the X-ray (1.5405A0), D is the particle size, θ is the Bragg diffraction angle and β is the full width half maximum (FWHM) of the diffraction peak respectively.

The particle size of pure and Lanthanum doped ZnO was found. It is observed that as the doping concentration increases, the intensity of the peaks decreases which in turn decreases the size of the nanoparticles.

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Table 1. Structural Analysis of La doped ZnO nanoparticles.

Particle Size (D) nm

Dislocation Density (δ) m-2

Micro strain Χ10-3

Samples

2θ

FWHM (β) (rad)

1

Pure ZnO

42.6

0.0103

15.12

4.37 Χ1015

9.56

2

0.1M

41.1

0.0167

8.11

1.51 Χ1016

15.63

3

0.2M

41.1 3

0.0118

11.48

7.58 Χ1015

11.04

4

0.3M

42.1 6

0.0104

12.98

5.93 Χ1016

9.70

No

Crystal structure

Hexagonal

When lanthanum was doped into ZnO matrix, diffraction peaks of the doped products are almost similar to those of undoped hexagonal ZnO crystal. Their crystalline structure remains unchanged, which indicates that La3+ uniformly disperses across the hexagonal ZnO matrix[10].The sharp diffraction peaks manifests that the pure ZnO and La-doped ZnO nanostructures have crystalline nature EDAX Analysis.

Fig. 2. (a, b) EDAX spectrum of pure and Lanthanum doped ZnO nanoparticles.

In EDAX spectrum, the peaks were evident related to Zn, O and La, which clearly support that nanoparticles are made of Zn, O and La. No other peaks related to impurities was detected in the spectrum, which further confirms the purity of the compounds.

Morphological analysis. The morphological studies were investigated using scanning electron microscopy and displayed in Fig. 3 for pure and La doped ZNO nano particles.

These micrographs exhibited the formation of nanoparticles of doped ZnO. Crystal formation in solution can be divided into two stages: crystal nucleation and growth rates. These two stages are

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responsible for the formation of the different morphologies of ZnO particles with different morphologies.

Fig. 3. (a, b, c and, d) SEM photographs of pure and Lanthanum doped ZnO nanoparticles.

Fig. 4. FTIR spectrum of pure and Lanthanum doped ZnO nanoparticles Fourier Transform Infrared Spectroscopy Study.

Synthesized La doped ZnO material was analysed by FT-IR in the range from 400 to 4000cm−1 at room temperature. The FT-IR spectrum contains several bands with remarkable features. The spectral band at 416 cm−1 and the band at 607 cm-1 clearly show the presence of ZnO and La. Bands at 1065cm−1 correspond to C-O stretching vibrations. Bands at 1394 cm-1 corresponds to C=O, 1580 cm-1 indicates C=O stretching vibration, 2976 cm-1 indicates CH2 unsymmetrical stretching vibrations and 880 cm-1 corresponds to N–O deformation vibration .Also the bands at 3331cm−1 indicate the presence of N-H axial deformation. It is evident from the FTIR data that the Zn–O vibrational mode was more prominently observed and this clearly concludes a strong doping between La doped ZnO nanoPrticles materials.

UV-Vis Spectral Analysis of La doped ZnO Nanoparticles.

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Fig. 5. UV-Vis spectrum of pure and Lanthanum doped ZnO nanoparticles.

The optical band gap increased from 3.28 ev to 3.44 ev with an increase in the concentration of La doping. There are two reasons that’s may contribute to the variations in band gap energies, namely, quantum size effect and electronic structure modifications. In the case of quantum size effect, appropriate interaction between surface oxidic size of ZnO and La3+ may also be the cause for shift of wavelength. Instead, La3+ doping in ZnO could modify the electronic structures Photoluminescence (PL).

Fig. 6. PL spectra pure and Lanthanum doped ZnO nanoparticles.

The PL spectra are useful to disclose the efficiency of charge carrier trapping, immigration and transfer and also to understand the fate of electron hole pairs in semiconductor particles since PL emission results from the recombination of free carriers . Photoluminescence (PL) spectra of the pure and La doped ZnO for different different doping concentration is as shown in Fig. 6. The luminescence peak of pure ZnO was observed at 388 nm and for La doped ZnO was observed at 422 nm. There is substantial enhancement of luminescence intensity due to increase of La concentration, which acts as effective luminescent centers. The PL results show that doped rare earth elements are MMSE Journal. Open Access www.mmse.xyz

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the major luminescent component and can effectively improve the luminescence of La doped ZnO. In this study 1 mol% La doped ZnO had the most oxygen vacancies (Fig. 6) [12].

Summary. Pure and Lanthanum doped ZnO nanoparticles were successfully synthesized by sol-gel method. The XRD pattern of La doped ZnO it clearly shows that the sharp peak obtained from ZnO planes. The particle size of pure and Lanthanum doped ZnO nanoparticles and the microstrain in lattice has been determined. The dislocation density of grains is determined to be ~4.37×1015m-2 and the microstrain in lattice is found to be 9.56×10-3. X-ray analysis reveals that La doped ZnO crystallized in Hexagonal structure. The morphology of the ZnO particles was obtained from SEM. Elemental compositions have been estimated by EDAX. Chemical and optical properties are studied FTIR and UV-VIS spectrophotometer. From the UV-Vis spectral analysis we have calculated the band gap of La doped ZnO, which is found to be approximately 3.33eV, at the wavelength 364 nm.

From I-V studies, we observed that in the doped mixture, the current conductivity gets increased significantly to 4.06×10-4 (1/Ωm), due to the incorporation of La. The PL results show that doped rare earth elements are the major luminescent component and can effectively improve the luminescence of La doped ZnO. References [1] Zhigang Jia, Linhai Yue, Yifan Zheng, Zhude Xu, Materials Chemistry and Physics, China, 2008, DOI:10.1016/j.matcemphys.2007.06.061 [2] Santi Septiani Sartiman, Nadia Febiana Djaja, Rosari Saleh, Materials Science and Application, FMIPA-Universitas Indonesia, 2013, DOI;org/10.4236/msa.2013.49065 [3] G.A.Prinz, Magnetoeletronics Science, 1998, DOI:10.1126/Science.282.5394.1660 [4] V.Porkalai, D.Benny Anburaj, B.Sathya, G.Nedunchezhian, R.Meenambika, J.Mater Sci:Mater Electron DOI 10.1007/s10854-016-5826-1 (2016).

[5] M.Giahi, N.Badalpoor, S.Habibi, DOI:10.5012/bkes.2013.34.7.2176

H.Taghavi,

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[6] N.Satio, H.Haneda, T.Sekiguchi, N.Ohashi, I.Sekaguchi, K.Koumoto, Adv.Mater.14, 418 (2002) [7] Alenezi, M.R., Henley, DOI;/10.1039/C3RA43301c

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[10] G Nedunchezhian, D Benny Anburaj, B Gokulakumar, S Johnson Jeyakumar, Microwave Assisted Synthesis And Charecterization Of Silver And Zinc Doped Hydroxyapatite Nanorods From Mussel, Romanian Journal Of Biophysics 11-20, 26 (1), 2016.

Cite the paper V. Porkalai, D. Benny Anburaj, B. Sathya, G. Nedunchezhian, R. Meenambika (2017). Study on the Synthesis, Structural, Optical and Electrical Properties of ZnO and Lanthanum Doped ZnO Nano Particles by Sol-Gel Method. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.77.37.393

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Structural and Functional Group Characterization of Nanocomposite Fe3O4/TiO2 and Its Magnetic Property30 V. Maria Vinosel1,a, M. Asisi Janifer1, S. Anand1, S. Pauline1 1 – Department of Physics, Loyola College, University of Madras, Chennai, India a – vinovincent90@gmail.com DOI 10.2412/mmse.36.92.83 provided by Seo4U.link

Keywords: Fe3O4, TiO2,XRD, SEM, FTIR, VSM.

ABSTRACT. Nanocomposites of Fe3O4/TiO2 were prepared by non-thermal method in the ratio 1:4. In this method magnetite and TiO2 anatase nanoparticles were prepared individually by hydrothermal and sol-gel respectively.

X-ray diffraction analysis (XRD) of the sample reveals that the peaks can be indexed either to Fe 3O4 or TiO2.

The morphology and phase composition were characterized by High resolution scanning electron microscope (HRSEM) and Energy dispersive X-ray analysis (EDAX). The Fourier transform infrared (FTIR) spectra reveal information about metal oxygen in the composite. The magnetic properties of the sample were determined by Vibrating sample magnetometer (VSM).

Introduction. Titanium dioxide (TiO2) has much attention due to its applications in environmental purification like detoxification of wastewater, luminescent material, solar cells, gas sensors and medical fields. Titanium dioxide is an n-type semiconductor with a wide energy band gap exhibiting photocatalytic activity. This ceramic material has three different structures: rutile, anatase and brookite. Since the energy band gap (3.23 eV) of the anatase phase is wider than that of rutile (3.02 eV) the anatase phase is known to exhibit better photocatalytic behavior [1]. In such semiconductors, photogenerated carriers (electrons and holes) can tunnel to a reaction medium and participate in chemical reactions. The efficiency of photocatalyst is enhanced by the wider separation of an electrons and holes. Titanium dioxide is extensively used in the fabrication of core-shell systems as a photocatalytic agent because of its exceptional properties such as strong oxidation reaction, large effective surface area and low toxicity [2].

Fe3O4 is a magnetic material with wide applications in many areas such as gas sensors, optoelectronic and spintronic devices, biomedicine, etc. Fe3O4 is a kind of functional material and has attractive physical properties such as half-metallic character and strong spin polarization at room temperature.

Its magnetic properties can be tuned by size, shape and dimension [3]. The researcher has been investigating on the design of magnetic core TiO2 shell structure for many applications. They have developed several ways to improve the activity of photocatalysts, such as carbon-doped TiO2, carboncoated TiO2, carbon–nanotube–TiO2 and graphene–TiO2 nanocomposites among these graphene TiO2 nanocomposites showed fantastic activity [4]. Fe3O4-TiO2 core–shell nanoparticles were prepared by a homogeneous method. They found, that Fe3O4-TiO2 core–shell nanostructure has higher photocatalytic activity in contrast to TiO2 nanoparticles and plays a crucial role in the field of malignant tumor therapy was reported by He et al [5]. Even though TiO2 has many advantages, there are some basic challenges in the applications of titanium dioxide nanoparticles 1) collecting and retrieving titania nanoparticles from reaction media is impossible, therefore, the nanoparticles used are not accessible anymore and their recycling is not possible 2) recombination of electrons and holes 30

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excited by ultraviolet radiation would easily take place that reduces the photocatalytic activity of TiO2. In order to overcome these problems, titanium dioxide was supplemented with magnetite nanoparticles (Fe3O4) to increase the photocatalytic activity as well as their recyclability with the help of an external magnetic field [6]. The magnetite was used to enhance separation properties of the photocatalyst from the treated water, whereas the titanium dioxide was useful for the degradation of organic contaminants.

In the present study, nanocomposite of Fe3O4/TiO2 was synthesized by non-thermal method. The magnetite and TiO2 anatase nanoparticles were prepared individually by hydrothermal and sol-gel methods respectively. A. Hasanpour et al [7] reported TiO2 shell coating on Fe3O4 core nanoparticles by novel non-thermal method.

Experimental.

Preparation of Fe3O4 nanoparticles. In a typical procedure, 2M of FeCl2 and 4M of NaOH was dissolved in 40 ml of distilled water. The aqueous solution of NaOH was added drop by drop into the above solution under the vigorous stirring for 20 min. Then the solution was transferred into the autoclave for heat treatment at 180°C for 12 h. It was allowed to cool down to room temperature after the reaction. The precipitate was washed several times with ethanol and acetone by centrifugation.

The final product was dried at 50°C for 12 h.

Preparation of TiO2 nanoparticles. In the present study, TiO2 nanoparticles were prepared by Solgel method. 100 ml of isopropyl alcohol was added to 15 ml of Titanium (IV) isopropoxide (TTIP).

The mixture was stirred for 25 min then 10 ml of water was added drop by drop to the above solution for hydrolysis reaction. It was continuously stirred for 2 h. After an aging period it gets transformed to gel. Then it is filtered and dried in vaccum oven at 80°C for 3 h. The obtained TiO2 was calcinated at 550°C for 4 h.

Preparation of Fe3O4/TiO2 nanocomposite. To prepare the nanocomposite of Fe3O4/TiO2 the as prepared magnetite and TiO2 was dispersed in 40 ml of deionised water and kept under ultrasonication for about 30 min. TiO2 nanoparticles was added into Fe3O4 solution. Molar ratio of Fe3O4 to TiO2 was kept at 1:4. The mixture solution was then kept under sonication for about 1 h. Then the solution was centrifuged and precipitate was dried at 300°C for 12 h. The final product was Fe3O4/TiO2 nanopowder.

Result and Discussion X-ray diffraction analysis. Fig.1 shows the XRD pattern of Fe3O4/TiO2 nanocomposite. Diffraction peaks corresponding to both Fe3O4 (JCPDS 85-1436) and TiO2 (JCPDS 21-1272) are clearly observed in the coupled diffraction pattern. For pure Fe3O4, the diffraction peaks are located at 2Ө = 35.53°, 30.20°, 43.05°, 57.48°, 62.69° are associated with [220], [311], [400], [511], [440] planes respectively.

This pattern has been indexed as magnetite phase with lattice constants a=b=c=8.381 Ă…. The observed diffraction peaks of TiO2 at 2Ó¨ = 25.4°, 37.9°, 48.1°, 53.9°, 62.8° are associated with [101], [004], [200], [105], [204] planes respectively, which can be assigned to be anatase phase with the lattice parameters of a=b= 3.785 Ă… c=9.513 Ă…. From the XRD diffraction peak it is found that the intensities of Fe3O4 have been decreased by TiO2. At the interface between titania and magnetite there is no new phase formation that indicates absence of extra peaks. There is no chemical reaction between Fe 3O4 and TiO2 in non-thermal mechanism. The crystallite size of the sample was calculated by Debye Scherrer formula. đ??žđ?œ†

d = đ?›˝đ?‘?đ?‘œđ?‘ Ó¨

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where đ?‘‘ is the average crystallite size (nm), đ??ž is the grain shape factor (0.9), đ?œ† is the X-ray wavelength (nm), đ?›˝ is the full width at half maximum in radians and Ó¨ is the Bragg diffraction angle of the 2Ó¨ peak.

The average crystalline size was estimated to be 21 nm.

Fig. 1. XRD pattern of Fe3O4/TiO2 nanocomposite.

Fourier Transform Infrared (FT-IR) analysis. Helin Niu et al [8] have reported similar absorption peaks observed in the synthesis of Fe3O4/TiO2 visible light active and magnetically recyclable nanocomposite. The FTIR transmission spectra of Fe3O4/TiO2 nanocomposite are shown in Fig. 2.

The strong band at 620 cm-1 was assigned to the Ti–O metal oxygen bond. The Fe3O4 high intensity band at 585 cm-1 has been weakened. The broad band around 3432 cm-1 is the asymmetric and symmetric stretching vibrations of O-H group, whereas the band around 1630 cm-1and 2919 cm-1 is the H-O-H bending vibrations of the coordinated water. The Fe3O4 surfaces are linked with hydroxyl group it also enhances the affinity between Fe3O4 and TiO2 nanoparticles.

Fig. 2. FTIR spectrum of Fe3O4/TiO2 nanocomposite.

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Scanning electron microscopy (SEM) analysis. Using electron microscope the surface structure of the as prepared sample was probed. Fe3O4/TiO2 composites were investigated by High resolution scanning electron microscopy (HR-SEM). Fig. 3 shows SEM images for different magnification. The morphology of the as synthesized nanocomposite was spherical in shape and uniform sizes of nanoparticles with strong agglomeration. A. Banisharif et al. [9] reported the similar nanospheres morphology for Fe3O4/TiO2 nanocomposite synthesized by ultrasonic- assisted deposition precipitation method.

Fig. 3. SEM micrographs of Fe3O4/TiO2 nanocomposite.

Energy dispersive X-ray (EDX) analysis. Energy dispersive X-ray (EDX) spectra revealed the presence of stoichiometric proportion of Fe, Ti and O elements without extra signals confirms the pure phase of Fe3O4/TiO2 nanocomposite.

Fig. 4. EDX spectrum of Fe3O4/TiO2 nanocomposite.

Vibrating sample magnetometer (VSM) analysis. Chu- Ling Zhu et al [3] have reported similar magnetization for Fe3O4/TiO2 nanotubes prepared by wet chemical method. The magnetic behavior MMSE Journal. Open Access www.mmse.xyz

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of the sample was investigated using M-H curve from VSM analysis. Fig.5 shows the hysteresis loop of Fe3O4/TiO2 nanocomposite. For Fe3O4/TiO2 nanocomposite saturation magnetization (Ms), remanant magnetization (Mr), coercivity (Hc) was estimated to be 16.80 emu/g, 3.723 emu/g, 181.35 Oe, respectively. The narrow magnetic hysteresis loop with extremely small coercivity and remanence values indicates a near superparamagnetic behavior of Fe3O4/TiO2 nanocomposite. Taking into account the sample contains 20% of Fe3O4 nanoparticle. The Ms is much lower than that of the corresponding bulk Fe3O4 (92 emu/g), which may be due to the small size of the Fe3O4 nanoparticles.

The lower values are attributed by the presence of non-magnetic TiO2.

Fig. 5. M-H curve of Fe3O4/TiO2 nanocomposite.

Summary. In summary, the crystalline Fe3O4/TiO2 nanocomposites were synthesized by non-thermal method. Each were individually prepared by hydrothermal and sol-gel methods. The X-ray diffraction confirms the pure phase of Fe3O4/TiO2 nanocomposites. The FTIR spectrum reveals the formation of metal oxygen bonds without interactions. The absorption band at 584 cm-1 is assigned to Fe-O stretching band and the strong band at 620 cm-1 was assigned to be Ti-O stretching bands. SEM indicates the formation of agglomerated uniform nanospheres. EDAX confirms the stiochiometric proportion of elements. The magnetic behavior of the sample was analysed by VSM. The Fe3O4/TiO2 nanocomposite exhibits ferromagnetic behavior at room temperature. The as prepared sample has excellent magnetic property it can be used for photocatalytic application using magnetic separation method in various environmental and medical fields.

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[5] Q. He, Z. Zhang, J. Xiong, Y. Xiong, H. Xiao, Opt. Mater. 31 (2008) 380–384. doi:

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Karimipour Eur. Phys. J. Plus (2015) 130: 144. doi: 10.1140/epjp/i2015-15144-y [7] A. Hasanpour, M. Niyaifar, H. Mohammadpour, J. Amighian Journal of Physics and Chemistry

of Solids 73 (2012) 1066–1070. http://dx.doi.org/10.1016/j.jpcs.2012.04.003 [8] Helin Niu, Qinmin Wang, Hongxia Liang, Min Chen, Changjie Mao, Jiming Song, Shengyi

Zhang, Yuanhao Gao and Changle Chen, Materials 2014, 7, 4034-4044. doi:10.3390/ma7054034 [9] A. Banisharif, S. Hakim Elahi, A. Anaraki Firooz, A. Khodadadi, Y. Mortazavi1 Int. J. Nanosci.

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Cite the paper V. Maria Vinosel, M. Asisi Janifer, S. Anand, S. Pauline (2017). Structural and Functional Group Characterization of Nanocomposite Fe3O4/TiO2 and Its Magnetic Property. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.36.92.83

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Optimized Synthesis of Gold Nanoparticles using Green Chemical Process and its Invitro Anticancer Activity Against HepG2 and A549 Cell Lines31 S. Rajeshkumar 1,a, S. Venkat Kumar 1, C. Malarkodi2, M. Vanaja3, K. Paulkumar3, G. Annadurai3 1 – School of Bio-Sciences and Technology, VIT University, Vellore, TN, India 2 – Department of Chemistry, University of Delhi, Delhi, India 3 – SPKCES, Manonmaniam Sundaranar University, Alwarkurichi, Tamilnadu, India a – rajeshkumar.s@vit.ac.in, ssrajeshkumar@hotmail.com DOI 10.2412/mmse.95.26.479 provided by Seo4U.link

Keywords: Padina tetrastromatica, gold nanoparticles, XRD, TEM, HepG2, cyclophosphamide.

ABSTRACT. In the present study, the biosynthesis of gold nanoparticles (AuNPs) was achieved by using marine brown seaweed Padina tetrastromatica (PT) as a reducing and capping agent. The optimized Au Nps were performed by changing the concentration of algae extract, pH and temperature was analyzed by UV-vis spectrophotometer. The synthesized Au NPs were characterized byXRD, FTIR, SEM, TEM, EDX and SAED. The X-ray diffraction showed the Au NPs which can state by the presence of peaks at (1 1 1), (2 0 0), (2 2 0) and (2 2 2). The FTIR result clearly showed that the extracts containing -OH as a functional group (sugar molecules) act in capping the nanoparticles synthesis. SEM images revealed that all particles were spherical in shape. TEM image confirms the spherical in shape with an average size ranges from 8-10 nm. Synthesized Au NPs were evaluate for the in vitro cytotoxic activity of human liver cancer (HepG2) and lung cancer (A549) cell line at the different concentrations compared with standard drug cyclophosphamide.

Introduction.The Metal nanoparticles are acquired great interest in the field of nanotechnology and nanomedicine due to their unique properties such as optical, electrical, mechanical and chemical properties which have exhibit diverse sizes and shapes than the bulk state of the metal [1-3]. Thus, the activity of nanoparticles was mainly determined by their size, small size of nanoparticles exhibit high surface area due to the large fraction of the atoms and generates the active sites on the surface of nanoparticles [4]. The unique size and shape of nanoparticles were extensively used in catalysis, electronics, plasmonics and sensing [1, 5, 6]. Among the metal nanoparticles, gold has been used to cure various diseases in several centuries ago. Gold is inert, less toxic, highly thermal stability which has been used in various applications including biolabeling, gene and drug delivery system [7]. Many of the methods are available to synthesis of metal nanoparticles which has been exhibits inevitable due to the use of harmful and toxic chemicals [8]. Among the synthesis methods, green synthesis methods using biological probes predicted to avoid the using the toxic chemicals in the fabrication of nanoparticles. The biological probes are bacteria, fungi, yeast, actinomycetes, plants and algae involved in the green chemistry of nanoparticles; they provide large scale production, less time consumption and eco benign. Algae mediated synthesis nanoparticles were better reflection compare to the other biological probes. Algae have many phytochemicals could acts as both reducing and stabilizing agent for the nanoparticles and they are easily available marine sources [9-10]. The compounds isolated from PT like sulphated polysaccharides are having good medicinal properties such as anti-inflamtery activity, anti-oxidant effect, anti-hyper glycemic activity and hypo lipedemic properties [25-27]. In this study we report that green reduction of gold ions to AuNPs using the algae extract of PT, which is available throughout the year. This brown algae exhibits medicinal properties 31

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such as anti hepatitis B virus [11] and with high value phytochemicals such as several fatty acids, phenols, terpenoids and sterols [12], which is motivating us to carry out the synthesis of AuNPs using PT biomass and evaluated anticancer property against lung and liver cancer cells.

Materials and Methods. All the annalytical grade chemicals and media were purchased from Himedia and Sigma.

Synthesis of AuNPs using PT. The brown algae PT was collected from coastal area of tuticorin, TN, India. The algal extract and nanoparticles were prepared based on our previous studies [9, 10] To study the effect of parameters such as algae extract concentration, pH and temperature on the nanoparticles synthesis was carried out by following experiments. Different concentrations of algae extract (5, 7.5 and 10ml) were added into the 1 mM of gold chloride solution. The pH of the extract was adjusted (6, 7, 8 and 9) to study the effect of pH on nanoparticles formation. The reaction mixture was incubated at different temperature conditions are 20 °C, 40 °C and 80 °C respectively. After incubation nanoparticles formation was measured by UV-vis spectrophotometer at different wavelength and time intervals.

Characterization of synthesized AuNPs. The synthesized Nanoparticles were characterized by techniques are UV-vis spec, FT-IR (Perkin elmer), SEM (Philips XL-30), TEM and SAED (Philips CM200) and XRD (Philips PW 1830).

Anticancer activity of AuNPs against HepG2 and A549 cell lines. The viability of cells was assessed by MTT assay using HepG2 and A549 cell lines.

Results and discussion Visual observation. Fig. 1 (a, b and c) shows the PT extract alone, PT and gold chloride solution at initial stage and PT after 24 h incubation respectively. After addition of PT extract to the aqueous gold chloride, the yellow colour of the gold chloride solution is changed to brownish pink colour.

After that, the colour of the solution is vigorously changed to ruby red while increasing the incubation time from 30 min to 48 hr. After 48 hr incubation, the colour of the solution is stable reveals that the synthesis of gold nanoparticle process was completed. The formation of dark ruby red colour indicates the gold chloride is reduced into AuNPs by using the extract of PT. The gold nanoparticle synthesis process was started at 1 h and 4h the process was completed at 15 hr [13, 14]. However, in the present study, the gold nanoparticle synthesis process is rapidly started at 40 min and completed at 48 hr.

Fig. 1. Visual observation of synthesis of AuNPs by using PT (a) Algae extract (b) Initial and (c) final colour change and UV-vis absorption spectrum.

UV-vis spectroscopy analysis. Fig. 1 shows the reduction of gold chloride into AuNPs by using the extract of marine algae. The absorbance of AuNPs is monitored at different time intervals from 20 min to 48 h. Singh et al. [15] have reported the synthesis of AuNPs by using the P. gymnospora, a marine algae. In the report of UV-vis spectrophotometer, they have illustrated that the gold nanoparticle synthesis process was started at 1 hr and ended at 12 hr and the SPR band was occurred at 527 nm. The formation of SPR peak is assigned to the oscillation of electrons at the surface of the MMSE Journal. Open Access www.mmse.xyz

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nanoparticles is well matched for various metal nanoparticles with size ranging from 2 to 100 nm [16]. The synthesis of gold nanoparticle by PT is gradually increased while increasing the time of incubation from 20 min to 48 h.

Effects of algae extract concentration, pH and temperature. Fig. 2 shows the varying algae extract concentrations, pH and temperature on AuNPs synthesis. 7.5 ml concentration of algae extract was effective to synthesis of AuNPs, the maximum synthesis was attained in the concentration of 7.5 ml.

At 5 ml and 10 ml concentration, the SPR band was broadened and obtained at 500-540 nm indicates formation of anisotropic gold nanoparticles.

Fig. 2. Effect of Algal extract concentration, pH and temperature on AuNPs synthesis.

The narrow SPR band formed at 545 nm at 7.5 ml concentration of algae extract indicates even distribution small size nanoparticles. In low concentration, size reduction was slowly occurred due to the insufficient quantity of reducing agent and at high concentration synthesis process was hasty and cause competing for metal ions due to highly availability of reducing agent in the extract. The color intensity and the peaks for nanoparticles is pH dependent [17]. A sharp and symmetric peak is obtained at pH 6. At high pH broad peak was formed at 550 nm indicates large sized particles [18].

More stable and small size nanoparticles was synthesized at pH 6 and 7. In this study the position of SPR band does not show much variation, but their absorbance increases with pH. Maximum conversion rate of gold ions to nanoparticles was occurred at higher temperature and the narrower SPR band was formed at 525 nm. At low temperature 20 and 40º C, the SPR band was broad and positioned at 545 and 530 nm respectively indicates formation of larger nanoparticles. Rapid and maximum synthesis of AuNPs with small size was obtained at 80º C. The maximum synthesis and faster rate of reduction was achieved at high temperature [19].

XRD and SEM. The XRD spectrum (Fig. 3) bragg reflection of PT derived AuNPs were observed at the 2Ɵ values of 38o, 44 o, 64 o and 77 o which are corresponding to the set of lattice planes (1 1 1), (2 0 0), (2 2 0) and (3 1 1), respectively and it was indexed for fcc gold. The peak of synthesized AuNPs is compared with the standard pure gold which was published by JCPDS (File no. 04-0784).

The association of bimolecular with synthesized nanoparticles could be avoided by continuous centrifugation process. The synthesized AuNPs are mostly spherical in shape and its size ranges were varied from 40-90 nm for PT (Fig. 3a). The AuNPs are predominantly aggregated with each other and some of the individual monodispersed AuNPs are also viewed under TEM (Fig. 4). The SEM images exhibited that different shape of AuNPs obtained in the bark extract of C. fistula.[20]. The EDS spectra of PT synthesized AuNPs were shown in Fig. 3b. The EDS profile shows a strong signal at 3 keV reveals the presence of AuNPs.

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Fig. 3. SEM image of AuNPs synthesized using PT (a) and its corresponding EDS spectrum (b) and XRD spectrum.

Whereas, the other signals oxygen and carbon with elemental gold indicates the accumulation of algal biomass with gold nanoparticles. The biomolecules of algal extract play an important role in the reduction of gold metal ions into gold nanoparticles. It is a one of the advantage for the green synthesis of metal nanoparticles when compare to other processes.

TEM analysis. The PT synthesized AuNPs are monodispersed and mostly spherical in shape. The aggregation of NPs leads to the formation of large sized particles. The spherical and undefined shapes are also found in the TEM images indicated that these particles are synthesized at the beginning of the reaction (i.e) at 6-18 hr incubation. After 24 hr, incubations the particles are aggregated and form a bulk structure. Due to the absence of stabilizing agent in the brown algal extracts, the particles are aggregated with each other and form a bulk structure. The sizes of the AuNPs are found in the range of 8 to 10 nm for PT.The SAED pattern also suggested that the synthesized AuNPs are crystalline in nature. The result of SAED pattern was coincided with the result ofXRD. The appearance of rings is attributed to set of diffraction planes (1 1 1), (2 0 0), (2 2 0) and (3 1 1) of fcc gold (Fig. 4b and 3b).

Similar SAED pattern was obtained by using the algae and plants [13, 24]. The synthesis of metallic gold nanoparticle using the marine sponge and plant leaves of Mangifera indica they reported that the synthesis of gold nanoparticle are crystalline in nature and had ring at (111), (200), (220) and (311) of fcc gold [14, 21].

Fig. 4. Transmission electron microscopy images of AuNPs synthesized using PT (a) 50 nm (b) SAED pattern and FT-IR spectrum.

FTIR. The FT-IR spectrum shown in Fig. 4. The AuNPs synthesized from PT having the strong and broad intense peak formed at 3340 cm-1 indicating the presence of O–H stretching or H–bonded alcohols and phenols, weak band at 2340 cm-1 was occurred due to the C-O stretching vibrations of carboxylic acid, 1633 cm-1 is assigned to N–H bending of primary amines, 1383 cm-1 indicates presence of aliphatic NO2 groups of nitro compounds, sharp narrow band at 1035 cm-1 arise from C– O stretching of carboxylic acids or C–N stretching of aliphatic amines, the intense band at 835 cm-1 MMSE Journal. Open Access www.mmse.xyz

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characteristics to CH bending of aromatics, the bands are located at 670 and 432 cm-1 may be attributes to alkyl halides. Sugar molecules such as l-fucose, l-rhamnose, d-xylose, d-arabinose, dgalactose and d-glucose were identified and half-ester sulphate and d-mannuronic acid and a neutral laminaran were present in the PT was proved [22].

Cytotoxic activity of gold nanoparticles. Anticancer activity AuNPs was increased while increasing the concentration of AuNPs (Fig.5). Maximum cytotoxicity activity 47% was observed at 100 µg of gold nanoparticles. AuNPs efficiently facilitate into the cancer cell lines to suppress the cell proliferation. AuNPs enter into the cells cause oxidative stress, this elevated stress reduced the cell viability and increased DNA damage. Increased Reactive oxygen species (ROS) generation cause cell death in different type of cells. AuNPs interact with functional groups of intracellular groups with the nitrogen bases and phosphate groups in DNA cause cell damage [23] and also suppress the signaling of proteins [24].

Fig. 5. Anticancer activity of AuNPs. Summary. In this study, eco-friendly green synthesis of AuNPs was carried out by using algae extract of PT. Size and shape were controlled by different concentration of algae extract, pH and temperature and analyzed by UV-vis spectrophotometer. High quantity of algae extract concentration leads to formation of larger sized nanoparticles and the absorbance intensity was increased with increased pH. The temperature affect the nanoparticles synthesis was identified by UV-vis spectrophotometer. The optimum conditions for AuNPs synthesis is 7.5 ml algae extract concentration, pH 6 and temperature is 80ºC. SEM shows spherical shape of nanoparticles and the size ranges from 8 to 10 nm. FTIR indicates to presence of amine and carboxyl groups in algae extract may be responsible for reduction of gold ions to gold nanoparticles. Highest cytotoxicity of AuNPs was assessed against (HepG2) and lung cancer (A549).

Acknowledgements Authors gratefully acknowledge to STIC, Cochin for providing SEM and EDX facility, IIT Bombay for TEM facility, VIT, Vellore for XRD and FTIR analysis.

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[26] S Mohsin and G Muraleedhara Kurup. Biomed Prev Nutr. 2011, 1, 294-301. http://dx.doi.org/10.1016/j.bionut.2011.09.004 [27] S. M Divya, S Mini and G K Muraleedhara Ban J Pharmacol 2014, 9, 37-42 DOI: http://dx.doi.org/10.3329/bjp.v9i1.17153

Cite the paper S. Rajeshkumar, S. Venkat Kumar, C. Malarkodi, M. Vanaja, K. Paulkumar, G. Annadurai (2017). Optimized Synthesis of Gold Nanoparticles using Green Chemical Process and its Invitro Anticancer Activity Against HepG2 and A549 Cell Lines. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.95.26.479

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Phyto-Assisted Synthesis of Silver Nanoparticles using Solanum Nigrum and Antibacterial Activity Against Salmonella Typhi and Staphylococcus Aureus32 Venkat Kumar S.1, Karpagambigai S.2, Jacquline Rosy P. 3, Rajeshkumar S.1,a 1 – School of Bio-Sciences and Technology, VIT University, Vellore, TN, India 2 – Department of Chemistry, Global Institute of Engineering and Technology, Vellore, TN, India 3 – Department of Chemistry, IFET College of Engineering, Villupuram, TN, India a – ssrajeshkumar@hotmail.com DOI 10.2412/mmse.86.22.967 provided by Seo4U.link

Keywords: silver nanoparticles, green synthesis, antibacterial activity, TEM, salmonella typhi.

ABSTRACT. This study aims to provide a simple and eco-friendly approach for the synthesis of Ag NPs using medicinal plant Solanum nigrum aqueous leaf extract. Fresh leaf extract mediated the reduction of silver from higher excited state to the ground extract when mixed with 1 mM silver nitrate solution. Reduction led the synthesis of silver nanoparticle with the size range of 20-40 nm was confirmed by TEM analysis. UV-Vis analysis demonstrates the synthesis of Ag NPs by its standard peak due to SPR (Surface Plasmon Resonance). XRD analysis confirmed the crystalline nature of Ag NPs. It was further characterized by FT-IR for the confirmation of functional groups responsible for Ag NPs synthesis and elements analyzed using EDX. Our study also showed the high antibacterial effect of nanoparticle against disease causing virulent bacterial strains (Salmonella typhi and Staphylococcus aureus).

Introduction. Solanum nigrum is one of the most important traditional medicinal plants belonging to the family of solanaceae. The parts of S. nigrum like leaves, stem and fruits are playing a vital role in Indian daily foods.

Synthesis of silver nanoparticles using plant extracts such as fresh bark of Pongamia pinnata [14], papaya fruit extract [15], Boswellia ovalifoliolata stem bark [16], leaves of Alternanthera dentate, Boerhaavia diffusa, Ziziphora tenuior, Ficus carica, Cymbopogan citratus, Acalypha indica and Premna herbacea [17-23], seed extracts of Pistacia atlantica, Trachyspermum ammi, Argyreia nervosa and Psoralea corylifolia [24 – 27], fruit extract of pomegranate and grape (Vitis vinifera) [28-29], With these points under consideration, the present study was carried out to investigate thesynthesis of silver nanoparticles using medicinal plant Solanum nigrum, characterized the silver nanoparticles by using UV-visible spectrophotometer, analyse the morphology of silver nano particles by using transmission Electron Microscope (TEM) and the nature of the silver nanoparticles by using X-Ray Diffaraction Assay (XRD pattern), analyze the phytochemicals by using Fourier transform infrared spectroscopy (FTIR) present in the medicinal plants responsible for the nanoparticals synthesis.

MATERIALS AND METHODS Collection of plant. The plant leaves of Solanum nigrum were collected from Katpadi, Vellore district, Tamil nadu, India.

Preparation of plant extract. Fresh leaves were collected and dried under shade. The dried leaves were powdered by mixer grinder. 10 g of Solanum nigrum powdered was taken and added 100 ml of

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distilled water in a beaker and boiled for 5 to 10 minutes and are filtered through filter paper whatmann no 1. The extracts were allowed to store and are used for experimental animals.

Table 1. Biomedical applications of Solanum nigrum.

S. No Applications

References

1

antibacterial activity against gram+ and gram- bacteria

[1, 2, 3]

2

anticancer activity against HeLa cell line

[4]

3

Antifungal activity

[5]

4

Antiviral activity

[6]

5

Anti ulcerogenic effect

[7]

6

Hepatoprotective activity

[8, 3]

7

Anti-inflammatory activity

[9]

8

Anti-seizure activity

[10]

9

Hypoglycaemic activity

[11]

10

Free radical scavenging property

[12]

11

Cardioprotective activity

[13]

12

Anti-seizure activity

[10]

Synthesis of nano particles. The filtered extract was mixed with silver nitrate solution. (1mm of AgNO3) and 90 ml of distilled water and 10ml of extracts and kept in shaker. Every 4 hour silver nitrate was detected by UV-Visible Spectrophotometer at the range of wave length of 370-510 nm.

Preparation of nanoparticles powder for characterization The silver nanoparticles was prepared using centrifugaition techniques, it was based on our previsous studies [14]. The prepared particles were characterized using FT-IR, Transmission electron microscope and EDX. Antibacterial activity of AgNPs.Antibacterial activity was performed against typhoid causing bacteria (Salmonella typhi) and skin disease causing bacteria (Staphylococcus aureus) using disk diffusion method. Disks were impregnated with 3 different concentration of nanoparticle (25 mg/ml, 50 mg/ml, 75 mg/ml). The antbacterial effects of nanoparticles were measured against a positive control (cephalexin disk). The experiment was performed in triplicate.

RESULTS AND DISCUSSION Phytosynthesis of silver nanoparticles using S. nigrum FT-IR Analysis Fourier transform infrared spectroscopy (FT-IR) is the best tool for identify the chemical groups of different biological extracts [28]. The chemical groups Solanum nigrum leaves and its based synthesis of silver nanoparticles was analysed using FT-IR shown in Fig. 1and 2. In that the main peaks at 3282.13, 2918.33 and 1613.47 corresponds to the functional groups of C-H Stretch of alkynes, C≥C Stretch 0f alkynes and c-c=c symmetric stretch respectively. In the Solanum nigrum assisted synthesis of silver nanoparticles shows well developed peak at 3332.94 and 1634.30 indicates the chemical groups of Hydrogen bonded O-H Stretch and C-C=C Symmetric stretch respectively confirms the plant phytochemical are responsible for synthesis of nanoparticles [14, 28].

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Fig. 1. Solanum nigrum plant leaves extract.

Fig.2. Solanum nigrum plant leaves extract mediated silver nanoparticles.

UV-vis spectroscopy analysis.The UV–visible absorption spectra result reveals a one step procedure for the preparation of the Ag NPs. The scale of wavelength was fixed between 380 and 480 nm, the surface Plasmon resonance (SPR) of the Ag NPs formed corresponded to 430 nm and there was an increase in intensity till 10 min 24 hr as a function of time without any shift in the peak wavelength (Fig. 3). It can be observed that the reduction of silver ions reaches saturation within 24 hr of reaction and after that, only slight variations can be noted in the intensity of SPR bands. This result indicates that the reaction is completed in 24 hrs [27, 30].

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6hrs

12hrs

Absorbance (AU)

18hrs

wavelength (nm)

Fig. 3. UV-vis spectrum of siver nanoparticles by solanum nigrum.

TEM and EDX analysis

Fig. 4. Tem image and EDX spectrum of silver nanoparticles synthesized by S. nigrum.

Fig. 5. Tem image and EDX spectrum of silver nanoparticles synthesized by S. nigrum.

The morphology of phytochemical mediated silver nanoparticles was viewed by TEM. Fig. 4 shows a well-dispersed AgNPs has identified in the sizes range 20–40 nm. The particles are clearly identified by their spherical, pseudosphericaland some of undefined shapes because the nanoparticles are associated with phytochemicals present in the Solanum nigrum leaves extract. The phytochemicals MMSE Journal. Open Access www.mmse.xyz

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of plant extracts have been bind with the nanoparticles and some time it shows undefined shape in the background of the images and EDX analysis [24, 25, 30]. The results of elemental analysis also confirmed that the silver nanoparticles are bind with the biochemicals present in the plant extract (Fig. 5).

Antimicrobial activity of silver nanoparticles.The synthesized AgNPs were used for the antibacterial actvtiy against disease causing pathogens such as Salmonelltyphi and Staphylococcus aureus. Silver nanoparticles are the very major antimicrobial agents having good antimicrobial capability against different type of gram positive and gram negative microorganisms [14, 30, 31].

The Fig. 6 and 7 shows the antibacterial actvtiy of AgNps and its zone of inhibition against S. typhi and S. aureus.

Antibacterial actvtiy of AgNPs

Staphylococcus aureus, 75 µl, 15 Salmonell typhi

Zone of Inhibition (mM)

Staphylococcus Salmonell typhi, 75 µl, aureus, 50 µl, 13 13

Staphylococcus aureus, 25µl, 12 Salmonell typhi, 50 µl, 11 Salmonell typhi, 25µl, 10

Concentration of AgNPs

Fig. 6. Antibacterial analysis of AgNPs.

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Staphylococcus aureus Salmonell typhi, Antibiotics, 11 Staphylococcus aureus, Antibiotics, 10

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Fig. 7. Antibacterial analysis of AgNPs against Salmonella typhi and Staphylococcus aureus.

Summary.The present study confirms the synthesis of Ag nanoparticles by Solanum nigrum leaf extract. The extract acted as both reducing and capping agent and thus, stabilized the nanoparticles efficiently clearly demonstrated by the results. Uv-vis analysis confirmed the nanoparticle synthesis and EDX analysis depicts the presence of elemental silver. TEM analysis shows the synthesized nanoparticles with size range 20-40 nm. Nanoparticles show considerably high anti microbial effect against both the strains i.e. salmonella typhi and staphylococcus aureus when compared to standard antibiotic used. This suggests that it could be used as a potential drug against both the bacterial strain in future.

References [1] Kavishankar G.B, Lakshmidevi N, MahadevaMS.Phytochemicalanalusis and antimicrobial properties ofselected medicinal plants against bacteria associated with diabetic patients. International Journal of Pharma and BioSciences. 2 (4): 2011;509-518 [2] Ali NS, Singh K, Khan MI, Rani S. Protective effect of ethanolic extracts of Solanum nigrum on the blood sugar of albino rats. IJPSR. 1 (9): 2010; 97-99.

[3] R. Bhavani, G. Geetha, J. Santhoshkumar and S Rajeshkumar, (2015) Evaluation of Antibacterial action and Hepatoprotective efficiency of Solanum nigrum leaves extract on acetaminophen induced hepatotoxicity. Research J. Pharm. and Tech. 8 (7) : 893-900.

[4] Patels S, Gheewala N, Suthar A,, Shah A. 0In-vitrocytotoxicity activity of Solanumnigrum extracts againstHela cell lines and Vero cell lines. International journal ofpharmacy and pharmaceutical sciences. 1 (1): 2009;38-46.

[5] Sridhar TM, Josthna P, Naidu CV. Antifungal activity, phytochemical analysis of Solanumnigrum (L.)-animportant antiulcer medicinal plant. Journal ofEcobiotechnology 3 (7): 2011 (Linn.) - An important antiulcer medicinal plant. Journal ofExperimental Sciences. 2 (8): 2011; 24-29.

[6] Javed T, UsmanAA, Sana R, Sidra R, Sheikh R. In-vitroantiviral Solanumnigrumagainst Hepatitis CVirus. Virology Journal.8:2011; 26.

activity

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[7] Jainu M, Devi CSS.Antioxidant effect of methanolicextractsofSolanumnigrumberries on aspirin induced gastricmucosalinjury.Indian Journal of Clinical Biochemistry, 19 (1): 2004; 57-61.

[8] Elhag RAM, Badwi MAE, Bakhiet AO, Galal M. Hepatoprotective activity of Solanumnigrumextracts onchemically induced liver damage in rats. Journal on Veterinary Medicine and Animal Health. 3 (4): 2011;45-50.

[9] Ravi V, Saleem TSM, Patel SS, Raamamurthy J Gauthaman K. Anti-inflammatory effect of methanolic extract of Solanumnigrum Linn berries. International Journal of Applied Research in Natural Products. 2 (2): 2009;33-36.

[10] Noel NW, Joseph AA, Helen OK, Steven SG, Asa A. Antiseizure activity of the aqueous leaf extract of Solanum nigrumlinn (solanaceae) in experimental animals.AfricanHealth Sciences.2008; 8 (2), 74-79.

[11] Akubugwo I. E, Obasi N.A, Chinyere G.C and Ugbogu A. Mineral and phytochemical contents in leaves of Amaranthus hybridus L and Solanum nigrum L. subjected todifferent processing methods.

African Journal ofBiochemistry Research. 2 (2): 2008; 040-044.

[12] Rawani A, Ghosh A Chandra G.nMosquitolarvicidalactivities of SolanumnigrumL. leaf extract against Culexquinquefasciatus. Parasitol Res. 107: 2010;1235–1240.

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[13] Balaji R, Prakash G, Suganyadevi P, Aravinthan K M.Evaluation of cardio protective Activity of Methanolic Extract Of Solanum nigrum Linn. in Rats. International Journal of Drug Development & Research. 3 (3):2011; 139-147.

[14] S Rajeshkumar (2016) Synthesis of silver nanoparticles using Fresh bark of Pongamia pinnata and its antibacterial action against gram positive and gram negative pathogen Resource-Efficient Technologies 2 (2016) 30–35.

[15] D.Jain, H.K.Daima, S.Kachhwaha, S.L.Kothari. Synthesis of plant-mediated silver nanoparticles using papaya fruit extract and evaluation of their anti-microbial activities. Digest Journal of Nanomaterials and Biostructures.2009; 4: 557–563.

[16] Kannan Badri Narayanan, Hyun Ho Park, NatarajanSakthivel Extracellular synthesis of mycogenic silver nanoparticles by Cylindrocladiumfloridanum and its homogeneous catalytic degradation of 4-nitrophenol SpectrochimicaActa Part A: Molecular and Biomolecular Spectroscopy 116 (2013) 485–490.

[17] Nakkala JR, Mata R, Kumar Gupta A, Rani Sadras S. Biological activities of green silver nanoparticles synthesized with Acorous calamus rhizome extract. Eur J Med Chem 2014;85:784–94.

[18] U. Kanagavalli, A. Mohamed Sadiq, Sathishkumar, S. Rajeshkumar. Plant Assisted Synthesis of Silver Nanoparticles Using Boerhaavia diffusa Leaves Extract and Evolution of Antibacterial Activity. Research J. Pharm. and Tech 2016; 9 (8):1064-1068.

[19] Ulug B, HalukTurkdemir M, Cicek A, Mete A. Role of irradiation in the green synthesis of silver nanoparticles mediated by Fig. (Ficus carica) leaf extract. Spectrochim Part A: Mol Biomol Spectrosc 2015;135:153–61.

[20] Geetha N, Geetha TS, Manonmani P, Thiyagarajan M. Green synthesis of silver nanoparticles using Cymbopogan Citratus (Dc) Stapf. Extract and its antibacterial activity. Aus J Basic Appl Sci 2014;8 (3):324–31.

[21] Masurkar SA, Chaudhari PR, Shidore VB, Kamble SP. Rapid biosynthesis of silver nanoparticles using Cymbopogan Citratus (Lemongrass) and its antimicrobial activity. Nano-Micro Lett 2011;3 (3):189–94.

[22] Kumarasamyraja D, jeganathan NS. Green synthesis of silver nanoparticles using aqueous extract of acalypha indica and its antimicrobial activity. Int J Pharm Biol Sci 2013;4 (3): 469–76.

[23] Kumar S, Daimary RM, Swargiary M, Brahma A, Kumar S, Singh M. Biosynthesis of silver nanoparticles using Premna herbacea leaf extract and evaluation of its antimicrobial activity against bacteria causing dysentery. Int J Pharm Biol Sci 2013;4 (4):378–84.

[24] Sadeghi B, Rostami A, Momeni SS. Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity. Spectrochim Part A: Mol Biomol Spectrosc 2015;134:326–32.

[25] Vijayaraghavan K, Nalini S, Prakash NU, Madhankumar D. One step green synthesis of silvernano/microparticles using extracts of Trachyspermum ammi and Papaver somniferum. Colloid Surf B Biointerfaces 2012;94:114–7.

[26] Thombre R, Parekh F, Patil N. Green synthesis of silver nanoparticles using seed extract of Argyreia nervosa. Int J Pharm Biol Sci 2014;5 (1):114–9.

[27] Sunita D, Tambhale D, Parag V, Adhyapak A. Facile green synthesis of silver nanoparticles using Psoralea corylifolia. Seed extract and their in-vitro antimicrobial activities. Int J Pharm Biol Sci 2014;5 (1):457–67.

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[28] Gnanajobitha G., Rajeshkumar, S., Kannan C and Annadurai, G. 2012. Preparation and characterization of fruit-mediated silver nanoparticles using pomegranate extract and assessment of its antimicrobial activity (2013) Journal of Environmental nanotechnology 2 (1), 04-10.

[29] G Gnanajobitha, K Paulkumar, M Vanaja, S Rajeshkumar, C Malarkodi, G Annadurai and C Kannan Fruit mediated Synthesis of Silver Nanoparticles using Vitis vinifera and Evaluation of their Antimicrobial Efficacy (2013) Journal of Nanostructures in Chemistry 3 (67): 1-6.

[30] S. Rajeshkumar Phytochemical constituents of fucoidan (Padina tetrastromatica) and its assisted silver nanoparticles for enhanced antibacterial activity (2016) IET Nanobiotechnology doi: 10.1049/iet-nbt.2016.0099.

[31] Rajeshkumar S, Malarkodi C, Vanaja M,, Annadurai G Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens Journal of Molecular Structure 1116 (2016) 165-173.

Cite the paper Venkat Kumar S., Karpagambigai S., Jacquline Rosy P., Rajeshkumar S. (2017). Phyto-Assisted Synthesis of Silver Nanoparticles using Solanum Nigrum and Antibacterial Activity Against Salmonella Typhi and Staphylococcus Aureus. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.86.22.967

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Temperature Based Investigation on Structure and Optical Properties of Bi2S3 Nanoflowers by Solvothermal Approach33 J. Arumugam1, A. Dhayal Raj1, a, A. Albert Irudayaraj1, T. Pazhanivel2 1 – Department of Physics, Sacred Heart College, Tirupattur, Vellore Dist, Tamilnadu, India 2 – Department of Physics, Periyar University, Salem, Tamilnadu, India a – dhayalraj03@gmail.com DOI 10.2412/mmse.73.16.231 provided by Seo4U.link

Keywords: Bi2S3 nanostructures, XRD, SEM, UV-Vis, FTIR.

ABSTRACT. A solvothermal process has been employed to synthesis Bi 2S3 nanostructures which has a wide spread applications in photodiode, hydrogen storage, high energy batteries, as well as luminescence and catalytic fields. Bismuth nitrate, thiourea and PolyVinyPyrrolidene (PVP), used as the starting materials are dissolved in ethylene glycol for different reaction times. It was found that the temperature plays a key role in determining the shape of the products. The crystalline phase and structure of the Bi2S3 nanostructures were investigated by power X-ray diffraction (XRD). The surface morphology has been analyzed by Scanning electron microscopy (SEM), the optical properties of the Bi2S3 nanoparticles were analyzed using UV-Vis spectroscopy. The functional groups present in the Bi 2S3 nanoparticles were characterized by FT-IR spectroscopy. The novel Bi2S3 nanoparticles will be exploited for its application as photocatalyst.

Introduction. Recently, nanostructured materials have gained their importance in science and technology due to their novel optical, electric, magnetic and catalytic properties as compared to the corresponding bulk counter parts due to their large surface areas, smaller size, reduced numbers of free electrons and possible quantum confinement effects [1]. The integration of one-dimensional nanoscale building blocks into two-and three-dimensional ordered superstructures or complex functional architectures, which not only open up possibilities for advanced nanodevices but also offers opportunities to explore their novel collective properties, has recently been proposed [2]. In particular, nanostructures like nanopariticles and nanoflowers of semiconductor materials have attracted much attention due to their possible applications in nanoscale electronic and optoelectronic devices. Nanowiskers so called by reason off their appearance have become the subject of intensive study in recent years because of their remarkable characteristics [3]. However, the organization of building blocks into ordered patterns through direct manipulation receives increasing research interest in the synthesis of nanomaterials.

Bismuth sulfide (Bi2S3) is one of the most studied semiconductors with Eg of 1.3eV [4] owing to its wide spread applications, such as photodiode arrays, photovoltaic converters, photodetectors, thermoelectric and electrochemical hydrogen storage as an imaging agent in X-ray computed tomography, in biomolecules detection, H2 sensing and so on. Extensive research has been focused on the synthesis of one dimensional Bi2S3 nanostructures in a controlled fashion by various methods [5]. Qiaofeng Han et al., have reported the Orthorhombic Bi2S3 nanorods with diameters in the ranging of 20-35 nm and with lengths of hundreds of nanometers by hydrothermal treatment [6].

Xuefeng Qian et al., have reported Bi2S3 naniwiskers through microwave method and influence of PVP and sulfur sources on the morphology of the prepared Bi2S3 have also been reported [3].

Yonghong Ni et al., have reported flowerlike Bi2S3 microspheres and have studied catalytic activity 33

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[7]. Anukorn Phuruangrat et al., have reported the Influence of PVP on the Morphologies of Bi2S3 Nanostructures synthesized by Solvothermal Method [8], K. Kavi rasu et al., have reported the structural and optical properties of PVP/Bi2S3 nanoparticles by chemical method [9]. Ding et al., have synthesized the 3D Hierarchical Bi2S3 nanostructures through PolyVinylPyrrolidone (PVP) and Chloride Ion-assisted synthesis [10]. However, most of the techniques mentioned above are of higher temperature and pressure, or the preparation procedures are complex. Therefore, it remains a challenge to develop a facile route to fabrication of Bi2S3 nanomaterials in order to investigate its unusual properties [11].

In this study, we report the facile route to synthesize flower-like Bi2S3 nanostructures via a solvothermal approach with different reaction temperature.

Experimental Procedure: Bismuth Nitrate, Thiourea, Polyvinylpyrrolidone (PVP) and ethylene glycol (EG) were purchased from merck without further purification. In a typical procedure required amount of bismuth nitrate, thiourea and PVP were successively mixed in 40 ml of ethylene glycol.

The resulting mixtures were sonicated to obtain a clear yellow solution, which was then transferred in to 40 mL Stainless steel Teflon-lined autoclave. The autoclaved was maintained for different temperatures (60°C, 100°C, 120°C, 160°C and 200°C). Finally, the sample was collected, washed with double distilled water and ethanol for few times and then dried at 60°C in hot air oven. Further the sample was characterized byXRD, HR-SEM, EDAX, UV-Vis and FTIR. Result and discussion Structural analysis. Fig.1 shows the XRD pattern of the Bi2S3 nanostructures obtained via a one-pot Solvothermal method. All the peaks can be indexed to the orthorhombic Bi2S3 phase (JCPDS no. 170320), with lattice constants a=11.15Ă…, b=11.30Ă… and c= 3.981Ă… and no characteristic peaks of any other phases or impurities are observed. Furthermore, the intense and sharp peaks indicate the product is well crystallized. In another investigation, the average crystalline size was derived from DyeScherrer formula as shown below: đ?‘˜đ?œ†

đ??ˇ = đ?›˝ đ?‘?đ?‘œđ?‘ đ?œƒ, where D is the average crystalline size, k is a constant whose value is typically 0.9 of non-spherical crystals, β is the full width at half maximum (FWHM) of the diffraction peak (in radians) that has the maximum intensity in the diffraction pattern, Îť is the wavelength of incident X-ray beam (0.154184 nm) and θ is diffraction angle or Bragg angle.

From this formula, the average crystalline size of Bi2S3 was calculated as 17 nm, 21nm, 28 nm, 30 nm and 32nm for samples prepared at 60°C, 100°C, 120°C, 160°C and 200°C respectively. When the reaction temperature is increased up to 200°C, the diffraction peaks become stronger gradually. When reaction temperature is reached at 200°C, the diffraction peaks are narrow and strong, indicating that the improvement in crystallinity.

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Fig. 1. XRD Pattern of Bi2S3 nanoparticles prepared for 24 hours at (a) 60°C (b) 100°C (c) 120°C (d) 160°C (e) 200°C.

Morphological analysis: Fig.2 Shows the HR-SEM image of Bi2S3 nanoparticles obtained at different temperatures by solvothermal approach. The SEM image in Fig.2 (a) corresponding to the sample prepared at 60°C, shows numerous well-distributed flower-like nanostructures formed from the reactant Bi2S3 powder.

Inset the Fig.2 (a) shows a single flower-like structure. The flowers are approximately of 1µm in size and composed of tens of petals. The petals of these Bi2S3 nanoflowers are smooth flaks-structures and approximately 250 nm in width and 166 nm in thickness as shown in Fig.2 (a). As the reaction temperature is increased the nanoflowers turn up to nanoparticles with some agglomeration. The average particle size has been calculated as 166nm, 180 nm, 249nm and 250nm for sales prepared at 100°C, 120°C, 160°C and 200°C respectively. When the reaction temperature is increased the particle size also increased. The composition of the nanoflowers as extracted from the energy dispersive spectroscopy (EDAX) spectrum and are presented in Fig. 2 (f) which confirms the presence of Bi and S atoms. The deficiency of S with respect to stoichiometry in the nanoflowers can be attributed to the vapour pressure of S higher than that of Bi. Little evidence of O was detected in this spectrum.

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a

b

c

d

cps/eV

e

12

f

10

Counts

8

6

S

S Bi

O

4

2

0 1

2

3

4

5 keV

6

Energy (eV)

Fig. 2. HR-SEM image of Bi2S3 nanoparticles obtained at different temperatures (a) 60°C, (b) 100°C, (c)120°C, (d)160°C, (e)200°C and (f) EDAX spectrum of Bi2S3 nanoflowers prepared by solvothermal approach for 24 hours.

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Fig. 3. UV absorption spectra of Bi2S3 nanoparticles prepared for 24 hours at (a)60°C, (b) 100°C, (c)120°C, (d)160°C (e)200°C.

Optical analysis. Fig.3 shows the UV-Vis spectra of Bi2S3 nanoparticles obtained at different temperatures by solvothermal approach. The optical properties of Bi2S3 semiconducting compounds result from band structures of the materials and are very important in a large number of applications.

The (αhυ)2 ~ hυ curve are shown as inset in Fig.3. From the Fig., the band gap of Bi2S3 semiconductor nanoflowers and nanoarticles could be determined to be about 1.70 to 1.82 eV by extrapolating the linear portion of (αhυ)2 Vs hυ curve. The band gap values thus obtained is higher than that of the bulk Bi2S3 (1.3eV). The blue shift might be ascribed to the quantum effect due to the high aspect ratio of the nanoflower and nanoparticles.

Functional group analysis.

Fig. 4. FTIR spectra of Bi2S3 nanoparticles prepared for 24 hours at (a) 60°C by solvothermal approach.

The composition and quality of the product were analyzed by FT-IR spectroscopy. Fig.4 FTIR spectra of Bi2S3 nanoflowers prepared for 24 hours at 60°C by solvothermal approach. The broad absorption MMSE Journal. Open Access www.mmse.xyz

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band centered at 3426 cm−1, must be associated with the (OH) stretching vibration. A broad band at 3300 to 3500 cm-1 attributed to the stretching vibration of H2O, while the band centered at 1623cm-1 corresponds to the bending vibrations of H2O. The strong peaks at 1370 cm−1 attributed to C-S stretching vibration [12], indicating the formation the [Bi (Tu)x]3+ complex in the porous nanoflowers, as shown in the Fig. 4. The peaks at 1207 cm-1 could be attributed to the stretching of C–O–C– bonds [13]. The strong absorption band at 428 cm−1 and 478 cm-1 is due to Bi [14]. The peak at 618 cm-1 may be attributed to stretching vibrations of sulphur indicating the formation of Bi2S3.

Summary. Well-crystallined Bi2S3 nanoflowers have been successfully synthesized by solvothermal approach with low reaction temperature. The structure of the Bi2S3 nanoparticles is confirmed to be orthorhombic from the X- ray diffraction patterns. The Vibrational peaks at 423 cm-1and 618 cm-1 confirm the formation of Bi2S3. From the optical absorption spectra, the band gap of Bi2S3 nanostructures were found to be in the range 1.70 to 1.82eV, which are higher than that of bulk Bi2S3 materials. The as-synthesized Bi2S3 nanoflowers, can be potentially applied in the field of photocatalysis.

Acknowledgments The authors would like to acknowledge the management, Sacred Heart College for extending support to complete this work successfully.

References [1] R. Chen, M.H. So, C.M. Che, H. Sun, Controlled synthesis of high crystalline bismuth sulfide nanorods: using bismuth citrate as a precursor, J. Mater. Chem., 15 (2005) 4540-4545. DOI: 10.1039/B510299E [2] J. Ma, J. Yang, L. Jiao, T. Wang, J. Lian, X. Duan, W. Zheng, Bi2S3 nanomaterials: morphology manipulation and related properties, Dalton Trans., 40 (2011) 10100-10109. DOI: 10.1039/C1DT10846H [3] R. He, X. Qian, J. Yin, Z. Zhu, Preparation of Bi2S3 nanowhiskers and their morphologies, J. Cryst growth, 252 (2003) 505-510. DOI:10.1016/S0022-0248 (03)00968-0 [4] X. Yu, C. Cao, Photoresponse and Field-Emission Properties of Bismuth Sulfide Nanoflowers, Cryst. Growth Des., 8 (2008) 3951-3955. DOI: 10.1021/cg701001m [5] J. Ma, Z. Liu,, J. Lian, X. Duan, T. kim, P. Peng, X. Liu, Q. Chen, G. Yao, W. Zheng, Ionic liquids-assisted synthesis and electrochemical properties of Bi2S3 nanostructures, Cryst Eng Comm., 13 (2011) 3072-3079. DOI: 10.1039/C0CE00913J [6] Q. Han, J. Chen, X. Yang, L. Lu, X. Wang, Preparation of Uniform Bi2S3 Nanorods Using Xanthate Complexes of Bismuth (III), J. Phys. Chem. C, 111 (2007) 14072-14077. DOI: 10.1021/jp0742766 [7] F. Guo, Y. Ni, Y. Ma, N. Xiang, C. Liu, Flowerlike Bi2S3 microspheres: facile synthesis and application in the catalytic reduction of 4-nitroaniline, New J. Chem., 38 (2014) 5324-5330. DOI: 10.1039/C4NJ00900B [8] A. Phuruangrat, T. Thongtem, S. Thongtem, Influence of PVP on the Morphologies of Bi2S3 Nanostructures Synthesized by Solvothermal Method, Journal of Nanomaterials, 1155 (2013) 1-6.

DOI:10.1155/2013/314012 [9] K. Kavi Rasu, D.Vishnushankar, V. Veeravazhuthi, Optical and Structural Properties of PVP/Bi2S3 Nanoparticles by Chemical Method, Advanced Materials Research, 678 (2013) 248-252.

DOI:10.4028/www.scientific.net/AMR.678.248 [10] T. Ding, J. Dai, J. Xu, J. Wang, W. Tian, K. Huo, Y. Fang, C. Chen, 3D Hierarchical Bi2S3 Nanostructures by Polyvinylpyrrolidone (PVP) and Chloride Ion-Assisted Synthesis and Their

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Photodetecting Properties, Nanoscale Res. Lett., 10 (2015) 286- 274. DOI 10.1186/s11671-015-09931 [11] X. Zhou, H. Shi, B. Zhang, X. Fu, K. Jiao, Facile synthesis and electrochemical application of surface-modified Bi2S3 urchin-like nano-spheres at room temperature, Mater Lett., 62 (2008) 32013204. DOI:10.1016/j.matlet.2008.02.019 [12] C.Tang, C. Wang, F. Su, C. Zang, Y. Yang, Z. Zong, Y. Zhang, Controlled synthesis of urchinlike Bi2S3 via hydrothermal method, Solid State Sci., 12 (2010) 1352-1356, Doi:10.1016/j.solidstatesciences.2010.05.007 [13] Y.Y Wang, K Feng Cai, Xi Yao, One-pot fabrication and enhanced thermoelectric properties of poly (3, 4-ethylenedioxythiophene)-Bi2S3 nanocomposites, J. Nanopart. Res., 14 (2012) 2-7, 10.1007/s11051-012-0848-y.

[14] M. Salavati-Niasari, Z. Behfard, O. Amiri, E. Khosravifard, S. Mostafa Hosseinpour-Mashkani, Hydrothermal synthesis of Bismuth Sulfide Bi2S3 Nanorods: Bismuth (III) Monosalicylate Precursor in the Presence of Thioglycolic Acid, J. Clust. Sci., 24 (2013) 349–363, DOI 10.1007/s10876-0120520-9.

Cite the paper J. Arumugam, A. Dhayal Raj, A. Albert Irudayaraj, T. Pazhanivel (2017). Temperature Based Investigation on Structure and Optical Properties of Bi2S3 Nanoflowers by Solvothermal Approach. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.73.16.231

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Structural, Optical and Magnetic Properties of Cr Doped CdSe Powders Prepared by Solid State Reaction34 J. Sivasankar1, P. Mallikarjuna1, N. Madhusudhana Rao2,a, S. Kaleemulla2, M. Rigana Begam3, G. VenugopalRao4 1 – Department of Physics, Rayalaseema University, Kurnool, AP, India 2 – Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore, TN, India 3 – Indira Gandhi College of Engineering and Technology of Women, Chengalpattu, Kancheepuram, T.N., India 4 – Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, India a – drnmrao@gmail.com DOI 10.2412/mmse.7.43.833 provided by Seo4U.link

Keywords: room temperature ferromagnetism, Cr doped CdSe, X-ray diffraction, optical properties.

ABSTRACT. As the key factor to study dilute magnetic semiconductors (DMS) for spintronic applications is the potential to harvest high-quality-single-phase dilute magnetic semiconductors. In this paper, we report the room temperature ferromagnetism (RTFM) in Cr doped CdSe powders synthesized through solid state reaction. The structural, optical and magnetic properties of Cd1-xCrxSe (x= 0.00, 0.04 and 0.08) powders at room temperature has been investigated. X-ray diffraction (XRD) studies confirmed the chromium (Cr) incorporation into the CdSe crystal lattice without disturbing the hexagonal (wurtzite) structure. The lattice parameters are found to be increased with increased Cr concentration in CdSe lattice. The band gap of Cd1-xCrxSe powders has been found to be red shifted as compared to pure CdSe. Magnetic hysteresis (M-H) loops at room temperature reveal the persistence of ferromagnetism in Cd 1-xCrxSe powders. The saturation magnetization values increased with increase of ‘x’ in Cd 1-xCrxSe. The observed RTFM might due to carrier mediated exchange interactions present in the system.

Introduction. The novel combination of material properties such as room temperature ferromagnetism and semiconducting behavior has spawned interest in spin current injection for storage devices. Dilute magnetic semiconductors (DMS) are traditional semiconductors in which magnetic transition metal impurities with partially filled ‘d’ statesand lanthanide series elements with partially filled ‘f’ shell electrons replace cations of the host semiconducting materials. DMS are assumed to be potential resources for practical spintronic based devices [1-3]. It is an exciting field of research wherein both the charge and spin are used for transportation, storage and processing of information in a single spintronic device [4].Room temperature ferromagnetism (RTFM) is an essential property for DMS materials. In order to acquire RTFM in DMS materials, transition metal (Fe, Ni, Co, Mn, Cr) has been doped in different semiconductors such as ZnO [5], GaN [5], TiO2 [6], CdS [7], CdSe [8] and SnO2 [9]. II-VI and III-V DMS offer unique combination of structural, electronic and magnetic properties, which strongly depends on the nature and concentration of the dopant. The transition metals find greater solubility in II–VI compound semiconductors, when compared with III-VI semiconductors[10] .Till date extensive reports are available on nitride, oxide and chalcogenide DMS with different theories and mechanisms explaining the interactions such as double exchange, super-exchange and RKKY type in both the theoretical and experimental aspects with conflicting results on room temperature ferromagnetism. Yet, the origin of observed magnetism in DMSs is still a topic of debate[11, 12]. Apart from this, various reasons for the observed magnetism 34

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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are contaminants, metal clusters, structural changes and defects present in pure and doped DMS materials [13, 14]. Among II–VI semiconductors, cadmium selenide (CdSe) is a well-known semiconductor, crystallizing in either the wurtzite or the zinc blende structure [15-20]. It has suitable properties for applications in electronics and optoelectronic devices such as laser diodes, high efficiency solar cells, sensors and biomedical imaging devices [21-23]. In present investigation, we have synthesized Cr doped CdSe powders via solid state reaction by varying the chromium concentration.

Experimental. Cr doped CdSe powders were synthesized at high temperatures by using a solid state reaction method. Commercially available pure CdSe, Cr and Se (99.99 %, M/S Sigma-Aldrich) were used as starting materials. To prepare CrSe, stoichiometric amount of Cr and Se were weighed and were physically grounded thoroughly in an agate mortar with a pestle until physical homogeneity is attained. These solid mixtures were packed tightly into a graphitized quartz tube of length 20 and 0.7 cm diameter. The tube was sealed in a vacuum of 2  10-6 mbar and it is kept in a horizontal furnace and fired at 1000 C for about 2 hours. Later the furnace was cooled slowly to room temperature to get good polycrystalline CrSe powder. Then, appropriate quantities of freshly prepared CrSe and CdSe were mixed and ground thoroughly for 18 h to ensure homogeneity and then sintered at 600 C for 6 hours under a pressure of 10-3 mbar. The calcined Cr doped CdSe powders were investigated to study structural, optical and magnetic properties.

Results and discussions.

Structural Properties.The X-ray diffraction patterns of the pure and Cr doped CdSe samples were shown in Fig.1. All the diffraction peaks perfectly matches with the standard JCPDS data (00-772307) for CdSe system exhibiting wurtzite structure. No traces of chromium metal clusters or oxides were observed in XRD patterns. The lattice constants ‘a’ and ‘c’ of the Cd1-xCrxSe powders were calculated from XRD data. The lattice constants are found to be increased with increasing Cr concentration as shown in Fig.2.These results imply that the Cr2+ has been incorporated into the crystal lattice of CdSe by replacing Cd in CdSe lattice, which produces a strain in the host lattice.

Similar variation of lattice constant with dopant was observed by the authors in Cu doped CdSe[24] and Cr doped ZnTe[25] . Fig. 3 shows the EDAX spectra and SEM images of Cr doped CdSe powders. EDAX spectra confirms the existence of Cr in the powder samples and SEM images illustrate that the Cr doped CdSe powder are in submicron size.

Optical properties. The optical properties of pure and Cr doped CdSe powders have been studied by recording diffuse reflectance at room temperature. Diffused reflectance spectra and the band gap estimation plots of pure and Cr doped CdSe powers were shown in Fig.4 Pure CdSe powder samples exhibited a band gap of 1.65 eV, whereas Cr 4 at.% and Cr 8 at.% doped CdSe samples have band gap of 1.675 and 1.689 eV, respectively. It is clearly seen from the spectra that the absorption edge shifts towards lower wavelength with increasing chromium concentration. Hence an increase in optical band gap was observed. This may be due to the increase in the carrier concentration by the inclusion of chromium ions and creation of defect levels in the band gap.

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c) d) Fig. 3. (a), (b) EDAX spectra and (c), (d) SEM images of Cd1-xCrxSe powders with x= 0, 04 and 0.08.

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Magnetic properties.Fig. 5 shows the field depended magnetization of Cd1-xCrxSe powders with x= 0.00, 0.04 and 0.08 measured by vibrating sample magnetometer at room temperature. The inset of Fig. 5 shows the M-H loops of Cr doped CdSe. The pure CdSe showed diamagnetic nature as its magnetic susceptibility is negative () = -2.2510-7 emu g-1 Oe-1[26] and hence ferromagnetism was MMSE Journal. Open Access www.mmse.xyz

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not expected and Cr is antiferromagnetic in nature. But, as the Cr doping concentration is increased from 4 to 8 at.% the magnetic moment increased showing clear hysteresis loops. A ferromagnetic behaviour with weak magnetic moment was observed for 4 at.% Cr doped CdSe. It is evident that the diamagnetic dominating characteristic is responsible for reduced magnetic moment in the case of lower chromium ions doped CdSe. Whereas for 8 at.% Cr doped CdSe, the S-type hysteresis loop was observed with a significant impact of high magnetic moment. The hysteresis loops observed in the present study display a characteristic pattern of soft magnetic materials. It can be interpreted that this RTFM might be due to creation of spin-split impurity band at the fermi level, below the conduction band due to the hybridization between the charge carriers of chromium and cadmium. In the present investigations, neither trace of metal clusters nor impurity phases were detected in the XRD measurement, which confirms the substitution of Cr ions into the CdSe host lattice. It is also seen that the wurtzite structure is unaltered even after the substitution of Cr2+ ions for Cd2+ ions, resulting in ferromagnetic behavior. In addition to that, as Cr ions are antiferromagnetic in nature[10], probability of inducing an extrinsic ferromagnetism due to Cr ions is not possible. Therefore, it is clear that the observation of ferromagnetism may be ascribed to the exchange interaction between free delocalized carriers and localized ‘d’ spins of Cr ions[27]. Similar kind of trend was observed in Cu doped CdSe powders [24] and Cr doped CdSe nanoparticles[28]. In contrast to the case of Ni doped CdSenanorods[29], the magnetic moment has been found to be decrease with increased Ni concentration due to direct coupling between Ni2+ions.

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Summary.Cd1-xCrxSe powders at x= 0.00, 0.04 and 0.08 were prepared using solid state reaction method and the role of dopant concentration on the structural, optical and magnetic properties of the Cd1-xCrxSe powder samples were investigated. Structural analysis indicated that the pure CdSe and Cr doped CdSe powder samples were hexagonal in structure. and no other secondary phases were found in the samples indicating that Cr ions are substituted at the Cd sites. Diffuse reflectance spectra has shown blue shift in the band gap. Ferromagnetic strength increases with Cr concentration in Cd1xCrxSe powder samples. Such ferromagnetism is attributed to the intrinsic nature of the samples rather than any secondary magnetic phases.

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Cite the paper J. Sivasankar, P. Mallikarjuna, N. Madhusudhana Rao, S. Kaleemulla, M. Rigana Begam, G. Venugopal Rao (2017). Structural, Optical and Magnetic Properties of Cr Doped CdSe Powders Prepared by Solid State Reaction. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.7.43.833

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Structural, Optical and Magnetic Properties of Co doped ZnSe Powders35 P. Mallikarjuna1, J. Sivasankar1, M. Rigana Begam2, N. Madhusudhana Rao2,a, S. Kaleemulla2, J. Subrahmanyam3 1 – Department of Physics, Rayalaseema University, Kurnool, AP, India 2 – Thin Films Laboratory, Center for Crystal Growth, School of Advanced Sciences, VIT University, Vellore, TN, India 3 – Department of Physics, N.B.K.R. S&A College, Vidyanagar, India a – drnmrao@gmail.com DOI 10.2412/mmse.90.5.465 provided by Seo4U.link

Keywords: solid-state reaction, X-ray diffraction, optical studies, Co doped ZnSe.

ABSTRACT. Co doped ZnSe nano crystalline powder samples were prepared by solid-state reaction method.Structural, optical and magnetic properties of pure and Co doped ZnSe powders were studied. Both Pure and doped ZnSe samples were in cubic structure. Lattice parameter and band gap of pure and doped ZnSe powders decreased with increase of Co concentration. The Raman shift in the Raman spectra of the samples confirms the Co doping in to the ZnSe lattice.Band gap of the samples decreased with increase of Co concentration. Codoped ZnSe powders exhibited half-metallic ferromagnetism at room temperature with low Co concentration and paramagnetism with high Co concentration.

Introduction.Dilute magnetic semiconductors (DMS) have earned good interest in recent years because of its feasibility to have magnetic and semiconducting properties in the same materials.DMS materials are the traditional non-magnetic semiconductors doped with transition metal or rare earth metal ions at very low concentration. The host material is exhibiting some peculiar properties after doping with suitable transition metal ions[1]. DMS materials find more attention because of their applications inopto-electronics and spintronics devices, which utilizesboth the spin and charge of the electrons[2, 3]. Further these find significant role in designing of spin valves, spin light emitting diodes and ultra-fast optical switches[4]. Extensive studies had been carriedout on several II-VI DMS compounds.Among all II-VI semiconductors, ZnSe is a potential candidate to fit in various applications as solar cells [5], bio-medical tags [6]and light emitting diodes [7].ZnSe is a blue-lasing material and can be employed in designing modulated hetero structures and optical wave guides[8].

Doping magnetic ions of +2 oxidation state into II-VI DMS such as CdSe, CdTe and ZnSe is easy.Co is one of the suitable ferromagnetic transition metal to dope in to II-VI semiconductors. Different model or mechanisms such as double exchange, RKKY carrier induced intractions, super- exchange were applied to explain the origin of ferromagnetism in these II-VI DMS compounds [9, 10]. The present work focus on the effect of Co doping concentration on structural, optical and magnetic properties of Co doped ZnSe powders.

Experimental details.Pure and Co doped ZnSe powder samples were prepared with different concentrations of Cobalt by solid state reaction. There sets of powders sample-1: pure ZnSe, sample2: 5at. % Co doped ZnSe and Sample-3:10 at.% Co doped ZnSe were prepared. Stoichiometric quantities of ZnSe and freshly prepared Co doped ZnSe were weighed and subjected to continuous mechanical grinding for about14-16 hours.Thepowders were sintered at 800oC for 10 hours under a

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pressure of 10-3mbar.The pure ZnSe and Co doped ZnSe powders were characterized to study their structural, raman, optical and magnetic properties.

Results and Discussion.

Structural analysis.Fig.1 shows the X-ray diffraction patterns of the pureZnSe and Co doped ZnSe powder samples at different Co doping concentrations. The diffraction peaks of all the samples are found to be matched with ZnSe cubic structure pattern having JCPDS data [card no 88-2345].The crystal structure of the host material has not been altered on increasing dopant concentration. These observations indicate that Co ions were doped in the corresponding metal sites of Zn ions.It is also observed from the XRD studies that the intensity of the peaks increased as the concentration of the dopant ions of cobalt increased from 5% to 10%.

ZnSe:Co(10%)

(311)

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Intensity a.u

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(222)

(200)

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0 25000

(400)

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(111)

25000

ZnSe:Co(5%)

20000 15000 10000 5000 0 15000

Pure ZnSe

10000 5000 0 20

30

40

50

60

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2 theta (degree)

Fig. 1. XRD patterns of pure ZnSe and Co doped ZnSe powders.

5.66 5.65

Latticeparameter (a)(A)

5.64 5.63 5.62 5.61 5.60 5.59 0.00

0.02

0.04

0.06

0.08

0.10

Cobalt composition(X)

Fig. 2. Variation of lattice parameter of Co doped ZnSe with Co concentration.

Fig. 2 shows the variation of lattice parameter ZnSe with increase of Co concentration. The lattice parameter increased with increase of Co doping concentration which might be due to substitution doping of Co in Zn metal ion sites in ZnSe host compounds. Similar lattice contraction was observed

by Begam et.al. in Co doped CdTe powders[11] and in Co doped CdSe[12].Fig. 3presents the typical Raman spectrum of the all samples. The obtained dominant Raman peaks at 138 cm-1, 248 cm-1 and MMSE Journal. Open Access www.mmse.xyz

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287 cm-1 are attributed to the second transverse acoustic (2TA), transverse optical (TO) and longitudinal optical (LO) phonon modes of ZnSe, respectively. The observations agree well with the reported results for ZnSenanobelts and nanowires [13].All the aboveresults further confirm that the as-prepared products present a cubic structure of ZnSe phase. Fig. 4 shows the EDAX spectra and SEM images of Cr doped CdSe powders. EDAX spectra confirm the existence of Cr in the powder samples and SEM images illustrate that the Cr doped CdSe powder are in submicron size.

Fig. 3. Raman spectra of pure ZnSe and Co doped ZnSe powders.

a)

b)

c)

d)

Fig. 4. (a), (b) EDAX spectra and (c), (d) SEM images of Co doped ZnSe powders with 5% and 10% Co concentration.

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Optical properties. Fig. 5 shows the diffused reflectance spectra of pure and Co doped ZnSe powders. The bandgaps for different substitutions of Co ions (x=0.05, 0.10) are calculated using Tauc’s relation as shown in the Fig.6.It can be found that the band gaps of Co doped ZnSetend to decrease from 2.378 eV (pure ZnSe) to 2.199eV and 1.835eV.The red shift in the band gap with increase in Co doping can be explained on account of the sp-d exchange interaction taking place between the conduction band electrons and the localized ‘d’ electrons of Co ions that replace the host Zn ions. Babuet. al. also observed same trend of decrease in band gap with increase of dopant concentration in Mn doped ZnSe thin films up 15 at. wt. % of Mn concentration [14].

Magnetic properties. The M-H curves for Co doped ZnSe powders at room temperature are showed in the Fig.7. Inset of the Fig. 7 shows the M-H curve of pure ZnSe at room temperature. It confirms that ZnSe is diamagnetic in nature. Themagnetization values (Ms) observed in the present samples for5at% and 10at% Co concentrations are 0.024088 emu/g and 0.05728 emu/g.

In general the manifestation of ferromagnetic behavior in DMS compounds may be understood from the mutual exchange interaction present between free delocalized charge carriers and d spins of Co ions. But these Co doped ZnSe samples exhibit half metallic ferromagnetism. This type of magnetism is attributed due to polarization of electronic spins.

Benstaali et.al.[15] in Co doped ZnSe, Mohamood et. al.[16] in Ti doped ZnSe and Arifet. al. [17] in Co doped CdSe were reported half metallic ferromagnetism due to polarization of the spin in their theoretical investigation and further suggested these materials are suitable for spintronic materials.

100 Pure x = 0.05 x = 0.10

Reflectance (%)

80

60

40

20

500

1000

1500

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Wavelength (nm)

Fig. 5. Diffused reflectance spectra of undoped and Co doped ZnSe powders 4.0

Pure ZnSe 3.5

ZnSe:Co(5%) ZnSe:Co(10%)

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[h]



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1.0

0.5

0.0 1.8

2.0

2.2

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h (eV)

Fig. 6. Plots of (αhν)2Vshν of undoped and Co doped ZnSe powders.

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Zn0.95 Co0.05Se Zn0.90Co0.10 Se At 300K

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Magnetisation (emu/g)

Moment/mass(emu/g)

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-0.015 -10000

-0.05

-5000

0

5000

10000

Magnetic field (gauss)

-0.06 -10000

-5000

0

5000

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Field(G)

Fig.7. M-H plots of pure ZnSe and Co doped ZnSe powders.

Summary. ZnSe powders doped with Co were synthesized by solid state reactions andinvestigations were carried at different concentrations of Zn1-xCoxSe (x=0.05 and x=0.10) and studied the effect of Co concentration on structural, optical and magnetic properties of the prepared samples. The X-ray diffraction studies and Raman analysis confirmed that all the samples are in cubic structure. Optical studies denote a decrease in band gap with increase in Co compositions. Half metallic ferromagnetism is observed in the present Co doped ZnSe powder samples at room temperature.

Acknowledgement. Authors are very much thankful to VIT-SIF for providing XRD and DRS facilities to carry out the present work. Authors also render their sincere thanks to SAIF-IIT Madras, Tamilnadu, India, for providing vibrating sample magnetometer facilities.

References [1] B. Amin, S. Arif, I. Ahmad, M. Maqbool, R. Ahmad, S. Goumri-Said, K. Prisbrey, Cr-Doped III– V nitrides: potential candidates for spintronics, Journal of Electronic Materials, 40 (2011) 1428-1436, DOI: 10.1007/s11664-011-1539-7.

[2] H. Ohno, Making Nonmagnetic Semiconductors Ferromagnetic, Science, 281 (1998) 951, DOI: 10.1126/science.281.5379.951.

[3] S.A. Wolf, D.D. Awschalom, R.A. Buhrman, J.M. Daughton, S. von Molnár, M.L. Roukes, A.Y. Chtchelkanova, D.M. Treger, Spintronics: A Spin-Based Electronics Vision for the Future, Science, 294 (2001) 1488, DOI: 10.1126/science.1065389.

[4] S.J. Pearton, C.R. Abernathy, D.P. Norton, A.F. Hebard, Y.D. Park, L.A. Boatner, J.D. Budai, Advances in wide bandgap materials for semiconductor spintronics, Materials Science and Engineering: R: Reports, 40 (2003) 137-168, DOI: 10.1016/S0927-796X (02)00136-5.

[5] B. Wang, J. Zhang, Y. Hu, S. Wang, R. Liu, C. He, X. Wang, H. Wang, Role of Co 2+ incorporation in significant photocurrent enhancement of electrochemical deposited CdSe quantum dots sensitized TiO 2 nanorods arrays solar cells, Int. J. Electrochem. Sci, 8 (2013) 7175-7186, DOI : 80507175.

[6] I.-F. Li, C.-S. Yeh, Synthesis of Gd doped CdSe nanoparticles for potential optical and MR imaging applications, Journal of Materials Chemistry, 20 (2010) 2079-2081, DOI: 10.1039/B924089F. [7] Z. Li, A.J. Du, Q. Sun, M. Aljada, L.N. Cheng, M.J. Riley, Z.H. Zhu, Z.X. Cheng, X.L. Wang, J. Hall, Cobalt-doped cadmium selenide colloidal nanowires, Chemical Communications, 47 (2011) 11894-11896, DOI: 10.1039/C1CC13467A. [8] C.M.I. Okoye, First-principles study of the electronic and optical properties of zincblende zinc selenide, Physica B: Condensed Matter, 337 (2003) 1-9, DOI: 10.1016/S0921-4526 (03)00175-3.

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exchange interactions in dilute magnetic semiconductors, Journal of Physics: Condensed Matter, 19 (2007) 436227, DOI: 10.1088/0953-8984/19/43/436227.

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[11] M. Rigana Begam, N.M. Rao, G.M. Joshi, S. Kaleemulla, M. Shobana, N. Sai Krishna, M. Kuppan, Structural, Optical and Magnetic Properties of Co Doped CdTe Alloy Powders Prepared by Solid-State Reaction Method, Advances in Condensed Matter Physics, 2013 (2013) 5, DOI: 10.1155/2013/218659.

[12] J.S. N. Madhusudhana Rao, P. Mallikarjuna, M. Rigana Begam, S. Kaleemulla, C. Krishnamoorthi, N. Sai Krishna, M. Kuppana, M. Shobana, Structural, Optical and Magnetic properties of Co doped CdSe powders, International Journal of ChemTech Research, 6 (2014) 19841987, [13] Z.D. Hu, X.F. Duan, M. Gao, Q. Chen, L.M. Peng, ZnSe Nanobelts and Nanowires Synthesized by a Closed Space Vapor Transport Technique, The Journal of Physical Chemistry C, 111 (2007) 2987-2991, DOI: 10.1021/jp067556e.

[14] R.B.K. Mohan Babu T, Madhusudhana Rao N., Vijayalakshmi R.P., D.R Reddy, Structural and optical properties of ZnxMn1-xSe (0≤x≤0.20) films, Optoelectronics And Advanced Materials – Rapid Communications, 4 (2010) 1612, [15] W. Benstaali, S. Bentata, A. Abbad, A. Belaidi, Ab-initio study of magnetic, electronic and optical properties of ZnSe doped-transition metals, Materials Science in Semiconductor Processing, 16 (2013) 231-237, DOI: 10.1016/j.mssp.2012.10.001.

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Cite the paper P. Mallikarjuna, J. Sivasankar, M. Rigana Begam, N. Madhusudhana Rao, S. Kaleemulla, J. Subrahmanyam (2017). Structural, Optical and Magnetic Properties of Co doped ZnSe Powders. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.90.5.465

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Structural, Magnetic Properties of Wide Band Gap Oxide Semiconductors36 B. Balaraju1, M. Kuppan1, S. Harinath Babu2, S. Kaleemulla1,a, N. Madhusudhana Rao1, C. Krishnamoorthi1, Girish M. Joshi3, G. Venugopal Rao4, K. Subbaravamma5, I. Omkaram6, D. Sreekantha Reddy7 1 – Thin films Laboratory, Centre for Crystal Growth, VIT University, Vellore-632014, Tamilnadu, India 2 – Department of Physics, Annamacharya Institute of Technology and Sciences, New Boyanapalli, Rajampet-516 126 andhra Pradesh, India 3 – Polymer Nanocomposite Labrotory, Centre for Crystal Growth, VIT University, Vellore-632014, Tamilnadu, India 4 – Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, Tamilnadu, India 5 – Department of Physics, AMET University, Kanthur, Chennai-603112, Tamilnadu, India 6 – Department of Electronics and Radio Engineering, KyungHee University, Yongin-si, Gyeonggi-do 446-701, Republic of Korea 7 – Department of Physics and Sungkyukwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwan – 440746, Republic of Korea a – skaleemulla@gmail.com DOI 10.2412/mmse.95.56.253 provided by Seo4U.link

Keywords: iron oxide, oxide semiconductors, particle geometry, magnetic measurements.

ABSTRACT. Iron oxide (Fe2O3), Manganese oxide (MnO2) and Nickel oxide (NiO) nanopowder samples were prepared using mechanical grinding method and subjected to their structural and magnetic properties. Microstructures, crystallite size of the nanoparticles were studied using X-ray diffractometer (XRD). Magnetic measurements were carried out using vibrating sample magnetometer low temperature (100 K). From the magnetic studies, it was found that the magnetic moment increased with increase of applied field in iron oxide and saturation was not observed even at high magnetic fields. The magnetic studies of NiO revealed ferromagnetic behaviour whereas MnO2 undergoes paramagnetic behaviour.

Introduction. In recent years dilute magnetic oxide semiconductors are finding much interest due to their important properties such as optical transmittance, electrical conductivity and ferromagnetism.

Due to these reasons much focus is being put on wide band gap metal oxide semiconductors such as indium oxide, tin oxide, zinc oxide, titanium oxide, copper oxide etc. These oxide materials are so important because they possess high carrier density, wide bang gap, ease of preparation, low cost and high Curie temperature. Among the other oxides, α-Fe2O3 also one of the most important material as it finds in many potential applications. It can form four different polymorphs such as alpha, beta, gamma and epsilon [1]. If the Fe2O3 nanoparticles were prepared of the order of single domain, they exhibit interesting properties such as superparamagnetism and large coerciviy. These nanoparticles find potential applications such as gas sensors, catalyst, photovoltaics, high density magnetic storage devices, bio separation, magnetic resonance imaging agent etc.[2-5]. Moreover efforts were put for the synthesis of nanoparticles using different physical and chemical methods. The literature survey indicates that different synthesis methods such as sputtering, decomposition, hydrothermal, solvothermal, sol-gel and electrochemical processes [6-9] were applied for the synthesis of

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nanoparticles. Here in order study the impurity free α-Fe2O3, simple mechanical milling method was applied for the preparation of α-Fe2O3 nanoparticles.

Experimental. The commercially available α-Fe2O3 powder was procured from Sigma Aldrich (India). α-Fe2O3 nanoparticles were prepared by simple mechanical milling method. The powder was milled using Agate mortar and ground thoroughly for 16 hours using pestle. After that the samples were characterized for structural, optical and magnetic properties. X-ray diffraction (X-ray diffractometer, D8 Advance, BRUKER) patterns were used to study the structural aspects. The optical reflectance and absorbance spectra were recorded using UV-VIS spectrophotometer (JASCO-V-670) in the wavelength range of 200 nm to 2500 nm. The magnetic studies were performed upto 0.1T field at low temperature (100 K) using vibration sample magnetometer (VSM Lakeshore 7404).

Results and discussion.

Fe2O3 (3 0 0)

(a)

(1 2 2) (2 1 4)

2000

(0 2 4)

(1 1 0)

(0 1 2)

2500

(1 1 3)

(1 0 4)

3000

(1 1 6) (0 1 8)

Structural properties. Fig. 1 shows the X-ray diffraction profile of the Fe2O3 nanoparticles. The diffraction peaks such as (0 1 2), (1 0 4), (1 1 0), (1 1 3), (0 2 4), (1 1 6), (1 2 2), (2 1 4) and (3 0 0) were found in their respective diffraction angles. From this, the structure of the nanoparticles was found to be in rhombohedral structure. These are in good agreement with that of standard XRD pattern of α-Fe2O3 derived from the JCPDS Card No. 33-664 [10]. No other diffraction peaks related to either FeO or Fe3O4 were found in the profile indicating that the source material is pure from any kind of impurities. Fig. 1 (b) shows the X-ray diffraction patterns of the MnO2 nanopowder. As shown in Fig. 1 (b), the diffraction peaks such as (1 1 0), (3 1 0), (2 1 1), (3 0 1), (4 1 1) and (5 2 1) reflections were found at 12.8°, 28.8°, 37.5°, 42.0°, 50.0°, 60.3° can be respectively.

MnO2 (3 1 2)

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(c)

(4 4 0)

6000

(4 0 0 )

1000

(2 2 2)

Intensity (arbitrary units)

1500

70

80

2 (degrees)

Fig. 1. X-ray diffraction profiles of NiO, MnO2 and Fe2O3 nanoparticles.

These reflections clear indexed to a tetragonal structure of standard MnO2 having JCPDS data Card no. 44-0141. Here also no other phases such as MnO, Mn2O3, Mn3O4 and Mn were found in the profile. Fig. 1 (c) shows the XRD profile of nickel oxide nanopowder. From the diffraction peaks it was found that the nanoparticle were in face centred cubic structure without any other impurity phases MMSE Journal. Open Access www.mmse.xyz

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within the detection limit of X-ray diffractometer. The observed results are found in good agreement with the standard JCPDS data Card No. 65-2901. The crystallite size (G) of all the samples has been calculated by using the Debye-Scherer formula, đ?‘˜đ?œ†

đ??ş = đ?›˝đ?‘?đ?‘œđ?‘ đ?œƒ

(1)

where k is particle geometry dependent constant (for spherical shape k ~1), ď Ź is the wavelength of used (ď Ź = 1.5406 Ă…), ď ˘ is the full width-at-half maximum (FWHM) and ď ą is the diffracted angle, respectively.

The estimated average crystallite size of Îą-Fe2O3, MnO2 and NiO are found to be about 39 nm, 32 nm and 19 nm respectively.

Optical properties. Fig. 2 shows the diffuse reflectance spectrum of Îą-Fe2O3 nanoparticles. From the optical reflectance data, the optical band gap of the nanoparticles was estimated. The optical bang gap (Eg) was obtained by plotting (ÎąhĎ…)2 versus the photon energy (hĎ…) and by extrapolating the linear region (Îą = 0). The optical band gap was estimated using the Tauc equation

100

Fe2O3

Reflection (%)

80

60

40

20

0 500

1000

1500

2000

Wavelength (nm)

Fig. 2. Diffused reflectance spectrum of Îą-Fe2O3 nanoparticles. đ?›źâ„Žđ?œˆ = đ??´âˆšEg − â„Žđ?œˆ

(3)

where hν is the photon energy, ι is the absorption coefficient and n is either 1/2 for a direct transition or 2 for an indirect transition.

The optical band gap of semiconductor can be estimated from the intercept of the extrapolated linear fit for the plotted experimental data of (ιhν)n versus incident photon energy hν near the absorption edge. An optical band gap of 2.08 eV was observed for ι-Fe2O3 nanoparticles. The observed optical band gap is inconsistent with that of published work [11].

Magnetic properties. Fig. 3 shows the magnetic hysteresis measurements for MnO2, NiO and ÎąFe2O3 samples at 100 K. It can be seen that the magnetization increases almost linearly under an applied magnetic field for all three samples. The saturation in the magnetization could not be observed even under the high magnetic field of 0.1T for Îą-Fe2O3. This observation is similar to the earlier study[12]. The ferromagnetism is observed in NiO nanoparticles unlike bulk NiO at low temperature MMSE Journal. Open Access www.mmse.xyz

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due to surface magnetization effect occurring at nanoscale. The MnO2 nanoparticles show paramagnetism at low temperature. Magnetic properties of similar oxides were studied and found that they exhibit diamagnetism in nature whereas on doping ferromagnetism was observed at 100 K [1315].

1.5

MnO2 Magnetization (emu/g)

1.0

NiO -Fe2O3

0.5 0.0 -0.5 -1.0 -1.5 -10.0k

-5.0k

0.0

5.0k

10.0k

Applied Field (Oe)

Fig. 3. M-H loop of MnO2, NiO and α- Fe2O3 nanoparticles.

Summary. Powder samples of α-Fe2O3, MnO2 and NiO has been reduced to nanosize by mechanical grinding. They are then subjected to structural, optical and magnetic studies. The structural studies confirm the single phase formation of all the samples. The optical properties of α-Fe2O3 have been studied confirming the previous reports. The magnetic property of α-Fe2O3, MnO2 and NiO samples shows their inability to reach saturation magnetization at low temperature even on applying high field.

The α-Fe2O3 and NiO nanoparticles showed ferromagnetism with maximum magnetization values as 0.198 emu/g and 1.507 emu/g respectively at 100 K. The MnO2 nanoparticles showed paramagnetic behaviour at 100 K. References [1] M.A. Chougule, S. Sen, V.B. Patil, Facile and efficient route for preparation of polypyrrole-ZnO nanocomposites: Microstructural, optical and charge transport properties, Journal of Applied Polymer Science, 125 (2012) E541-E547, DOI : 10.1002/app.36475.

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[13] S.H. Babu, S. Kaleemulla, N.M. Rao, G.V. Rao, C. Krishnamoorthi, Microstructure, ferromagnetic and photoluminescence properties of ITO and Cr doped ITO nanoparticles using solid state reaction, Physica B: Condensed Matter, 500 (2016) 126-132, DOI : 10.1016/j.physb.2016.07.037.

[14] N.S. Krishna, S. Kaleemulla, G. Amarendra, N.M. Rao, C. Krishnamoorthi, M. Kuppan, M.R. Begam, D.S. Reddy, I. Omkaram, Structural, optical and magnetic properties of Fe doped In2O3 powders, Materials Research Bulletin, 61 (2015) 486-491, DOI : 10.1016/j.materresbull.2014.10.065.

[15] M. Kuppan, S. Kaleemulla, N. Madhusudhana Rao, N. Sai Krishna, M. Rigana Begam, D. Sreekantha Reddy, Physical Properties of Sn (1−x) Fe (x) O2 Powders Using Solid State Reaction, Journal of Superconductivity and Novel Magnetism, 27 (2014) 1315-1321, DOI : 10.1007/s10948013-2457-0.

Cite the paper B. Balaraju, M. Kuppan, S. Harinath Babu, S. Kaleemulla, N. Madhusudhana Rao , C. Krishnamoorthi, Girish M. Joshi, G. Venugopal Rao, K. Subbaravamma, I. Omkaram, D. Sreekantha Reddy (2017). Structural, Magnetic Properties of Wide Band Gap Oxide Semiconductors. Mechanics, Materials Science & Engineering, Vol 9. doi: 10.2412/mmse.95.56.253

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Preparation and Characterization of Metal Oxide as Nano Particles - Varatika Bhasma37 Shebina P. Rasheed1, M. Shivashankar1 1 – VIT University Vellure, Tamil Nadu, India DOI 10.2412/mmse.24.38.124 provided by Seo4U.link

Keywords: nanoparticles, metal oxide, herbomineral formulation.

ABSTRACT. Varatika bhasma is a herbomineral formulation coming under the holistic concept of Ayurveda. Varatika is the outer covering shell of marine organism Cyprea moneta Linn or commonly known as Money cowry. Chemical composition of Varatka is Calcium carbonate. The present study involves the processing of varatika in to metal oxides by a special process known as Bhasmikaran in Ayurveda, the ancient system of medicine. Varatika is subjected to calcination there by the Calcium carbonate present in varatika is converted fine particles of calcium oxide, producing potent, biosafe and efficacious nanoparticles with less side effects are produced. The evaluation of the final product are done for physicochemical parameters and by sophisticated analytical tools like Xray, SEM, AFM, Zeta potential EDAX, particle size analysis and by Thermogravimetric curves. The produced bhasma was found as very fine nano particle which may produce very potent and biosafe antiulcer activity.

Introduction: Ayurveda is an ancient system of medicine where natural materials are used as remedies for a large no of diseases and the system is based upon the balance of spiritual mental and and physical functions of human body. A large number of formulations are available in ayurvedic system.Out of this 35-40% contains minimum one metals as major ingredient. A branch of Ayurveda known as Rasoushadi includes a class of ayurvedic medicines containing metals. Bhasma are coming under rasoushadies as they are herbo-metallic ashes prepared by repeated calcination of metals with various herbal ingredients to form organometallic complexes [3] These process known as Bhasmikarn converts metals in to metal oxides of nanosize having unique electrical, optical catalytical and medicinal properties. These formulations are very very important because of their uniqueness like alpamathra (a low dose), non toxicity, good palatability and potent and fast acting and with the ability of targeted drug delivary.In this present study Varatika bhasma is prepared from the outer covering of the marine organism Cyprea moneta Linn or commonly known as Money cowry.This is mainly used for its antiulcer property as it contains calcium carbonate. Varatika is subjected to bhasmikaran process whereby the organic components are eliminated and metals are converted to its high oxygenated state. The repeated heating reduces the particle size to nanosize whereby nano medicine with increasedmetabolism at cellular level because of its high zetapotential and rapidly acting, nontoxic less side effects producing herbo mineral formulation Varatika Bhasma is obtained. This study also attempts to characterize the varatika bhasma prepared by physico-chemical properties through conventional methods like Nischandratvam (lusterless), Apunarbhava (metal irreversibility test), Varitaratvam (floating test) and by physicochemical parameters and using modern analytical methods likescanning electron microscope (SEM)and X-ray fluorescence (XRF) spectrophotometer [2-5].

Experimental

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Bhasma Preparation. The Varatika is subjected to Bhasmikaran process which is the most important step which determines the effectiveness of bhasma. All the metal part has to be converted to oxide form during this step. Any metal not converted to oxide form will remain as such and can be detected in evaluation process. Materials: varatika and Aloe vera juice are obtained from local market of Nilambur, Malappuaram, Kerala and Cow dung-from local people.

Methodology 1. Authentication: Authentication is done by HOD, Rasoushadi Department, Pariyaram Ayuveda Medical College, Kannur, Kerala 2. Purification of Varatika 3. Varatika Bhasma Nirmanam 3.1. Varatika Shodhana- 50 gms of varatika which is authentified is taken and subjected to shodhana.

Shodhana involves powdering of Varatika in to small pieces and then it is tied in to two folded cloth and it is made to hang on a stick placed across a pot which is filled with kanji (a sour liquid). Then it is subjected to heat for 3hrs.After three hours it is taken out and washed in warm water and dried.

Varatika must immerse fully in to the kanji while heating.

3.2. Marana (Bhasma Nirmana)-Purified varatika is taken and kept in mud vessel then covered by another vessel .The mouth of vessel is covered tightly by a cloth which is smeared with gopichandanam (A type of mud).Cow dung cakes are used as fuel. Vessel must be placed over the cow dung cakes and set the fire. After the combustion the vessel is taken and varatika must be collected. The same procedure is done for 3 times after making it in to a paste by adding aloe vera gel Which is known as Putta. The no of putta determines the quqlity of Bhasma.These process convert the minerals and metals of varatika in to very fine powders of nano size and thus more effective and less toxic materials are obtained as shown in Fig.1[1] Evaluation of Prepared Bhasma.The prepared Bhasma has to be Evaluated for assuring the effectiveness, quality and safety. They have evaluated by following methods Physical Standardization. Traditional method of characterization has done by following methods.

Verna: The colour of bhasma is checked. It was found light ash color. Niswadhutha: Taste of bhasma was checked by keeping a pinch of bhasma on tongue. Nischandratvam: A pinch of bhasma is observed under bright light.it was found without lusture. Rekhapurnatwa: Fineness test, by rubbing bhasma in between the fore finger and thumb.as bhasmas are fine the will enter in to the furrows of the fingers.Floating test: Pinch of bhasma was over the surface of water. It was found floating, indicating lightness of bhasma.

Physio Chemical StandardizationAsh values, XRD, SEM TGCEDAX analysis are carried out to study the physical chemical compatibility (1) Atomic Absorption Spectroscopy (AAS): AAS analysis carried out as per the reference (3, 5-8).

Result and Discussion. The Varatika Bhasma was prepared as per the Rasatharangini, an official ayurvedic text. The metal calcium present in the Varatika has converted in to a higher oxidation state, as calcium oxide and the nano sized fine ash are produced. The heating at higher temperature burns out all carbonaceous matter and the nanoparticles formed has improved physiochemical and biological properties. The Evaluation method shows following results. Nischandratvam: Found without Metalic lusture .Rekhapurnatwa: Fineness. As bhasma produced are fine they will enter in to the furrows of the fingers. Floating test: It was found floating, indicating lightness of bhasma. These results shows that the bhasma prepared are in very fine form. Fig. 2, Fig.3, Physiochemical Standardization: Ash values obtained are given in Table 2.

XRD Analysis The pattern obtained in Fig. 5 .The size of the crystals formed are calculated by Scherrer formula and the size lay in the range of 80nm-117nm. SEM The particle size are nearly 659 MMSE Journal. Open Access www.mmse.xyz

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nm which gives insight that the method of preparation ie the no. of calcination, Fig.6. TGA-The TGA analysis curve shows the decomposition temperature of 736.70c, which shows that the bhasma contains pure calcium oxide.

EDAX Analysis The stotiometry of particles is studied by EDAX. The results are in Fig. 8. and the other heavy metals are within the limits of official books. The results are shown in Table 2. All these analysis confirms the nano nature of the varatika bhasma and this oxygen deficient state improves the therapeutic activity. Further animal experiments are required to confirm bioactivity.

Fig. 1. Physical properties for Shanka Bhasma.

(a) Fig. 2. Fineness test for Shanka Bhasma.

(b)

Fig. 3. XRD Analysis of Shanka Bhasma.

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Fig. 4. SEM images of Shanka Bhasma.

Fig. 5. TGC curve for Shanka Bhasma.

Fig. 6. EDAX images of Shanka Bhasma.

Table 1. Preliminary tests for Varatika Bhasma.

Sno 1 2 3

Test Total ash Acid insoluble ash Loss on drying at 1050C

Values 78.06% 9.83% 0.6577%

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Table 2. AAS results of Varatika Bhasma.

S.N 1 2 3 4 5

Element Zinc Cobalt Cadmium Copper Lead

Concentration 0.6219 1.129 0.298 0.534 4.76

Absorbance 0.1214 0.0119 0.0206 0.0012 0.484

Summary.The naturally obtained varatika has converted to nano sized particles by effective specialized product Bhasma. There by efficacious nontoxic formulation with better quality is obtained The nano character has evaluated byXRD, EDAX and SEM analysis and also by conventional and modern parameters. Varatika Bhasma is a traditional antiulcer Bhasma and the standardization reduces toxic effects and gives dose control and improves effectiveness.

Acknowledgments: The authors would like to express heartfelt thanks to the staffs and management of SAS, VIT University, Vellore, for their instrumental support and valuable suggestions.

References [1] N. Chaudhary A, Singh, Herbo Mineral Formulations (Rasaoushadhies) Of Ayurveda An

Amazing Inheritance Of Ayurveda Pharmaceutics, Anc Sci Life. Jul 30 (1), 2010, 18-26.

[2] M Sumithra, P.Raghavendra Rao, A.Nagaratnam, Y.Aparna Characterization Of SnO2

Nanoparticles In The Traditionally Prepared Ayurvedic Medicine, Science Direct.2, 2010, 46364639, DOI:10.1016/J.MarApril.2015. 10.086.

[3] R.Madhavan R.Sathish And M.Murugesan Standardisation Of Sangu Parpam A Herbo Marine

Siddha Drug, 3 (6), 2016.77 -84.

[4] Chavare, A., Et.Al, Safety And Bioactivity Studies Of Jasad Bhasma And Its In-Process

Intermediate In Swiss Mice Journal Of Ethnopharmacology 2016.DOI.org/10.1016/j.jep.2016.06.048 [5] Thakur Rakesh Singh, Laxmi Narayan Gupta, Neeraj Kumar, Standard Manufacturing Procedure

of Teekshana Lauha Bhasma, Journal of Ayurveda And Integrative Medicine Aug 7 100-108 (2015).

DOI.org/10.1016/j.jaim.2015.08.003 [6] Shebina P.Rasheed Murugesh Shivashankar, Evaluation of Herbomineral Formulations Bhasma-

An Overview, International Journal of Research in Ayurveda pharmacy.2015, 6 3.

[7] Santhosh S. Kulkarni Bhasma and Nanomedicine, Int.Res.J.Pharm.2013. 4 (4) 10-16.

[8] Sanjoy Kumar Pal The Ayuvedic Bhasma: The Ancient Science of Nanomedicine, Recent Patents

in Nanomedicine 5, 2015, 12-18.

Cite the paper Shebina P. Rasheed, M. Shivashankar (2017). Preparation and Characterization of Metal Oxide as Nano Particles - Varatika Bhasma. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.24.38.124

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Design and Simulation of Nano Wire FET38 M. Anil Kumar1, Y.N.S. Sai Kiran1, U. Jagadeesh1, M. Durga Prakash1• 1 – Department of Electronics and communication Engineering, K L University, Guntur Andhra Pradesh, India a – mdprakash@kluniversity.in DOI 10.2412/mmse.97.91.539 provided by Seo4U.link

Keywords: nanowire, FET, threshold voltage, SILVACO.

ABSTRACT. As the era of classical planar metal-oxide-semiconductor field-effect transistors (MOSFETs) comes to an end, the semiconductor industry is beginning to adopt 3D device architectures, such as FETs, starting at the 22 nm technology node. Since physical limits such as short channel effect (SCE) and self-heating may dominate, it may be difficult to scale Si FinFET below 10 nm. In this regard, transistors with different materials, geometries, or operating principles may help. For example, gate has excellent electrostatic control over 2D thin film channel with planar geometry and 1D nanowire (NW) channel with gate-all-around (GAA) geometry to reduce SCE. High carrier mobility of single wall carbon nanotube (SWNT) or III-V channels may reduce VDD to reduce power consumption. Therefore, as channel of transistor, 2D thin film of array SWNTs and 1D III-V multi NWs are promising for sub 10 nm technology nodes. To simulate these devices, accurate modelling and design based on gate-material are necessary to assess their performance limits, since cross-sections of the multi-gate NWFETs are expected to be a few nano-meters wide in their ultimate scaling.

In this paper we have explored the use of SILVACO with different materials for simulating and studying the short channel behaviour of nanowire FETs.

Introduction. CMOS Technology is facing many problems over the last 30 years .In conventional MOSFET we have certain electrostatic limitations like source to drain tunnelling, carrier mobility, static leakages etc. [1-5]. As the size of nanomaterials is very small we can use a more number of transistors on a single chip so that size of the chip is reduced its additional features are robust against short channel effects and relatively simple steps of fabrication so device and circuit developers are using this type of devices and also can use different types of materials used to make these type of materials at low cost [2]. For an Ultra-small MOSFET we have to face several problems like electrostatic limits, source-to-drain tunneling, carrier mobility degradation, process variations and static leakage etc., all these problems can damage the MOSFET by reducing its performance [1-5].

In the VLSI industry it is critically necessary to have a device which has low power dissipation and has high performance along with long time durability. In order to achieve such characteristic features in a real time operation scenario it will be a hard tenacious task. The trend toward ultra-short gate length MOSFETs requires a more and more effective control of the channel by the gate leading to new device architecture [4]. It appears that non-classical device architectures can extend the CMOS lifetime and provide solutions to continue scaling. More in the present modern world the electronic device must have low response time along with low power consumption provided the cost of the device must be in a nominal range.

Using a conventional MOSFET device can no longer sustain such a modern day challenge. So if we use Nano-Materials we can meet the modern day challenge [3].

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In this paper, we had replaced the Poly-Silicon material present on the Gate Terminal of the MOSFET device with different Nano-Materials like Si (Silicon Nano-Wires), ZnO (Zinc Oxide Nano-Wires), CSi (Carbon-Silicon or Silicon Carbide NanoWires).

Fig. 1. Schematic of Nano Wire FET.

(a)

(b)

(c)

(d)

Fig. 2. Schematic of different Nano Wire MOSFETs: a) PolySilicon; b) Silicon Nano Wire; c) Zinc Oxide Nano Wire; d) Carbon Silicon materials in Silvaco Software.

Equations Saturation region drain current: Id= (µcox ω)/ (2L) (Vgs-Vt)2 (1-Vds/VA) ; Vds>=Vgs-Vt Ohmic region drain current: Id= (µcoxω)/ (2L)[2 (Vgs-Vt)Vds -Vds2] (1-Vds/VA) ; Vds<Vgs-Vt MMSE Journal. Open Access www.mmse.xyz

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Oxide capacitance: cox > €ox/tox Transconductance: gm> (µcox ω/L) (Vgs-Vt) Output resistance: Ro=|VA|/Ido Input capacitance: Cin>Cgs+Cgd=CoxLω Transition frequency: Fc>gm/ (2 pi Cin) Surface mobility holes: µ>200cm2/V-s Surface mobility electrons: µ>450cm2/V-s Nomenclature: drain current – Id; oxide capacitance – cox; transconductance – gm; output resistance – Ro; input capacitance – Cin; transition frequency – Fc; electronic field strength in oxide – €ox; gate to source voltage – Vgs; drain to source voltage – Vds; thickness of oxide layer – tox; threshold voltage – Vt.

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(a)

(d)

(b)

(e)

Fig. 3. Igs vs Vds sub threshold values for: a) PolySilicon ; b) Silicon Nano Wire ; c) Zinc Oxide Nano Wire ; d) Carbon Silicon Nano- Wire material FET in Silvaco Software.

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(a)

(b)

(c)

(d)

Fig. 4. Ids vs Vds Drain Current Values for : a)PolySilicon ; b) Silicon Nano Wire ; c) Zinc Oxide Nano Wire ; d) Carbon Silicon Nano- Wire FET in Silvaco Software.

Table 1. Igs vs Vds sub threshold values.

S.No

1 2 3 4

Nano-Wire Material (N.W.M.) NAME Poly silicon Silicon N.W.M. Zinc-Oxide N.W.M. Carbon silicon N.W.M.

THRESHOLD VOLTAGE (Volts) 0.75 0.749 0.743 0.75

RESPECTIVE CURRENT VALUE (Amperes) 3.989•10-6 3.923•10-6 4.31•10-6 3.973•10-6

Table 2. Ids vs Vds curve values.

Material Name

Respective Drain Current Value Ids (Amperes) when Vds (Volts) At 1.1 V

At 2.2V

At 3.3V

Poly Silicon

4.24·10-4

2.45·10-4

5.38·10-5

Silicon Nano Wire

3.62·10-15

3.35·10-15

3.02·10-15

Zinc Oxide Nano Wire

4.25·10-15

4.14·10-15

5.39·10-15

Respective Drain Current Value Ids (Amperes) when Vds (Volts) Carbon Silicon Nano Wire

At 3 V

At 3.5 V

At 4 V

2.28·10-4

8.73·10-5

5.44·10-7

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Summary. From Igs vs Vds sub threshold values Ids vs Vds curve values we can observe that the FET designed using the Nano-wire Materials has less drain current, drain voltage, low sub-threshold voltage. From this we can conclude that the drawbacks of the normal conventional FET has been covered upto certain level using the FET designed from using the Nano-Wire Materials.

References [1] Yi Cui, Zhaohui Zhong, Deli Wang, Wayne U. Wang and Charles M. Lieber, High Performance Silicon Nanowire Field Effect Transistors, Department of Chemistry and Chemical Biology and Division of Engineering and Applied Science, Harvard University, Cambridge, Massachusetts 02138 Received November 1, 2002 (NAN0 LETTERS 2003 VOL 3, NO-2, 149-152.

[2] H. S. P. Wong, “Beyond the conventional transistor” Solid State Electronics, vol. 49, pp. 755762, May 2005 [3] J. T. Park, J. P. Colinge, “Multiple-gate SOI MOSFETs: device design guidelines” IEEE Trans.

Electron Devices, Vol. 49, No. 12, pp. 2222 -2229, Dec. 2002.

[4] Iwai Hiroshi, Natori Kenji, Shiraishi Kenji, Iwata Jun-ichi, Oshiyama Atsushi, Yamada Keisaku, Ohmori Kenji, Kakushima Kuniyuki & Ahmet Parhat, “ SI Nanowire FET and its modeling”, “Science China”, MAY 2011, Vol. 54, No-5:1004-1011, DOI:10, 1007/s11432-011-4220-0.

[5] Bipul C.Paul, Ryan Tu, Shinobu Fujita, Masaki Okajima, Thomas H Lee, Yoshio Nishi, “An Analytical Compact Circuit Model for Nano Wire FET”, IEEE Transactions on Electronic Devices, Vol. 54, No.7, July 2007.

Cite the paper M. Anil Kumar, Y.N.S. Sai Kiran, U. Jagadeesh, M. Durga Prakash (2017). Design and Simulation of Nano Wire FET. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.97.91.539

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Modeling and Simulation of Dual Gratings based Ultrathin Amorphous Silicon Solar Cells39 S. Saravanan1,a, R.S. Dubey1, S. Kalainathan2 1 – Advanced Research Laboratory for Nanomaterials and Devices, Department of Nanotechnology, Swarnandhra College of Engineering and Technology, Seetharampuram, Narsapur (A.P.), India 2 – School of Advanced Sciences, VIT University, Vellore, (T.N.), India a

– rag_pcw@yahoo.co.in DOI 10.2412/mmse.45.64.871 provided by Seo4U.link

Keywords: solar cell, RCWA method, dual gratings, plasmonic, photonic modes, Fabry-Perot resonance.

ABSTRACT. We present the modeling and simulation of a 50 nm ultrathin amorphous silicon solar cell using RCWA method. Optimized solar cell design showed enhanced cell efficiency up to 16.02 and 15.2% for the TE and TM polarization cases. An enhancement in optical performance is found that is associated with efficient light trapping design.

The proposed design is observed to be supported with photonic and plasmonic modes. We have also explored the field distribution within the solar device with Fabry-Perot (FP) resonance and surface plasmon polariton (SPP) modes.

Introduction. Nowadays, there is a trend of making silicon solar cellsby employing thin absorption layer in order to reduce the fabrication cost. But this absorber layer is inefficient for the absorption of high wavelength light [1].According to the literature, the penetration depth of the photons in 180µm thick silicon solar cell was observed to be 3mm within the wavelength range 900-1100 nm. Therefore, the challenging issue is to design an efficient light trapping structure which can reuse the unabsorbed light coming after crossing the thin active region. Among various light trapping schemes, grating based design is found to be promising for the photons trapping. However, the metal and dielectric gratings at the bottom and top respectively are demanded for the better harvesting of light [2]. Ge et al. have proposed a solar cell design based on metallic gratingswithone-dimensional (1D) photonic crystaland observed an enhancement in the optical path length. They have obtained a wide range of optical absorption for both TE and TM polarization modes using rigorous coupled wave analysis (RCWA) method.The designed hybrid solar cell showed enhancement in photon absorption over the entire spectral region irrespective to the angle of incidence[3].Mutitu et al.havepresented a design and fabrication of hybrid dielectric-metallic back reflectors for amorphous silicon solar cells and reported the enhanced reflectance with the use of more distributed Bragg layer (DBR) pairs. This proposed idea of solar cell design has explored the experimental realization of thin filma-Si solar cells using hybrid dielectric-metallic back surface reflector[4].Abass et al. have numerically studied the complex dual-interface grating systems (plasmonic Ag grating at the bottom and dielectric ITO gratings at the top)to enhance light absorption in silicon thin film solar cells. The proposed grating could felicitate the effect of both plasmonic and photonic modes[5].Theuring et al.have presented the design and fabrication of plasmonic and photonic light trapping structure by using metallic (Ag) and non-metallic (SiO2) nanoparticle respectively. The solar cell integrated with SiO2 nanoparticles could give good result as comparison to the solar cell based on Ag nanoparticles [6].

In this paper, we propose a design of an ultrathin amorphous silicon solar cell which is integrated with a thin ITO (top) and Ag (bottom) gratings for the light trapping. In Section second designing 39

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approach is described and simulated results are discussed in Section third. Finally, section fourth concludes the paper.

Designing Approach. A schematic diagram of ultrathin a-Si solar cell structure is shown in Fig. 1.

The designed solar cell is integrated with 70 nm ITO (ARC layer), 50 nm thin absorber (a-Si) and 200 nm Ag back reflector. Here, bottom Ag layeris considered as a perfect back reflector and top ITO layer acting as a suitable contact layer. Within absorber layer, bottom Ag (triangular) and top ITO (rectangular) gratings were embedded to reduce the reflection of light and toboost the path length of the photons [7].Here, thestructural parameters of both ITO and Ag gratings were the same.For the simulation, rigorous coupled wave analysis (RCWA) method is employed. This method also known as simple and fast method in which the periodic boundary conditions (PBC) were applied in x- and y-axis whereas the perfect match layer (PML) condition was in z-axis. The solar radiation (AM 1.5) was illuminated at normal incident angle from 300 to 1200nm spectral range. Below, we have investigated the differentsolar cell structures and compared for the both TE and TM polarizations conditions.

Fig. 1. Schematic diagram of ultra-thin a-Si solar cell integrated with metal and dielectric gratings.

Results and Discussion.Fig. 2 (a) shows the absorption spectra of proposed solar cell design in which high absorption can be observed from 550 to 610 nm. Fig. 2 (b)- (f)shows the transverse electric field intensity profileat various wavelengths. In Fig. 2 (b) and 2 (c), at wavelength 550 and 610nm the surface reflection is suppressed and hence, light absorptionis enhanced.

The use of front grating could give strong absorption and also extended towards the bottom of the solar cell. We have also observed that when the wavelength is increased, a strong peak is appeared in the vertical axis refer to Fig. 2 (d) and 2 (f). Subsequently, in longer wavelength 1090 and 1140 nm strong absorption peaksare observed because of the induced Fabry-Perot resonance as shown in Fig. 2 (e) and 2 (f).

Fig. 3 shows the absorption curve of TM polarization and field distribution at various wavelengths.

The absorption curve shown in Fig. 3 (a) reveals the decreased light absorption as comparison to TE mode. At 530 nm, light interaction is high with surface guided resonance with field excitation at the tip of the grating as shown in Fig. 3 (b). Fig.3 (c) depicts strong field intensity between the metal and dielectric interface at wavelength 670 nm. However, at wavelength 700 nm stronger field is observed which is due to the plasmonic effect as can be seen in Fig. 3 (d). For the longer wavelength i.e. 780 and 1030 nm, localized surface plasmon resonance (LSPR) and surface plasmon polaritonare observed on the metal gratings as shown in Fig.3 (e) and 3 (f).Furthermore, this excitation of plasmonic effect appropriate for the scattering by the metal triangular gratings [8].

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a

+

d

b

c

e

f

_

Fig. 2. Absorption spectra for TE polarization (a) and electric field distribution at λ= 550nm (b), λ=610nm (c), λ= 750nm (d), λ=1090nm (e) and λ=1140nm (f) respectively.

+

a

d

b

c

e

f

_

Fig. 3. Absorption spectra for TM polarization (a) and magnetic field distribution at (b) λ= 530nm, (c) λ=670nm, (d) λ= 700nm (e) λ=780nm (f) λ=1030nm respectively.

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b

a

T E

TM

Fig. 4. Absorption spectra of various solar cell structures for TE (a) and TM (b) respectively.

Fig. 4 shows the absorption spectra of various solar cells for TE and TM polarization conditions. The use of bottom Ag (triangular) grating yields sharp absorption peaks (green and blue lines) in the near IR spectral region for the TE mode as depicted in Fig. 4 (a). For the TM mode, the collection of the photons are increasedin visible region while sharp and wider absorption peaksare obtained in IR regionas shown in Fig. 4 (b) which is associated with the effect of metal grating.The dual grating based solar cell design showsenhanced absorption for the TM polarization because of the induced plasmonic modes. However, as comparison to TE polarization the light absorption is less in TM case.

This performance has been attributed to the strong surface guided and Fabry-Perot resonance modes.

In simple words, here TE mode is more dominant as a result of combined effect of metal and dielectric gratings.

Summary. We have investigatedthe performance of an ultrathina-Si solar cell for both TE and TM polarization conditions using RCWA method. The photonic and plasmonicmodesshowed optimal performance within 50 nm absorber region due to the use of dual gratings. Further, the dual gratings based cell design could yield efficiency 16.02% (TE), 15.2% (TM) with short-circuit current density 24.35 and 23.13mA/cm2respectively.An excellent relative absorption enhancement ~172% is achievedas compared to the reference solar cell. The combination of metal and dielectric gratings could give enhanced performance of the solar cells due to the assisted plasmonic and photonic modes respectively.

Acknowledgement The authors gratefully acknowledge the financial support from the Defence Research Development Organization (DRDO), New Delhi (India) for the financial support.

References [1] L. Zeng, Y. Yi. C. Hong, J. Liu, N. Feng. X. Duan, L.C. Kimerling, B. A. Alamariu, Appl. Phys.

Let.89, 111111 (2006). http://dx.doi.org/10.1063/1.2349845 [2] F. Qin, H. Zhang, C. Wang, J. Zhang, C. Guo, Opt. Commun. 331, 325-329 (2014). http://dx.doi.org/10.1016/j.optcom.2014.06.049 [3] Zheng Gai-Ge, Xian Feng-Lin, LI Xiang-Yin, CHIN. PHYS. LETT. 28 (5), 054213-1-4 (2011).

DOI: 10.1088/0256-307X/28/5/054213 [4] James G. Mutitu, Shouyuan Shi, Allen Barnett and D.W. Prather, Energies 3, 1914-1933 (2010). doi:10.3390/en3121914

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[5] Aimi Abass, Khai Q. Le andrea Alu, Marc Burgelman and Bjorn Maes, Physical Review B 85, 115449-1-8 (2012). https://doi.org/10.1103/PhysRevB.85.115449 [6] Martin Theuring, Peng Hui Wang, Martin Vehse, Volker Steenhoff, Karsten von Maydell, Carsten Agert and Alexandre G. Brolo, J. Phys. Chem. Lett. 5, 3302â&#x2C6;&#x2019;3306 (2014). DOI: 10.1021/jz501674p [7] S. Saravanan, R.S. Dubey, S. Kalainathan, (2016).http://dx.doi.org/10.1016/j.optcom.2016.05.028

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Cite the paper S. Saravanan, R.S. Dubey, S. Kalainathan (2017). Modeling and Simulation of Dual Gratings based Ultrathin Amorphous Silicon Solar Cells. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.45.64.871

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Study of Structural and Optical Properties of Zinc-doped Titanium Dioxide Nanoparticles40 V.G. Vasavi Dutt1, R.S. Dubey1,a 1 – Advanced Research Laboratory for Nanomaterials and Devices, Department of Nanotechnology, Swarnandhra College of Engineering and Technology, Seetharampuram, Narsapur (A.P.), India a – rag_pcw@yahoo.co.in DOI 10.2412/mmse.79.67.635 provided by Seo4U.link

Keywords: TiO2 nanoparticles, doping, sol-gel method, X-ray diffraction, crystalline phase.

ABSTRACT. Titanium dioxide (TiO2) nanoparticles have been extensively investigated for potential applications in various fields due to their unique physical and chemical properties. In this investigation, Zn-doped TiO2 nanoparticles were prepared by sol-gel method and characterized for their structural and optical properties using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV-Vis Spectroscopy and Photoluminescence (PL). The precursors titanium tetraisopropoxide and zinc chloride dopant were used as the source of titanium and zinc. Hydrochloric acid was used to maintain the pH of the solution during the process. A red shift of the light absorption edge of Zn-doped TiO2 has been observed as compared to undoped TiO2 nanoparticles. The crystallite sizes of Zn-doped TiO2 nanoparticles ~8 nm were estimated by using Scherrer’s formula.

Introduction. Titanium dioxide (TiO2) material has been widely investigated and used as photocatalysts, sensors, catalysts for photo-electrochemical water splitting, for hydrogen storage and photovoltaic applications. This material is chemically and physically stable, inexpensive and nontoxic to the human being and our environment. TiO2 exists in both crystalline and amorphous forms with three crystalline polymorphs of TiO2 are anatase, rutile and brookite. These three polymorphs have different crystalline structures; anatase and rutile have tetragonal structure whereas brookite has orthorhombic structure. The structure of anatase and rutile can be described in terms of chains of TiO6 octahedron. The two crystal structures differ by the distortion of each octahedron and by the assembly pattern of octahedral chains [1]. TiO2 nanoparticles are synthesized via various methods such as Hydrothermal, Solvothermal, Electrodeposition, Sonochemical, Flame Pyrolysis and Sol-gel methods. Among these, sol-gel is one of the most preferable techniques for preparation of titanium dioxide particles in nanometer range because of its cost effectiveness, controlled particle growth and ability to produce nanoparticles with high degree of homogeneity [1-4]. Heterogeneous photocatalysis employs TiO2 and UV light to give an efficient new route for the degradation of toxic substances, decomposition of water and hydrogen generation [5, 6]. TiO2 nanoparticles show high reactivity and chemical stability under ultraviolet light, whose energy exceeds the band gap of 3.3 eV in the anatase crystalline phase TiO2, thus limiting the reactivity in visible range. Many studies were carried out to decrease its band gap with lower rate of recombination of the electron–hole pair. It can be achieved by proper doping of metal ions, surface modification and dye photosensitization of TiO2 surface [6, 7]. Several literatures have reported the tenability of TiO2 particles through doping with transition metals like chromium, manganese, iron, cobalt, nickel, copper, zinc, etc. For dye sensitized solar cell application, optimal light harvesting can be attained by doping the metal in titanium dioxide which results in altering the optical band gap. In order to increase the photocatalytic activity of TiO2 nanoparticles, various synthesis methods have been explored [8, 9]. Zn-doped TiO2 powders 40

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synthesized by sol–gel route showed the effect of doping on the crystalline phase, degree of crystallinity, particle size, distribution and morphology [10]. In addition, double-layer films doped with Zn-ions have also been reported with various morphologies and phase compositions which could enhance the cell efficiency of the dye-sensitized solar cell [11].

In this paper, we present the preparation of undoped and doped TiO2 nanoparticles via sol-gel route.

The prepared sample is studied for its structural and optical properties using different characterization techniques. The materials and experimental details are described in Section second and the obtained results are discussed in Section third. Finally, Section fourth concludes the paper.

Experimental Details. All the chemicals were analytical grade and used without purification.

Titanium tetraisopropoxide (TTIP) with a purity of 97% (Aldrich, UK) was used as a titanium precursor; analytical grade hydrochloric acid (HCl, Merck) was used as catalyst for the peptization.

Water–acid mixture (in the range of pH = 1–2) was stabilized at a constant temperature. TTIP was added to maintain the molar ratio of Ti:H2O=1:100. As a result, white precipitates were formed and further peptized for 2 hours to form a stable sol. For the preparation of Zn-doped TiO2 solution, zinc chloride (ZnCl2, Finar) was dissolved in the water-acid mixture with 0.03 mol %. The solution was then heated at 100 °C for 3 hours to obtain as-synthesized Zn-doped TiO2 powders. Subsequently, the as-synthesized powders were calcined at 450 °C for 2 hours to attain the crystallinity. The morphology and structure of the particles were studied using Scanning Electron Microscopy (SEMJSM-6360). The crystalline nature of the nanoparticles were characterized using X-ray Diffractometer (Shimadzu, 6000)) and the crystallite size was calculated using Scherrer’s formula. The absorption spectra of nanoparticles were measured using UV-VIS spectrophotometer (Schimadzu, UV-1800) and Fourier transform infrared spectroscopy (FTIR) measurements have been performed with (Shimadzu, 8400) in the mid infrared area, ranging from 450-4000 cm-1.

Results and Discussion. Fig. 1 shows the XRD pattern of Zn-doped TiO2 nanoparticles calcined at 450 °C. The diffraction peaks at 2Ɵ = 25.3°, 37.8°, 48.0°, 53.9° and 55.0° corresponds to the anatase phase of TiO2 (JCPDS No. 96-500-0224). A low intense diffraction peak at 2Ɵ = 30.7° is attributed to the brookite phase of TiO2. Anatase is the predominant phase in the prepared sample. X-ray diffraction peak at 25.3° corresponds to the characteristic peak of crystal plane (101) of anatase and peak at 27.4° corresponds to a crystal plane (121) of brookite. The calculated crystallite size from Scherrer’s formula is found to be around 8 nm.

Fig. 1. XRD pattern of as-synthesized Zn-doped TiO2 sample (A, anatase; B, brookite).

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Fig. 2 depicts the scanning electron microscopy image of Zn-doped TiO2 particles which shows the particle distribution of as-synthesized Zn-doped TiO2 nanoparticles. The nanopowder exhibited a homogeneous spherical morphology of the particles.

Fig. 2. Scanning Electron Microscopy image of as-synthesized Zn-doped TiO2 nanoparticles.

Optical absorbance spectra of undoped and Zn-doped TiO2 particles calcined at 450 °C were recorded and shown in Fig. 3. Absorption spectra shows the red shift of the light absorption edge of Zn-doped TiO2 nanoparticles as compared to pure TiO2 particles. The band gap energy can be estimated from the value of wavelength where the absorption edge starts to take off and the band gap energy of TiO2 nanoparticles were observed to be decreased from 3.17 to 2.93 eV with Zn-doping. The red shift has been attributed to the formation of impurity by the dopant within the band gap states of TiO2 [10].

Fig. 3. UV–vis absorbance spectra of undoped TiO2 and Zn-doped TiO2 calcined at 450 °C. Fig. 4 depicts the FTIR spectra of as calcined Zn-doped TiO2 nanoparticles. A broad peak appearing at 3100–3600 cm−1, precisely at 3325cm-1 is attributed to the stretching vibration of O–H hydroxyl groups representing physically adsorbed water as the moisture. The peak observed at 1632 cm -1 is attributed to the bending modes of adsorbed water. Another peak at 2973 cm-1 is assigned to the C-H MMSE Journal. Open Access www.mmse.xyz

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vibrations. This could be because of the organic residues remained in TiO 2 even after calcination.

The sharp peaks appearing at 1128, 1088 and 1046 cm-1 can be attributed to C-O vibration while peaks at 500 cm-1 to 900 cm-1 corresponds to O-Ti-O bands [12, 13].

Fig. 4. FTIR spectrum of as-synthesized Zn doped TiO2sample Summary. In this work, Zn-doped TiO2 nanoparticles were successfully synthesized by sol-gel method and studied for their structural and optical properties. XRD pattern showed anatase crystalline phase of Zn-doped TiO2 nanoparticles. A low intensity XRD peak has also been observed which is attributed to the brookite phase. Scanning electron microscopy study has confirmed the prepared particles of homogeneous spherical morphology. The absorption spectra of the as-synthesized nanoparticles showed strong absorption below 400 nm and a red shift was observed in Zn-doped TiO2 as compared to the undoped TiO2 nanoparticles.

Acknowledgment. Authors extend sincere thanks to University Grant Commission, New Delhi (INDIA) for the financial assistance to carry out this research work.

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Cite the paper V.G. Vasavi Dutt, R.S. Dubey (2017). Study of Structural and Optical Properties of Zinc-doped Titanium Dioxide Nanoparticles. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.79.67.635

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Temperature Induced Structural and Photoluminescence Properties of Poly Ethylene Glycol (PEG) Capped/Uncapped Cadmium Oxide Nanoparticles (CdO NPs)41 P. Lokanatha Reddy 1, S.K. Khadheer Pasha1, a 1 – Sensor Laboratory, Materials Physics Division, School of Advanced Sciences, VIT University, Vellore, Tamil Nadu, India a – khadheerbasha@gmail.com DOI 10.2412/mmse.31.67.343 provided by Seo4U.link

Keywords: cadmium oxide nanoparticles (CdO NPs), X-ray Diffraction (XRD), photoluminescence (PL).

ABSTRACT. Uncapped and PEG capped CdO NPs were successfully synthesized by precipitation technique. XRD and TEM studies were used to investigate the particles structure, size and shape. As synthesized samples showed major hexagonal Cadmium Hydroxide [Cd (OH)2] phase and were completely transformed into cubic CdO crystalline phase above 400 °C annealing temperature. A good crystallinity was noticed in PEG capped CdO NPs. TEM images brought out the information about the synthesized nanoparticles (NPs) existed spherical in shape. The weight loss from thermogravimetric analysis (TGA) graphs depicted the formation of CdO NPs from Cd (OH)2. PEG on CdO NPs evidently increased the direct band gap emission intensity around 480 nm and while indirect band gap emission intensity of around 620 nm was increased in uncapped CdO NPs. Beside this, PL spectra revealed interesting changes with the effect of PEG, annealing temperature and excitation wavelengths. Hence PL spectra ascertained their possible use for optical and electronic applications.

Introduction. CdO nanostructures have attracted considerable attention to various applications such as solar cells, photocatalytic and photodiodes due to its little electrical resistivity, high carrier concentration and high optical transmittance in the visible region [1]. CdO is an important n-type and II–VI semiconductor material with a direct band gap of 2.5eV and an indirect band gap of 1.98 eV [2, 3]. Due to dual band gap nature, CdO finds its potential applications in the field of optoelectronic devices [4]. Being convenient to synthesis NPs, the chemical precipitation method was selected due to low production cost, higher yield rate, low temperature maintenance and easy performance at any climate [5]. It is known that size of the NPs and crystalline structure can be restricted easily through the use of surfactants in the synthesis process of the system. Various surfactants (CTAB, PVP, PEG) can alter the shape, size and other surface properties to different extent depending upon their molecular structure of NPs. It is reasonable that short chain polymers can also promote the formation structure of nanosystems [6]. In the current study, PEG is found to be selectively promoting the formation of CdO NPs. From literature survey there is no report available on systematic investigation of structural and PL properties of PEG capped CdO NPs. Hence we were reporting the effect of PEG and annealing temperature on optimization of structural and photoluminescence properties of CdO NPs. Experimental Synthesis procedure. The cadmium acetate dihydrate [Cd (CH3COO)2·2H2O], sodium hydroxide (NaOH) and PEG were the starting materials obtained from Sigma-Aldrich and used as received without further purification. First, cadmium acetate dihydrate added in the 100 ml of DI water to form 41

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0.2 M of acetate aqueous solution under continuous stirring till getting clear solution. Then 2M NaOH solution was slowly added drop wise in order to fix pH = 9. After controlling the pH, using hot plate of the stirrer, the temperature of obtained the solution was raised and maintained at 60 °C under continuous stirring for 6 h. After the completion of reaction, the reaction mixture was allowed to cool at the room-temperature (RT) .White colored precipitate was obtained which was poured and washed with DI water for several times. The obtained material was dried at 60 °C temperatures in the hot air oven for 4 h and after drying, annealed at different ambient temperatures 100, 200, 300, 400 and 500 °C for 2h in the muffle furnace. The same procedure was applied for both PEG capped and uncapped CdO NPs. Result and Discussions. Structural and Morphological Studies. XRD measurements were performed and the spectra of as prepared and annealed uncapped/PEG capped samples were given in Fig. 1 (a) – (b).

Fig. 1. (a) – (b). XRD pattern of (a) uncapped and (b) PEG capped CdO NPs annealed at various temperatures.

Fig. 3. TEM images of (a) uncapped and (b) PEG capped CdO NPs annealed at 400 °C temperatures.

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As-prepared uncapped sample revealed the presence of many diffraction peaks. The major peaks at (0 0 1), (1 0 0), (0 1 1), (2 0 0), (0 1 2), (1 1 0), (1 1 1), (2 0 1), (2 0 2) revealed the Cd (OH)2 hexagonal crystalline phase [JCPDS No. 73-0969], along with minor amount of peaks Cd (OH)2 monoclinic phase. While PEG capped as prepared sample showed only Cd (OH)2 hexagonal crystalline phase [JCPDS No. 73-0969] due to PEG selective formation. Uncapped annealed sample at 200 °C temperature showed mixed phase of cubic CdO along with hexagonal and monoclinic Cd (OH)2 crystallinity [3, 5]. At 300 °C temperature it showed pure cubic CdO crystalline nature with minor peak of monoclinic Cd (OH)2 crystallinity and a perfect cubic CdO was observed at 400 °C with diffraction peaks (111), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes with JCPDS card No: 05-0640 [5].

PEG capped sample showed major cubic CdO and hexagonal along with minor phase of monoclinic Cd (OH)2 crystalline phase at 200°C and monoclinic Cd (OH)2 crystalline phase was diminished with annealing temperatures 300 °C, 400 °C and perfect cubic crystalline phase was observed above 400 °C without any impurity. The average crystallite size for PEG capped and uncapped samples at 400 °C are calculated to be 40 nm. TEM images depicted pseudo spherical shape of CdO NPs and were showing little agglomeration than PEG capped CdO NPs as shown in Fig.3. The average size of the particles was in the range of 30 nm - 40 nm.

Thermal studies. The thermal behavior of all samples and translation temperature of Cd (OH)2 to CdO NPs were carried out by TGA between RT and 800 °C with a heating rate of 10 °C/min.

Fig. 4. (a) - (f) TGA patterns of uncapped CdO and PEG capped CdO NPs showing weight loss in (%) at various annealing temperatures.

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Fig. 4 shows the TGA traces of PEG capped and uncapped CdO samples. The overall weight losses were estimated about 15%, 17% in uncapped and PEG capped samples as shown in Fig. 4 (a) - (b).

The total weight loss was 7% and 5% observed in 300 °C and 400 °C annealed samples as shown in Fig.4 (c) - (f). This weight loss was very little as compared with as prepared samples. Hence we may confirmed that Cd (OH)2 and CdO samples consists of only OH− ions and organic residues without any other impurities.

Photoluminescence studies. PL spectra were recorded at different temperatures with different excitation wavelengths (325 nm, 336 nm and 350 nm) as shown in Fig. 5. It was observed that the PL spectra consist of maximum emission intense peaks centered around 480 nm and 620 nm along with multiple subsidiary peaks in blue and red regions for both uncapped and PEG capped samples at annealing temperatures 300 °C, 400 °C and 500 °C. The subsidiary peaks below 480 nm may be attributed to the combination of the holes from the valence band (VB) and electrons from the conduction band (CB) and the major peak at 480 nm was attributed to the excitonic transition of CdO NPs [7] was size-dependent. Another broad intense emission peak at 620 nm was attributed to indirect near band edge emission from CdO or may be due to oxygen vacancies (VO), cadmium interstials (Cdi) exist in the CdO crystal lattice ascribed to the heat treatments or oxidation associated with the process which helps form the recombination centers [8]. The surfactant, PEG quenches the electron - hole recombination in PEG capped samples and controlled the formation of defects by enhancing the crystallinity. This decrease in intensity with PEG indicates the decrease in the proportion of electron-hole recombination, which favored the photocatalytic activity for degradation of pollutants.

Hence it was concluded that emission intensity and direct & indirect band nature were controlled by surfactant PEG and annealing temperature for better applications in photocatalytic activity and other optoelectronic devices.

Fig. 5. (a) – (f). Photoluminescence Spectra of uncapped and PEG capped CdO NPs at different excitation wavelengths and annealing temperatures.

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Summary. Uncapped and PEG capped CdO NPs were successfully synthesized by chemical precipitation method. XRD spectra depicted the formations of cubic crystalline phase of CdO NPs from hexagonal crystalline phase Cd (OH)2 nanoparticles after systematic annealing temperature above 400 °C. The observed weight loss from TGA graphs at different annealing temperatures revealed the systematic transformation Cd (OH)2 phase to CdO NPs. It was noticed that the PL emission intensity was influenced by capping agent as well as annealing temperature. Direct band PL emissions of CdO NPs were enhanced in capped PEG and while indirect band gap emission was dominated in uncapped CdO NPs. References [1] R.K. Gupta, K. Ghosh, R. Patel, S.R. Mishra, P.K. Kahol, Highly conducting and transparent tindoped CdO thin films for optoelectronic applications, Mater. Lett., 62, 2008, 4103-4105, DOI:10.1016/j.matlet.2008.06.008.

[2] Y.C. Chang, Cadmium hydroxide and oxide nanoporous walls with high performance photocatalytic properties, J. Alloys Compd., 637, 2015, 112-118, DOI:10.1016/j.jallcom.2015.02.214.

[3] T. Prakash, G. Neri, E. Ranjith Kumar, A comparative study of the synthesis of CdO nanoplatelets by an albumen-assisted isothermal evaporation method, J. Alloys Compd., 624, 2015, 258-265, DOI:10.1016/j.jallcom.2014.10.204.

[4] G.R. Khayati, H. Dalvand, E. Darezereshki, A. Irannejad, A facile method to synthesis of CdO Nanoparticles from spent Ni–Cd batteries, Mater. Lett., 115, 2014, 272-274, DOI:10.1016/j.matlet.2013.10.078.

[5] N. Shanmugam, B. Saravanan, R. Reagan, N. Kannadasan, K. Sathishkumar, S. Cholan, Effect of Thermal Annealing on the Cd (OH)2 and Preparation of CdO Nanocrystals, Modern Chemistry & Applications, 2 (1), 2014, 1000124 (1-5), DOI:10.4172/2329-6798.1000124.

[6] Z. Li, Y. Xiong, Y. Xie, Inorg. Chem., Selected-control synthesis of ZnO nanowires and nanorodsvia a PEG-assisted route, Inorg. Chem., 42 (24), 2003, 8105-8109, DOI: 10.1021/ic034029q.

[7] N.C.S. Selvam, R.T. Kumar, K. Yogeenth, L.J. Kennedy, G. Sekaran, J.J. Vijaya, Simple and rapid synthesis of Cadmium Oxide (CdO) nanospheres by a microwave-assisted combustion method, Powder Technol., 211, 2011, 250-255, DOI:10.1016/j.powtec.2011.04.031.

[8] S.H. Mohamed, N.M.A. Hadia, A.K. Diab, A.M. Abdel Hakeem, Synthesis, photoluminescence and optical constants evaluations of ultralong CdO nanowires prepared by vapor transport method, J. Alloys Compd., 609, 2014, 68-72, DOI:10.1016/j.jallcom.2014.04.065.

Cite the paper P. Lokanatha Reddy, S.K. Khadheer Pasha (2017). Temperature Induced Structural and Photoluminescence Properties of Poly Ethylene Glycol (PEG) Capped/Uncapped Cadmium Oxide Nanoparticles (CdO NPs). Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.31.67.343

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Optical Analysis of Ho3+ Ions Doped BaGd2Ti4O12 Ceramics42 B. Munisudhakar1, C. Nageswara Raju2, P. Sreenivasulu Reddy3, S. Hemasundara Raju3, a 1 – Department of H&S, SV College of Engineering, Tirupati, India 3 – Department of Physics, Sri Venkateswara Degree College, Kadapa, India 2 – Department of H&S, SV College of Engineering, Kadapa, India a – hemaredi_raju2010@yahoo.com DOI 10.2412/mmse.84.39.432 provided by Seo4U.link

Keywords: XRD, SEM, emission, excitation.

ABSTRACT. Ho3+ (5 mol %) ions doped Barium Gadolinium Titanate (BaGd2Ti4O12) powder ceramics were synthesized by solid state reaction method. From the X-ray diffraction profiles it is observed that the prepared ceramics were crystallized in the form of orthorhombic structure. Agglomeration and the nanometer particle size were observed from the SEM images of the ceramics. The emission spectrum Ho 3+: BaGd2Ti4O12 powder ceramics has shown blue emission at 467 nm (5F3 → 5I8) with an excitation wavelength 208 nm.

Introduction. One of the most important electro ceramics is barium titanate. Barium titanate is a good dielectric material with a high dielectric constant and it is a ferroelectric, piezoelectric and pyroelectric with good nonlinear optical properties. Barium titanate compound is an electrical insulator because of its energy and it has been used for a wide range of scientific and industrial applications such as capacitors, ultrasonic transducers, piezoelectric sensors, Barium titanate ceramics applications in various fields such as optical limiting, switches, flat panel displays, modulated-type optical devices and second harmonic generation. Rare-earth ions doped titanate based phosphors have attracted significant importance for potential applications in white-light emitting diodes [1]. Gadolinium compounds doped with rare earth ions are used as the red phosphors for the preparation of WLEDs and gadolinium containing host lattices are also used for making green phosphors for colour TV tubes. From the literature, it is observed that many authors have been reported on PL analysis of titanate based systems such as gadolinium titanate, zirconium titanate, compounds can find potential applications in optoelectronic devices [2]. Rare earth ions doped ceramic hosts have a wide range of applications in the fields of lamp phosphors, solid state lighting in display devices, white light generation [3]. So for no reports have been made on the photoluminescence property of thulium doped barium gadolinium titanate (BaGd2Ti4O12) ceramics.

In this paper, we report on the synthesis,XRD, SEM and PL analysis of Ho3+ ions doped BaGd2Ti4O12 ceramics for novel applications.

Experimental studies. BaGd2-xTi4O12: REx3+ (RE = Ho and x = 5 mol %) ceramics were prepared by solid state reaction method. The starting chemicals used for the preparation of these ceramics were purchased from the Sigma Aldrich with 99.9 % purity and the chemicals purchased were used as received without any further purification. The starting materials such as BaCO3, Gd2O3, TiO2 and Ho2O3 were taken in an appropriate stoichiometric ratio. Then, these powders were grounded thoroughly in an agate mortar and the mixtures were put into alumina crucibles. They were heated in

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an electric furnace at a temperature 10000C for 2h. The final samples were white powders and then used for the characterization.

Structural characterization of these samples has been carried out from the X ray powder diffraction measurements on a XRD 3003 TT Seifert diffractometer with CuKα radiation (λ=1.5406A0 ) at 40 kV and 20 mA and the 2θ range was varied between 100 and 800. Morphology of the ceramic powder was examined on a ZEISS-EVO-MA15 ESEM. The scanning electron microscopy (SEM) image was obtained for samples by using a 35mm camera attached to a high resolution recording system. Both the excitation and emission spectra were obtained on a SPEX Fluorolog-2 Fluorimeter (Model II) with data max software to acquire the data with a Xe-arc lamp (150 W) as the excitation source.

Results and Discussion XRD analysis. Fig.1. shows the XRD profile of 5 mol% of Ho3+: BaGd2Ti4O12 ceramics, from the XRD profiles, it is observed that these powder ceramics are having the orthorhombic structure (using the software namely JCPDS No: 43-0233) having diffraction peaks which are consistent. The rare earth ions Ho3+: doped BaGd2Ti4O12 ceramic does not influence the crystal structure.

Fig. 1. XRD profile of 5 mol% of Ho3+: BaGd2Ti4O12 ceramics.

SEM analysis. Fig. 2 shows SEM micrograph of the 5 mol% of Ho3+: BaGd2Ti4O12 ceramic powder, from this image shows that the particles are agglomerated with various shapes and sizes and the average grain size is around at ~200 nm.

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Fig. 2. SEM image of Ho3+: BaGd2Ti4O12 ceramics.

Fig. 3. Excitation spectrum of 5 mol% of Ho3+: BaGd2Ti4O12 ceramics.

Ho3+: BaGd2Ti4O12 ceramics. Fig.3 shows the excitation spectrum of 5 mol % Ho3+: BaGd2Ti4O12 powder ceramics, from this spectrum the excitation wavelengths at 208 nm and 249 nm corresponding to the transitions 5I8→ 3F3, 5I8→ 3D3 respectively. Among these transitions the transition at 5I8→ 3F3 is most intense transition compared to other one and has been selected for the measurement of emission spectrum of Ho3+: Ba3Y2WO9 powder ceramics. The emission spectrum of 5 mol % Ho3+: BaGd2Ti4O12 powder ceramics is shown in Fig.4. From the emission spectrum, the wavelengths at 467 nm, 560 nm, 606 nm and 628 nm corresponding to the transitions 5F3→ 5I8, 5S2+ 5F4→ 5I8, 5F5→ 5 I8 and 5F5→ 5I8 respectively. Among these the transition 5F3→ 5I8 is most intense compared to others and is the characteristic of blue emission. From the emission spectra Ho3+: BaGd2Ti4O12 powder ceramics shows tricolor emissions at blue (465 nm), green (558 nm) and red (609 nm). Assignments to these bands have been made by the previously published articles [24]. Among these transitions the transition at 5S2→ 5I8 is more efficient for laser action.

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Fig. 4. Emission spectrum of 5 mol% of Ho3+: BaGd2Ti4O12 ceramics.

Summary. It is concluded that, 5 mol % of Ho3+: BaGd2Ti4O12 powder ceramics have been synthesized by using a solid state reaction method. The XRD profile indicates the tetragonal phase structure of the prepared ceramics. The emission spectrum of Ho3+: BaGd2Ti4O12 powder ceramics have shown an intense blue emission at 467 nm with the excitation wavelength λexci = 208 nm. These powder ceramics may be used as novel luminescent materials in various optical systems.

References [1] Parveen Kumar, Sangeeta Singh, Manjula Spah, J.K. Juneja, Chandra Prakash and K.K.Raina Synthesis and dielectric properties of substituted barium titanate Ceramics. J. Alloy. Compd. 489, 5963 (2010).

[2] Sheela Devi and A.K. Jha Structural, Dielectric and Ferroelectric properties of Tungsten substituted Barium Titanate ceramics. Asian J. Chem. 21, S117- 124 (2009).

[3] K.V.Syamala, G. Panneerselvam, G.G.S. Subramanian and M.P. Antony Synthesis, characterization and thermal expansion studies on europium titanate (Eu2TiO5). Thermochim Acta 475, 76-79 (2008).

[4] V. Lojpur, M. Nikolic, L. Mencic, O. Milosevic, M.D. Dramicanin Y2O3: Yb, Tm and Y2O3:Yb, Ho powders for low-temperature thermometry based on up-conversion fluorescence. Ceramics international 39-2, 1129-1134 (2013).

[5] C. Joshi, Y. Dwivedi and S.B. Rai Structural and optical properties of Ho2TeO6 micro-crystals embedded in tellurite matrix. Ceramics international 37 (2011) 2603-2608.

[6] Zhao Junfeng, Chen Xi, Rong Chunying, Yu Liping, Lian Shixun “A tunable yellow emission from three-band emission of singly doped single-phased phosphor BaY2S4:Ho3+”. J. Rare earths 29 (2011) 436.

Cite the paper B. Munisudhakar, C. Nageswara Raju, P. Sreenivasulu Reddy, S. Hemasundara Raju (2017). Optical Analysis of Ho3+ Ions Doped BaGd2Ti4O12 Ceramics. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.84.39.432

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Green Synthesis and Characterization of Sodium Banana Peel Xanthate Carbon Dot (SBPX C-Dot) and Preparation and Utility of Carbon Composite Paste Electrode for Selective Potentiometric Sensing of Hg (II) Ions43 M. Muthukumaran1, K .Samuel Barnabas1, S. Niranjani1, K. Venkatachalam1, T. Raju1,a 1 – Department of Analytical Chemistry, University of Madras, Guindy Campus, Chennai, India a – proftraju2004@yahoo.com DOI 10.2412/mmse.23.43.244 provided by Seo4U.link

Keywords: sodium banana peel xanthate C-Dot (SBPX C-Dot), carbon composite past electrode (CCPE), potentiometric sensor.

ABSTRACT. A green approach has been used for the synthesis of fluorescent sodium banana peel xanthate Carbon Dot (SBPX C-dot) with the use of yellow banana peels as carbon source. The Carbon Dot were synthesized by hydrothermal treatments. pigments and other low molecular weight hydrocarbons, most of the above materials on reaction with carbon disulphide Banana peel is mostly composed of cellulose (8.4 nmol L-1), pectin (10-21%), hemicellulose (6.4-9.4 %), lignin (6-12%). Banana peel was first treated with 10% NaOH for a day to hydrolyze or digest or disentigrate into the low molecular weight and bigger molecular weight compounds, with a lot of hydroxyl functional groups, which make the Banana peel a potential substrate for the synthesis of Banana Peel Xanthate C-Dot (SBPX C-Dot). The Banana Peel Xanthate C-Dot (SBPX C-Dot) are analyzed and identified by FT-IR, Raman Spectroscopy and UV-Visible spectroscopy.

Effect of pH on UV-Visible and Fluorescence Spectroscopy were carried out in the pH range (pH=1-10). Field Emission Scanning Electron Microscopy was used to study the surface morphology. The utility of (SBPX C-Dot) with Carbon Paste to form a Composite Electrode (CCPE) for potentiometric sensing of Hg (II) ion was accomplished in aqueous acetate and chloride medium at different pHs (pH=1-10) . Reasonable and selective sensing was observed with CCPE for Hg (II) ion is observed.

Introduction. Xanthates are one of the important organosulphur compounds used in mining and rubber industry. They are the derivative of xanthic acid. They are also known as xanthogenates, carbon dithioates and salts of xanthic (dithiocarbonic) acids, These organosulfur compounds are important in two areas, the production of cellophane and related polymers from cellulose and secondly in mining for the extraction of certain ores. Different xanthates have different strengths. The interaction of typical collector xanthate with pyrite, the most abundant sulfide minerals is electrochemical in nature [1]. The strength of xanthate as a collector is based on the alcohol chain attached to the xanthate molecule with ethyl being the weakest and amyl being the strongest. They are also versatile intermediates in organic synthesis. They also have wide ranging properties such as optical, electrical and magnetic characteristics. Their thin films show different properties such as an antibacterial agent, magnetic and semiconductor material, which allowed them to be used for data storage, solar cell production and water purification [2]. The xanthates are widely used as chelating reagents in analytical chemistry. Although many analytical methods such as titrimetric, polarography and photometry are available for the determination of xanthate, the hydroxyl group was chemically modified by introducing sulfur groups with the carbon disulfide treatment in alkaline medium. The carbon disulphide is a type of compound called hetero-allene, which by its symmetric nature and possession of more bonding character, is a good complexing agent [3].

EXPERIMENTAL METHOD 43

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Preparation of Sodium Banana Peel Xanthate. The banana peel collected from the market was cut into small pieces stoichometric amount and was treated (10% NaOH) solution to hydrolyze banana peel was used as a base for further reaction as such to prepare banana peel xanthate carbon disulfide (0.76 g) was slowly drop by drop added to the above cooled solution. The reaction mixture was stirred for 12 hrs and was used as such for further work.

Synthesis of Sodium Banana Peel Xanthate C-Dot. The sodium banana peel xanthate [4] obtained above was transferred to an autoclave and kept in a muffle furnace at 180oC [hydrothermal condition] for 12 hrs to prepare banana peel xanthate carbon dot and the resultant banana peel xanthate carbon dot was collected and stored in an airtight container. The sodium banana peel xanthate C-dot as prepared was found to be aqueous soluble and fluorescent nature.

Preparation of Composite Carbon Paste Electrode (CCPE). The composite carbon paste electrodes was prepared by mixing the xanthate C-Dot as electro active material with a binder (paraffin wax) and the blend was mixed until a homogenous paste besides graphite powder [5]. The electrode was prepared as a paste in the ratio of xanthate C-Dot: paraffin wax and graphite (5:1:1w:w:w). The composite paste was heated in a water bath and the composite was then packed in a disposable glass tube (3 mm i.d, ) and a mild pressure was applied and then the electrode was removed from the tube by manual means. Electrical contact to the composite carbon paste electrode was made with a crocodile clip copper wire. The electrode surface was polished every time for a fresh surface using an emery paper of 600 grit.

RESULT AND DISCUTION

a)

b)

Fig. 1. FT-IR & Raman Spectroscopy of Sodium banana peel xanthate C-Dot. The FT-IR spectrum for the Sodium Banana Peel Xanthate C-Dot was shown in the Fig. 1, a which indicates the appearance of the various absorption bands and the peaks at 3441 cm-1 was very broad and strong and can be assigned to the Stretching vibration of hydroxyl (-OH) group either from water or from adsorbed moisture or both. A prominent and very sharp peak observed at 1625 cm-1 which was concluded to be due to the Stretching vibrations of C-O-C group, the other bands to 1409 and 1012 cm -1 allotted respectively to the Stretching vibrations of connections C-O-C-S and (C=S). The peak at 677 cm-1is due to the Stretching vibration of C-S the infra red spectrum. Hence these FT-IR peak confirmed the presence of Sodium Banana Peel Xanthate C-Dot peaks.

The Raman spectra of Sodium Banana Peel Xanthate C-Dot are shown in the Fig. 1, b. It was assigned that the bands by analogy to the data as follows: 977 cm-1 for Stretching vibration of V (C=S), 1057 cm-1 for Stretching vibration of Vs (COC single bond), 1316 cm-1 for Stretching vibration of Vas MMSE Journal. Open Access www.mmse.xyz

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(SCS single bond ) and 1559 cm-1for Wagging vibration of (CH3), and 2714 cm-1for Stretching vibration of (CH2). The functional group conformation of Raman spectrum of the bands which leads to the assumption that the Sodium Banana Peel Xanthate C-Dot is the main / major products present in the Sodium Banana Peel Xanthate C-Dots.

a)

b)

Fig. 2. UV-Vis & PL Spectroscopy of Sodium banana peel xanthate C-Dot. The Ultra Violet-Visible (UV-Vis) spectroscopy of sodium banana peel xanthate C-Dot in Effect of pH solutions (pH=1-10) shows the Fig. 2, a absorption peak increases and decreases in effect of pH solutions. Shows the absorption peak at 226 nm. This shows the presence of π -π• transition. This transition occurs from the C=S bond, this bond is a part of the xanthate. The Ultra Violet-Visible (UV-Vis) spectroscopy of sodium banana peel xanthate C-Dots is concentration 10mg/10ml (pH=110) shows peak in ultraviolet region in aqua’s solvents used in soluble of sodium banana peel xanthate C-Dot. The photoluminescence spectroscopy of sodium banana peel xanthate C-Dotin solution, are strongly affected by changes in pH Shows the Fig. 5 with the spectra recorded at low pH being weaker than those at high pH. Effect of pH solutions (pH=1-10) shows the intensity peak increases and decreases in effect of pH solutionsn intensity peak at 447 nm. This shows the presence of π -π• transition.

Inwhich transition occurs from the C=S bond, The photoluminescence spectroscopy of sodium banana peel xanthate C-Dot is the concentration 10mg/10ml (pH=1-10) in aqua’s solvents used in soluble of sodium banana peel xanthate C-Dot.

Fig. 5. FESEM & EDX micrascopy image of Sodium banana peel xanthate C-Dots MMSE Journal. Open Access www.mmse.xyz

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Fig. 6. FESEM & EDX micrascopy image of Sodium banana peel xanthate C-Dots.

The surface morphology and size of the sodium banana peel xanthate C-Dot shows the Fig. 5 were observed by the Field Emission Scanning Electron Microscopy (FESEM) analysis. The sodium banana peel xanthate C-Dot naturally presents in the surfactant in the banana peel. FESEM morphology of the image of sodium banana peel xanthate C-Dot which is clear spherical in shape.

The partial size of sodium banana peel xanthate C-Dot is 135 nm. shows the Fig. 6 EDX was also performed on the sodium banana peel xanthate C-Dot. the elements for C, O, S and Na were observed.

Fig. 7. Potentiometric Sensing of Sodium banana peel xanthate C-Dot in different metal ions solutions.

The sensitivity of a potentiometric CCPE depends on the carbon composite paste electrode. The influence of C-Dot in the composite carbon paste was studied. The working electrode is (CCPE) and reference electrode (SCE) were dipped in 10 ml of electrolyte solution (0.0001 M KCl) added and 5ml of DD water taken into beaker.

The metal ion influence on the potentiometric responses were tested with for different metal ions at different pHs. The potentiometric behavior was noted and individual behavior was noted in a graph.

Out of the metal ions tested (Cu2+, Cd2+, Hg2+, Zn2+, Pb2+) Hg2+ show a very promising results and was shown in the Fig. 7 The Fig. exhibits good response and linearity. This sensor revealed a great enhancement in selectivity for mercury ions in comparison with the previously reported mercury sensors [6]. The developed electrode exhibits higher selectivity for mercury ions compared with other metal ions it was successfully used as an indicator electrode (CCPE) in potentiometric sensor of Hg2+ against. It is obvious that the slope (R2= 0.9948) of the linear part is near to the expected according to the Nernst equation. However, the electrode does not exhibit Nernstian responses for other cations and even the potential responses have no significant change with the increase of the concentration of MMSE Journal. Open Access www.mmse.xyz

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Hg2+ (0.0001 M) sodium banana peel xanthate C-Dot was selected as the carrier for the construction of the mercury ion selective electrode. It is well known that selectivity, sensitivity and linear range of the ion selective electrode are influenced strongly by the carrier composite electrode. Thus, it is indispensable to investigate the influence of carrier amounts on the potential responses of the developed CCPE. The experiment was repeated for concordant potential values.

The potentiometric Sensing of SBPX C-Dot with mercury chloride & mercury acetate solution carried out electrochemical reaction by taking the 10 ml of buffer solution added and 5 ml of DD water taken into beaker. Then indicator electrodes (CCPE) and reference electrode (calomel electrode) are immersed in that beaker solution. Electrodes are connected to potentiometer and sensing against 0.0001M of mercury Chloride (HgCl2) & 0.0001M of mercury acetate (Hg (CH3COO)2) solution in the pH range 1.0-10. Electrode (Fig. 8 (a, b) the effect of pH on the response of the electrode was respectively investigated in the two Hg2+ solutions (namely HgCl2 and Hg (CH3COO)2 solutions and different pHs. As shown in the Fig. 8 (a) (HgCl2), the potential does not change apparently at pH range 1.0, 3.0, 4.0, 6.0 and 10, which can be used as the working pH range of the proposed electrode.

PH 8.0 and 9.0 is potential slightly change. In addition, pH 2.0, 5.0 and 7.0 is potential is good compare with other PH solutions. The show in the Fig. 8 (b) (Hg (CH3COO)2) shows that the potential does not change apparently at pH range 1.0, 2.0, 4.0 and 9.0 which can be used as the working pH range of the proposed electrode. PH 3.0, 5.0 and 10 is potential slightly change. Moreover, pH 6.0, 7.0 and 8.0 is potential is good compare with other PH solutions.While, outside this range, the potential changed significantly. The potential was increases and decreases in effect of pH solutions.

SBPX C-Dot potential noted.

a)

b)

Fig. 8. Potentiometric Sensing of Sodium Banana Peel Xanthate C-Dot at Effect of pH (pH=1-10) solutions (a). HgCl2, (b).Hg(CH3COO)2 Summary. Sodium banana peel xanthate C-Dot (SBPX C-Dot) were synthesized using hydrothermal method and characterize by UV-Visible and Raman, FT-IR studies. The Sodium banana peels xanthate C-Dot as florescent nature and study with photo luminance spectroscopy (PL). The C-Dot materials newly prepared by Composite Carbon paste electrode. Using the potentiometric metal ion sensing were d10 and d9 metals to know their behavior in presence of buffer. The xanthate C-Dot e.m.f of the cell is the difference in the potentials (voltages) of cathode and anode contact with suitable electrolytes at the electrode. The potential depend on the concentration of the electrolyte and chemical of the electrode. different metal ions added in the (Cd2+, Cu2+, Zn2+, Pb2+) is not behavior and only metal of (Hg2+) is very good sensing the CCPE can be employed with successful results for the potentiometric sensors.

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References [1] A.N. Buckley, R. Woods, Chemisorption the thermodynamically favoured process in the interaction of thiol collectors with sulphide minerals, International Journal of Mineral Processing, 1977. DOI: 10.1016/S0301-7516 (97)00016-1 [2] H. J. Gao, Z. X. Bian, H. Y. Chen, Z. Q. Xue and S. J. Pang, A new type of organometallic system for high density data storage by scanning tunneling microscopy, Chemical Physics Letters, 1997. DOI: 10.1016/S0009-2614 (97)00513-7 [3] N. Zohir, B. Mustapha, D.A. Elbaki, Synthesis and Structural Characterization of Xanthate (KEX) in Sight of Their Utilization in the Processes of Sulphides Flotation, Journal of Minerals & Materials Characterization & Engineering, 2009. DOI: 10.4236/jmmce.2009.86041 [4] B. Dea, N. Karak, A green and facile approach for the synthesis of water-soluble fluorescent carbon dot from banana juice, RSC Advances, 2013. DOI: 10.1039/C3RA00088E [5] C. Apetrei, I.M. Apetrei, J.A.D. Saja, M.L.R. Mendez, Carbon Paste Electrodes Made from Different Carbonaceous Materials: Application in the Study of Antioxidants, Sensors, 2011. DOI: 10.3390/s110201328 [6] A.A. Ismaiel, M.K. Aroua, R.Yusoff, Potentiometric Determination of Trace Amounts of Mercury (II) in Water Sample Using a New Modified Palm Shell Activated Carbon Paste Electrode Based on Kryptofix 5, American Journal of Analytical Chemistry, 2012. DOI: 10.4236/ajac.2012.312113

Cite the paper M. Muthukumaran, K .Samuel Barnabas, S. Niranjani, K. Venkatachalam, T. Raju (2017). Green Synthesis and Characterization of Sodium Banana Peel Xanthate Carbon Dot (SBPX C-Dot) and Preparation and Utility of Carbon Composite Paste Electrode for Selective Potentiometric Sensing of Hg (II) Ions. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.84.39.432

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Pulsed Electrodeposited Nickel – Cerium for Hydrogen Production Studies44 T. Sivaranjani1, T.A. Revathy1, K. Dhanapal1, V. Narayanan2, A. Stephen1,a 1 –Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai, India 2 – Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai, India a – stephen_arum@hotmail.com DOI 10.2412/mmse.20.74.142 provided by Seo4U.link

Keywords: pulsed electrodeposition, catalysts, rare earth metals.

ABSTRACT. The approach of alloying different elements results in new alloy phase with exclusive properties that could be a potential candidate in various applications. In the present work an attempt has been made to electrodeposit NickelCerium (Ni-Ce) alloy. Nickel is an intriguing metal with much availability in earth’s crust. The catalytic power of Nickel based alloys towards hydrogen evolution reaction has been already reported for Nickel-Metal alloys, NiO/Ni and NickelRare Earth metals [1, 2]. Furthermore, alloying of Nickel with rare earth materials induces significant properties. Amongst rare earth elements, Cerium is a unique lanthanide element which has attracted more attention owing to its different electronic structures such as Ce3+ and Ce4+ which could result in different optical and catalytic properties. Ni-Ce coatings were electrodeposited on stainless steel substrate by pulsed electrodeposition technique [3] form acidic aqueous bath of Nickel acetate and Cerium acetate. Boric acid is used as an additive for smoother deposition of the sample. The deposition was found to be favoured at applied current density of 10 mA/cm2. X-Ray diffraction, High Resolution scanning Electron Microscopy and Energy dispersive spectroscopy were used to characterize the prepared sample.

Introduction. Hydrogen Evolution Reaction (HER) is of great importance since hydrogen is one amongst eco-friendly sources of energy with large energy density which makes it a potential candidate in energy storage and as an energy carrier. The splitting of water, hydrogen production from acidic/alkaline solutions are the popular methods of HER. The most efficient way of producing hydrogen with least amount of energy is to scale down the cathodic over potential in the electrolysis process. Accordingly a suitable choice of electrode material is necessary. Noble metals such as platinum and its alloys are developed and exhibit good activities indeed. However, high costs of these materials are often very prohibitive. Ni-based catalysts show improved properties [1, 2] as electrodes and catalysts for HER. Rare earth elements are major alloying elements and the inclusion of rare earth elements gives higher functional properties to the material. An attempt has been made to alloy cerium with nickel through pulsed electrodeposition and characterized. The electrochemical activity of the Nickel-Cerium (Ni-Ce) are investigated through cyclic voltammetry.

Experimental Procedure The Nickel-Cerium film is electrodeposited by employing galvanostatic pulsed electrodepostion technique on Stainless steel (cathode) substrate of grade 316L while graphite sheet serves as the anode. The electrodes were kept stationary with a distance of 2 cm between them. 0.1 M of Boric acid added as an additive which helps for smooth deposition of sample on the substrate. The electrolytic bath consists of Nickel acetate tetrahydrate and Cerium (III) acetate hydrate in the ratio of 4:1. The cathodic deposition is made on an area of 10 cm2 in the stainless steel with a applied current density of 10 mA/cm2. The pH of the bath is maintained ~2. The duration of deposition is 40

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minutes with 40% Duty cycle at room temperature. After deposition, the deposits were rinsed 4 to 5 times with de-ionized water and dried.

Results and discussion Structural studies

Fig. 1. XRD pattern of as-deposited Ni-Ce, Pure Ni, stainless steel substrate.

The structural analysis of the as-deposited Ni-Ce is characterized usingXRD. From the XRD pattern (Fig.1), there is no distinct peaks for Ni-Ce appears in the pattern but there is a shift in the peaks towards higher angle on comparison with pure Ni peaks (JCPDS no. 01-089-7128). There is no intermetallic phase formed between Ni and Ce. However there is a possibility of formation of Ni-Ce solid solution.

Morphological Studies

Fig. 2. HRSEM images of Ni-Ce. The surface morphology of the Ni-Ce film is characterized through HR-SEM. The SEM image reveals smooth depostion of irregular shaped grains. The size of the grains are calculated using ImageJ MMSE Journal. Open Access www.mmse.xyz

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software which ranges from 90 nm to 400 nm. The thickness of the film is calculated from the cross section view and estimated to be approximately one micrometre.

Compositional analysis and Elemental mapping

Fig. 3. EDX Image of Ni-Ce. Fig. 3 denotes the EDX spectrum of the Ni-Ce which evidences the presence of Ni and Ce in the film.

The standard electrode potentials of Ni (-2.5 V) and Ce (-2.3 V) are nearly close and this favours the deposition of Nickel and Cerium simultaneously. Elemental mapping of Ni-Ce film (Fig.4) further confirms the presence of cerium in the sample. The red spots represent the presence of nickel and the green dots represents the occurrence of cerium in the sample. Absence of any other peaks in the spectrum shows the purity of the sample.

Fig. 4. Elemental mapping of Ni-Ce. Electrochemical studies The cyclic voltammetry (Fig. 5 (a)) and linear sweep voltammetry (Fig.5 (b)) curves are recorded using three electrode electrochemical cell setup at room temperature. Ni-Ce deposited on the stainless steel substrate was taken as the working electrode and platinum is taken as the counter electrode while saturated calomel electrode serves as the reference electrode. The performance of Ni-Ce towards HER was tested in 0.5 M KOH alkaline solution at a scan rate of 50 mV/s.

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(a)

(b)

Fig. 5. Cyclic voltammetry (a) and Linear sweep voltammetry (b) of Ni-Ce. From the LSV the tafel plot of Potential Vs log i is drawn (Fig.6) over the kinetically controlled region. The tafel slope is evaluated to be 304 mV/decade. The tafel slope values for the rate determining step of HER are 120 mV/dec, 40 mV/dec and 30 mV/dec for Volmer, Heyrovsky and Tafel steps respectively. The obtained tafel slope of 304 mV/dec suggests that hydrogen evolution on Ni-Ce electrode probably occurs by tafel mechanism[5].

Fig. 6. Tafel plot of Ni-Ce. Summary. Nickel-Cerium coating on stainless steel substrate is successfully deposited using pulsed electrodeposition method. The prepared film is characterized throughXRD, HRSEM, EDX and Cyclic Voltammetry. The XRD peaks show the formation of Ni peaks. The HRSEM depicts the formation of irregularly shaped grains. The EDX and elemental mapping analyses confirmed the presence of nickel and cerium in the sample. From the electrochemical studies, the tafel slope is calculated and suitable mechanism for hydrogen evolution with Ni-Ce as working electrode is proposed.

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References [1] D. M. F. Santos, L. Amaral, B. Sljuki, D. Maccio, A. Saccone and C. A. C. Sequeiraa, Journal of The Electrochemical Society, 161 (4), 2014, F386-F390 [DOI: 10.1149/2.016404jes] [2] Chun Tang, Lisi Xie, Xuping Sun, Abdullah M Asiri and Yuquan He, Nanotechnology, 27, 2016, 20LT02 (7pp), [DOI: 10.1088/0957-4484/27/20/20LT02] [3] K. Dhanapal, V. Narayanan, A. Stephen, Materials Chemistry and Physics, 166, 2015, 153-159 [DOI: 10.1016/j.matchemphys.2015.09.039] [4] Philipp J. Rheinlander, Juan Herranz, Julien Durst, Hubert A. Gasteiger, Journal of The Electrochemical Society, 161 (14), 2014, F1448-F1457, [DOI: 10.1149/2.0501414jes] [5] A.Stephen, D.Kalpana, M.V. Ananth, V.Ravichandran, International Journal of Hydrogen Energy, 24, 1999, 1059-1066, [DOI: 10.1016/S0360-3199 (98)00139-6]

Cite the paper T. Sivaranjani, T.A. Revathy, K. Dhanapal, V. Narayanan, A. Stephen (2017). Pulsed Electrodeposited Nickel â&#x20AC;&#x201C; Cerium for Hydrogen Production Studies. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.20.74.142

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Electrochemical Detection of Dopamine at Poly (o-anisidine)/Silver Nanocomposite Modified Glassy Carbon Electrode45 D. Sangamithirai1, V. Narayanan2, A. Stephen1,a 1 – Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai, India 2 – Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai, India a – stephen_arum@hotmail.com DOI 10.2412/mmse.91.86.223 provided by Seo4U.link

Keywords: poly (o-anisidine), silver nanoparticles, electrochemical sensor, dopamine.

ABSTRACT. Poly (o-anisidine) and silver nanoparticles based nanocomposite (POA-AgNPs) modified electrode was used for the electrocatalytic detection of dopamine (DA). POA-AgNPs nanocomposite was synthesized via simple and cost-effective chemical oxidative polymerization method. The composite was characterized by x-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The face centred cubic structure of silver and the semicrystalline nature of poly (o-anisidine) is evident from XRD studies. The formation of polymer matrix-type nanocomposite with the embeddment of silver nanoparticles is determined from HRTEM. The synthesized POA-AgNPs nanocomposite was found to exhibit electrocatalytic activity towards the detection of DA at a potential of +0.45 V. Under the optimal conditions, the modified electrode showed enhanced catalytic current and a linear response was observed in the concentration range of 10.0-140.0 µM with a detection limit of 0.2 µM (S/N=3).The results revealed the potential application of the fabricated sensor for other such biomolecules.

Introduction. The arrival of conjugated materials with π-conjugated backbones is a landmark in analytical science and they have been widely used as signal-enhancing elements in electroanalytical applications [1]. Conducting polymers consist of a troop of compounds (such as polyaniline, polypyrrole, polythiophene and their derivatives) with very distinct properties which have been employed in many fields of electrochemical research. In recent times, poly (o-anisidine) (POA), a new electrically conducting polymer of polyaniline derivatives have received a significant attention towards electrochemical studies owing to their good electrochemical activity, biocompatibility, cost effective and most importantly its ability to dissolve in common organic solvents [2-4]. However, pure POA had few limitations such as low sensitivity, poor selectivity and interference from other species which is why they have not been commercialized to date. Thus, recently conducting polymer nanocomposites with improved properties have been developed to overcome the limitations of pure conducting polymers.

Silver nanoparticles (AgNps) are extensively used due to their variety of applications including antibacterial activity, inhibition of diseases like HIV and tumor, sensing of various biomolecules, ions and pH [5-7]. Though silver is a promising material, the disadvantages arise by the agglomeration of silver, the primary one being the increase of particle size. These disadvantages can be overcome by the combination of AgNps with conducting polymers in the form of polymer matrix type nanocomposite enabling the growth and spatial arrangement of nanoparticles, which is highly desirable to inquire the peculiar properties and applications of both the moieties.

The major advantage of poly (o-anisidine)-silver nanocomposite is that the drawback broughtup by the usage of poly (o-anisidine) and silver seperately are overcome. Based on the aforementioned facts, 45

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the present work is focussed on the preparation and characterization of poly (o-anisidine)-silver nanocomposite (POA-AgNPs). The prepared nanocomposite was characterized by XRD and HRTEM. The employement of the prepared nanocomposite towards the detection of dopamine has also been studied and analyzed.

Detction of dopamine (DA) is important since dopamine is a significant neurotransmitter in the mammalian central nervous systems. Several nervous system diseases are found to be encountered due to the dysfunction of DA including Parkinsons’s disease, schizophrenia and HIV infection [8].

Thus, the sensitive and accurate determination of DA is highly significant in the clinical diagnosis to conveniently trace and treat such diseases. Here, poly (o-anisidine)-AgNPs has been successfully utilized for the determination of DA using cylic voltammetry.

2. Experimental 2.1 Materials The o-Anisidine, β-napthalene sulfonic acid (β-NSA), ammonium persulfate [(NH4)2S2O8, APS] and dopamine (98% purity) were purchased from Sigma Aldrich. AgNO3 (99.9% purity) and NaBH4 were received from Finar reagents. Doubly distilled water was utilized for all the experiments.

2.2 Synthesis of POA-AgNPs Nanocomposite Silver nanoparticles (AgNPs) were chemically synthesized by reduction of AgNO3 using NaBH4.

POA-silver nanocomposite (POA-AgNPs) was prepared by insitu polymerization of o-anisidine in the presence of AgNPs. In a typical procedure, a required amount of AgNPs was added to 100 mL of 0.2 M of β-napthalene sulfonic acid (β-NSA) solution holding 1 mL of o-anisidine monomer and allowed to stir for 30 min. Then, 20 mL of 2.5 g of ammonium persulfate (APS) solution was prepared and added dropwise to the o-anisidine suspension mixture and the solution was continued to stir for 12 h at 5 oC. The obtained dark green product was filtred and washed with methanol and deionized water to remove the impurities. The POA with AgNPs was synthesized under the same conditions.

2.3 Instrumentation The X-ray diffraction studies of the prepared materials were done by GE X-ray diffraction system – XRD 303 TT. HRTEM was carried out using Tecnai instrument operating at 200 kV. The electrochemical experiments were performed on a CHI 1103A electrochemical instrument comprising of the conventional three electrode system; glassy carbon electrode (GCE), saturated calomel electrode (SCE) and platinum wire was used as working electrode, reference electrode and counter electrode, respectively.

3. Results and Discussion 3.1 Structural Investigation The XRD patterns of pure POA and POA-AgNPs nanocomposite are shown in Fig. 1 (a) & (b). The XRD pattern of POA (Fig. 1a) shows a medium broad peak centred at 2θ ~12.5° and 25.3º, which is a characteristic of the semicrystalline nature of polymer. POA-AgNPs (Fig. 1b) exhibits the presence of peaks corresponding to both poly (o-anisidine) (2θ ~ 12.5° and 25.3°) and silver (2θ ~ 38.2°, 44.4° and 64.6°). The XRD peaks of AgNPs are in good agreement with the JCPDS card no. 04-0783. The preponderant (111) reflection is indicative of the oriented growth of the silver nanoparticles in FCC structure. The XRD results match well with the reports previously available [7, 9]. The average crystallite size of ~ 8 nm was estimated using Scherrer’s formula.

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Fig. 1. XRD patterns of (a) pure POA and (b) POA-AgNPs nanocomposite.

3.2 Morphology Studies

Fig. 2. HRTEM micrographs of POA-AgNPs nanocomposite.

The morphology of POA-AgNPs was studied using HRTEM (Fig. 2). The obtained images revealed the embeddment of silver nanoparticles in the polymer matrix. The silver nanoparticles are found to be in spherical shape. The average particle size as measured from the HRTEM image was estimated to be ~ 45 nm. Fig.2 clearly shows the POA matrix in which the silver nanoparticles are embedded (black particles). The studies suggest that the reduction in agglomeration of silver nanoparticles has been efficiently prevented by the presence of polymer matrix in the nanocomposite system.

3.3 Electrochemical sensing of dopamine (DA): 3.3.1 Cyclic Voltammetry Cyclic voltammograms of dopamine (DA) at the surface of bare GCE and POA-AgNPs/GCE were recorded from the solution of 1.0 mM DA in 0.1 M PBS (pH 7.0) as shown in Fig. 3.

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Fig. 3. Cyclic voltammograms of (a) bare GCE/DA and (b) POA-AgNPs/GCE/DA ([DA] = 1mM; 0.1 M PBS, pH 7.0).

At the surface of bare GCE (Fig. 3, a), DA exhibited a broad and ill-defined reversible peaks with the oxidation and reduction potentials of Epa=0.522 V and Epc=0.218 V, respectively together with the redox peak currents of Ipa=4.64 µA and Ipc=-2.310 µA, respectively. The redox peak currents and the redox potentials of POA-AgNPs/GCE (Fig. 3b) were found to be Ipa=+11.4 µA; Ipc=-5.77 µA and Epa=+0.47 V; Epc=0.415 V. The observed increment in the catalytic response suggests the synergistic effects of POA and AgNPs toward the redox reaction of DA. The obtained results clearly signifies the large surface area, subtle electronic properties of AgNPs and the appreciable ion-exchange characters of POA. The modified POA-AgNPs/GCE not only improved the redox peak currents but also enabled the redox reaction of DA more reversible. This strongly suggests that the hybrid composite of POA and AgNPs have tuned the electron transfer significantly and results in improved response towards the detection of DA while compared to bare GCE. 3.3.2 Differential Pulse Voltammetry DA. Inset: Calibration plot of concentration of DA vs peak current.

Differential pulse voltammograms (DPV) of POA-AgNPs/GCE in PBS (pH 7.0) was determined with different concentrations of DA and the results are shown in Fig. 4. It is observed that with the addition of DA, a peak around +0.45 V has emerged. With the increase of DA concentrations, the anodic peak current of DA was apparently increased. From the inset of Fig. 4, linear regression equation of DA detection was found to be Ipa = 1.8963CDA μM + 9.63 with a correlation coefficient of 0.9832 (n=14) and the range of linearity was from 10.0 to 140.0 μM with a sensitivity of 6.72 μAμM-1. The limit of detection (LOD) of DA at the POA-AgNPs/GCE in 0.1 M PBS (pH 7.0) was 0.2 μM (S/N=3). High performance in the detection of DA indicates that POA-AgNPs nanocomposite has significantly improved the electron transfer between DA and GCE.

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Fig. 4. Differential pulse voltammograms of POA-AgNPs/GCE in 10.0 to 140.0 μM concentration.

Summary. Poly (o-anisidine) and silver (POA-AgNPs) nanocomposite prepared via insitu polymerization method was successfully employed for the detection of dopamine (DA). XRD studies revealed the face centred cubic structure of silver and the semi-crystalline nature of poly (o-anisidine).

The embeddment of silver nanoparticles in the polymer matrix was evident from HRTEM. The synthesized POA-AgNPs nanocomposite was found to exhibit electrocatalytic activity towards the detection of DA at a potential of +0.45 V. The modified electrode showed enhanced catalytic current and a linear response in the concentration range of 10.0-140.0 µM with a detection limit of 0.2 µM (S/N=3).

Acknowledgement: The author DS thanks DST INSPIRE for the financial support. The authors thank NCNSNT, University of Madras.

References [1] H. Shirakawa, E.J. Louis, A.G. MacDiarmid, C.K. Chiang, A.J. Heeger, Synthesis of electrically conducting organic polymers: halogen derivatives of polyacetylene, (CH)x, J. Chem. Soc., Chem.

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[4] D. Sangamithirai, S. Munusamy, V. Narayanan, A. Stephen, Fabrication of neurotransmitter dopamine electrochemical sensor based on poly (o-anisidine)/CNTs nanocomposite, Surfaces and Interfaces, 4, 2016, 27-34.

[5] J.S. Kim, E. Kuk, K.N. Yu, J.H. Kim, S.J. Park, H.J. Lee, S.H. Kim, Y.K. Park, Y.H. Park, C.-Y. Hwang, Y.K. Kim, Y.S. Lee, D.H. Jeong, M.-H. Cho, Antimicrobial effects of silver nanoparticles, Nanomedicine: Nanotechnology, Biology and Medicine, 3, 2007, 95-101.

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[6] S. Lee, Y.-S. Nam, H.-J. Lee, Y. Lee, K.-B. Lee, Highly selective colorimetric detection of Zn (II) ions using label-free silver nanoparticles, Sensors and Actuators B: Chemical, 237, 2016, 643651.

[7] E.A.K. Nivethaa, V. Narayanan, A. Stephen, Synthesis and spectral characterization of silver embedded chitosan matrix nanocomposite for the selective colorimetric sensing of toxic mercury, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 143, 2015, 242-250 [8] C. Zhao, Z. Jiang, X. Cai, L. Lin, X. Lin, S. Weng, Ultrasensitive and reliable dopamine sensor based on polythionine/AuNPs composites, Journal of Electroanalytical Chemistry, 748, 2015, 16-22.

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Cite the paper D. Sangamithirai, V. Narayanan, A. Stephen (2017). Electrochemical Detection of Dopamine at Poly (oanisidine)/Silver Nanocomposite Modified Glassy Carbon Electrode. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.91.86.223

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Visible Light Induced Photocatalytic Degradation of Methylene Blue using Polyaniline Modified Molybdenum Trioxide46 S. Dhanavel1, E.A.K. Nivethaa1, V. Narayanan 2, A. Stephen1,a 1 – Material Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai, India 2 – Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai, India a – stephen_arum@hotmail.com DOI 10.2412/mmse.63.64.916 provided by Seo4U.link

Keywords: polyaniline, molybdenum trioxide, photocatalyst, methylene blue.

ABSTRACT. Polyaniline/Molybdenum trioxide composite was prepared by a chemical oxidative polymerization method. The obtained Polyaniline/Molybdenum trioxide composite was characterized by X-ray diffraction analysis (XRD), Fourier transform infrared (FT-IR) spectroscopy and transmission electron microscopy (TEM). The XRD pattern showed the diffraction peaks to be in good agreement with the structure of MoO 3. The obtained results confirm the successful formation of the Polyaniline/Molybdenum trioxide composite. Finally, the composite was employed as photocatalyst for the photodegradation of methylene blue under visible light irradiation. Further the photodegradation mechanism also discussed in detail.

Introduction. In recent years, synthetic organic dyes have become one of the leading pollutants in wastewater because of their extensive use in various industries such as plastic, rubber, cosmetics, textile, printing and paper industries as colouring agents [1]. The release of these coloured waste water in the ecosystem cause various environmental issues such as, biochemical oxygen demand (BOD), chemical oxygen demand (COD), increase of toxicity and colour of the water. As a result, the removal of organic pollutants like Methylene Blue (MB), Congo red (CR) and Rhodamine B has been the subject of various researches using different techniques such as chemical oxidation, reverse osmosis, electrochemical process or photochemical degradation, adsorption[2, 3]. Among them, photodegradation and adsorption are the two main reliable and effective methods for the removal of the toxic dyes. Recently, adsorption process has been proved to be an excellent method which offers significant advantages like easy operations, low cost and reusability of the adsorbent. But this technique transfers pollutants merely from aqueous to solid phase rather than their degradation and generates secondary waste problems. Compared with adsorption, Photocatalysis technology is considered as one of the most promising method for the removal of the carcinogenic pollutants because of mineralization of dyes based on solar energy [4].

Recently, a lot of studies have been carried out on the degradation of organic pollutants via photocatalysis of various semiconductors [5] such as ZnO, TiO2, CeO2 etc., Among them, MoO3 a ntype semiconducting material has received considerable amount of attention due to its large surface area, inexpensive and pollution-less. Various methods such as hydrothermal process and template free solution growth technique have been employed for the fabrication of different MoO3 morphologies such as nanofibers, nanorods, etc., Recently, Ying Ma et al. and A. Chithambararaj et al., have reported the removal of organic dye using MoO3 [6, 7]. Improving the catalytic performance of MoO3 and its composites has been the major aim of many researchers.

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There are many literature reports that report the combination of semiconducting photocatalyst with electrically conducting materials such as carbon nanotubes and graphene to enhancing their photocatalytic performances [8]. Recently, conducting polymers such as Polythiophene, polyindole, polypyrrole and polyaniline have extensively studied for some applications such as gas sensors, biosensors, solar cells and battery applications [9]. Among these, polyaniline (PANI) has elicited great attention because of its unique electrochemical stability, optical properties, low cost and simple synthesis. Previously, PANI was reported to effectively improve the photocatalytic performance of many metal oxides such as TiO2, ZnO and MnO2 [4]. It has been reported that incorporation of PANI with metal oxides not only reducing the recombination rate of electon-hole pairs but also enhancing the photocatalytic activity. Considering the advantages of PANI, it was incorporated with the MoO3 in this study to enhance the photocatalytic performance.

Materials and methods Aniline (99%) and ammonium heptamolybdate tetrahydrate (98%) were purchased from Rankem.

Camphor-10-sulphonic acid (98% pure) and ammonium peroxydisulphate (98% pure) were obtained from Sigma Aldrich chemicals. Methylene Blue (MB) was obtained from Qualigens. All experiments were done using double distilled water.

Preparation of PANI/ MoO3 composite photocatalyst Initially, MoO3 nanoparticles were synthesized from ammonium heptamolybdate tetrahydrate through solid state decomposition method at 500 °C as per previous report [3]. The obtained powder was washed with distilled water and dried. Then, 1g of MoO3 nanoparticles were dispersed in 50 mL of deionized water containing aniline (0.3 g). To this, camphor-10-sulphonic acid (aniline: CSA = 1:0.5, molar ratio) solution was mixed. Then, ammonium persulfate (APS) ( (aniline: APS = 1:1)) solution was added drop wise to the above solution and allowed to react for 12 h with constant stirring at 0-4 °C. A dark green precipitate was obtained and washed with water followed by ethanol and dried in an air oven.

Photocatalytic experiments The photocatalytic activity under visible light in the literatures is followed [7]. The photocatalytic performance of PANI/ MoO3 composite was evaluated by the degradation of methylene blue which was taken as a model organic compound. Reaction suspensions were prepared by adding 500 mg of the catalyst into the 500 ml of MB solution with an initial concentration of 1.5×10-5 mol l-1. Prior to the irradiation, the suspensions were magnetically stirred in the dark for about 30 min to ensure the establishment of an adsorption-desorption equilibrium between the MB dye and photocatalyst.

Visible light irradiation for this experiment was carried out using projection lamp (7748XHP 250 W, Philips, 532 nm) in a photocatalytic reactor. Then the prepared suspension was kept under the irradiation under continuous stirring at room temperature. During the irradiation, the suspensions were sampled at every 30 min and immediately centrifuged to remove the catalyst particles. Then the absorption of MB aqueous solution was measured by UV-Vis spectrophotometer.

Degradation efficiency can be calculated using the following equation: η = (1- Ct/ C0)

(1)

where Ct and C0 are the concentrations of the solution after illumination for t minutes and before illumination (t = 0) respectively.

Characterization of the photocatalysts X-ray diffraction (XRD) pattern was recorded using GE X-RAY Diffraction System-XRD 3003 TT with CuKα1 radiation (λ = 1.5406Å ) for 2θ= 10–70°. Fourier transform infrared (FTIR) spectrum MMSE Journal. Open Access www.mmse.xyz

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was obtained from Perkin-Elmer FTIR system. The optical absorption properties of photocatalysts were obtained ANALYTIK JENA SPECORD 200 PLUS. HRTEM analysis was carried out using TECHNAI INSTRUMENT operating at operating voltage of 200 kV. Results and discussion Structural and morphological characterization XRD pattern of MoO3 and PANI/ MoO3 is presented in Fig. (1). For the MoO3, all the diffraction peaks are attributed to the orthorhombic structure of MoO3 (JCPDS card No. 05-0508) indicating well crystallization. The XRD pattern of PANI/ MoO3, clearly shows the maintenance of MoO3 crystal structure even after the addition of polyaniline. Moreover, also there is no change in the peak position. It implies that, the polymerization of aniline monomers takes place on the surface of metal oxide. While adding the polyaniline, amorphous nature was observed with the crystalline pattern which indicates the formation of PANI/ MoO3 composite [3].

Fig. 1. XRD Pattern of MoO3 and PANI/ MoO3.

Fig. 2. HRTEM image of PANI/ MoO3.

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Fig. 2 shows the HRTEM image of PANI/ MoO3. It can be observed that MoO3 particles wrapped by the grey colored layer. It clearly shows that MoO3 particles were covered by the PANI. The obtained result is in good agreement with the XRD results. The size of the particles was measured using imagej software. It was found to be in the range of ~100 - 400 nm.

FTIR analysis

Fig. 3. FTIR spectrum of PANI/ MoO3.

FTIR spectrum of PANI/MoO3 in the range of 4000 – 400 cm-1 is shown in Fig. 3. FTIR spectrum shows peaks at ~3236, 1570, 1487, 1302, 1243 and 1146 and 630 cm-1. The peak at around ~3236 cm-1 attributed to the N-H stretching vibrations. The peaks observed at ~1570 and ~1487 cm-1 assigned to the stretching vibration of quinonoid ring and benzenoid ring respectively. The peak at ~1243 cm-1 corresponds to the C–N+ stretching vibration. Peaks at ~1302 and ~1146 cm-1 corresponds to the C–N stretching of an aromatic amine and C–H in plane bending mode respectively. The peak appearing at ~630 cm-1 attributed to the bending mode vibration of the Mo–O–Mo [3, 7].

Evaluation of Photocatalytic activity Initially, PANI/ MoO3 composite was added to the MB solution under dark condition to establish adsorption–desorption equilibrium between the dye molecules and PANI/ MoO3. The concentration of the MB in the supernatant solution was analyzed using UV-Vis spectrophotometer at the wavelength of maximum absorbance at 665 nm. The decrease in the peak intensity suggests that MB dye was removed by the PANI/ MoO3.

Fig. 4 shows the MB removal percentage at regular interval of time. Nearly, 46% percentage of the dye was adsorbed on to the composite. It is due to the electrostatic interactions between cationic dye and negatively charged metal oxide surface. Also the presence of negatively charged sulphonic group present in the system as well as by the presence of pi–pi stacking interactions between aromatic ring of PANI and MB is reasonable for the migration of dye molecules onto the surface of composites [3, 7].

The photocatalytic activity of PANI/ MoO3 composite catalyst was evaluated by measuring the decomposition rate of MB dye under visible-light irradiation. The decontaminating efficiency of the catalyst was calculated using the equation (1). Upon visible light irradiation, PANI can absorb visible light delivering the excited-state electrons of the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). Then, the excited-state electrons in the LUMO of PANI molecules can drift into the CB of MoO3 subsequently, they migrate to the surface of MoO3 MMSE Journal. Open Access www.mmse.xyz

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and react with water to produce superoxide radical, which could oxidize the organic molecules. Here PANI acting as a photosensitizer which contribute to the higher photocatalytic activity. i.e hydroxyl radicals and superoxide anions were produced by the composite catalyst leading to the decomposition of organic dyes [4, 7]. The results demonstrate that 95.4% of the dye was removed in 150 min from the initial concentration.

Fig. 4. Photodegradation for PANI/ MoO3 composite under visible light.

Summary. Polyaniline/Molybdenum trioxide composite was successfully prepared by a chemical oxidative polymerization method. The formation of composite was confirmed from the FTIR analysis. Polymerization of aniline monomers on the surface of MoO3 was confirmed from the XRD and HRTEM analysis. The decontaminating (including photocatalytic degradation and adsorption) activity of PANI/ MoO3 was demonstrated and evaluated on MB. Acknowledgements. One of the authors S. D. acknowledges UGC-UPE-Phase II for its financial assistance in the form of fellowship.

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[8] Min-Quan Yang, Nan Zhang and Yi-Jun Xu, ACS Appl. Mater. Interfaces, 2013, 5 (3), pp 1156â&#x20AC;&#x201C; 1164. DOI: 10.1021/am3029798 [9] Y. Shi, L. Peng, Y. Ding, Y. Zhao and G. Yu, Chem Soc Rev, 2015, 44, 6684-6696. DOI: 10.1039/C5CS00362H.

Cite the paper S. Dhanavel, E.A.K. Nivethaa, V. Narayanan, A. Stephen (2017). Visible Light Induced Photocatalytic Degradation of Methylene Blue using Polyaniline Modified Molybdenum Trioxide. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.63.64.916

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Green Synthesis of Silver Nanoparticles Mediated using Lagerstroemia Speciosa and Photocatalytic Activity Against Azo Dye47 V. Sai Saraswathi1, K. Santhakumar2,a 1 – Department of Chemistry, SAS, VIT University, Vellore, India 2 – CO2 Research Centre, VIT University, Vellore, India a – ksanthakumar@vit.ac.in DOI 10.2412/mmse.72.63.602 provided by Seo4U.link

Keywords: dye degradation, methyl orange, X-ray diffraction, transmission electron microscopy, Lagerstroemia speciosa.

ABSTRACT. The present paper reports that the method is simple in the biosynthesis of silver nanoparticles using the aqueous leaves of L. speciosa. The functional groups for the plant extract and silver ions were explained by FTIR. The biosynthesized silver nanoparticles were characterized by UV- VIS spectroscopy, X- Ray Diffraction -XRD, High Resolution- Transmission Electron Microscopy, Zeta potential and particle size analysis. The maximum absorbance peak was found at 427 nm. The average silver nanoparticles were found to be 12 nm by XRD and it was spherical in shape.

The nanoparticles were subjected to dye degradation process for methyl orange. Hence the biosynthesis silver nanoparticles possess photocatalytic. This evident helps to analysis the silver nanoparticles for various applications in future.

Introduction. Human activities such as pollution are causing major challenge to the environment [1].

The organic dye pollutant from textile, paper etc is now considered to be major threat to the biodiversity. Several methods were being proposed to remove dyes from the textiles viz. physical, chemical and biological methods. [2]. Recent literature states that a metal nanoparticle degrades the dyes as an effective photocatalyst at ambient temperature with visible light illumination. [3] Using micro-organisms, plants, enzymes were being suggested to be eco-friendly compared to the chemical methods [4]. Lagerstroemia Speciosa contains a wide range of biologically active compounds such as being rich in alkaloids, glycosides, flavonoids, tannins, terpenoids, phenols, saponins, alkaloids and vitamins. [5]. This paper explains about the green synthesis of silver nanoparticles mediated using leaf extract of Lagerstroemia speciosa, characterization and photocatalytic activity against azo dye.

Materials and Methods Silver Nitrate (99.99%), Methyl Orange, Methylene blue reagents were procured from Merck Inc. (Mumbai, India) of Analytical grade. The leaves of Lagerstroemia speciosa (Fig. 1) was collected during March- Aug, from VIT University, garden, Vellore, INDIA. The plant leaves were authenticated by Dr. P. Jayaraman, Plant Anatomy Research Centre, Chennai, India.

Preparation of Phyto-reducing agent About 10 g of air dried leaves were taken into the clean beaker and it was boiled with 100 mL double distilled water for half an hour at 60°C for decoction extract. The extract turns the colour from colourless to yellow brown colour indicates the extraction is complete. It was subjected to preliminary screening for phytoconstituents by J.B. Harborne [6].

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Biosynthesis of Silver Nanoparticles Approximately 20 gm of dry leaves were cut into pieces and about 0.10 g of silver nitrate was added to the extract slowly and continuous stirring for 1 h at 75°C. The reduction of Ag+ to Ag0 was monitored by visual color change from yellow to dark blackish brown in color. It was centrifuged at 2000 rpm for 20 min for thrice. It was characterized using UV-Vis spectrophotometer (UV-2450 Shimadzu). Infrared (IR) spectra, powder X-ray diffraction in (X-per pr- D8 Advanced, bruker, Germany) X- ray diffractometer. The morphology was studied by Scanning Electron Microscope (SEM, Model JSM 6390 LV, JOEL, USA), Transmission Electron Microscopy. (Model JSM 6390 LV, JOEL, USA). The electrophoretic mobility was analysed by zetasizer Nano ZS (Malvern Instruments, Ltd. UK) and zeta potential was measured by henry equation.

Phytoremediation activity against dyes The phytoremediation studies were carried for methyl orange (C14H14N3NaO3S) using sunlight as the source during the month of Aug- Sep 2016 between 11 am to 3 pm. The light flux was measured during the reaction, at the begin of the analysis it was 1250 W/m2 and increased to 1300 W/m2 following 290 minutes. About 0.1 mg of Ag NPs was weighed and mixed to 10 ml dye solution and the mixture was sonicated for 20 min in dark room. Similarly control was prepared and maintained in same condition. Dye degradation was finalized visually by the colour change. For methyl orange (MO) the solution changes from deep orange to yellow colour. Optical absorption spectra were resolved after varying light exposure durations utilizing an UV/Vis spectrophotometer (JASCO- V730) to screen the rate of degradation methyl orange at the maximum wavelength (λmax = 460 – MO).

The degradation efficiency (PE) was ascertained as in condition1:

where I0 is the initial absorption intensity of methyl orange solution at λmax= 460 nm (MO) and I is the absorption intensity after photo-degradation. C0 is the first concentration of methyl orange solution and C is the concentration after photo-degradation. [7] 3. Results & Discussion It was observed during the qualitative analysis; that the phyto-constituents like tannins, phytosterols, carbohydrates, alkaloids, terpenoids, flavonoids, glycosides, proteins were found to be predominant, while gums and mucilage were found to be absent. The leaf extract of L. speciosa when incubated with silver nitrate under stirring in dark condition, the brown colour of the extract changed to blackish brown colour. The formation of metal silver nanoparticle in aqueous solution was presented by UVVIS spectroscopy. From the Fig. 1 (a, b) The absorption spectra of prepared Ag NPs from leaves of L. speciosa showed the absorbance at 427 nm. [8] There is a peak at 361 nm indicates the active compounds which is interacting with silver ions into the solution and helps for possible reduction of metal ions present in the solution.

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b)

a)

Fig. 1. UV spectra of (a) plant extract of L. speciosa (b) Ag NP. The XRD pattern of the biosynthesized AG NPs is shown in Fig. 5. The diffraction pattern were observed from 20° to 80°. The four braggâ&#x20AC;&#x2122;s reflection was observed at 38.45°, 46.35°, 64.75° and 78.05° corresponds the planes of ( 1 1 1), (2 0 0), (2 2 0) and (3 1 1) respectively (JCPDS card no.

89- 3722). All diffraction peaks of the sample represents to the characteristic face centered cubic crystal structure of silver nanoparticles (a, b, c = 4.085 Ă&#x2026;). [9]. The average particle size of ZnO-NPs can be estimated using the Debye-Scherer equation which gives a relationship between peak broadening in XRD and particle size is explained with the following equation:

đ??ˇ=

đ??žđ?&#x153;&#x2020; â&#x201E;Ť đ?&#x203A;˝ đ??śđ?&#x2018;&#x153;đ?&#x2018; đ?&#x153;&#x192;

Using the Scherer equation the average crystalline size of Ag NPs is found to be 12.4 nm. Diffraction pattern doesnâ&#x20AC;&#x2122;t have any impurity peak hence the prepared Ag NP is highly pure.

2500

(111)

JCPDS Card No: 89-3722

Intensity (a.u.)

2000

1500

1000

(200) (220)

500

20

40

60

(311)

80

2ď ą(Degree)

Fig. 2. XRD spectra of prepared silver nanoparticle from L. speciosa leaf extract.

The HRTEM of the biosynthesized Ag NPs from the leaf extract of L. speciosa extract are shown in Fig. 6a & 6b. The Ag NPs predominantly showed spherical in shape morphology showing the average particle size of 14 nm [10]. This attribute the secondary metabolic present in the plant act as reducing agents.

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b)

a)

Fig. 3. A), b) HR – TEM micrograph of Ag NPs from leaves of L. speciosa – 100nm The particle size and zeta potential of synthesized Ag NPs were determined by DLS (Fig. 4a and b).

The higher the zeta potential value the higher the electric charge on the surface of the particles. Here, using water as dispersant the zeta potential is found to be −37 mV for Ag NPs (Fig. 7b). [11].

b)

a)

Fig. 4. a) Zeta sizer and b) zeta potential of photosynthesized Ag NPs. The photocatalytic degradation was carried for methyl orange using silver nanoparticle prepared from leaves of L. speciosa. The procedure was carried out, using sun as the main source of light. [12] The time dependent UV- Vis spectra of the MO are explained in Fig. 5. The maximum absorption of MO was found at 460 nm was degraded to 10% after irradiating with sunlight for 310 min [13].

2.0 1.8 1.6

Absorbance (a.u.)

1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 200

300

400

500

600

700

800

Wavelength (nm)

Fig. 5. Photocatalytic degradation of Methyl orange using Ag NPs from L. Speciosa.

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Summary. To conclude this paper, a convenient method for preparation of efficient visible photocatalytic nanoparticles, using the plant leaf extract of L. speciosa. The green synthesize was confirmed by the visual colour change and by UV-VIS spectroscopy at 427nm. The prepared Ag NPs had cubic and spherical shape in XRD and TEM respectively with average particles size as 12.4 nm.

The biosynthesized was environmental friendly nanomaterials, by degrading the various dyes like methyl orange. But further investigations are required to scale up the Ag NPs for wider medical applications in future.

Reference [1] Sudhir S. Arbuj, Preparation, characterization and photocatalytic activity of TiO2 towards methylene blue degradation, 2010. http://dx.doi.org/10.1016/j.mseb.2009.11.010 [2] W. Z. Tang, H. An, UV/TiO2 photocatalytic oxidation of commercial dyes in aqueous solution.

Chemosphere. 1995. DOI: 10.1016/0045-6535 (95)80015-D [3] M. Faisal, M. A. Tariq, M. Muneer, Photo catalysed degradation of two selected dyes in UVirradiated aqueous suspensions of Titania. Dyes Pigm. 2007. DOI: 10.4236/msa.2011.26093 [4] S. Basavaraja, S. D. Balaji, Arun kumar lagashetty, A. H. Raja sab, A. Venkataraman, Extracellular biosynthesis of silver nanoparticles using the fungus Fusarium semitectum, Materials Research Bulletin, 2008. http://dx.doi.org/10.1016/j.materresbull.2007.06.020 [5] Sujoy K. Das, Calum Dickinson, Fathima Lfir, Dermot F, Brougham and Enrico Marsili, Synthesis, Characterization and catalytic activity of gold nanoparticles biosynthesized with Rhizopus oryzae protein extract, Green Chem, 2012. DOI: 10.1039/C2GC16676C [6] V. Sai Saraswathi, D. Thirumalai, Pothula Kusal Yadav, M. Saranya, Pharmacognostic preliminary photochemical study of lagerstroemia speciosa leaves, IJRAP, 2011.http://www.ijrap.net/admin/php/uploads/518.pdf [7] V. Sai Saraswathi, J. Tatsugi, Paik-Kyun Shin, K. Santhakumar, Facile biosynthesis, characterization and solar assisted photocatalytic effect of ZnO nanoparticles mediated by leaves of L. speciosa. 2016. doi:10.1016/j.jphotobiol.2016.12.032 [8] Mambo Moyo, Makore Gomba, Tichaona Nharingo., Afzelia quanzensis bark extract for green synthesis of silver nanoparticles and study of their antibacterial activity, International Journal of Industrial chemistry, 2015. DOI: 10.1007/s40090-015-0055-7 [9] Meghnath Prabhu, Santhosh Kumar Dubey et al., One –pot rapid synthesis of Face centered cubic silver nanoparticles using Fermented Cow urine, A Nanoweapon against fungal and bacterial pathogens, Journal of Bionanoscience, 2014. DOI: 10.1166/jbns.2014.1235 [10] M. Juvekar, A. Juvekar, M. Kulkarni, et al., “Phytochemical and pharmacological studies on the leaves of Couroupita guianensis Aubl” Planta Medica. 2009 http://dx.doi.org/10.1155/2013/598328 [11] Suman Singh, Amardeep Bharti, Vijay Kumar Meena, Structural, thermal, zeta potential and electrical properties of disaccharide reduced silver nanoparticles, Journal of Materials Science: Materials in Electronics, 2014. DOI: 10.1007/s10854-014-2085-x [12] P. Kumar., M. Govindaraju, S. Senthamilselvi, K. premkumar, Photocatalytic degradation of methyl orange dye using silver (Ag) nanoparticles synthesized from Ulva lacctuca., Colloids and surface: Biointerfaces., 2013. http://dx.doi.org/10.1016/j.colsurfb.2012.11.022 [13] S. K. Kansal, M. Singh, Sudo, Studies on TiO2/ZnO photocatalysed degradation of Lignin. J. Hazard Mater. 2008. http://dx.doi.org/10.1016/j.cej.2012.09.066 Cite the paper V. Sai Saraswathi, K. Santhakumar (2017). Green Synthesis of Silver Nanoparticles Mediated using Lagerstroemia Speciosa and Photocatalytic Activity Against Azo Dye. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.72.63.602

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Impedance Analysis of Microwave Processed Lead Nickel Titanate48 C. Pavithra1, S. RoopasKiran1,a, W. Madhuri1, 2 1 – Ceramic Composite Laboratory, CCG, SAS, VIT University, Vellore, TN, India 2 – Magnetic composites and applications group, IFW, Leibniz Institute for Solid State and Materials Research, Technische Universität Dresden, 01069 Dresden, Germany a – roopasiitm@gmail.com DOI 10.2412/mmse.18.22.667 provided by Seo4U.link

Keywords: lead nickel titanate, impedance analysis, microwave processing, sol-gel method.

ABSTRACT. Pb1-xNixTiO3 (PNT) with x varying between 0 and 1 is synthesised by sol-gel technique and then processed in microwave at 1000oC. The X-ray diffraction confirms the cubic structure in PNT. The electrical conduction and frequency response is investigated on the basis of impedance spectroscopy. PNT exhibited a negative temperature coefficient of resistance and non-Debye type of relaxation for all the recorded temperature.

Introduction. Ferroelectric ceramics are widely used in spintronic, optoelectronics as sensors and transducers. Ferroelectric with perovskite structure can exhibit a wide range of application in semiconductor devices. The fundamental interest of ferroelectric and ferromagnetic coexistence is to cause an electric polarisation by applying magnetic field or magnetisation in applied electric fields.

In non-volatile memory devices writing data bit with an electric field by creating magnetic field used to read the data will be possible [1-2]. Researchers are interested in microwave sintering technique for ceramic due to its advantages over conventional sintering.Microwaves when passing through a specimen the molecular dipoles oscillate with the applied microwave frequency (2.45GHz in the present case) and produce alarge amount of latent heat which is again absorbed the material results in sintering. The process is quite fast compared to conventional heating with added benefits of low energy consumption, cost, sintering temperature and uniform densification [3-4].The present work is focused on thesol-gel synthesis of Pb1-xNixTiO3 (PNT) sintered using microwaves. The sol-gel technique is adopted in lieu of its ability to produce high purity, ultrafine nanoparticles at low processing costs [5-7].

Experimental Procedure.

Lead acetate Pb (CH3COOH)2 3H2O, Nickel nitrate Ni (NO3)2 6H2O and Titanium Butoxide Ti (C4H9O)4 were taken as starting materials to prepare PNT. To prepare PNT, stoichiometric ratios of starting materials are taken. Lead acetateand nickel nitrateare dissolved in pure glacial acetic acid.

The prepared solution is dehydrated at 100°C for 10min and cooled down to room temperature. After cooling down, Titanium Butoxide added drop by drop to that solution then continuous stirring for 30 min at room temperature. Then the mixture of deionized water and ethanol are addedat a slow rateso as to initiate hydrolysis and prevent fast gelation of the solution. Thus prepared gel is heated at 100°C for 2 hours in theoven to obtain the PNT powder. For the calcination step, microwave furnace is used to at 730°C for 45min at a rate of 30°C per min.The green powder samples aregrindedat 8 hours using agate mortar. Thegrinded powders are sintered at 1000°C using microwave furnace. The prepared

48

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samples are used in different characterization. For making a pellet 1 cm diameter die is used with PVA as abinder.

Results and Discussion. Structural analysis X-ray diffraction:

(214) (300)

(116) (018)

(024)

(110)

(012)

1.0

(113)

(104)

The X-ray diffraction pattern of PNT powder is calcined at 730°C at 45min at the rate of30°C/min using microwave furnace. Fig.1 shows the X-ray diffraction of PNT, x=0.0 and x=1.0 isfor lead titanate (PT) and nickel titanate (NT). It confirms the tetragonal structure for P4mmspace group for x=0.0 (PT) and rhombohedral structure for R3 space group for x=1.0 (NT). The transformation from tetrahedral to rhombohedral occurred gradually with increase in x. Pseudo cubic structure can be noticed for x = 0.4 to 0.6 in agreement with earlier reports [8-9]. The co-existence of tetragonal and rhombohedral (probably-cubic) phase [1].

Intensity (a.u)

0.6

15

20

30

35

40

(211)

(112)

(200)

50

(211)

(200)

45

(102) (201) (210) (112)

(111) (002)

25

(102) (201)

(002)

(111)

(101)

(001) (100)

(110)

X=0.0

(101)

(100)

(001)

0.4

(110)

0.5

55

60

65

2ď ą (deg)

Fig. 1. XRD pattern of PNT. Electrical Conductivity Measurements Complex impedance analysis Complex impedance spectroscopy technique is used to investigate the electrical properties of materials. Ferroelectric ceramics are in general electrically heterogeneous. The variation of real with theimaginary part of the impedance is known as Nyquist plots. In general Nyquist plot is asemicircular arc for understanding the grains and grain boundary effect on the electrical property of the materials. Complex impedance spectroscopy is a powerful non-destructive testing tool to examine the effect of microstructure on electrical behaviour. Complex impedance analysis is the representation of impedance Z, electrical modulus M and admittance Y as complex parameters. A Debye-type relaxation in the ceramics results in a semicircular Nyquist plot with its centre lying on the abscissa.

However, the centre is expected to be lying below the abscissa for non-Debye type relaxations. The complex impedance is generally represented as below [8]: đ?&#x2018;? â&#x2C6;&#x2014; = đ?&#x2018;? â&#x20AC;˛ + đ?&#x2018;&#x2013;đ?&#x2018;?" =

đ?&#x2018;&#x2026; 1+(

đ?&#x153;&#x201D; đ?&#x203A;ź ) đ?&#x153;&#x201D;đ?&#x2018;&#x153;

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(1)

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where Îą is the measure of electrical deviation from theideal response and can be estimated from the centre of the Argand semicircle.

The deviation Îą tends to zero for mono-dispersive Debye type relaxations and it is non-zero and positive for non-Debye and poly-dispersive type of relaxations. The Nyquist plots of PNT at selected temperatures are shown in Fig. 2. The contribution to electrical response in polycrystalline solids is by grains, grain boundaries and space charge. A semicircle at alow frequency would indicate space charge relaxation, at theintermediatefrequency, it would be grain boundaries and at high frequency, it is due to grains. The Cole-cole plots show single semicircle indicating the dominance of grains over grain boundaries and space charge effect. Furthermore, all the relaxations are found to be thenonDebye type with the centre of the semicircular arcs lying below the abscissa. The electrical responses from impedance spectroscopy can always be represented as anequivalent electrical circuit as series of parallel RC elements. In the present case, single parallel RC (Rbâ&#x2022;&#x2018;Cb) circuit represents the relaxation of grains to the applied field. The values of Rb, Cb and relaxation time Ď&#x201E; are estimated using relaxation Eqn. (2) and are presented in Table 1.

Table 1. Resistance, Capacitance, Relaxation time and Conductivity value at different temperature.

Ratio

X=0.0

X=0.4

X=0.5

X=0.6

X=1.0

Temperature (°C)

Rb (ohm)

440 460 480 490 500 520 540 440 460 480 500 520 540 440 460 480 500 520 540 440 460 480 500 520 540 440 460 480 500 520 540

764.90 451.20 303.12 259.37 244.47 233.60 169.05 22656.25 8233.17 3635.81 1985.57 1075.12 640.02 5161.29 1941.10 1168.75 933.77 640.10 609.27 35009.61 6269.47 2392.78 1382.52 1057.78 854.08 7250480.77 2207932.69 1385576.92 938701.92 533653.84 475096.15

Cb (Ă&#x2014;10-10 farad) 2.97 4.41 7.50 8.77 8.14 6.81 1.04 0.35 0.64 1.09 2.00 3.70 4.97 0.617 1.17 1.36 0.852 0.829 0.522 0.758 1.26 1.66 0.575 0.752 0.621 0.0732 0.0721 0.111 0.0565 0.0596 0.0335

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Ď&#x201E; (Ă&#x2014;10-7sec)

đ?&#x203A;&#x201D;dc (S/cm)

2.27 1.99 2.27 2.27 1.99 1.59 1.76 7.96 5.30 3.98 3.98 3.98 3.18 3.18 2.27 1.59 0.79 0.53 0.31 26.5 7.96 3.98 0.79 0.79 0.53 530.7 159.0 159.0 53.0 31.8 15.9

6.13Ă&#x2014;10-3 0.010 0.015 0.018 0.019 0.020 0.027 1.51Ă&#x2014;10-4 4.17Ă&#x2014;10-4 9.46Ă&#x2014;10-4 1.73Ă&#x2014;10-3 3.19Ă&#x2014;10-3 5.37Ă&#x2014;10-3 9.03Ă&#x2014;10-4 2.40Ă&#x2014;10-3 3.99Ă&#x2014;10-3 4.99Ă&#x2014;10-3 7.28Ă&#x2014;10-3 7.65Ă&#x2014;10-3 1.23Ă&#x2014;10-4 6.87Ă&#x2014;10-4 1.80Ă&#x2014;10-3 3.11Ă&#x2014;10-3 4.07Ă&#x2014;10-3 5.04Ă&#x2014;10-3 3.77Ă&#x2014;10-7 1.24Ă&#x2014;10-6 1.97Ă&#x2014;10-6 2.91Ă&#x2014;10-6 5.13Ă&#x2014;10-6 5.76Ă&#x2014;10-6

Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

a) 2000

Z"(ohm)

1500

40000

1000

500

1000

1500

2000

Z'(ohm)

20000

400

440C 460C 480C 500C

800

6000

Z" (ohm)

Z" (ohm)

0 0

30000

1000

7000

500

800 600

8000

440C 460C 480C

500C 520C 540C

Z" (ohm)

50000

1000

b)

5000

400

200 0 0

200

400

200 0 0

4000

510C 520C 540C

600

200 400 600 800 1000

Z' (ohm)

3000 2000

10000

1000

0

0

0

10000

20000

30000

40000

0

50000

1000

2000

3000

4000

5000

Z' (ohm)

Z' (ohm)

c)

d) 5

7

500C 520C 540C

5

6

Z" (ohm)

8.0x10

6

6.0x10

Z" (ohm)

6.0x10

7000

8000

440C 460C 480C

8.0x10

1.0x10

6000

5

4.0x10

5

5

2.0x10

2.0x10

0.0 0.0 5

2.0x10

5

4.0x10

5

6.0x10

5

8.0x10

Z' (ohm) 6

4.0x10

6

2.0x10

0.0 0.0

5

6.0x10

4.0x10

5

0.0 0.0

5

8.0x10

6

2.0x10

6

4.0x10

6

6.0x10

6

8.0x10

7

1.0x10

Z' (ohm)

e) Fig. 2. (a) x=0.0 (b) x=0.4 (c) x=0.5 (d) x=0.6 (e) x=1.0 shows the cole- cole plot at different temperatures.

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5

2.0x10

5

4.0x10

5

6.0x10

5

8.0x10

600

800

Mechanics, Materials Science & Engineering, April 2017 â&#x20AC;&#x201C; ISSN 2412-5954

đ?&#x153;?=

1 đ?&#x153;&#x201D;

= RbCb

(2)

where Ď&#x2030;=2Ď&#x20AC;νmax, νmax denotes applied frequency corresponding to the arc maximum, Rb and Cb are bulk resistance and bulk capacitance respectively.

The conductance of the material is calculated using the relation (3): Ć&#x2013;

đ?&#x153;&#x17D;đ?&#x2018;&#x2018;đ?&#x2018;? = đ??´đ?&#x2018;&#x2026;

đ?&#x2018;?

(3)

where Ć&#x2013; and A are the thickness and cross-sectional area of the pelletized sample.

These values are also tabulated in Table 1. It is also noticed that bulk resistance decreases with increase in temperature indicating negative temperature coefficient of resistance.

Summary. The lead nickel titanate (Pb1-xNixTiO3, PNT) is synthesised by sol-gel route followed by microwave sintering. X-ray diffraction confirms the cubic structure for x = 0.4 to 0.6. The impedance analysis of PNT is studied for grain and grain boundary effects. PNT exhibited thenon-Debye type of relaxations at all temperatures recorded. An equivalent RC circuit is proposed in each case along with estimated resistance, capacitance and relaxation time that is observed to be very low of the order of 10-7sec. DC electrical conductivity is also estimated at selected temperatures. It is noticed that PNT is a negative temperature coefficient material.

Reference [1] Chaisan, W., Ananta, S., &Tunkasiri, T. (2004). Synthesis of barium titanateâ&#x20AC;&#x201C;lead zirconate titanate solid solutions by a modified mixed-oxide synthetic route. Current Applied Physics, 4 (2), 182-185. DOI: 10.1016/j.cap.2013.11.004 [2] Yuvaraj, S., Nithya, V. D., Fathima, K. S., Sanjeeviraja, C., Selvan, G. K., Arumugam, S., & Selvan, R. K. (2013). Investigations on the temperature dependent electrical and magnetic properties of NiTiO 3 by molten salt synthesis. Materials Research Bulletin, 48 (3), 1110-1116.DOI:10.1016 /j.materresbull.2012.12.001 [3] Reddy, M. P., Madhuri, W., Balakrishnaiah, G., Reddy, N. R., Kumar, K. S., Murthy, V. R. K., & Reddy, R. R. (2011). Microwave sintering of iron deficient Niâ&#x20AC;&#x201C;Cuâ&#x20AC;&#x201C;Zn ferrites for multilayer chip inductors. Current Applied Physics, 11 (2), 191-198.DOI:10.1016/j.cap.2010.07.005 [4] Reddy, M. P., Madhuri, W., Sadhana, K., Kim, I. G., Hui, K. N., Hui, K. S., ... & Reddy, R. R. (2014). Microwave sintering of nickel ferrite nanoparticles processed via solâ&#x20AC;&#x201C;gel method. Journal of Sol-Gel Science and Technology, 70 (3), 400-404. DOI:10.1007/s10971-014-3295-7 [5] BeltrĂĄn, H., Cordoncillo, E., Escribano, P., Carda, J. B., Coats, A., & West, A. R. (2000). Sol-gel synthesis and characterization of Pb (Mg1/3Nb2/3) O3 (PMN) ferroelectric perovskite. Chemistry of materials, 12 (2), 400-405. DOI: 10.1021/cm991100a [6] Gupta, R., Das, S., Sinha, T. P., & Bamzai, K. K. (2015). Effect of cadmium doping on electrical properties of lead nickel niobateâ&#x20AC;&#x201C;lead zirconate titanate [Pb 1.0 (Ni 0.167 Nb 0.333 Zr 0.155 Ti 0.345) O 3] ceramics. Ceramics International, 41 (10), 13241-13249. DOI:10.1016/j.ceramint.2015.07.103 [7] Nguyen-Phan, T. D., Nguyen-Huy, C., & Shin, E. W. (2014). Morphological evolution of hierarchical nickel titanates by elevation of the solvothermal temperature. Materials Letters, 131, 217221.DOI: 10.1016/j.matlet.2014.05.201

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[8] Khamman, O., Yimnirun, R., Sirikulrat, N., & Ananta, S. (2012). Phase formation and transitions in the lead nickel niobate–lead zirconate titanate system. Ceramics International, 38, S17-S20. DOI: 10.1016/j.ceramint.2011.04.039 [9] Oanh, L. T. M., Bich Do, D., & Van Minh, N. (2015). Physical Properties of Sol-Gel Lead Nickel Titanate Powder Pb (Ti 1− x Ni x) O 3. Materials transactions, (0).DOI: 10.2320/matertrans.MA201508

Cite the paper C. Pavithra, S. RoopasKiran, W. Madhuri (2017). Impedance Analysis of Microwave Processed Lead Nickel Titanate. Mechanics, Materials Science & Engineering, Vol 9. doi:10.2412/mmse.18.22.667

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Synthesis, Characterization and DFT Calculations of Thiosemicarbazone 4- Methoxy Benzaldehyde Zinc Chloride 49 S. Attralarasan 1, A. Shiny Febena 1, M. Victor Antony Raj1, J. Madhavan1, a 1 – Department of Physics, Loyola College, Chennai, India a – jmadhavang@yahoo.com DOI 10.2412/mmse.98.79.782 provided by Seo4U.link

Keywords: BLZC, UV-Vis, FT-IR, DFT, HOMO-LUMO, SHG, KDP

ABSTRACT.In this work, nonlinear optical single crystal of Thiosemicarbazone 4-Methoxy Benzaldehyde Zinc Chloride (BLZC) was grown by slow evaporation technique. The grown crystal was subjected to optical characterization by UVVis techniques. The Fourier transform infrared (FT-IR) spectrum was recorded in the range 4000cm-1 - 500cm-1.

Meanwhile, the DFT computations are performed at B3LYP/6-31G (d, p) level to derive equilibrium geometry, vibrational wavenumbers and first hyper polarizability. The nonlinear characteristic and thermal stability of the crystal were also investigated. The HOMO-LUMO energies show that charge transfer occurs within the molecule. The SHG efficiency was measured using the Kurtz powder technique. The efficiency was found to be higher than that of Urea crystal.

Introduction. Applications in NLO materials demand good quality single crystals which derives large NLO coefficient coupled with improved physical parameters [1].The synthesis of new and efficient frequency conversion materials has resulted in the development of new amino acid based NLO materials. Optical second harmonic generation (SHG) requires organic NLO crystals possessing high conversion efficiencies owing to their practical applications in the field of optoelectronics and photonics [2].Natural amino acids have a donor NH2 and COOH due to the possibility of intermolecular charge transfer which exhibits the nonlinear optical property. The donor/acceptor of benzene derivatives can produce high molecular non linearity [3]. There has been much interest in the coordination chemistry of aryl hydrazones such as semicarbazones and thiosemicarbazones due to their importance for drug design, organo catalysis and for the preparation of hetero cyclic rings.

This paper is an investigationwork of Thiosemicarbazone 4-Methoxy Benzaldehyde Zinc Chloride (BLZC).

Experimental Procedure Synthesis and solubility of BLZC.The starting material was synthesized from the analytical reagent grade of thiosemicarbazide, 4-methoxy benzaldehyde and zinc chloride in 2:2:1 molar ratio using ethanol as solvent. According to the reaction scheme, the calculated amount of thiosemicarbazide, 4methoxy benzaldehyde and zinc chloride were taken and dissolved in hot ethanol. The resulting solution was stirred well. Then the solution was filtered, kept at room temperature (30°C) and allowed to evaporate the solvents into the atmosphere. Well defined BLZC crystals with good transparency were obtained in the beaker. The purity of the synthesized material was improved by recrystallization process. The solubility curve is as shown in Fig. 1. The as grown crystal is as shown in Fig. 2.

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Fig. 1. Solubility curve of BLZC.

Fig. 2. Photograph of BLZC crystal.

Powder X-ray diffraction analysis Powder X-ray diffraction studies was carried out for the title compound .The sample was scanned over the range 10°to 40°and it was operated in at a scan rate of 4°/min. The graph is drawn between intensity and 2θ values. From the single crystal analysis, it was observed that BLZC belongs to orthorhombic crystal system having non-centrosymmetry with Aba2 space group. The powder XRD pattern of the grown BLZC crystal is shown Fig. 3. The simulated powder XRDPattern is shown in Fig. 4.

Fig. 3. Experimentally obtained Powder XRD.

Fig. 4. Theoretically simulated Powder XRD.

Computational Details. Using the Gaussian 03 software package combined with the 6-31 G (d, p) basis set, the Quantum chemical density functional theory (DFT) calculations was performed [4], The optimized geometrical parameters and fundamental vibrational frequencies were calculated.

Molecular Geometry. The numbering scheme for BLZC is shown in Fig. 5.

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Fig. 5. Atomic numbering system.

FT-IR Analysis.FT-IR spectrum of BLZC was recorded in the range 4000 cm-1 to 500 cm-1, using KBr pellet technique on BRUKKER IFS FT-IR Spectrometer. The experimental IR spectrum is compared with the results of B3LYP/6-31 G (d, p) calculation. Due to the gaseous phase of isolated molecular state some bands are not observed in theoretically obtained graph. The experimental FTIR is shown in the Fig. 6. The theoretically simulated FT-IR spectrum is shown in Fig. 7.

C-H vibrations.Presence of band in the region 2954cm-1, 2978cm-1 (Theory) and 2936cm-1, 2979cm1 (Experiment) is the characteristic region of C-H stretching vibrations [5]. The C-H bending vibrations are usually occurred in the region 1288cm-1 (Theory)-1447 cm-1 (Theory) and 1310 cm-1 (Experiment), 1377cm-1 (Experiment) (Socrates 2001). In aromatic compounds, the carbon-hydrogen stretching vibrations normally occur at 3072cm-1 (Theory), 3081cm-1 (Experiment).

100

878 3433

3600

Transmittance (%)

498

957 935

768 569 521

642

1055 808

1463

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20 1018

3200

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500

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Wave number (cm )

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Fig. 6. Experimental FT-IR Spectrum.

Fig. 7. FT-IR Spectrum of BLZC crystal by 631 G (d, p) method.

NH2 vibrations The NH2 asymmetric stretching vibrations [6] give rise to a strong band in the region 3350cm-1 (Theory) and the symmetric NH2 stretching is observed as weak band in the region 3151cm-1 3185cm-1 (Theory) and 3180cm-1(Experiment).

C-N vibrations C-N stretching absorptions for primary aromatic amine with nitrogen directly on the ring are assigned in the region 1270cm-1 ,1382cm-1 (Theory) and 1310 cm-1, 1377cm-1 (Experiment). The frequencies are slightly up shifted from the expected value for melamine due to the substitution effect [7].

Hyperpolarizability NLO techniques are considered as one among most the structure-sensitive methods to study molecular structures and assemblies [8]. Molecularhyperpolarizability becomes one of the key factors in the second-order NLO materials design [9]. The calculated first order hyperpolarisability is 15.3863 x 10-30e.s.u.

Homo-Lumo Energy Gap In order to evaluate the energetic behavior of BLZC, the energies of HOMO and LUMO their orbital energy gaps using B3LYP/ 6-31 G (d, p) and shown in Fig 8.

SHG efficiency studies.NLO efficiency of BLZC crystal was determined using Kurtz and Perry second harmonic generation (SHG) test [10]. A sample of urea was powdered to the same particle size as the experimental sample, which is used as a reference material in the present measurement.

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The measured amplitude of SHG for BLZC and urea were 4.51 V and 0.93 V respectively. Thus, the powder SHG efficiency obtained for BLZC is about six times that of urea crystal.

Fig. 8. HOMO – LUMO plot.

Optical absorption spectrum. UV–vis spectral study was carried out in the range 200–1000nm by 5E UV-Vis Instrument spectrophotometer. An optically transparent crystal of BLZC was used for this measurement. The BLZC crystal has sufficient transmittance in the visible and IR regions with lower cut-off wavelength 275 nm as shown in Fig. 9 Using the Tauc relation, the plot of (αhν)2 versus hν was drawn. The direct band gap energy (Eg) of BLZC is determined as 4.7 eV from the Fig. 10.

1.20E+008

2.2

1.00E+008

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8.00E+007

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6.00E+007

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(h) [(eV) (m )]

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4.7eV 0.00E+000

0.8 200

400

600

800

1000

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Wavelength (nm)

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4

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Energy(eV)

Fig. 9. Optical absorption spectrum.

Fig. 10. Optical band gap.

Summary. Optically good quality single crystals of BLZC were grown by slow solvent evaporation technique. X-ray powder diffraction analysis confirms the crystalline nature of the grown crystal.

Density functional theory (DFT) computations using (B3LYP) level with 6-31 G (d, p) basis set gives MMSE Journal. Open Access www.mmse.xyz

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optimized structure parameters of BLZC molecule. Molecular energy gap of BLZC was found as 0.175 a.u by HOMO-LUMO analysis. Optical absorption spectrum was recorded for the given crystal and it is found that it has minimum absorption between 275-1200 nm. The optical band gap of the material is found as 4.7 eV. SHG studies were carried out and the frequency conversion efficiency of the BLZC crystal is found to be six times that of Urea crystal.

References [1] Badan J, Hierle R., Perigaud A, American Chemical Society, Washington, 1993.

[2] Ramesh Kumar G., Gokul Raj S., Mohan R, Jayavel R., (2005), Journal of Crystal Growth, Vol.283, pp. 193–197. DOI: http://dx.doi.org/10.1016/j.jcrysgro.2005.04.103 [3] Marder S R, Sohn J E and Stucky G D (1991), ‘Materials for nonlinear optics – Chemical perspectives’, American Chemical Society, Washington, DC.DOI: 10.1002/actp.1993.010440216 [4] Frisch M J, Trucks G W et al ,Gaussian 03, Revision C.02, Gaussian Inc., Wallingford CT, 2004.

[5] Ramalingam S, Periandy S, Narayanan B, Mohan S, Spectrochim. Acta A 76 (2010) 84–92.DOI: http://dx.doi.org/10.1016/j.saa.2010.02.050 [6] Roeges N G P, A Guide to the Complete Interpretation of the Infrared Spectra of Organic Structures, Wiley, NY, 1994.

[7] Marchewka M K, Pietraszko A, J. Phys. Chem. Solids 64 (2003) 2169 –2181.

DOI:http://dx.doi.org/10.1016/S0022-3697 (03)00218-X [8] Varsanyi, vols. 1 and 2 Assignments for Vibrational Spectra of Seven Hundred Benzene Derivatives, Academia kiado, Budapest, 1973.

[9] Rice J E, Handy NC, J ChemPhys, 94 (1991) 4959. DOI.org/10.1063/1.460558.

[10] Li H, Han K, Shen X, Lu Z, Huang Z, Zhang W, Zhang Z, Bai L, J Mol Strut (Theochem), 767(2006)113.DOI: DOI.org/10.1016/j.theochem.2006.05.008.

Cite the paper S. Attralarasan, A. Shiny Febena, M. Victor Antony Raj, J. Madhavan (2017). Synthesis, Characterization and DFT Calculations of Thiosemicarbazone 4-Methoxy Benzaldehyde Zinc Chloride. Mechanics, Materials Science & Engineering, Vol 9. doi 10.2412/mmse.98.79.782

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Spectroscopic Characterization, NLO Properties and DFT Study of Amino Acid Single Crystals of Glycine Nickel Chloride50 A. Shiny Febena1, a, M. Victor Antony Raj1, J. Madhavan1 1 – Department of Physics, Loyola College, Chennai, India a – shinyfebena@gmail.com DOI 10.2412/mmse.48.92.693 provided by Seo4U.link

Keywords. DFT, HOMO-LUMO, TG-DTA, SHG, Kurtz and Perry powder.

ABSTRACT. Semi Organic nonlinear optical single crystal of Glycine Nickel Chloride was successfully grown by the Slow Evaporation Solution Growth Technique (SEST). Formation of the crystalline compound, the cell parameters and the non-centrosymmetric nature was confirmed by single crystal X-ray diffraction studies.Structural confirmation was done by identifying the vibrational modes using FT- IR spectroscopic studies. The quantum chemical analyses were performed by density functional theory (DFT) using B3LYP/6-31G (d, p) basis set. The calculated first order hyperpolarizability of GNC is 0.233 x 10 -30 e.s.u. The HOMO and LUMO energies show that charge transfer occurs within molecule. The thermal behavior was analyzed by simultaneous TG-DTA studies. The UV–visible studies were employed to examine the high optical transparency and influential optical constants for tailoring materials suitability for optoelectronics applications. The second harmonic generation (SHG) measured by the Kurtz and Perry powder technique was found to be 3.2 times that of KDP. The result suggests Glycine Nickel Chloride as a promising candidate for optical devices applications.

Introduction. Advanced optoelectronic technology requires nonlinear optical (NLO) materials for frequency conversion, optical modulation and optical switching [1, 2]. Efforts have been made on the amino acid mixed organic and inorganic complexes for suitable device applications. The intense charge transfer between metal and ligands causes NLO nature and good transparency in visible region and high resistance to optical damage [3, 4].In the present work, glycine with nickel chloride formed a non-centro symmetric glycine nickel dichloride dihydrate crystals.

Experimental Details Synthesis and Solubility of GNC. High purity Glycine and Nickel (II) chloride were used for growing single crystals of GNC. The synthesized salt was purified by repeated crystallization process.

Fig. 1 shows the solubility curve of GNC. Supersaturated solution of GNC was prepared in accordance with the solubility data. A few drops of H2O2 were added to the mother solution as antimicrobial substance.Good optical grade crystals of dimension up to 9 x 2 x 4 mm3were harvested.

Fig. 2 shows the photograph of as grown GNC single crystal.

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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Fig. 1. The solubility curve.

Fig. 2. Photograph of as grown crystal.

Results and Discussion.

X-ray diffraction analysis. Among the grown crystals of GNCwell-shaped, transparent, single crystal was selected and it was subjected to single crystal XRD analysis usingENRAF NONIUS CAD4 X-ray diffractometer with MoK radiation at room temperature. From the analysis data it was observed that the crystal belongs to monoclinic crystal system having non-centrosymmetry with P21 space group. The details of crystal parameters are summarized in Table 1. XRD pattern of GNC is shown in Fig. 3. Theoretically Simulated XRD pattern of GNC single crystal with indexed peak is given in Fig. 4. Both the patterns coincide well.

Computational Details and Molecular Geometry. The optimized molecular structure of GNC and corresponding vibrational harmonic frequencies were calculated using Beckee-3-Lee-Yag-Parr (B3LYP) combined with 6-31 G(d, p) basis set [5].The optimized molecular structure of the isolated GNC molecule is calculated using Density Functional Theory at B3LYP/6-31 level is shown in Fig. 5.

Vibrational assignments. It is found that GNC molecule has 19 moieties and is in stable conformation with C1 symmetry then exhibits 51 normal modes of vibrations. The normal modes of GNC is distributed amongst the symmetry species as Γ3N-6 = 35A′ (in-plane) +16A″ (out-of-plane) respectively.

Fig. 3. XRD spectrum of GNC.

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Fig. 4. Theoretically simulated XRD pattern.

Table 1. Crystal parameters of GNC. Empirical Formula Formula weight Wave length Crystal system, Space group

C2H9Cl2NNiO4 240.71 0.71073 nm Monoclinic P21

Fig. 5. Atomic numbering system.

Unit cell dimensions a = 8.183 Ǻ α =γ=90° b = 5.480 Ǻ β=90.97° c = 8.315 Ǻ

Fig. 6. Experimental FT-IR.

FT-IR Analysis. The FT-IR spectrum was recorded in the range 500 cm-1 to 4000 cm-1, using KBr pellet technique on IFS 66V FT-IR Spectrometer. Recorded FT-IR spectrum is shown in Fig. 6.

C-N vibrations. The stretching vibration bands of C-N ring occur in the region 1600 cm-1-1500 cm- 1[6]. The theoretical and experimental peaks appear at 1500 cm-1 and 1496 cm-1 respectively.

NH2 vibrations. The NH2 asymmetric stretching vibrations [7] give rise to a strong band in the region 3390±60 cm-1 and the symmetric NH2 stretching is observed as weak band in the region 3210±60 cm- 1. The theoretical asymmetric stretching appears at 3359 cm-1 and 3422 cm-1 and the experimental value coincides well at 3378 cm-1.

C-Cl vibrations. The band at 366 and 367cm-1 is assigned for C-Cl in-plane bending for FT-IR 144 cm-1 and 142 cm-1 is for out-of-plane bending vibrations for FT-IR [8]. The vibrational assignments of fundamental modes of GNC by DFT methods are reported in Table 2.

Hyperpolarizability. In the second-order NLO materials designMolecular hyperpolarizability β is an important key factor [9, 10].The calculated first order hyperpolarizability of GNC is 0.233 x 10-30 e.s.u.

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HOMO and LUMO analysis. The HOMO–LUMO energy gap of GNC is calculated at B3LYP/631G (d, p) levels are shown in Fig. 7.

HOMO energy (B3LYP) = -0.272a.u.

LUMO energy (B3LYP) = -0.046 a.u.

HOMO–LUMO energy gap (B3LYP) = 0.226 a.u.

Table 2. Selected Experimental and Calculated B3LYP/6-31 G vibrational frequencies of GNC. Frequency cm-1 Spectroscopic No. assignment B3LYP Expt.

1.

515.9829 516 COO- d+ CCl st 2.

655.1160 661 COO- d +NH opd 3.

691.5787 674 NH opd+NH2 wag 4.

875.2665 887 CH3 opb 5.

953.3112 913 C=O opd 6.

1099.547 1029 OH ipb 7.

1165.119 1113 II CH ipd 8.

1265.0148 1254 COO- st&b 9.

1456.8423 1447 COO- sym st 10.

1500.4299 1496 NH3+ sym d+CN st 11.

1633.7591 1622 NH3+ asy d 12.

2314.5824 2029 CH vib(IR) 13.

3359.1695 3373 NH3+ asy st

(d,

p)

level

of

SHG efficiency studies.A Q-switched Nd: YAG laser beam of 1064nm wavelength with 6.5mJ input power, 8ns pulse width was used. SHG was confirmed by the emission of green light. Using reference material as potassium dihydrogen phosphate (KDP), the output of SHG signal was compared and found that the SHG conversion efficiency of GNC is 3.2 times that of KDP.

Fig. 7. HOMO – LUMO plot of GNC at B3LYP/6-31 G (d, p).

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Optical absorption spectrum. The optical absorption spectral analysis of GNC was recorded between 190nm and 1100nm. It is evident that GNC crystal has UV cut off at 236 nm. The recorded absorption spectrum is shown in Fig. 8.A graph to estimate the direct band gap valuehas been plotted between photon energy and (αhν)2 where α is the absorption coefficient and hν is the energy of the incident photon. From the Fig. 9, the band gap energy is found to be 3.27 eV. Thermo gravimetric analysis. The weight loss was observed in four steps. In the first stage the weight loss starts at 44.4°C and completes at 175°C this may be due to adsorption of water molecules as the loss is recorded as 8.47%. On further heating, the second mass loss starts at 175°C and ends at 375°C. The maximum weight loss of 48.89% is observed in this stage. The third and fourth stage extends from 375°C to 910 °C with a total weight loss of 25.86%. The DTA curve shows sharp endothermic peaks which are in good agreement with TGA trace. TGA and DTA graphs are shown in Fig. 10.

Fig. 10. TGA and DTA curve of GNC crystal.

Summary. In this work, report on the preparation, growth, and the characterization of Single crystal of an aminoacid based nonlinear optical material GNC have been reported. XRD data indicates the monoclinic structure of GNC.FT-IR analysis confirmed the functional groups. The UV-Vis spectrum reveals minimum absorption in the entire visible region. Thermal stability with high power efficiency exhibits the potential of GNC in the field of laser and opto-electronic device fabrications.

References [1] Lydia Caroline M, Vasudevan DOI.org/10.1016/j.matlet.2007.11.059.

S,

Mater.

Lett.

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(2008)

2245–2248.

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[2] Madhavan J , Aruna S , Anuradha A , Premanand D, Vetha Potheher I , Thamizharasan K, Sagayaraj P, J Optical Materials 29 (2007) 1211–1216.DOI.org/10.1016/j.optmat.2006.04.013.

[3] Arularasan P, Thayanithi V, Mohan R, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 144 (2015) 8–16.DOI: 10.1016/j.saa.2015.01.078.

[4] Joseph G P, Korah I, Rajarajan K, Thomas P C, Vimalan M, Madhavan J and Sagayaraj P (2007), Cryst. Res. Technology, Vol. 42, pp. 295-299. DOI: 10.1002/crat.200610816.

[5] Frisch M.J, et al, Gaussian 03, Revision C.02, Gaussian Inc.,Wallingford, CT, 2004.

[6] Socrates G, Infrared and Raman Characteristic Group Frequency, third ed., Wiley, New York, 2001.

[7] Roeges N G P, A Guide to the Complete Interpretation of the Infrared Spectra of Organic Structures, Wiley, NY, (1994).

[8] Krishnan A R, Saleem H, Subash Chandara Bose S, Sundaraganesan N, Sebatain S, Spectrochim.

Acta A 78 (2011) 582. DOI.org/10.1016/j.saa.2010.11.027.

[9] Rice J E, Handy N C., J Chem Phys., 94 (1991)4959. DOI.org/10.1063/1.460558.

[10] Li H, Han K, Shen X, Lu Z, Huang Z, Zhang W, Zhang Z, Bai L, J Mol Strut (Theochem), 767(2006)113. DOI.org/10.1016/j.theochem.2006.05.008.

Cite the paper A. Shiny Febena, M. Victor Antony Raj, J. Madhavan, (2017). Spectroscopic Characterization, NLO Properties and DFT Study of Amino Acid Single Crystals of Glycine Nickel Chloride. Mechanics, Materials Science & Engineering, Vol 9. doi 10.2412/mmse.48.92.693

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Experimental and Computational Studies on L - Histidinium DipicrateDihydrate51 R. Subaranjani1, a, M. Victor Antony Raj1, J. Madhavan1 1 – Department of Physics, Loyola College, Chennai, India a – subaranjani07@gmail.com DOI 10.2412/mmse.82.65.951 provided by Seo4U.link

Keywords: XRD, FT-IR, SHG, NLO, UV-visible, DFT. ABSTRACT. Good quality single crystal of L-Histidiniumdipicrate dehydratewas grown by slow evaporation method.

The structure of the grown crystal as determined by single crystal XRD diffraction analysis revealed that it belongs to the monoclinic system with space group P21. The presence of functional groups in the LHDP was confirmed by FT-IR. FTIR spectrum of the grown crystal was recorded in the range 400 cm-1 to 4000 cm-1 using KBr pellet technique on BRUKKER IFS FT-IR Spectrometer. Vibrational patterns and the good crytstallinity were indicated by powder X-ray diffraction method. The crystal system was identified by single crystal XRD method using ENRAF NONIUS CAD-4 single X-ray diffractometerwith MoKα radiation (λ=0.71073 Å). Thermogravimetric and differential thermal analyses revealed the thermal stability of the crystal. The Optical band gap energy (E g) for the crystal was calculated to be 4.9eV.

Introduction.Nonlinear optical (NLO) materials are gaining enormous demand due to their wide applications in the recent technologies like, optical communications, optical switching, information storage and photonics technology [1, 2]. Organic crystals are of special interest compared to inorganic crystals.L-histidine gained the status of promising NLO materials after detailed research [3]. It is reported that L-histidinetetrafluoro borate has higher NLO properties than L-Arginine Phosphate (LAP). The function and role of histidine and its residues in living matter is characterized by the imidazole group. The NLO process requires materials that manipulate the amplitude, phase, polarization and frequency of optical beams. FTIR and UV–vis–NIR studies of the title compound are discussed.

Experimental Procedure.The synthesis of the title compound LHDP was achieved by adding Lhistidine and picric acid (E-Merck) in 1:2 stoichiometric proportions in distilled water. The solution was thoroughly mixed to get a clear yellow solution which was filtered and kept aside. The solubility (g LHDP / 100ml H2O) of LHDP was measured by the method described by Wang et al (1999)[4].

The solubility curve is shown in Fig. 1. The crystals are grown by using the slow solvent evaporation technique at room temperature. Crystals of dimension up to 17 x 3 x 6 mm3 were obtained after a period of 45 days. The crystals are highly transparent and free from visible inclusions. Fig. 2 shows the photograph of as grown crystal of LHDP. Characterization

Single crystal XRD Analysis. Single crystals of LHDP have been grown by slow evaporation technique and crystal system was identified by single crystal XRD method using ENRAF NONIUS CAD-4 single X-ray diffractometerwith MoKα radiation (λ=0.71073 Å). The crystal data is given in Table 1.

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Fig. 1. Solubility curve of LHDP.

Fig. 2. Photograph of as grown LHDP single crystal.

Powder X-ray Diffraction analysis.The powder XRD study was also carried out to check the correctness of the data and to identify the diffraction planes of the grown crystal. Experimental Powder XRD pattern is shown in Fig 3. Theoretically Simulated XRD pattern of LHDP single crystal is given in Fig 4. Both XRD patterns are almost similar in comparison.

Fig. 3. Experimentally obtained powder XRD.

Fig. 4. Theoretically simulated powder XRD.

Computational Details. The equilibrium optimized geometrical parameters of LHDP molecule and the harmonic wavenumbers associated with its vibrational normal modes were calculated at B3LYP level of theory using the Gaussian 03 program package. The optimized geometry corresponding to the minimum on the potential energy surface has been obtained by solving self-consisting field equations iteratively. The optimized structural parameters were used to analyze all stationary points as minima for Infrared (IR) calculations at the same level of theory. By combining the theoretical results vibrational frequency assignments were made with a high degree of accuracy. The optimized geometrical parameters and fundamental vibrational frequencies were calculated using B3LYP/6-31(d, p).

Table 1. Crystal parameters of LHDP. Empirical Formula Formula weight Wave length Crystal system, Space group

C18H19N9O18 255.614 g/mol 0.71073 Å Monoclinic P21

Unit cell dimensions α =γ=90° a = 6.6065(1) Ǻ β=107.536° b = 25.7004(2)Ǻ c =7.9629(2)Ǻ

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Molecular Geometry The molecular structure along with numbering of atoms of LHDP was as shown in the Fig. 5.The selected vibrational assignment of LHDP molecule is given in Table 2.

Vibrational Analysis. The vibrational spectral assignments were carried out with the aid of normal co-ordinate analysis (NCA) followed by force field calculation with the same level of theory as was employed for the geometry optimization of the molecule. The title molecule LHDP has 64 atoms. It has 186 (3N – 6) normal vibrational modes .The theoretical and experimental wavenumbers are in fair agreement, and assignments of wavenumbers for different functional FT-IR spectrum of the grown crystal was recorded in the range 400 cm-1 to 4000 cm-1, using KBr pellet technique on BRUKKER IFS FT-IR Spectrometer. The experimental IR spectrum is compared with the results of B3LYP/6-31 G (d, p) calculation carried out for the title compound. The experimental FT-IR spectrum is shown in Fig. 6.

Fig. 5. Atomic numbering system of LHDP molecule.

Table 2. Selected Vibrational Assignments of LHDP molecule.

Frequency cm-1 Spectroscopic No Assignment B3LYP Experimental 1 2990.9085 2991 C-H st 2 2854.0305 2861 NH3asy st 3 1828.7112 1859 C O st 4 1637.6173 1617 NH3sy b 5 1587.4007 1588 NH3asydef 6 1333.3448 1326 CH opb 7 1449.8902 1438 OH ipb 8 1161.6827 1163 CH2 roc 9 1276.3151 1281 OH ipb 10 922.8158 914 NH3 roc 11 835.2978 833 CH opb 12 724.7566 712 R opb 13 626.8864 626 O-H opb 14 548.2281 555 C-C ben St-stretching; syst- symmetry stretching;asyst- asymmetry stretching; ipb-in-planebending; opb- out-of-plane bending; roc – rocking; asydef – asymmetric deformation

NH3 Vibrations

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The NH3 asymmetric deformation vibrations usually appear in the region 1660–1610 cm-1 and that of the symmetric deformation in the region 1550–1485 cm−1 [5]. In LHDP, the NH3 asymmetric deformation vibrations are observed as a very strong band at 1587 cm−1 in IR and the symmetric bending modes are observed as a strong band in IR at 1637 cm−1.Both the vibrations have its experimental values at1588 and1617 cm-1. The NH3 rocking modes appear as a weak band in IR at 922 cm−1 and experimental shows at 914cm-1.

Hydroxyl vibrations The OH stretching vibrations are sensitive to hydrogen bonding. The non-hydrogen-bonded or free hydroxyl group absorbs strongly in the 3600–3400 cm-1 region, whereas the existence of intermolecular hydrogen-bond formation can lower the O-Hstretching wavenumber around to the 3500 cm-1 region increase in IR intensity and breadth [6, 7].The strong band observed in IR at 3414cm-1 corresponds to OH stretching vibrations. The O–H out of plane bending vibration gives rise to a strong band in the region 700–600 cm−1[8]. The calculated values of OH group vibrations are in good agreement with the experimental results.

Fig. 6. Experimentally obtained FT-IR spectrum of LHDP.

UV-Vis study. The optical absorption spectrum of the grown LHDP crystal was recorded UV–Visible spectrophotometer in the wavelength range from 200 nm to 1000 nm. The recorded spectrum is shown in Fig. 7.In 280 nm, the lower cut-off wavelength of the crystal is found and thus ascertain fact that the crystal can be used for laser applications.Using Tauc relation a graph was plotted to estimate the band gap values. Fig. 8 shows the plot of (αhν)2 versus hν, where α is the optical absorption coefficient and hν is the energy of the incident photon. The energy gap (Eg) is determined by extrapolating the straight line portion of the curve to (αhν)2 = 0. From this graph, the band gap (Eg) is found to be 4.9eV.

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Fig. 7. Optical absorption spectrum of LHDP.

Fig. 8. Energy band gap of LHDP.

Thermal analysis. The thermo gravimetric analysis and differential thermal analysis (TG/DTA) of LHDP crystal are displayed in Fig 9. The first stageofdecompositioncommencesat 179°C and ends at 310°C. The next weight loss occurs between 310°C to500°C with the loss percentage of 15.6.The third weight loss is between 500°Cand 900°C. The TG study of the LHDP crystal shows that the crystal is stable up 179°C. LHDP decomposes completely as no residue remains after 900°C. The DTA traces coincide well with the TGA traces.

Fig. 9. TG-DTA curves of LHDP single crystal.

Summary. Good quality single crystals of LHDP were grown by the slow evaporation solution growth technique. The lattice parameters were confirmed using single crystal X-ray diffraction analysis. The functional groups were ascertained by FT-IR and Raman studies. The energy gap (Eg) is determined by extrapolating the straight line portion of the curve to (αhν)2 = 0. From this graph, the band gap (Eg) is found to be 4.9eV.The thermal behavior of the grown LHDP was studied using TG–DTA. References [1] Kumaresan P., MoorthyBabu S., Anbarasan P.M., Opt. Mater. 30 (2008) 1361. http://dx.doi.org/10.1016/j.optmat.2007.07.002 [2] Prasad P.N., Williams D.J., Introduction to nonlinear optical effects in organic molecules and polymers, Wiley, New York, 1991.

[3] Marcy H.O., Rosker M.J., Warren L.F., Cunningham P.H., and Thomas C.A., Optics Letters, 20 (3) (1995) 252. DOI: 10.4236/jmmce.2009.85035 [4] Wang J, Ren M, Wang S, Qu Y, Spectrochim. Acta A, 78(3) (1999) 1126-1132 http://dx.doi.org/10.1016/j.saa.2010.12.064 [5] Silverstein R. M, Webster. F. X., Spectrometric Identification of Organic Compounds., John Wiley and sons, New York, 2003.

[6] Socrates G., Infrared Characteristic Group Frequencies, John Wiley and Sons, New York, 1980

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[7] Dhanaraj G., Srinivasan M.R., 181DOI: 10.1002/jrs.1250220307

Bhat

H.L.,

Raman

Spectrosc.

22

(1991)

177â&#x20AC;&#x201C;

[8] Colthup N.B, L.H. Daly, S.E. Wiberley., Introduction to Infrared and Raman Spectroscopy., Academic Press, New York, 1990.

Cite the paper R. Subaranjani, M. Victor Antony Raj, J. Madhavan, (2017). Experimental and Computational Studies on L Histidinium DipicrateDihydrate . Mechanics, Materials Science & Engineering, Vol 9. doi 10.2412/mmse.82.65.951

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Alkali Fusion Process of Waste Stone Dust to Synthesize Faujasite Using Rotaky Kiln52 Shinji Onishi1, a, Takaaki Wajima1, Toshio Imai2, Sano Susumu2 1 – Chiba University, Chiba, Japan 2 – Taiheiyo Cement Corporation, Tokyo, Japan a – afca3242@chiba-u.jp DOI 10.2412/mmse.49.15.388 provided by Seo4U.link

Keywords: Alkali fusion, Faujasite zeolite, rotaly kiln, waste stone dust.

ABSTRACT. During quarrying, a large amount of waste stone dust is discharged as industrial wastes, and most parts of it dumps at landfill sites. The lack of landfill sites in Japan causes an increase of disposal cost, and new effective use is needed. In our previous studies, we attempted to synthesize zeolite from the dust using alkali fusion treatment to increase the solubility of silicon and aluminum in the dust, and we succeeded to synthesize faujasite zeolite from the dust. However, little information can be available on alkali fusion treatment of waste stone dust to synthesize zeolite. In this study, we attempted to treat continuously the dust by alkali fusion using a rotary kiln, and the effect of alkali fusion process on synthesis of faujasite from the fused material was examined. The mixture of the dust and NaOH powder with the weight ratios of 1:1.2, 1:1.4 and 1:1.6 was put into a rotary kiln, and heating at 400 -500 oC for 30 min, and the obtained fused material was converted into zeolite product by heating at 80 oC for 12 h followed by shaking 24h in distilled water at room temperature. It was confirmed that sodium silicate was formed using a rotary kiln, and the dissolution of Si and Al in the fused material increases with increasing NaOH addition. Faujasite can be synthesized on all fused conditions, and the cation exchange capacity of the product decreases with increasing NaOH addition. Regardless of fusion temperature, sodium silicate was formed using a rotary kiln, and the dissolution of Si and Al in the fused materials obtained on all condition are almost same. Faujasite can be synthesized on all fused conditions, and the cation exchange capacity of the product decreases with increasing temperature.

Introduction. In Japan, exhaustion of natural resources has become a problem and effective utilization and recycling of unused resources has become an important issue. On crushed stone industry, waste stone dust was discharged as by product when producing crushed stone product from raw stone. The amount of waste stone dust is about 10% weight of crushed stone products, and annual output is 50 million tons [1]. Although a part of the waste stone dust is used for civil engineering material, the major parts of it disposed in landfills. However, in recent years, landfill is difficult due to the lack of disposal sites, and the cost of landfill increases in Japan. Therefore, a new effective method of crushed stone dust is required.One of the effective utilization is to convert waste stone cake into zeolitic materials. Zeolites are a group of over 40 crystalline, hydrate alumino-silicate minerals with a structure based on a three-dimensional network of aluminum and silicon tetrahedra linked by sharing of oxygen atoms [2]. Due to specific pore sizes and large surface areas, zeolites have the potential for a wide range of applications such as molecular sieves, adsorbents, and catalysts.In our previous studies, we succeeded in synthesizing highly functional faujasite type zeolite by subjecting waste stone dust to alkali fusion[3]. However, effective fusion process is necessary for a large amount of dust generated annual. Therefore, we proposed to treat a large amount of waste stone dust with rotary kiln.In this study, we attempted to use a rotary kiln for continuously alkali fusion process to be synthesized to zeolites material. © 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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Experimental. The waste stone dust was obtained from one of the plant in Japan. The chemical composition of raw stone dust was shown in table 1, and the mineral composition, as measured by powder X-ray diffraction (XRD, Rigaku, MiniFlex600), was shown in Fig. 1. Waste stone dust is mainly composed of SiO2 in the form of quartz and Al 2O3, which is enough to synthesize zeolite.

Impurity, CaO in the form of calcite, is also confirmed.

Table 1. Chemical composition of raw stone dust.

Content (wt.%) SiO2

62.8

Al2O3

19.2

CaO

2.8

Fe2O3

6.1

Na2O

1.9

MgO

1.7

SO3

1.4

Fig. 1. XRD patterns of raw stone dust.

Rotary kiln was used for alkali fusion process in this experiment. Fig. 2 shows the photo of the rotary kiln, and the specifications of rotary kiln was shown in Table 2.

Fig. 2. Photos of rotary kiln.

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Table 2. Specifications of rotary kiln.

Core tube dimensions (mm) Raw material input 7 kg/h

Heat source Core pipe length

Inner diameter

Effective heating width

1560

150

700

Electrical

Rotational speed

Angle of inclination

Maximum tempreture

Heat source

64 - 256 (rpm)

～5 °

1500 ℃

Electrical

The following operations were carried out to perform the alkali fusion process of waste stone dust.

Firstly, effect of NaOH addition on alkali fusion to synthesize zeolite was examined. The waste stone dust and NaOH powder was mixed to prepare the mixture. The weight ratios of the dust to NaOH were 1: 1.2, 1:1.4 and 1:1.6. These each mixtures were charged into a rotary kiln. The heating temperature of the rotary kiln is 400oC, the inclination angle is 2 o, the rotational speed is 80 rpm, the retention time in the kiln is 30 min. Secondly, effect of heating temperature on alkali fusion to synthesize zeolite was examined. The mixture with mixing ratio of 1: 1.4 was charged into rotaly kiln at 400, 450 and 500 oC. Inclination angle, rotation speed and retention time are the same conditions.

Mineral composition of the discharged sample was analyzed by XRD. The solubility of Si and Al in the fused sample was estimated as follows. 0.1 g of fused sample was added into 1 M HCl solution (10 mL), and shaken for 6 h. After shaking, the Si and Al concentration in the filtrate was measured by atomic absorption spectrophotometer (AAS, Perkin Elmer, AAnalyst200), and the solubility was calculated.

The following operations were carried out to synthesize zeolite from the fused materials. 0.5 g of the fused materials was added into 20 mL of distilled water, and shaken for 24 h. After shaking, it was heated for 12 h at 80 。C in the oil bath. After heating, the solid was filtered and dried overnight in a drying oven at 60 。C to obtain the resulting product. The product was analyzed by XRD, and the cation exchange capacity (CEC) of the products was measured by the method reported by Wajima et al. [4].

Results and discussion. Fig. 3 shows the XRD pattern of the alkali fusion samples with different amounts of NaOH addition, and Table 3 shows the solubility of Si and Al. From Fig. 3, peaks of sodium silicates which have high solubility were confirmed on all condition. The peaks of NaOH cannot be confirmed in all XRD patterns. It is considered that all added NaOH was reacted with silicate to form sodium silicate. From Table 3, the amount of dissolved Si and Al is greatly increased as compared with dust. The amount of dissolution increases as the amount of added NaOH increases, due to the formation of sodium silicate.

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Fig. 3. XRD pattern of the alkali fusion samples with different amounts of NaOH addition.

Table 3. Solubility of Si and Al in the alkali fusion sample.

Solubility (g/g) Weight ratios of the dust to NaOH

Temperature (oC) Si

Al

Raw dust

0.003

0.003

1 : 1.2

0.141

0.061

0.153

0.062

0.160

0.072

1 : 1.4

450

1 : 1.6

Fig. 4 shows the XRD pattern of the alkali fusion sample obtained at different temperatures, and Table 4 shows the solubility of Si and Al. Peaks of sodium silicate were also confirmed on all conditions. Regardless of heating temperatures, here was no significant change for XRD pattern and dissolution amounts, meaning that alkali fusion can be enoughly done above 400 oC.

Fig. 4. XRD patterns of the alkali fusion samples obtained at different temperature.

Table 4. Solubility of Si and Al in the fused samples.

Weight ratios of the dust to NaOH

Temperature (oC)

Si

Al

0.003

0.003

400

0.150

0.056

450

0.153

0.062

500

0.150

0.053

Raw dust

1 : 1.4

Solubility (g/g)

Fig. 5 shows the XRD pattern of the product synthesized from samples with different amounts of NaOH addtion, and Table 5 shown the cation exchange capacity of the products. Peaks of fuajasite type zeolite was confirmed in all products. The peaks of faujasite and the cation exchange capacity decrease as the added amount of NaOH increases. It is considered that excess NaOH addition causes the inhibition of faujasite zeolite synthesis.

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Comparing the cation exchange capacity of the commercially available faujasite type zeolite, Molecular Sieves 13X (Wako, Japan), CEC of the obtained product is about 1/3 times the commercially available zeolite.

Fig. 5. XRD patterns of the product synthesized from samples with different amounts of NaOH addition.

Table 5. Cation exchange capacity of the products.

Sample

Cation exchange capacity (mmol/g)

Raw dust

0.13

1 : 1.2

1.30

1 : 1.4

1.26

1 : 1.6

1.25

Molecular Sieves 13X

3.20

Fig. 6 shows the XRD pattern of the product synthesized from samples obtained at different temperatures, and Table 6 shows the cation exchange capacity of the products. Peaks of fuajasite type zeolite were also confirmed on all conditions. The peaks of faujasite decreases and the cation exchange capacity decreases as the fusion temperature increases. It is considered that alkali fusion at high temperature causes the inhibition of faujasite zeolite synthesise.

Fig. 6. XRD patterns of the product synthesized from samples obtained at different temperatures.

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Table 6. Cation exchange capacity of the products.

Sample

Cation exchange capacity (mmol/g)

Raw dust

0.13

1 : 1.2

1.28

1 : 1.4

1.26

1 : 1.6

1.22

Molecular Sieves 13X

3.20

Summary. By using a rotary kiln, a large amount of waste stone dust could be continuously converted into fused materials with high solubility to synthesize faujasite zeolite.

References [1] T. Wajima, Conversion of Waste Sandstone Cake into Crystalline Zeolite X Using Alkali Fusion, Materials Transactions, Vol. 51, 2010, 849-854. DOI: 10.2320/matertrans.MH200905 [2] T.Wajima, Synthesis of Zeolitic Material from Waste Sandstone Cake Using Alkali Fusion, Japan Society of Ion Exchange, Vol. 18, 286-289. DOI: 10.5182/jaie.18.286 [3] T.Wajima, Synthesis of Zeolite X from Waste Sandstone Cake Using Alkali Fusion Method, Materials Transactions, Vol. 49, 612-618. DOI: 10.2320/matertrans.MRA2007250 [4] T.Wajima, Zeolite synthesis from paper sludge ash at low temperature (90 °C) with addition of diatomite, Journal of Hazardous Materials, vol. 132, 244-252. DOI: 10.1016/j.jhazmat.2005.09.045 [5] Mori, H. Extraction of silicon dioxide from waste colored glasses by alkali fusion using potassium hydroxide, Journal of Materials Science (2003) 38: 3461. doi:10.1023/A:1025100901693 Cite the paper Shinji Onishi, Takaaki Wajima, Toshio Imai, Sano Susumu (2017). Alkali Fusion Process of Waste Stone Dust to Synthesize Faujasite using Rotaky Kiln. Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.49.15.388

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Growth, Structural and Optical Behaviour of L-Histidinium perchlorate: A Nonlinear Optical Single Crystal53 R. Vincent Femilaa1, M. Victor Antony Raj1, J. Madhavan1, a 1 – Department of Physics, Loyola College, Chennai, India a – jmadhavang@gmail.com DOI 10.2412/mmse.30.36.520 provided by Seo4U.link

Keywords: NLO, LHPCL, XRD, DFT, HOMO, LUMO, KDP.

ABSTRACT. In this work, a non linear optical (NLO) materialL-Histidinium Perchlorate (LHPCL) was reported for both the experimental and theoretical study, where the title compound, which is a single crystal was grown using a slow evaporation method at the room temperature and from the single crystal analysis, the crystal was observed to be a monoclinic crystal which had non-centrosymmetry with space group P21. From Powder XRD study, both the experimental and theoretical XRD patterns were found to be similar in comparison. From density functional theoretical (DFT) computations, the optimization of the molecular structure and the corresponding vibrational harmonic frequencies were calculated for the title compound and to evaluate the energetic behaviour of the material the HOMO and LUMO orbital energy gaps were performed. The NLO test was performed and a second harmonic efficiency was found nearly to be3.44 times that of KDP.

Introduction. Large number of L-histidine compounds had excellent nonlinear optical property [1].

By combining a counter inorganic ion and an organic ion, a typical semi-organic crystal was formed.

Amino acids and inorganic acids were good raw material for the production of semi-organic crystal [2]. To synthesize new organic materials with large second-order optical nonlinearities,many investigations were conducted in order to satisfy day-to-day technological requirements. In telecommunications, optical computing, optical data storage, etc they had an innumerable potential applications. Due to inherent ultra fast response, the large optical susceptibilities and high optical thresholds for laser power was compared to inorganic materials and the organic nonlinear materials attracted a great deal of attention [3]. In the present work an attempt was made to grow a NLO material L-Histidinium Perchlorate (LHPCL) using slow evaporation method with L-Histidine and Perchloric acid. Then the material was characterized and the results were reported from the characterization techniques such as XRD, DFT and HOMO-LUMO. Experimental Procedure. A stoichiometric amount of L-Histidine (Merck-99%) and high purity perchloric acid (Merck) was added in deionized water to achieve the synthesization of the title compound LHPCL and the solubility (g LHPCL / 100ml H2O) of LHPCL was measured [4]. Fig 1 shows the study of variation of solubility with temperature and its corresponding curve. After a period of 45 days, crystals of dimension up to 6mm x 5mm x 2mm were obtained. The crystals were free from visible inclusions and highly transparent. The photograph of as grown crystal of LHPCL was shown in Fig 2.

Using ENRAF NONIUS CAD 4 single crystal X-ray diffractometer with MoKα radiation (λ=0.71073 Å), the grown crystal was subjected to single crystal X-ray diffraction study at room temperature.

The crystal was observed to be a monoclinic crystal from the single crystal analysisand had noncentrosymmetry with space group P21. Table 1 shows the crystal and its structural refinement data. © 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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Fig. 1. Solubility curve of LHPCL.

Fig. 2. Photograph of grown LHPCL single crystal.

Table 1. Crystal parameters of LHPCL. Empirical Formula

ClO6C6N3H10

Formula weight

255.614 g/mol

Wave length

0.71073 Å

Crystal system, Space group

Monoclinic, P21

Unit cell dimensions

a =5.052(1) b =9.194(2) c = 10.388(2)

α = γ = 90° β =92.34°

Powder X-ray Diffraction. Using RICH SIEFERT X-ray Diffractometer with CuKα (Kα = 1.5406 Å) radiation, the grown crystal was subjected to powder X-ray diffraction studies at room temperaturewhere Fig 3 shows the experimental Powder XRD pattern and Fig 4 shows the theoretically simulated XRD pattern of LHPCL single crystal. As a result both XRD patterns were found to be similar in comparison.

Fig. 3. Experimentally obtained powder XRD pattern of LHPCL.

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(2 1 -1)

(0 1 4) (2 0 -1)

(1 1 2) (0 3 2) (0 0 4)

(1 0 3)

150

(0 3 1)

(1 2 -1)

(1 0 -2)

300

(1 0 1) (1 1 0) (1 1 0) (1 1 1)

450

(0 1 1)

Intensity (arb. units)

(1 1 1)

600

0 10

20

30

40

Two theeta

Fig. 4. Theoretically simulated powder XRD pattern of LHPCL. Computational Details. By wavenumber calculations, the stability of the optimized geometries was confirmed and this gave the positive values for all the obtained wave numbers. A high degree of accuracy was made with vibrational frequency assignments by combining the theoretical results.

Vibrational assignments. The title molecule has got 72 (3N – 6) normal vibrational modes and 26 atoms. Γvib = 49 A΄ (in-plane) + 23 A˝ (out-of-plane) was the distribution of the 72 normal modes of LHPCL amongst the symmetry species. In Infrared absorption, all the 72 fundamental vibrations were found active. Table 2 shows the selected vibrational assignments of LHPCL for the experimental FTIR frequencies along with the calculated frequencies.

Using KBr pellet technique on BRUKKER IFS FT-IR Spectrometer,the FT-IR spectrum of the grown crystal was recorded in the range 400cm-1 to 4000cm-1. The title compound was carried out for the experimental IR spectrum which was compared with the calculation of B3LYP/6-31 G (d, p). Some bands in the calculated IR spectra were not observed in the experimental spectrum due to the fact that the computed wave numbers corresponds to gaseous phase of isolated molecular state and the observed wave numbers corresponds to the solid state spectra. Fig 5 shows the experimental FT-IR spectrum.

Fig. 5. Experimentally obtained FT-IR spectrum of LHPCL. MMSE Journal. Open Access www.mmse.xyz

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C-Cl Vibrations. For the title molecule the C–Cl stretching vibrations were found at bands 623.83cm−1 and 565.82cm-1which was computedwith the help of 6-31G (d, p) basis set. Due to C–Cl stretching vibrations, sharp peaks were occurred at 560cm-1 and 626cm-1 in the experimental spectrum. Hence the carbon atom acquired small positive charge whereas chlorine atom acquired a small negative charge. An increase in the absorption frequencies from the inductive effect of chlorine attracts electrons from the C–Cl bond which increased the force constant. The FT-IR simulated values were coincided by the experimental values of C- Cl vibrations.

C-H Vibrations. The nature and position of the substituent does not affect these vibrations. Due to C-H stretching vibrations, a sharp peak was occurred at 3069.3475cm-1 using B3LYP/6-31 G (d, p) method and at 3070cm-1 a sharp peak was shown for the experimental FT-IR. Due to the effect of C– H in-plane bending vibrations, the infrared peaks were identified at 1489.048cm−1 (6-31G (d, p) basis set) and at 1491cm-1 an experimental counterpart was seen. Using 6-31G (d, p) basis set, the vibration at 1353.18cm-1 and peak at 1353cm-1 was due to the C-H out of plane bending mode. The high organic nature was revealed from a prominent C-H vibration which was exhibited for the candidate material.

HOMO-LUMO Gap. The two energies that generally interact when we deal with interacting molecular orbitals were HOMO and LUMO of the compound. The interaction was made more strong which was allowed by these pair of orbitals. The orbitals of the compound were called as the frontier orbitals of the electrons as they lie at its outermost boundaries. The interaction was made more strong which was allowed by these pair of orbitals. -0.18352a.u (4.9765eV) was found to be the value of HOMO-LUMO energy gap for the compound LHPCL and Fig 6 shows the orbital picture. The energy gap reflects the chemical activity of the molecule which was revealed from the HOMO-LUMO energy gap of LHPCL. The ability to obtain an electron was represented by the LUMO which was an electron acceptor whereas the ability to donate an electron was represented by HOMO.

Fig. 6. HOMO – LUMO plot of LHPCL molecule.

Nonlinear optical (NLO) test. Kurtz and Perry powder technique was carried out for the compound LHPCL inorder to confirm the nonlinear optical property [5].By passing a Q-switched, mode locked Nd: YAG laser of 1064nm and pulse width of 8ns (spot radius of 1 mm) on the powder sample of LHPCL, the SHG efficiency of the grown crystal was checked. Through an IR reflector, the input laser beam was passed and then it was directed on the microcrystalline powdered sample. The light emitted by the sample was detected by oscilloscope assembly and the photodiode detector. Taking KDP, which is a microcrystalline powder as the reference material, the SHG efficiency of the LHPCL crystal was evaluated. 90mV and 310mV were obtained as the SHG signal (532 nm) of KDP and MMSE Journal. Open Access www.mmse.xyz

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LHPCL samples respectively for a laser input pulse of 6.9mJ. The SHG efficiency of LHPCL was 3.44 times higher than that of KDP was observed.

Summary. By slow evaporation technique, at room temperature, the single crystals of LHPCL were grown. By XRD studies, the grown crystal was confirmed. Experimentally obtained FT-IR frequencies were compared by the theoretically calculated vibrational frequencies. For various vibrational frequencies, spectral assignments were carried out. For the selected moieties of LHPCL molecule, force constants and reduced masses were calculated.From HOMO-LUMO analysis,0.18352a.u (4.9765eV) was found to be the value of molecular energy gap of LHPCL. The grown crystal had its SHG efficiency 3.44 times that of KDP, which was determined from the Kurtz SHG test.

References [1] Reena Ittyachan, Xavier Jesu Raja S, Rajasekar S.A, Sagayaraj P, Materials Chemistry and Physics, 90 (2005) 10–15. DOI:10.1016/j.matchemphys.2004.04.025 [2] Nalini Jayanthi S, Prabakaran A.R, Subashini D, Thamizharasan K, Materials Today: Proceedings 2 ( 2015 ) 1356 – 1363. DOI:10.1016/j.matpr.2015.07.054 [3] Sajan D, Lynnette Joseph, Vijayan N, Karabacak M, Spectrochimica Acta Part A 81 (2011) 85– 98 DOI:10.1016/j.saa.2011.05.052 [4] Ramalingam S, Periandy S, Narayanan B, Mohan S, Spectrochim. Acta A 76 (2010) 84–92. DOI: http://dx.doi.org/10.1016/j.saa.2010.02.050 [5] Moovendaran K, Martin Britto Dhas S.A, Natarajan S, Optik 124 (2013) 3117-3119. DOI. org/10.1016/j.ijleo.2012.09.042 Cite the paper R. Vincent Femilaa, M. Victor Antony Raj, J. Madhavan, (2017). Growth, Structural and Optical Behaviour of L-Histidinium perchlorate: A Nonlinear Optical Single Crystal. Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.30.36.520

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Ab Initio Study of Electronic, Structural, Thermal and Mechanical Characterization of Cadmium Chalcogenides54 Devi Prasadh P.S.1, a, B.K. Sarkar2, b 1 – Department of Physics, Dr. Mahalingam College of Engineering & Technology, Pollachi, Coimbatore, India 2 – Department of Physics, Galgotias University, Greater Noida 201308, India a – psdprasadh@gmail.com b – bks@physics.org.in DOI 10.2412/mmse.32.38.817 provided by Seo4U.link

Keywords: density functional theory, chalcogenides, FP-LAPW+lo.

ABSTRACT. Based on Density Functional Theory, we have applied Full Potential Augmented Plane Wave plus local orbital method (FAPW+lo)to study the electronic, structural, optical, thermal and mechanical properties of some semiconducting materials. In this paper we discuss the Zinc blende, CdX (X = S, Se and Te) compounds with the fullpotential linear-augmented plane wave (FP-LAPW) method within the framework of the density functional theory (DFT) for electronic, structural, thermal and mechanical properties using the WIEN2k code. For the purpose of exchangecorrelation energy (Exc) determination in Kohn–Sham calculation, the standard local density approximation (LDA) formalism is utilized. Murnaghan’s equation of state (EOS) is used for volume optimization by minimizing the total energy with respect to the unit cell volume. The calculated lattice parameters and thermal parameters are in good agreement with other theoretical calculations as well as available experimental data.

Introduction. Cadmium Chalcogenides family is one of the II-VI wide band gap compound semiconductors. In that family CdS, CdSe and CdTe are some of the main materials. These materials have variousscientific applications, such as solar cells, high efficiency thin film transistors, high density optical memories, light emitting diodes, laser diodes, photovoltaic devices, etc. The recentinnovation of the blue-green laser diode based on the CdX compounds has changedconsideration in their physical properties. CdX compounds are having different phases or crystal structures (Zinc blende, wurtzite). For our convenience we have preferred the zinc blende phase for all three compounds. Because this structure has fewer atoms in unit cell so it is easier for computational treatment. In fact for CdTe, the zinc blende structure is the standard crystal structure or phase, but for the other two compounds CdS and CdSe have wurzite phase. In the past decades numerous experimental and theoretical investigations were carried out for CdX. Many computational methods based on DFT [1]have been studied. But the calculations carried out by using conventional DFT produce disagreeable electronic properties. There is a big variance between experimentally calculated and theoretical data. The variation in energy gap is completely based on the method to calculate the band structure. Some theoretical reports are in good agreement with the measured one.

They were calculated based on Local Density Approximation (LDA). The modern ab-inito calculation solves the discrepancies. We have used FP-LAPW+lo to calculate the band structure. The band structure of CdX binary compounds have been calculated by using Full Potential Linearized Augmented Plane Wave method Plus local orbits (FP-LAPW+lo) within the Generalized Gradient Approximation (GGA). There are several methods and theoretical reports available to calculate the band structure and optical properties but some controversies are at there. But the FP-LAPW+lo gives the closer values with the experimental data.In this paper we have presented the structural, elastic, electronic and thermal properties of CdX binary compounds. FP-LAPW+lo is the method used to © 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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investigate the properties and the values are compared with the experimental and other theoretical works for these compounds. Our values are in good agreement with the earlier reports.

Computational method: All the calculations of the structural, thermal and electronic properties were performed in the frame work of Density Funtional Theory (DFT). To calculate these properties, we employed the full potential linearized augmented plane wave plus local orbitals (FP-LAPW+lo) as executed in the WIEN2k code [2-3].We have used the generalized gradient approximation (GGA) as parameterized by Perdew, Burke and Ernzerhof (PBE) to explain the exchange and correlation effects [4].CdX compounds crystallize in the zinc-blende structure with space group F-43 m. The Cd atom is set at (0, 0, 0) whereas the X atom is set at (0.25, 0.25, 0.25). We have employed Murnaghan’s equation of state [5] for the optimization of the total energy with respect to the unit cell volume. Thus the equilibrium structural parameters have been calculated. The calculations were done with RMTkmax = 9, to attain energy Eigen value convergence. RMT is the smallest radius of the muffintin (MT) spheres and kmax is the maximum value of the wave vector. The corresponding values of muffin-tin radii (RMT) for Cd, S, Se and Te were taken to be 2.37, 1.73, 1.91 and 2.35 a.u. (atomic units) for all the calculations. The Gmax parameter was taken to be 14.0 Bohr-1. The wave function has been expanded inside the atomic spheres with the maximum value of the angular momentum lmax as 10. The irreducible Brillouin zone (BZ) of the zinc-blende structure has been decomposed into a matrix of 10×10×10 Monkhorst–Pack k-points [6]. The iteration procedure is continued with total energy and charge convergence to 0.0001Ry and 0.001e, respectively.

Results & discussions Structural and elastic properties: To find the elastic constants of CdX compounds with cubic structure we have used the numerical firstprinciple calculation by calculating the compounds of the stress tensor δ for small stains. Proper strains δ (-0.02-0.02) have been arranged to prevent primitive lattice vectors and then appropriately strained states were analysed. It is well known that for a cubic crystal it has only three independent elastic constants C11, C12 and C44 as we have studied the theory in a detailed manner in previous chapter. With the Murnaghan’s equation of state [5],the variation of the total energy versus unit cell volume yields to the equilibrium lattice parameter (a0), bulk modulus B0, and the pressure derivative of the bulk modulus B0′. The values of a0, B0 and B0′ for the ZB structure of the binary CdX at zero pressure are presented in table 1. For CdS, CdSe and CdTe, the energy minima take place for a0 = 5.805, 6.305 and 6.350 Å, our results are in good agreement with the experimental values of 5.830, 6.084 and 6.480 Å, respectively with the maximal error of 3.63% with respect to experimental values. It is clear that well defined structural properties are helpful for further study of electronic and thermal properties. The elastic constants of CdX compounds with cubic structure have been determined using the method developed by Charpinincorporated in WIEN2k code[7]. By applying appropriate lattice distortions in a cubic lattice, three independent elastic constants C11, C12, and C44 are determined. Table 1 displays the calculated values of elastic modulus. Our calculated lattice parameters values are in good agreement with experimentally calculated and other theoretical measured values. The bulk modulus B0 represents the resistance to fracture while the shear modulus G represents the resistance to plastic deformation. Ductility of the material can be characterized by B0/G ratio. The B0/G ratio for all CdX are greater than 1.75 (table 1) which tells that the compounds are ductile in nature. The peak value of B0/G ratio is 5.2334for CdSetelling it most ductile among all the CdX compounds. There is a correlation between the binding properties and ductility. The bond character of cubic compounds is expressed in terms of their Cauchy pressure (C12–C44). With increase in positive Cauchy pressure, compound is likely to form metallic bond. Hence, the ductile nature of all CdX compounds can be correlated to their positive Cauchy pressure having the metallic character in their bonds. As represented in table 1, the CdS and CdSehave a highest positive. Cauchy pressure resulting strong metallic bonding (ductility) in it as compared to other compounds. The calculated value of Young’s modulus (Y) is shown in table 1. It provides the degree of stiffness of the solid, i.e., the stiffer material has the larger value of Y and such materials have covalent bonds. The highest value of Y occurs for CdS demonstrating to be more covalent in nature as compare to other CdX compounds. Value of Poisson’s ratio (σ), as a measure of MMSE Journal. Open Access www.mmse.xyz

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compressibility for CdX compounds are between 0.39 and 0.41 which predict that all the compounds are compressible. Also the Poisson’s ratios having values between 0.25 and 0.5 represent central force solids. In our case, the Poisson’s ratios are around 0.4, which reveals that the interatomic forces in the CdX compounds are central forces.The structural properties results are compared with other theoretical results [13].

Calculation of Debye Temperature. The Debye temperature (D) is considered as a fundamental parameter for many physical properties of solids, such as specific heat, elastic constants and melting temperature. At low temperature, only the acoustic branches of phonons are active and the vibrational excitations take place exclusively from acoustic vibrations. Hence, the estimate of Debye temperature based on elastic constants at low temperature is consistent with the same as that determined from specific heat measurements. Once we have determined the elastic constants, we may obtain the Debye temperature (D) by using the average sound velocity Vm.We have calculated the density, sound velocities and Debye’s temperature by using the calculated elastic constants which are produced in table 1.

Electronic Properties. The electronic band structure of Cd chalcogenides has been calculated. The calculated band structure for CdX at equilibrium is shown in Fig. 1. The band profiles are almost similar for all the three components, with some minute difference.

Fig. 2. Shows the Band Structure and Density of States of CdTe.

Each member of CdX demonstrates the existence of the valence band maximum and conduction band minimum at the same symmetry point. This confirms the direct energy gap between the top of the valence band and the bottom of conduction band at Γ point. With the increase of the lattice parameters starting from the sulphide to the telluride, the X atom p bands shift up in energy as a common feature of II–VI compounds [14]. This is the regular performance related to the increase of the lattice parameters, which was also found for other II-VI compounds. Our results for the direct band gaps are represented in table1 with the experimental and other theoretical values.The calculated band gap is underestimated in contrast with experimental results, because of the simple form of GGA which cannot account the quasi particle self-energy.The density of states (DOS) for CdTe is shown in Fig. MMSE Journal. Open Access www.mmse.xyz

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1. The first structure in the total DOS is small and centered at around -10.8 eV for CdTe. This structure arises from the chalcogen s states and it corresponds to the lowest lying band with the dispersion in the region around the ᴦ point in the Brillouin zone. The next structure appears at -8.6 eV. It is an attribute of Cd d states with some p states of the chalcogen atoms.

Table 1. Calculated lattice constant (in A˚), bulk modulus B0 (in GPa), pressure derivative B0′, elastic constants (Cij in GPa), elastic modulus (in GPa), Sound velocities, Debye temperatures and energy gap (Eg) in eV for CdX compounds.

Properties a0 (Present Study)

CdS 5.805 5.820a, 5.840b, a0 (Other works) c d 5.948 , 5.810 B0 (Present Study) 64.90 62.00a, 61.69b, B0 (Other works) 53.838c, 72.42d B0′ (Present Study) 4.25 B0′ (Other works) 4.57a, 4.72c, 4.31d C11 (Present Study) 92.3 75.2e, 104.62b, 67.6f, C11 (Other works) 97.8d C12(Present Study) 51.2 55.0e, 46.25b, 46.3f, C12 (Other works) 59.7d C44 (Present Study) 26.3 39.1e, 77.28b, 29.5f, C44 (Other works) 30.6d G (GPa) (Present Study) 13.48 G (GPa) 21.25b B0/G (Present Study) 4.8145 C12-C44 (GPa) (Present 24.9

CdSe 6.305 6.050a, 6.201c, d 6.050 58.93 53.00a, 54.948c, 65.12d 4.13 4.67a, 1.584c, 4.20d 81.2 65.0e, 55.4f, 88.1d

CdTe 6.350 6.480a, 6.624c, d 6.480 42.70 42.00a, 37.44c, 48.94d 4.39 3.00a, 3.87c, 4.47d 59.9 56.5e, 53.2f, 68.1d

47.8 49.0e, 37.7f, 53.6d

34.1 32.1e, 23.2f, 39.3d

22.9 36.8e, 18.9f, 27.4d 11.26

20.1 31.8e, 22.1d 9.18

5.2334 24.9

4.6514 14.0

13.01f,

Study) Y (GPa) (Present Study) Y (GPa) (Other works) σ (Present Study) σ (Other works) A (Present Study)

55.76 25.68b 0.4029 0.34b 1.2798

45.77

35.15

0.4102

0.3997

1.3713

1.5581

ρ(Kg/m ) Vt(m/s) Vl(m/s) Vm(m/s) θD(K)

4870 2219 4460 2490 255

5655 1900 3903 2137 210

5860 1714 3347 1920 177

Eg (eV) (Present Study) Eg (eV) (Other works)

1.35 2.55a, 1.45d, 2.66c

0.77 1.90a, 1.08d, 1.89c

0.80 2.55a, 1.88d, 1.56c

3

a

Madelung O8, bAl Shafaay9,cHakanGurel10, dDeligoz11, e Kitamura12, f Ouendadji13

It is found that a wide spread in DOS in the energy range from -4.8 eV to zero energy for CdTe. The peaks in this energy interval arise from the chalcogen p states partially mixed with Cd s states and MMSE Journal. Open Access www.mmse.xyz

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they subsidize to the upper valance band. Above the Fermi level, the feature in the DOS create mainly from the s and p states of Zn somewhat mixed with little of chalcogen d states. Band width of valence band as determined from the width of the peaks in DOS dispersion below Fermi level equal to 11.5 eV. The results showing valence band width minimum for CdTe, clearly indicate that the wave function for CdTe is more localized than that for CdS. This is in consistence with the fact that when the atomic number of the anion increases, a material becomes non-polar covalent with valence band states being more localized.

Summary. This chapter reports a systematic study of the structural, electronic, elastic and thermal properties of zinc blende Cd-chalcogenides (CdS, CdSe and CdTe) have been studied with FPLAPW+ lo method in the framework of density functional theory (DFT). The quantities such as elastic constant and band structure were obtained. The generalized gradient approximation (GGA) was considered for the exchange and correlation effects calculations. The results from FP-LAPW + lo method were generally satisfactory with the experimental data in comparison to other calculation methods. The calculated lattice parameters, bulk modulus, Young’s modulus and Poisson’s ratio of binary compounds CdX are in good agreement with the experimental data. The elastic constants maintain all conditions to be satisfied for mechanical stability of the compound. The profound ductility in CdX compound was observed with the increase in chalcogen atomic number. The metallic character in their bonds is well demonstrated from the positive Cauchy pressure (C12–C44) values.

The band structure of all Cd-chalcogenides confirms the direct energy gap between the top of the valence band and the bottom of conduction band at Γ point.

References [1] P. Hohenberg, W. Kohn, Inhomogeneous electron gas. Phys. Rev. 136, B864–B871 (1964). doi: 10.1103/PhysRev.136.B864 [2] G. K. H. Madsen, P. Blaha, K. Schwarz, E. Sjöstedt, L. Nordström, Efficient linearization of the augmented planewave method. Phys. Rev. B 64, issue 19, 195134 (2001). doi: 10.1103/ PhysRevB.64.195134 [3] K. Schwarz, P. Blaha, G.K.H. Madsen, Electronic structure calculations of solids using the WIEN2k package for material science, Comp. Phys.Commun., Vol. 147, Issue 1, pp. 71–76 (2002). doi: 10.1016/S0010-4655(02)00206-0 [4] J. P. Perdew, K. Burke, M. Ernzerhof, Generalized gradient approximation made simple. Phys.

Rev. Lett. 77, 3865–3868 (1996). doi: 10.1103/PhysRevLett.77.3865 [5] F.D. Murnaghan, On the Theory of the Tension of an Elastic Cylinder, Proc. Natl. Acad. Sci., Vol. 30, No. 12, pp. 382–384 (1944), USA. PMID:16588670 PMCID:PMC1078732 [6] H.J. Monkhorst, J. D. Pack, Special points for Brillouin-zone integrations, Phys. Rev. B. 13, No. 12, pp. 5188–5192 (1976). doi: 10.1103/PhysRevB.13.5188 [7] P. Blaha, K. Schwarz, G.K.H. Madsen, D. Kvasnicka, J. Luitz, WIEN2k, An augmented plane wave plus local orbitals program for calculating crystal properties, (User’s Guide), Inst. of Physical and Theoretical Chemistry, Vienna University of Technology, Austria, pp. 1-205, (2001).

[8] O. Madelung, H. Weiss, and M. Schultz, eds. Landolt-Börnstein: Numerical Data and Functional Relationships in Science and Technology. Group III: Crystal and Solid State Physics. Vol. 17, Subvolume A: Physics of Group IV Elements and III-V Compounds. Berlin: Springer (1982).

[9] B. Al Shafaay, Structural, electronic, mechanical and thermodynamic properties of CdS compound, J. Che., Bio. And Phy. Sci., Vol. 4, No. 4; pp. 3606–3618 (2014).

[10] H. HakanGurel, OzdenAkinci, HilmiUnlu, First principles calculations of Cd and Zn chalcogenides with modified Becke–Johnson density potential, Superlattices and Microstructures, Vol. 51, Issue 5, pp. 725–732 (2012). doi: 10.1016/j.spmi.2012.02.010 MMSE Journal. Open Access www.mmse.xyz

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[11] E. Deligoz, K. Colakoglu and Y. Ciftci, “Elastic, Elec tronic, and Lattice Dynamical Properties of CdS, CdSe, and CdTe,” Physica B: Physics of Condensed Matter, Vol. 373 (2006), pp. 124-130. doi:10.1016/j.physb.2005.11.099 [12] M. Kitamura, S. Muramatsu & W. A. Harrison, "Elastic properties of semiconductors studied by extended Hückel theory", Physical Review B, Vol. 46, No. 3, (1992), pp. 1351-1357. doi: 10.1103/PhysRevB.46.1351 [13] S. Ouendadji, S. Ghemid, H. Meradji, F.El Haj Hassan, Theoretical study of structural, electronic, and thermal properties of CdS, CdSe and CdTe compounds, Comp. Mat. Sci., Vol. 50, pp.

1460–1466 (2011). doi: 10.1016/j.commatsci.2010.11.035 [14] M. Dadsetani, A. Pourghazi, Optical properties of strontium monochalcogenides from first principles, Phys. Rev. B, Vol. 73, No. 19, pp. 195102, (2006). doi: 10.1103/PhysRevB.73.195102 Cite the paper Devi Prasadh PS, B.K. Sarkar, (2017). Ab initio Study of Electronic, Structural, Thermal and Mechanical Characterization of Cadmium Chalcogenides. Mechanics, Materials Science & Engineering, Vol 9. doi 10.2412/mmse.32.38.817

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Growth, Structural, Spectral, Opticaland Photoconductivity Studies of Semiorganic Nonlinear Optical Single Crystal: Calcium5-Sulfosalicylate55 D. Shalini1, S. Kalainathan2, D. Jayalakshmi1 1 – PG and Research Department of Physics, Queen Mary’s College (A), Chennai, India 2 – School of advanced Sciences, VIT University, Vellore, India DOI 10.2412/mmse.5.1.614 provided by Seo4U.link

Keywords: growth from solution, crystal structure, calcium compounds, nonlinear optical material.

ABSTRACT. Good quality semi-organic nonlinear optical crystal Calcium5-Sulfosalicylate (CA5SS) was synthesized, and crystals were grown by slow evaporation solution growth technique. The cell parameters, molecular structure and crystalline perfection of the grown crystal were studied by single crystal x-ray diffraction analysis. The presence of various functional groups of the grown crystal was confirmed using Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) analysis. UV-Visible spectrum shows that CA5SS crystals have high transmittance in the range of 330–900 nm. The laser induced surface damage threshold, transient photoluminescence properties of the grown crystal were analyzed. The second harmonic generation efficiencies of the grown crystal (CA5SS) were studied and compared with that of KDP.

1. Introduction. Crystal engineering has the major purpose to understand the intermolecular interactions and principle of packing in molecular crystals and also helps in the deliberate design of novel materials with NLO application targeted structures and properties. The hydrogen bonding ability helps to modification of the chemical compounds changes the optical properties of corresponding crystals. The lack of boundless π-electron delocalization, moderate optical nonlinearity, low optical transparency, and low laser damage threshold are the major limitations in organic nonlinear optical (NLO) crystals. In order to beat the above shortcomings, some new class of crystals such as semi-organic crystals have been developed. The coordination ability of organic acids towards the metal ions is currently of great significance, due to their usage in the materials research for optical and nonlinear optical (NLO) properties [1-2]. To achieve such goal, we have selected a derivative of salicylic acid, proton-transfer compounds of 5-sulfosalicylic acid, to explore its structural diversities and interesting topologies [3]. 5-sulfosalicylicacid (5SSA) is an attractive ligand, possessing three substituent groups such as the sulfonic acid (SO3H), the carboxylic acid (COOH) and the phenolic groups (OH). The presence of the numerous oxygen atoms in three substituent groups usually results in hydrogen-bonding associations, and it can form mono, di and tri anionic ligand species through deprotonation, also the structures having significant interlayer π-π interactions between the cationic and anionic species [4]. In present work, we report for the first time on the growth and structure of Calcium 5-Sulfosalicylate single crystal using slow evaporation method.

2. Experimental procedure. CA5SS crystals were grown by slow evaporation solution growth technique. The starting compounds, namely, 5-Sulfosalicylic acid dihydrate (Loba Chemie, 99%) and Calcium chloride dihydrate (Loba Chemie, 99%) were used without further purification. 5Sulfosalicylic acid dihydrate and Calcium chloride dihydrate were mixed in the ratio of 2 : 1, and dissolved using deionised water as the solvent. The solution was stirred well for about 6 hours at room temperature and the saturated solution was filtered in clean beaker with Whatman filter paper

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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and kept undisturbed for crystallization to take place. Good quality single crystals of the title compound were obtained after 33 days. The grown crystal of CA5SS is shown in Fig. 1.

Fig. 1. As-grown CA5SS single crystals.

3. Results and discussion 3.1. Single crystal X-ray diffraction studies. The grown CA5SS crystal was confirmed by single crystal XRD analysis. Single crystal X-ray diffraction studies were carried out using a Bruker AXS Kappa APEX II single crystal CCD diffractometer coupled with graphite-monochromated MoKα (λ=0.7107Å) radiation. Unit cell dimensions a = 5.5947(1) Å, b = 18.5055(2) Å, c = 9.9824(1) Å, α = 90°, β= 102.197(4)°, γ= 90°.

3.2. FT-IR studies: FT-IR technique is a useful method for detecting the formation of such complexes like solids, liquids, gases, semi-solids, powders and polymers. The peak positions, widths, intensities and shapes all provide useful information. FT-IR spectrum of CA5SS crystal is shown in Fig.2. The FTIR spectrum of the CA5SS was recorded in the region 4000-500 cm−1 in the Stokes region using the 1064 nm line of a Nd:YAG laser for excitation. The peak at 3019 cm-1 is ascribed to aromatic C-H Stretching. The peak at 1481 cm-1 due to C=C ring stretching vibration. C=O Stretching vibration of sulfosalicylate was observed at 1657 cm-1.The peak at 1355 cm-1 due to O-H In-plane bending vibration. The peak at 736 cm-1 is due to S-O stretching vibrations. The band at 585 cm-1 is assigned to O-H Out-of-plane vibration.

1418

100

0

500

2754 2893 3019 3246

1190 1355 1481 1582 1657

0

1948

812

585

686

20

1064

40

2451

736

60

534

Transmittance %

80

1000

1500

2000

3453 2500

3000

3500

Wavenumber (cm-1)

Fig. 2. FTIR spectrum of CA5SS crystal.

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4000

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3.3. UV-Visible analysis: UVâ&#x20AC;&#x201C;Vis study was carried out to understand the linear transmission The selective electronic absorption spectrum of CA5SS crystal recorded absorption spectrum in the range 200-900 nm is shown Fig 3. Optically polished single crystal of thickness 1.2 mm was used for this study. The absorption spectrum shows the grown crystal has a lower cut-off wavelength at 330 nm, hence, the crystal shows minimum absorption and lower cut-off wavelength, and then the probability that the crystal is NLO active. This extensive range of transparency shows that the grown CA5SS crystal is a potential candidate for the optoelectronic applications and was free of volume defects.

2.0

Absorbance

1.5

1.0

0.5

0.0

300

400

500

600

700

800

Wavelength (nm)

Fig. 3.UV-Vis absorption spectrum of CA5SS crystal.

3.4. Laser damage threshold studies. The laser damage threshold of an optical crystal is an important factor affecting its applications. It leads to the breakdown of the materials catastrophically damaging the maximum permissible power for a particular crystal defined as damage threshold. In the present experiment, an actively Q-switched Nd:YAG laser source with 10 ns pulse width and 10Hz repetition rate were used. The output intensity of the laser was controlled with variable attenuator and delivered to the test sample located at the near focusing of the converging lens. The energy density of the input laser beam was recorded using power meter till the crystal got damaged.

The surface damage threshold of the crystal was calculated using the formula: đ?&#x2018;&#x192; = đ??¸ â &#x201E;đ?&#x153;?đ??´

(1)

where đ??´ = đ?&#x153;&#x2039;đ?&#x2018;&#x; 2 .

The laser damage threshold of CA5SS was measured 7.48Ă&#x2014;109 GW/cm2.The higher value of LDT will be useful for making laser based devices [5].

3.4. Photo conductivity studies. Photoconductivity of the grown CA5SS crystal was studied using Keithley 485 picoammeter. Dark conductivity of the sample was studied by connecting the sample in series to a DC power supply and a picoammeter. Electrical contacts were made at spacing (d) of about 1.2 mm on the sample using silver paint. The DC input was increased from 50 to 450 V in steps and the corresponding readings in the electrometer were recorded. Photoconductivity studies were carried out by focusing light from a halogen lamp (100W) on samples. The variation of photocurrent (Ip) and dark current (Id) with applied field is shown in Fig 4.

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3.0

Photo current Dark current

2.8 2.6

Current (nano ampere)

2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0

50

100

150

200

250

300

350

400

450

Applied field (volt/cm)

Fig. 4.Variation of current with applied field of CA5SS crystal.

The photocurrent of grown crystal is found to be less than the dark current at every applied electric field. This phenomenon is known as negative photoconductivity. This may attribute to their lifetime in the presence of radiation or the reduction in the number of charge carriers [6] 3.5. Nonlinear Optical Studies: SHG powder measurements were performed at room temperature.

The second harmonic generation efficiency of CA5SS crystal was measured by using Kurtz-Perry powder SHG technique [7] with potassium dihydrogen phosphate (KDP) crystal as reference material.

The SHG efficiency obtained for CA5SS is about 0.7 times higher than that of potassium dihydrogen phosphate crystal.

Summary. The semi-organic nonlinear optical Calcium5-sulfosalicylate single crystals were grown by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis confirms the crystal belongs to a monoclinic system with space group P1n1. The modes of vibration molecule groups present in the grown crystal were confirmed by FTIR spectral analysis. The lower cut-off wavelength and optical band gap energy of the grown crystal were examined by UV-Vis spectral analysis and it is suitable for potential device applications. The laser induced surface damage threshold value for CA5SS crystal was found to be 7.48×109 GW/cm2. Photoconductivity investigations reveal the negative photoconducting nature of CA5SS crystal. The SHG efficiency of the CA5SS crystal was found to be 0.7 times higher than that of standard KDP crystal.

Acknowledgment. One of the authors (D.JAYALAKSHMI) is grateful to the university grants commission for support under minor research project scheme.

References [1] Bojidarka B Ivanova, Michael spiteller Physical optical properties and crystal structures of organic 5-sulfosalicylates – Theoretical and experimental study. J.molstruc (2011) 1003:1-9. DOI: 10.1016/j.molstruc.2011.06.043 [2] Nalwa H, Watanabe T, Miyata S Nonlinear Optics of Organic Molecules and Polymers. Nalwa H S, Miyata S (Eds.) CRC Press, Boca Raton, (1997) pp.89–329.

[3] Sai Rong Fan, Long Guan Zhu (2007) Structural diversity and fluorescent properties of copper (II) complexes constructed by 5-sulfosalicylate and 2, 2′-bipyridine. J.molstruc pp.188-194.

DOI:10.1016/j.molstruc.2006.05.019 [4] Li Z H, Su K M (2007) Piperazine 1,4 diium bis (3-carboxy-4-hydroxybenzene sulfonate) dehydrate. Acta cryst E63:04744, DOI:10.1107/S1600536807057856

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[5] Nakatani H, Bosenburg W R, Cheng L K, Tang C L (1988) Laser-induced damage in beta-barium metaborate. Applied Physics Letters 53:2587. DOI:10.1063/1.100535.

[6] Pandi S, Jayaraman D (2001) Studies on photoconductivity of C60 and C60-doped poly (vinylchloride). Mater. Chem. Phys 71: 314-317. DOI:10.1016/S0254-0584(01)00285-1 [7] Kurtz S K, Perry T T (1968) A Powder Technique for the Evaluation of Nonlinear Optical Materials. J. Appl. Phys 39: 3798-3813. DOI: 10.1063/1.1656857.

Cite the paper D. Shalini, S. Kalainathan, D. Jayalakshmi (2017). Growth, Structural, Spectral, Opticaland Photoconductivity Studies of Semiorganic Nonlinear Optical Single Crystal: Calcium5-Sulfosalicylate.

Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.5.1.614

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Synthesis of Hydroxysodalite from Paper Sludge Ash Using NaOH-LiOH Mixtures56 Takaaki Wajima1 1 – Department of Urban Environment Systems, Chiba University, 1-33, Yayoi-cho, Inagek-ku, Chiba 263-8522, Japan DOI 10.2412/mmse.40.5.622 provided by Seo4U.link

Keywords: hydroxysodalite, katoite, gehlenite, paper sludge ash, NaOH-LiOH mixture, synthesis reaction.

ABSTRACT. Hydroxysodalite zeolite was synthesized at 90 oC from paper sludge ash, which is industrial wastes in paper manufacturing, using NaOH-LiOH mixed solution. Paper sludge ash was discharged from paper making plant as industrial wastes, and the amount is increasing annually. The new utilization of paper sludge ash is desired.

Hydroxysodalite can be used to remove HCl gas at high temperature, and there are papers for hydroxysodalite synthesis from various ashes, for example, coal fly ash. In my previous study, hydroxysodalite can be synthesized from paper sludge ash. However, little information can be available on the synthesis of hydroxysodalite from paper sludge ash. Therefore, we attempted to examine the synthesis of hydroxysodalite from paper sludge ash using NaOH-LiOH mixtures.

Hydroxysodalite [Na6Al6Si6O24‧8H2O] was obtained in the mixed solution with Li / (Li + Na) ratios smaller than 0.25, while katoite [Ca3Al2(SiO4)(OH)8] was formed in the mixed solutions with the other molar ratios, due to the dissolution of gehlenite [Ca2Al2SiO7]. The observed concentrations of Si and Al in the solution during the reaction explain the synthesis of reaction products, which depends on alkali species.

Introduction. Zeolites are a group of more than 40 crystalline hydrated aluminosilicate minerals with structures based on three-dimensional network of aluminum and silicon tetrahedra linked by sharing of oxygen atoms. Due to their unique pore structures and ion-exchange properties, zeolites can be used not only as cation exchangers and adsorbents but also molecular sieves and catalysts [1].Paper sludge is generated as industrial waste during the manufacture of recycled paper products, and the amounts are increasing annually. The sludge consists of organic fibers, inorganic clay-sized materials, and about 60% water, and is incinerated to produce paper sludge ash (PSA) by burning out the organic materials, thereby reducing the volume of waste. Although a small portion of the ash has been used as cemented fillers, lightweight aggregates in the construction industry and other minor applications [2, 3], most is dumped in landfills. The large daily output of PSA and the limited landfill capacity causes social and environmental problems, and new techniques of ash utilization for further recycling are desired. In our previous study, hydroxysodalite [Na6Al6Si6O24‧8H2O] was synthesized from PSA in NaOH solution at low temperature (< 100 oC) [4]. Hydroxysodalite is one of high aluminum containing crystalline tectoaluminosilicates, and used to remove HCl gas at high temperature for applying to waste incinerator [5]. It is one way to use PSA for recycling. However, little information can be available on the conversion of PSA into hydroxysodalite. To our knowledge, no previous effort has been made to determine the dependence of alkali species on alkali synthesis of zeolite from PSA. In the present study, hydroxysodalite was synthesized from industrial waste, PSA, using NaOH-LiOH mixtures.

Experimental. Raw PSA was obtained from one of the major paper manufacturers in Japan. The chemical composition of the ash, determined by scanning electron microscopy (SEM) (Hitachi, S2600H) equipped with energy dispersive spectrometry (EDS) (Horiba, EX-200) [4], is shown in Table 1. It is noted that Li content is analysed by an inductively coupled plasma method (ICP, SPS4000, © 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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SEIKO) after dissolving the sample in aqua regia, because EDS cannot detect Li content. The ash consists mainly of SiO2 (43.0 %), Al2O3 (23.9 %) and CaO (22.9 %) in the form of amorphous matter and the minerals gehlenite (Ca2Al2SiO7) and anorthite (CaAl2Si2O8), determined by X-ray diffraction (XRD) (Rigaku, Rint-2200U/PC-LH), as shown in Fig. 1. The remaining components are essentially lower-concentration impurities, such as Na2O, MgO, Fe2O3 and TiO2.

Intensity (cps)

300

●

●: Gehlenite [Ca2Al2SiO7] ▲: Anorthite [CaAl2Si2O8]

200

▲

●

100

●

▲

●

● ●

0

0

10

20

● ●●●

30

● ●

40

50

60

2θ[CuKα(degree)]

Fig. 1. Powder X-ray diffraction patterns of PSA. Table 1. Chemical composition of PSA and the products.

Sample

Reaction solution

SiO2

Al2O3

CaO

Na2O

MgO

Fe2O3

TiO2

Li

43.0

23.9

22.9

0.3

7.3

0.8

1.8

0.0

4M NaOH

38.1

19.4

26.3

6.4

7.1

0.9

1.7

0.0

3M NaOH + 1M LiOH

38.8

18.9

27.7

5.3

6.0

1.1

1.6

0.5

2M NaOH + 2M LiOH

46.5

21.0

20.4

1.1

7.0

0.5

1.2

2.4

1M NaOH + 3M LiOH

42.1

20.6

26.0

0.5

5.7

0.7

1.3

3.2

4M LiOH

31.9

27.4

26.5

0.1

7.5

0.9

1.5

4.2

PSA

The product

Chemical composition [wt.%]

Paper-sludge ash was converted to zeolites and other minerals by reaction with alkaline solutions. In order to investigate the effect of cation in alkali solution on zeolite synthesis, two-component alkali solutions of NaOH/LiOH was used as alkali sources. Total alkali concentration in the solution was 4 mol/L. The amounts of Na+ and Li+ were changed under constant of OH-. The alkali reaction using the above alkali solutions was carried out as follows. In each reaction experiment, 100 grams of ash were added to 1 L of alkali solution in a 1 L Erlenmeyer flask (made of poly methyl pentene) with a dimroth condenser, and the mixture (slurry) was continuously stirred at 90 °C. Five mL aliquots of each slurry were removed at varying time intervals to monitor the reaction process over a period of 24 hours. The aliquots were filtered, the solid residue was washed with purified water (using a Millipore Milli-Q Labo system) and dried for 12 hours at 60 °C in a drying oven. The solid residue was then analyzed by XRD to determine the minerals present. The intensity of the major XRD peaks for mineralogical phases: gehlenite (2 1 1), hydroxysodalite (1 1 0), and katoite (4 2 0), were used to determine changes in the mineralogical phases. The chemical composition of the product was analyzed by the same method as the ash. The filtrates were analyzed by ICP to determine the MMSE Journal. Open Access www.mmse.xyz

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concentration of Si and Al in the alkali solution during the reaction. The amounts of Na+, Ca2+ and Li+ released from the product in ammonium solution were examined as the fixation of Na+, Ca2+ and Li+ in the product structure for investigating synthesis mechanism. 0.1g of the solid residue was treated with 10 mL of 1 M-ammonium acetate solution, separate from the solution by centrifugation, and added again into fresh 1 M-ammonium acetate solution. This process was repeated three times for 20 min per exchange. The concentration of Na+, Ca2+ and Li+ in the ammonium acetate solution was analyzed by ICP to determine the amount of released Na+, Ca2+ and Li+ from the product.

Results and discussion. PSA was reacted with NaOH-LiOH mixed solutions at 90 oC for 24 h. XRD patterns of the reaction products in each NaOH-LiOH mixed solution after 24 h reaction are shown in Fig. 2. In the original ash, two mineral phases, gehlenite and anorthite, existed (Fig. 1). In the product, peaks of hydroxysodalite were confirmed as product phases, and those of anorthite diminished and gehlenite remained in the solids using NaOH-LiOH with low Li/(Li + K) ratios of 0 or 0.25, while calcium hydrate minerals, such as hydrocalumite [Ca2Al(OH)7•3H2O], katoite (Ca3Al2(SiO4)(OH)8) and portlandite (Ca(OH)2) were confirmed in the product, and both anorthite and gehlenite decreased using NaOH-LiOH with high Li/(Li + K) ratios more than 0.5. □

(e) □ ◎

△

□ □

Intensity [a.u.]

□

□□

◎ □

□ □ □

◎□

□

(d) □ ◎ △

□

□

◎

□

□ △

(c)

□

□□

◎ □

□

◎□

□ □

□ □ ◎

□ □

□

(b)

● ◎

□

□ □ □ □

□

□□

□

● ○

○

○

○

●

○

(a)

0

□

◎

□ △

●

10

●

○

20

30 40 2θ[CuKα,degree]

50

60

●:Gehlenite [Ca Al SiO ] □: Katoite [Ca Al (SiO )(OH) ] ◎: Portlandite [Ca(OH) ] 2 2 7 2 3

△: Hydrocalumite [Ca2Al(OH)7・3H2O]

2

4

8

○:Hydroxysodalite [Na Al Si O ・8H O] 6

6

6

24

2

Fig. 2. Powder X-ray diffraction patterns of the product derived from PSA with NaOH-LiOH mixtures; (a) 4 M NaOH, (b) 3 M NaOH + 1 M LiOH, (c) 2 M NaOH + 2 M LiOH, (d) 1 M NaOH + 3 M LiOH, and (e) 4 M LiOH. Table 1 shows the chemical compositions of PSA and the products synthesized in different alkali solutions. The Na content in the product increases with increasing the Na fraction of reaction solution, while the main contents, SiO2, Al2O3 and CaO, are almost same. The Li content in the product also increased with increasing Li content in the solution.

The intensities of the major mineralogical phases in the product, and the amounts of Na+, Ca2+ and Li+ released from the product after 24 h reaction are shown in Fig. 3. With increasing the Li/(Li +Na) ratio in the mixed solution, the intensities of gehlenite in the product at Li/(Li + Na) ratios = 0 and 0.25 were almost constant, and then gradually decreased to zero above Li/(Li + Na) = 0.5. The intensities of hydroxysodalite in the products at Li/(Li + Na) ratios = 0 was higher than that at other ratios and decreases, while those of katoite in the products at Li/(Li + Na) ratios = 0 was lower than

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at other ratios and increases, with increasing Li/(Li + Na) ratios of the mixed solution. It is considered that dissolution of gehlenite causes the formation of calcium hydrate minerals.

400

800

300

600

200

400

100

200

0

0

0.25 0.5 0.75 Ratio of Li+/total cation

Hydroxysodalite Na+

1

0

Katoite

Gehlenite

Ca2+

Li+

Released amounts of Na+ , Ca2+, and Li+ [cmol/kg]

Intensities of hydroxysodalite, katoite and gehlenite [cps]

The amount of Na+ released from the product was almost constant at 100 cmol/kg at Li/ (Li + Na) = 0 and gradually decreased to zero above Li/(Li + Na), which correlated with intensity of hydroxysodalite in the product due to the cation exchange property of hydroxysodalite zeolite. The amount of Ca2+ released gradually decreased to zero with increasing Li/(Li +Na) ratio in the mixed solution, which correlated with the intensity of katoite due to the fixation of calcium in the structure of calcium hydrate product. It is noted that the amount of Li+ released from the product lineally increased with increasing Li content in the solution, which means that Li+ is not fixed in the structure of the product to remove easily.

Fig. 3. Intensities of hydroxysodalite, katoite and gehlenite in the product and amounts of Na+, Ca2+and Li+ released from the product.

The reaction process was monitored by measuring the concentrations of Al and Si in the solutions and analyzing the properties of the solid product for Na+ and Ca2+ release during each 24 h experiment (Fig. 4). Although Ca is also a major elemental constituent of the ash, its concentration in solution is not a reliable indicator of the bulk system chemistry, because Ca is incorporated into insoluble solid phases in alkaline solutions [6]. The concentration of Al in solution always exceeded that of Si, even though the Si concentration exceeded that of Al in the starting ash. In the case of Li/(Na + Li) = 0 and 0.25 (Fig. 4 (a), (b)), the concentrations of Si and Al increased initially after introduction of PSA, then both Si and Al rapidly decrease after 1 - 2 h, and the Al content gradually increase and the Si content continued to rapidly decrease to approximately 10 mM after 2 h. The changes shown in Fig. 4 (b) is bigger than those shown in Fig. 4 (a). The Na+ release from the solid product increased and became almost constant after 4 h to 100 cmol/g and 65 cmol/g in Fig. 4 (a) and Fig. 4 (b), respectively, meaning that Al increase in the solution was caused by hydroxysodalite crystallization and Li addition did not promote zeolite synthesis. On the other hand, the Ca2+ release increased rapidly in the initial stage and gradually increased after 4 h to 300 cmol/kg and 350 cmol/kg in Fig. 4 (a) and (b), respectively, meaning that amorphous calcium aluminium silicate hydrate gel (CASH gel) with releasable Ca was formed in these solutions. In the case of Li/(Na + Li) ratios higher than 0.5 (Fig. 4 (c)-(e)), the concentrations of Si and Al initially increased after introduction of PSA and the Si and MMSE Journal. Open Access www.mmse.xyz

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300

60 200 40 100

20

0

0

4

8 12 16 Reaction time [h]

Si and Al concentrations [mM]

100

20

0 24

80

60

80

Na

Al

Ca

100

0

60 200 40

0

100

0

4

8 12 16 Reaction time [h]

20

Ca

20

300

20

Al

40

400 Si

Na

200

0

(d)

300 Si

0 24

4

8 12 16 Reaction time [h]

20

0 24

100

100

(c)

400

80

300

60

40

Si

Na

Al

Ca

100

20

0

0

4

8 12 16 20 Reaction time [h]

(e)

400

80

Si

Na

Al

Ca

300

60 200 40 100

20

0

0

4

200

8 12 16 Reaction time [h]

20

0 24

0 24

Released amounts of Na+ and Ca2+ [cmol/kg]

80

400

Released amounts of Na+ and Ca2+ [cmol/kg]

Ca

(b)

Si and Al concentrations [mM]

Al

100

Released amounts of Na+ and Ca2+ [cmol/kg]

Na

Si and Al concentrations [mM]

400 Si

Released amounts of Na+ and Ca2+ [cmol/kg]

(a)

Si and Al concentrations [mM]

Si and Al concentrations [mM]

100

Released amounts of Na+ and Ca2+ [cmol/kg]

Al concentrations decreased. The rates of decrease for Si and Al were faster with increasing Li content in the solution and the amounts of Si and Al dissolved decreased. The amount of Na+ released from the solid product decreased because of the decrease in hydroxysodalite zeolite crystal content. The Ca2+ release rapidly increased to 300 cmol/kg and then decreased, which was correlated with the Al content in the solution. The rate of decrease in Ca2+ release was also higher with increasing Li content in the solution. It is considered that with increasing the Li/(Na + Li) ratio of the solution dissolution of gehlenite is promoted to supply lager Ca and Al to the solution and the formation of calcium silicate hydrate minerals is promoted.

Fig. 4. Concentrations of Si and Al in the solution during the reaction, and the Na+ and Ca2+ release properties of the solid product after synthesis in each mixed solution; (a) 4 M NaOH, (b) 3 M NaOH + 1 M LiOH, (c) 2 M NaOH + 2 M LiOH, (d) 1 M NaOH + 3 M LiOH, and (e) 4 M LiOH. Summary. Hydroxysodalite was synthesized from PSA in NaOH-LiOH solutions at 90 °C. Hydroxysodalite, katoite, hydrocalumite and portlandite were synthesized in the products.

Hydroxysodalite was synthesized at Li/(Li + Na) ratios lower than 0.25, while calcium hydrate minerals, such as katoite, hydrocalumite and portlandite, were synthesized using other ratios.

Increasing the Li content gradually decreased Na+ and Ca2+ release from the product, increasing Li+ release from the product. The concentrations of Si and Al in the solution observed during the reaction explain the synthesis of products. The release of Na+ from the product depends on formation of hydroxysodalite zeolite crystals, while Ca2+ release depends on formation of CASH gel and calcium minerals, such as katoite, hydrocalumite and portlandite.

References [1] R.M. Barrer, Zeolites and Clay Minerals as Sorbents and Molecular Sieves, Academic Press, 1978.

[2] M. Singh, M. Garg, Cementitious binder from fly ash and other industrial wastes, Cem. Concr.

Res., Vol. 29, 1999, 309-314. DOI: 10.2138/am.2007.2251

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[3] R. Kikuhi, Recycling of municipal solid waste into cement clinker, Resour. Conserv. Recycl., Vol. 31, 2001, 137-147. DOI: 10.1016/S0921-3449(00)00077-X [4] T. Wajima, H. Ishimoto, K. Kuzawa, K. Ito, O. Tamada, M.E. Gunter, J.F. Rakovan, Material conversion from paper-sludge ash in NaOH, KOH, and LiOH solutions, Am. Mineral., Vol. 92, 2007, 1105-1111. DOI: 10.2138/am.2007.2251 [5] T. Wajima, Kinetics of the removal of hydrogen chloride gas using hydroxysodalite at high temperatures, Int. J. Chem. Eng. Appl., Vol. 7, 2016, 235-238. DOI: 10.18178/ijcea.2016.7.4.580 [6] J. Kragten, Atlas of Metal-ligand Equilibria in Aqueous Solution, Ellis Horwood Limited, 1978.

Cite the paper Takaaki Wajima, (2017). Synthesis of Hydroxysodalite From Paper Sludge Ash Using NaOH-LiOH Mixtures.

Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.40.5.622

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Morphological Changes of α-Lactose Monohydrate (α-LM) Single Crystals under Different Crystallization Conditions Using Polar Protic and Aprotic Solvents57 K.Vinodhini1, a, K.Srinivasan 1 , a

1 – Crystal Growth Laboratory, Department of Physics, School of physical sciences, Bharathiar University, Coimbatore, Tamil Nadu, India a – nivas_5@yahoo.com DOI 10.2412/mmse.79.40.404 provided by Seo4U.link

Keywords: lactose, solubility, nucleation, morphology, X-ray diffraction, differential scanning calorimetry.

ABSTRACT. In this study, polar protic (water) and aprotic (DMSO) solvents were used to analyse the morphological changes of alpha-lactose monohydrate (α-LM) single crystals. The solubility of α-LM determined in DMSO by gravimetric method is nearly 2.5 times higher than that found in water at 33 °C. Surprisingly, the weight of the solution increases with time in DMSO as it is highly hygroscopic, whereas the weight of the solution decreases with time in water as it evaporates. Also it is found that the supersaturation of aqueous solution gradually increases by evaporation of solvent, whereas the supersaturation of DMSO solution gradually increases by moisture absorption which reduced the solubility of α-LM. The increasing level of supersaturation in multiple ways in DMSO and water at 33°C induces the mean crystal size, which can be explained by taking into account the role of solvent in the growth environment. The form of grown crystals was confirmed by powder x-ray diffraction (PXRD) and differential scanning calorimetry (DSC) study.

1. Introduction. In aqueous lactose solution, both α and β-Lactose forms change into one another continuously in reversible equilibrium called mutarotation [1, 2]. When α-LM dissolves in water, it readily undergoes mutarotation to yield the β-isomer. DMSO an aprotic solvent reduces the rate of mutarotation of α to β-Lactose in solution [3]. For this reason, in this present study, DMSO and water were used as solvent for growth of α-LM at 33 °C. But there are always interactions of β-L on the nucleated α-LM crystals that are unavoidable as reported by many other researchers. Size and shape of the nucleated α-LM crystals act as an important parameters in the formulation of drug products used both orally and in the form of an inhaler because a small change in this attributes influence blending and mixing, caking, compatibility, flow ability, and aerosol performance. So the changes in the morphology of α-LM single crystals under different crystallization conditions using different solvents were investigated. Different habits of α-LM crystals were harvested from DMSO and water by slow and fast evaporation methods. These grown crystals were subjected to powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) study.

2. Experimental procedure. At 33°C, the solubility of α-LM were determined in differentsolvents, water as polar protic and dimethyl sulfoxide (DMSO) as polar aprotic by gravimetric method. The αLM powder was individually dissolved in DMSO and water with constant stirring at the rate of 250 rpm for 24 hrs. After reaching the equilibrium solubility, the solutions were filtered with Whatmann filter sheets and then 9 ml solutions were only collected, in order to reduce the weight variations of these filtered solutions. Thus the obtained solutions were taken in beakers with a perforated parafilm and kept for growth in water bath maintained at constant temperature of 33 °C. Solutions placed in the beakers were weighed for every 24 hrs to measure the total mass of solution. © 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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The above procedure was repeated again to individually observe the microscopic images of the nucleated α-LM crystals by fast evaporation. For this experiment, 500μl of the solutions were pipetted out on petri dishes and then the size and shape of the nucleated crystals were carefully analysed through microscope.

3. Result and discussion 3.1. Slow evaporation method 3.1.1. Growth of α-LM in DMSO The equilibrium solubility of α-LM in DMSO was found to be 6.8 g per 10 ml. From this solution, 9 g of the solutions were adopted by slow evaporation method. The initial weight of DMSO solution increased from 9 g to 12.16 g until the grown crystals were harvested as DMSO is highly hygroscopic.

DMSO absorbs water and gets diluted to a concentration of 66 to 67 % than the initial concentration when exposed to room temperature as the DMSO - water bond is 1.33 times stronger than the water - water bond [4]. Hence, the hygroscopic nature of DMSO naturally helps for the growth of α-LM because the solubility of α-LM in DMSO that diluted with water is always low [5]. When the interesting phenomenon of moisture absorbance is occurred to DMSO solution, another interesting phenomenon of colloidal creamy structure is formed within overnight. The photographs shown below (Figs.1a and 1b) illustrate the formation of creamy structure (milky white).

1a)

1b) α-LM +DMSO

50 μm

1c) α-LM +DMSO

(110) (100) (110)

1d) α-LM +DMSO

011

(010)

50 μm

Fig. 1. a) The photograph of formation of creamy structure (milky white), b) The microscomic image of creamy structure (milky white), c) The microscopic image of nucleaded α-LM crystals after the dissappearance of milky white, d) Photograph of the grown macroscopic α-LM crystals from DMSO by slow evaporation method After a few days, this creamy structure disappeared and then clears up again because of the occurrence of nucleated crystals in solution. The microscopic image in Fig.1c, illustrates the disappearance of milkiness. Although it is an interesting phenomenon, its nature is as so far unknown. If it were α-LM, there seems no reason why it clears up again. It may be anhydrous α-L, but it could not be confirmed through PXRD and DSC analyses because the anhydrous α-L is transferred into α-LM very quickly.

Hence, in DMSO solution nucleation was formed after a long time because there was time delay between the time of clearing the milky white and the time when the visible crystallization of lactose takes place. The photograph (Fig. 1d) shows crystals of α-LM grown in DMSO by slow evaporation 3.1.2 Growth of α-LM in water The equilibrium solubility of α-LM in water was found to be 2.7 g per 10 ml respectively. From this solution, 9 g of the solutions were adopted by slow evaporation method. The weight of the water solution decreased from initial weight of 9 g to 2.021 g until the grown crystals were harvested due to the evaporation of water. The induction period of α-LM in water was lower than that in DMSO. The Figures (2a and 2b) show the microscopic images of nucleated α-LM by slow evaporation. The Fig (2c) shows macroscopic photograph of α-LM crystals grown in water by slow evaporation.

Hence, increasing the supersaturation in different ways in different solvents at 33 °C induced a significant increase in the mean crystal size. During the slow evaporation process, meta stable zone is larger in lactose solution when compared to other sugar solutions because of the interconversion of α-L and β-L and vice versa [6]. Hence the interactions of β-L on the nucleated α-L crystals are MMSE Journal. Open Access www.mmse.xyz

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unavoidable. Due to this reason all the nucleated α-LM crystals are formed with tomahawk morphology as reported by many other researchers.

2(a)α-LM +Water

2c) α-LM +water

2(b) α-LM +Water

(11 0) (011) 50 50 μm μm

50 50 μm μm

(110)

(010)

Fig. 2. a) – b) The microscopic images of nucleaded α-LM crystals, c) Photograph of the grown macroscopic α-LM crystals from water by slow evaporation method.

3.2. Fast evaporation method 3.2.1. Growth of α-LM in DMSO and water During the fast evaporation process, solutions get supersaturated more rapidly and also time available for interconversion is comparatively low. So α-LM crystals nucleate within a short period of time and the interaction of β-L on the different growth faces of α-LM is significantly low. As a result, the growth of (010) face significantly increased and yielded more symmetrically needle-like crystals. It can be clearly visualized from 500μl solution that was observed from prepared DMSO and water solution as shown in Fig 3(a), (b), (c) & (d). In fast evaporation method also it was found that the induction period of α-LM in water was lower than that in DMSO because there was delay of several minutes between the time of milky white formation and then disappearance again and finally visible crystallization takes place. This interesting phenomenon is shown in fig (3a and 3b ) a) α-LM +DMSO

b) α-LM +DMSO

(011)

(010)

50 μm c) α-LM +Water

(100)

80 μm d) α-LM +Water

(011) (010) (100)

.

50 μm

50 μm

Fig. 3. The needle like morphology of α-LM single crystals grown from DMSO (a, b) and water (c, d) Fig. 3, a) and b) show the crystals formed through transitory milky white after 7.30 and 8.30 hrs respectively with DMSO. Fig. 3, c) and d) show the crystals formed after 16 and 20 minutes respectively with water.

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(5b) α-LM +Water α-LM +DMSO

(4b)

(4a)

α-LM +Water

(5a)

Dehydration of Water Melting point of α-LM

α-LM +DMSO

Fig. 4. a), b) PXRD pattern of α-LM crystals Fig. 5. a), b) DSC curve of α-LM crystals grown grown from DMSO and water by fast from DMSO and water by fast evaporation evaporation method. method The desired needle like morphology of α-LM crystals has been achieved only by fast evaporation method. Hence, in order to estimate the purity of α-LM crystals obtained with needle-like morphology in DMSO and water, the nucleated crystals were subjected to PXRD and DSC analyses. Fig.4a and 4b show the PXRD patterns of α-LM crystals grown from DMSO and water by fast evaporation method. The characteristic PXRD peak for α-LM was observed at 20° 2θ. Fig.5a and 5b show the Differential scanning calorimetry curve of α-LM crystals grown from DMSO and water by fast evaporation method. The DSC results also show that the grown crystals are α-LM. The endothermic peak observed at 148.54-157.47 °C obtained indicates the removal of water of crystallization from αLM crystals, whereas the endothermic peak observed at 204.56-211.02 shows the melting pont of αLM crystals.The obtained results by above estimation confirmed the form of crystallization of pure α-LM. Figs. 4a and 4b show the experimental PXRD and DSC analyses of α-LM crystals with needle like morphology grown from DMSO and water.

Summary. The solubility of α-LM in DMSO and water were determined. The α-LM crystals with tomahawk morphology were harvested in DMSO and water by slow evaporation method, whereas the α-LM crystals with needle like morphology were harvested by fast evaporation method. The fast evaporation method employed led to the achievement of crystals with desired morphology and hence the crystals were subjected to PXRD and DSC analyses. The obtained results confirmed the form of pure α-LM. Acknowledgements. One of the authors (KS) wishes to acknowledge the financial support of University Grants Commission (UGC), New Delhi, India for this work through a major research project [Grant#42-866/2013 (SR)].

References [1] P. L. H. McSweeney and P. F. Fox, Advanced dairy chemistry: Lactose, water, salts and minor constituents, New York, 2009, pp.339-959 [2] P. F. Fox, T. Uniacke-Lowe, P. L. H. McSweeny, J. A. O. Mohony, Dairy chemistry and bio chemistry, New York, 2015, pp.21-68 3] T. D. Dincer, G. M. Parkinson, A. L. Roh and M. I. Ogden, journal of Crystal growth, 1999, 205, 368-374.

[4] E. W. Smith and H. I. Maibach, Percutaneous Penetration Enhances, 1995, pp. 115–127 [5] K. Vinodhini and K. Srinivasan, CrystEngComm, 10.1039/C5CE00001G

2015,

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[6] S. L. Raghavan, R. I. Ristic, D. B. Sheen and J. N. Sherwood, Journal of Phys. chem, 2000,104, 12256-12262.

Cite the paper K. Vinodhini, K. Srinivasan, (2017). Morphological Changes of α-Lactose Monohydrate (α-LM) Single Crystals Under Different Crystallization Conditions Using Polar Protic and Aprotic Solvents. Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.79.40.404

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Growth Aspects, Structural, Thermal and Optical Propertiesof an Organic Single Crystal: 4-(Dimethylamino)Pyridinium 4-Amino Benzonate Dihydrate58 A. Thirunavukkarsu1,3, T. Sujatha1, P.R. Umarani2,3, A. Chitra1, R. Mohan Kumar3, a

1 – Department of Physics, S.I.V.E.T College, Chennai-600073, India 2 – Directorate of Collegiate Education, Chennai-600006, India 3 – Department of Physics, Presidency College, Chennai-600005, India a – mohan66@hotmail.com DOI 10.2412/mmse.5.65.404 provided by Seo4U.link

Keywords: Z-scan technique, X-ray diffraction, photoluminescence, mechanical properties, optical properties.

ABSTRACT. 4-(dimethylamino) pyridinium 4-aminobenzoate dihydrate (DMAPAB) single crystal was grown by employing the solution growth technique.The grown crystal was characterized by using single X-ray diffraction analysis and found that the title compound crystallizes in triclinic space group P1̅.From the FT-IR spectral analysis, the presence of functional groups of synthesized compound was identified. The transmission spectrum of DMAPAB crystal showed no absorption in the visible region. The fluorescence spectra of the title compound were analyzedto evaluate the excitation states. The thermal stability and decomposition stages of DMAPAB were elucidated from the TGA-DTA studies.Z-scan technique was employed to determine the third-order nonlinearity of grown crystal.

Introduction. The development of nonlinear opticalmaterials has been the subject of numerous investigations by both theoreticians and experimentalists in recent years due to their potential applications in optical signal processing. In recent years, researchershave shownmuch interest in the pyridine familycrystals due to their wide transparency window, extended thermal stability and high NLO coefficient. There is much interest in organic nonlinear optical crystals due to their potentially high non-linearity and rapid response in electro-optic devices compared to inorganic NLO materials.The organic NLO crystalsplay important role in third harmonic generation (THG), frequency mixing, electro-optic modulation and optical parametric oscillation [1]. Pyridine and benzoic acid mixedanalog NLO crystals are found to show extended optical and physical properties and hence they can be extensively used for molecular engineering application. Recently, DMAPAB possess the medium strength N—H···O andO—H···Ohydrogenbonds connected bythe adjacent anions and cations,involving water molecules into three dimensional framework. In continuation with the zeal of developing new organiccentric crystal,4-(dimethylamino)pyridinium4-aminobenzoate dihydrate (DMAPAB) crystal has been synthesized from aqueous solution. The present investigation deals with the synthesis, growth and characterizationof 4-(dimethylamino)pyridinium 4aminobenzoate dihydrate single crystal.

Materials and methods. Thestarting materials were of analytical grade reagents andthe synthesis, growth process were carried out by dissolving 4-Dimethylaminopyridine and 4-aminobenzoic acidin the stoichiometricratio of 1:1 in aqueous solution. Single crystal of 4-(dimethylamino) pyridinium 4-aminobenzoate dihydrate (DMAPAB) was grown by the slow evaporation solution technique. The crystalline precipitate was formed by proton transfer reaction, where a proton can be transferred from the electron donor group of 4-aminobenzoic acid to the © 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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electron acceptor group of 4-Dimethylaminopyridine. The saturated solution was keptat 32ºCwith moisture and dust free environment. The repeated recrystallizationprocess improved the purity of the compound. The high pure synthesised compound was used to grow the bulk crystal by slow evaporation method. The reaction scheme and photograph of grown single crystal of DMAPAB are shown in Fig.1.

Fig. 1. (a) Synthesis scheme and (b) Photograph of DMAPAB crystal.

Experimental. A Bruker Kappa Apex II single crystal X-ray diffractometer with MoKα (λ = 0.71013 Å) radiation was used to measure cell parameters of DMAPAB crystal with a typical cell dimension of about 0.36 x 0.32 x 0.30 mm3. Powder X- ray diffraction pattern of the grown crystal was recorded by using BRUKER AXS CAD 4 with 1.5406 Å CuKαradiation. The vibrational spectrum was recorded for DMAPAB compound by using FTIR-4100 type spectrometer at a resolution of 4 cm-1 in the range 400-4000 cm-1. UV-Vis transmission region of DMAPABcrystal was ascertained in the range 190-1100 nm by using LABINDIA T90+ UV-Vis spectrophotometer.TGDTA experiment was carried out by using a NETZSCH STA 409 instrument with a heating rate of 10ºC/min ranging from 30 to 500 ºC. Z-scan technique was employed to determine the third-order nonlinearity of grown crystal by using 632.8 nm He-Ne laser source.

Results and discussion.

X-ray diffraction studies. Single crystal X-ray diffraction analysis shows that the title compound crystallizes in the triclinic space group P1̅, with cell parameters of a = 9.3402(7) Å, b = 9.7999 (7) Å, c = 10.2132 (8) Å, α = 65.755 (3)°, β = 69.983 (2)°, γ = 89.212 (3)°, V = 792.08 (10) Å 3, and Z = 2 [2]. The sharpness of defined Bragg peaks in the powder X-ray diffraction pattern confirmed its crystallinity.X-ray powder pattern of DMAPAB is shown in Fig.2. The prominent Bragg peaks in the powder X-ray diffraction pattern were indexed. The peak corresponding to (200),(212),(012) planes have maximum intensity counts at 2θ values of20.10, 22.70 and 18.50 respectively. Thestrongest diffractionpeaks revealed the crystalline natureof the title compound.

FT-IR analysis. The infrared spectral analysis is effectively used to understand the chemical bonding and it provides information about the molecular structure of the synthesized compound. Theformation of charge transfer complex during the acid: baseinteraction of 4-Dimethylaminopyridine with 4aminobenzoic acid is stronglyevidenced through the realization of important bands ofdonor and acceptor in the resultant spectrum of the complexsaltas shown in Fig.3. The bands observed at 3451and 3350cm−1 may be due to the asymmetric and symmetric stretching modes of primary amine.

A strong broad NH+ stretching band observed at 3241cm−1. The vibrational frequency occurred at 2927and 2875cm-1are due to asymmetry and symmetry stretching vibrations of methylene group. The peaks arose at 2061, 1965 and1877 cm-1are due to aromatic overtones. The absorption peak noted at 1602 cm-1establishes the presence of carbonyl stretching frequency. The band yielded at 981 cm−1 is due toC-N in-plane bending vibration. The broad band observed at 796 cm-1 is due to C-H-N bending

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vibration. The peak observed at 623cm−1 is due to the N–H out-of-plane bending [3]. The recorded FT-IR spectrum clearly showed the formation of crystal lattice of DMAPAB.

Fig. 2. Powder XRD pattern of DMAPAB crystal. Fig. 3. FT-IR spectrum of DMAPAB.

UV-Vis transmission studies. Optical characteristics provide a good way of examining the properties of crystalline materials. Particularly, measurement of absorption coefficient for various energies gives information about band gap of the material. The recorded UV–Vis–NIR transmittance of DMAPAB is shown in Fig.4.From the UV-visible transmittance analysis, it is clear that the grown crystal exhibit good transparency of about 60% in the visible region with the lower cut-off wavelength 318 nm. The optical band gap (Eg) was evaluated from the transmission spectrum and the optical absorption coefficient (α) near the absorption edge was evaluated from the relation:

(αhν) = A ( Eg - hν)1/2

(1)

where A is a constant, Eg is the optical band gap, h is the Planck’s constant and ν is the frequency of the incident photons.

The Tauc’s plot [4] drawn between the product of absorption coefficient and the incident photon energy (αhν)2 with the photon energy (hν) (Fig.5) shows a linear behavior which is considered as evidence for direct transition. The Eg value obtained by extrapolating the curve was found to be 3.63eV. The wide optical band gap of the grown crystal confirms that the crystal possess large transmittance in the visible region.

Fig. 4. UV-Vistransmission spectrum of DMAPAB. MMSE Journal. Open Access www.mmse.xyz

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Fig. 5.Tauc’s plot drawn between (αhν)2 vs photon energy (hν).

Photoluminescence studies. Photoluminescence is a contactless, non-destructive method of probing the electronic structure of materials.Fluorescence may be expected generally in molecules that are aromatic or containing multiple conjugated double bond switches for a high degree of resonance stability.The sample was excited at 300 nm and the emission spectrum was measured in the range of 300–650 nm. From the recorded photoluminescence spectrum (Fig.6), it was observed that the material exhibits a high intense emission peak at 350 nm. Hence, the photoluminescence analysis concludes that DMAPAB crystal exhibits violet fluorescence. The maximum intensity which appears at 350 nm is attributed to n-π* transition with N-H and O-H functional group molecules.

Thermal analysis. The thermal analysis of DMAPAB was carried out in nitrogen atmosphere and thermograms of DMAPAB crystal areshown in Fig.7. In TGA, the first weight loss stage observed at 123oC is due to the presence of water molecules in the synthesized salt. It is seen, that the major weight loss started at 214oC and it continued up to 290oC. It indicates that this huge weight loss is due to the decomposition of functional group molecules in the form of NH and CH3 evaporation. The synthesized compound DMAPAB has thermal stability upto214oC. In the DTA, the weight loss occurred due to the water molecules; also the sharp endothermic peak observed at 180oC is due to decomposition or melting point of compound of DMAPAB crystal. The sharpness of endothermic peaks observed in DTA indicates the good degree of crystallinity of the sample.

Fig. 6. PL spectrum of DMAPAB. Fig. 7. TG/DTA thermogram of DMAPAB.

Z-Scan Measurement. The Z-scan study is needed to examine nonlinear opticalbehavior which is used to find the third-order nonlinearity, changes in the nonlinear refractive index and variation in MMSE Journal. Open Access www.mmse.xyz

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absorption [5]. The Z-scan plots measured in open and closed aperture modes are shown in Fig.8.

From the Z-scan data, the difference between the valley and peak transmittance (∆Tv-p) was evaluated in terms of the on-axis phase shift at the focus. Tvp  0.406(1  S)0.25  o

(3)

where S is the linear transmittance aperture and it was calculated using the relation,   2ra2 S  1  exp  2  a

  

(4)

where ra is the radius of aperture and ωa is the beam radius at the aperture.

The nonlinear refractive index (n2) was calculated by using closed aperture Z-scan data [6, 7].

n2 

 o KI o Leff

(5)

The third order nonlinear optical susceptibility was calculated using the relation [8],

 (3 ) 

(Re  ( ) )  (Im  ( ) ) 3

2

3

2

(6)

The calculated third order nonlinear optical parameters are given in Table 1. Z-scan studies confirm that the DMAPAB crystal can be a promising NLO material for optical device applications such as optical modulators and optical limiters.

Table 1. Optical parameters of DMAPAB measured in Z-scan experiment.

Effective thickness (Leff) 0.9974 mm Nonlinear refractive index (n2)

0.9584 ×10−10cm2/W

Nonlinear absorption coefficient ()

2.4283 ×10−3 cm/W

Third-order nonlinear optical susceptibility ((3))

1.8594 ×10−10esu

Fig. 8. Z-scan traces observed in (a) Open aperture and (b) closed aperture modes for DMAPAB Crystal.

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Summary. Organic single crystal of DMAPABwas grown by the slow evaporation solution growth technique. The crystal structure of DMAPABwas determined by single crystal XRD studies. From the UV-Vis spectral analysis, it was found that the DMAPABcrystal istransparent in the entire visible region and the cut-off wavelength was found to be 318 nm.

The photoluminescence analysis concludes that DMAPAB crystal exhibits violet fluorescence.Fromthe TG–DTA curve, it is clearly observedthat the synthesised material is stable up to 214 oC. The third order nonlinearoptical susceptibility, nonlinear refractive index and nonlinearabsorption coefficient were estimated by Z-scan studies.

References [1] T. Ishikawa, and T. Isobe, Modified guanidines as chiral auxiliaries, Chem. Eur. J. 8 (2002) 552– 557.

[2] A. Thirunavukkarasu, A. Silambarasan, G. Chakkaravarthi, R.Mohan Kumar, P.R. Umarani,Crystal structure of 4-(dimethylamino) pyridinium 4-aminobenzoate dihydrate,ActaCryst.

E, 71 (2015) o26–o27.

[3] R.M. Silverstein, F.X. Webster, D. Kiemle, D. L. Bryce,Spectrometric Identification of Organic Compounds, John Wiley & Sons, New York (2014).

[4] M.A. Gaffar, A. Abu El-Fadl, S.Bin Anooz, Influence of strontium doping on the indirect band gap and optical constants of ammonium zinc chloride crystals, Physica B, 327 (2003) 43–54.

[5] H. J. Coles, and S. V. Kershaw, Pretransitional isotropic Kerr effect in eutectic mixtures E120, E130 and E140, J. Chem. Soc., Faraday Trans 2,84 (1998) 987-996.

[6] R. Sureka, P. Sagayaraj, K.Ambujam, Third order nonlinear optical, luminescence and electrical properties of bis-glycine hydrobromide single crystals, Opt. Mater. 36 (2014) 945-949.

[7] G. AnandhaBabu, P. Ramasamy, Growth and characterization of 2-amino-4-picolinium toluene sulfonate single crystal, Spectrochim.ActaA, 82 (2011) 521-526.

[8] A. Subashini, R. Kumaravel, S. Leela, H.S. Evans, D. Sastikumar, K.Ramamurthi, Growth and characterization of 4-bromo-4'chloro benzylidene aniline: a third order nonlinear optical material, Spectrochim. ActaA, 78 (2011) 935-941.

Cite the paper A. Thirunavukkarsu, T. Sujatha, P.R. Umarani, A. Chitra, R. Mohan Kumar, (2017). Growth Aspects, Structural, Thermal and Optical Propertiesof an Organic Single Crystal: 4-(Dimethylamino)Pyridinium 4Amino Benzonate Dihydrate. Mechanics, Materials Science & Engineering, Vol 9. Doi 10.2412/mmse.5.65.404

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Growth Aspects, Structural and Optical Properties of 2-aminopyridinium 2,4 Dinitrophenolate Single Crystal59 S. Reena Devi1, B. Valarmathi1, R. Mohan Kumar1, a

1 – Department of Physics, Presidency College, Chennai, India a – mohan66@hotmail.com DOI 10.2412/mmse.6.55.34 provided by Seo4U.link

Keywords: Organic compounds, solution growth, Laser damage threshold, Nonlinear optic materials.

ABSTRACT. Organic single crystal of 2-aminopyridinium 2,4-dinitrophenolate single crystal was grown by slow evaporation technique. The cell parameters and space group (P1̅) were determined from single X-ray diffraction analysis.

HRXRD studies ascertained the crystalline quality. UV-Visible and PL spectral studies revealed the emission in red region, transparency (75%) cutoff wavelength around 440 nm respectively. The laser damage threshold of grown crystal was estimated by using Nd:YAG laser beam and these results were mutually related with specific heat capacity of the grown crystal. The third-order nonlinear optical parameters were estimated by Z-scan technique which is useful for optical applications.

Introduction. Organic nonlinear optical materials have many advantages over inorganic nonlinear optical materials due to their potential applications in scientific and technical fields like high density optical data storage, ultra compact laser and electro-optical amplitude modulation [1]. Generally, organic materials are having donor and acceptor groups located at either end of a required conjugation path and the organic backbone delocalized π-electron determines high molecular polarizability and thus exhibiting third order optical nonlinearity [2]. 2-aminopyridine, a heterocyclic molecule contains two nitrogen atoms which are used to understand the nucleic acid bases. Nitrophenolate derivatives are interesting NLO candidates and phenolic OH favors the formation of salts with large hyperpolarizabilities. 2-aminopyridine compound intercalated with 2,4-dinitrophenol forms hydrogen bonds which are having charge transfer complexes of donor π-acceptor structure. The structure of 2-aminopyridinium 2,4-dinitrophenolate in stoichiometry ratio was reported [3]. In the present investigation, 2-aminopyridinium 2,4-dinitrophenolate single crystal was grown by low temperature solution method and its structural, UV-visible, laser damage threshold, specific heat and third order nonlinear optical properties have been studied.

Experimental Material Synthesis and Crystal Growth.

The 2AP24DNP compound was synthesized from 2-aminopyridine and 2,4-dinitrophenol starting materials and they were purchased from (Sigma-Aldrich 97%) and (AR grade 90%) respectively.

They were taken in equimolar ratio and dissolved in mixed solvent of water and ethanol. The solution was stirred about 4 hr to obtain uniform density solution and it was filtered by using whatman filter paper. The saturated solution was allowed to evaporate at room temperature and after three weeks

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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period a good quality of 2AP24DNP crystal was harvested. The photograph of as grown 2AP24DNP crystal is shown in Fig.1(a).

Results and Discussion X-ray Diffraction Analyses. The grown crystal was subjected to single crystal XRD analysis and the lattice parameter values were found to be a = 7.6303 Çş, b = 9.3142 Çş, c=17.2518Çş, Îą = 90.339° β = 99.468° Îł = 99.556° and the volume of the unit cell V = 1191.91 Ǻ³. Single crystal XRD data confirms that the grown crystal belongs to triclinic crystal system with the space group (P1Ě&#x2026;). From the Fig.1(b), the HRXRD diffraction curve contains a single peak and represents that the 2AP24DNP crystal is free from structural grain boundaries. The full width at half maximum of the curve was found to be 6 arc sec which is somewhat more than that expected from plane wave theory of dynamical X-ray diffraction for an ideally perfect crystal [4]. This rocking curve clearly indicates that the crystal possess significantly interstitial defects instead of vacancy defects. However, these interstitial defects may be due to the self interstitials, impurity atoms including solvent atoms or molecules in the crystalline material. In this study, the single diffraction peak with low FWHM indicates that the crystalline perfection is fairly good.

Fig. 1. (a) Photograph of as grown crystal of 2AP24DNP, (b) HRXRD diffraction curve of 2AP24DNP crystal.

UV-visible and Photoluminescence studies. UV-Vis spectrum of grown 2AP24DNP single crystal was recorded by using Perkin-Elmer Lambda spectrometer in the wavelength range 400-800 nm. In the UV-visible studies, transmission range and cut off wavelength are important criterion.

2AP24DNP single crystal showed 75 % transmission with lower cut off wavelength around 440 nm as shown in Fig.2(a).

The optical absorption coefficient (Îą) can be calculated with transmission (T) value by using the relation,

Îą=

2.3026 đ?&#x2018;Ą

log (1/T)

(1)

where t is the thickness of the sample. The optical band gap determined from transmission spectrum and absorption coefficient (Îą) is given by:

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(Îąhν)2 = A (Eg â&#x20AC;&#x201C;hν)

Eg =

1240 đ?&#x153;&#x2020;

eV

(2)

(3)

where Îť is the lower cut off wavelength, Eg is the optical band gap of the material, A is the constant, h is the Planckâ&#x20AC;&#x2122;s constant and ν is the incident photon frequency. The optical band gap of 2AP24DNP crystal was estimated by plotting (Îąhν) 2 against hν as shown in Fig. 2(b). The band gap value was evaluated by extrapolating the linear part. It was found to be 2.8 eV which is in good agreement with theoretical value of optical band gap.

Photoluminescence is an important optical property for investigating the crystalline quality and fine structure of exciton which is obtained by monitoring emission at a fixed wavelength while varying the excitation wavelength. PL study was carried out by spectrofluorometer and the recorded spectrum of 2AP24DNP crystal is shown in Fig.2 (c). A broad emission peak was observed at wavelength of 645 nm with an excitation wavelength of 435 nm and it covered the red region of the visible spectrum which may be attributed to the Ď&#x20AC;*â&#x2020;&#x2019;n transition. Thus, the PL spectrum revealed the electronic transition and band gap energy of the grown 2AP24DNP crystal.

Fig. 2. (a) UV-Visible transmittance spectrum, (b) Plot of (ιhν)2 Vs photon energy and (c) Photoluminescence spectrum of 2AP24DNP crystal.

Laser-induced damage threshold and specific heat capacity. A Q-switched Nd:YAG laser of 1064 nm fundamental beam with pulse width 10 ns and 10 Hz repetition rate was used as the source. The cut and polished sample was placed at the focus of a plano convex lens of focal length 30 cm and multiple shot mode LDT measurement was made on well polished crystal. An attenuator was used to vary the energy of the laser pulses with a polarizer and a half wave plate. The laser damage threshold value was measured using combination of a phototube and an oscilloscope.

The surface damage threshold of the crystal was calculated using the relation:

Powder density P (d) =

đ??¸ đ?&#x153;&#x2039;đ?&#x2018;&#x; 2 đ?&#x153;?

W/cm2

where E is the energy (mJ), Ď&#x201E; is the pulse width (ns) and r is the radius of the spot (mm).

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(4)

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The laser damage threshold value of 2AP24DNP crystal was found to be 10.54 GW/cm2. The specific heat of solid is one of the factors that determine the laser damage threshold value of crystal, the threshold intensity is directly proportional to square root of specific heat of the material. The specific heat capacity of the 2AP24DNP crystal was measured by using DSC thermal analysis in the temperature range 30°C â&#x20AC;&#x201C; 95°C at a heating rate of 3.5°C/minute. Fig. 3 shows the dependence of the specific heat of 2AP24DNP with different temperatures.

When the laser radiation penetrated into the 2AP24DNP crystal, it absorbed thermal energy and caused damage on the surface of the crystal. At low temperature gradient, the crystal possessed high specific heat capacity. Hence the laser damage threshold is high for the crystal possessing low temperature gradient. The measured specific heat capacity of the compound is compatible with laser damage threshold value of 2AP24DNP crystal.

Fig. 3. Plot of specific heat capacity vs. temperature of 2AP24DNP crystal.

Z-scan studies. Z-scan technique is a simple and accurate method for determining third order nonlinear optical response of nonlinear refractive index (n2) and nonlinear absorption coefficient (β).

The favorable advantage of this method is used to measure both the sign and magnitude of nonlinear refractive index and nonlinear absorption coefficient using Z-scan plots measured in closed aperture and open aperture respectively. Z-scan experiment was performed using Nd:Yag laser with 532 nm as an excitation source and its propagation along Z-scan axis.

Fig. 4(a) shows the distinctive closed aperture Z-scan curve of the title crystal with normalized transmittance for the incident intensity. The closed curve was depicted by placing an aperture in front of the detector and sample moved towards the focus resulting higher transmittance (peak) due to increasing intensity. The sample moved away from the focus produced minimum transmittance (valley) due to decreasing intensity. Hence the peak followed by a valley from closed aperture Z-scan of normalized transmittance is the signature of negative refractive nonlinearity (n2 < 0). The negative nonlinear refractivity indicated the self defocusing effect which is in result of phase distortion transformation of the propagating beam. The value of â&#x20AC;&#x2DC;n2â&#x20AC;&#x2122; was obtained from the result of the difference between the normalized peak and valley transmittance (â&#x2C6;&#x2020;Tp-v) and it was calculated using the relation, â&#x2C6;&#x2020;Tp-v = 0.406(1-S) 0.25|â&#x2C6;&#x2020;đ?&#x203A;ˇo|

(5)

where â&#x2C6;&#x2020;ÎŚo is the on-axis phase shift at the focus, S is the linear transmittance aperture and it was calculated using the relation, MMSE Journal. Open Access www.mmse.xyz

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đ?&#x2018;&#x2020; = 1 â&#x2C6;&#x2019; exp(â&#x2C6;&#x2019;

2r2a Ď&#x2030;2a

)

(6)

where, ra is the radius of the aperture and Ď&#x2030;a is the diameter of the spot size at nearest position of the aperture. The nonlinear refractive index (n2) was determined using the closed aperture Z-scan data using the relation, â&#x2C6;&#x2020;đ?&#x203A;ˇđ?&#x2018;&#x153;

n2 = đ??ž đ??ź

(7)

0 đ??żđ?&#x2018;&#x2019;đ?&#x2018;&#x201C;đ?&#x2018;&#x201C;

where k is the wave number (=2Ď&#x20AC;/Îť), Io is the intensity of laser beam at the focus (z=0) and Leff= {[1exp(-ÎąL)])/Îą} is the effective thickness of the sample, where, Îą is the linear absorption and L is the thickness of the sample [5].

Fig. 4(b) shows the normalized transmission observed in open aperture Z-scan mode. For this measurement the aperture was removed, making the scan insensitive to nonlinear refraction. The intensity distribution of a Gaussian laser beam could be symmetric around the focus (Z=0) where it has minimum transmittance. The nonlinear absorption co-efficient (β) was estimated from the open aperture Z-scan data.

đ?&#x203A;˝=

2â&#x2C6;&#x161;2 â&#x2C6;&#x2020;T

(8)

I0 Leff

where â&#x2C6;&#x2020;T is the valley point at the open aperture Z-scan data. The value of â&#x20AC;&#x2DC;βâ&#x20AC;&#x2122; could be positive sign for two photon absorption and negative sign for saturable absorption which is equal to,

â&#x2C6;&#x2020;T = 1-TV

The enhanced transmission near the focus is indicative of saturable absorption at high intensity. The real and imaginary parts of the third order nonlinear optical susceptibility (Ď&#x2021;(3)) were estimated using the relations,

Re Ď&#x2021;3 (đ?&#x2018;&#x2019;đ?&#x2018; đ?&#x2018;˘) = Im Ď&#x2021;3 (esu) =

2đ?&#x2018;&#x203A; ) 10â&#x2C6;&#x2019;4 (đ?&#x153;&#x20AC;đ?&#x2018;&#x153; đ??ś 2 đ?&#x2018;&#x203A;đ?&#x2018;&#x153; 2

đ?&#x153;&#x2039;

2 đ?&#x153;&#x2020;đ?&#x203A;˝) 10â&#x2C6;&#x2019;2 (đ?&#x153;&#x20AC;đ?&#x2018;&#x153; đ??ś 2 đ?&#x2018;&#x203A;đ?&#x2018;&#x153;

4 Ď&#x20AC;2

(cm2/w)

(9)

(cm/w)

(10)

where Îľo is the vacuum permittivity, c is the velocity of light in vacuum, no is the linear refractive index of the sample and Îť is the wavelength of laser beam.

The third order nonlinear optical susceptibility was calculated using the relation,

Ď&#x2021; (3) = â&#x2C6;&#x161;(R e Ď&#x2021;(3) )² + (Im Ď&#x2021;(3) )²

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(11)

Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

From the above analysis, the nonlinear refractive index n2 = 7.32 x 10-8 cm2/W, nonlinear absorption coefficient, β = 0.37 x 10-4 cm/W and third order nonlinear susceptibility, χ(3) = 8.437 x 10-6 esu were determined by Z-scan technique.

Fig.4. Z-scan plot of 2AP24DNP crystal measured in (a) closed aperture mode and (b) open aperture mode

Summary. Third order nonlinear organic single crystal of 2AP24DNP with 11x7x4 mm³ dimension was grown by slow evaporation technique. From the single crystal and HRXRD studies, it was observed that 2AP24DNP crystal belongs to triclinic crystal system with the space group (P1̅) and shows good crystalline infallibility. UV-Vis transmittance studies imparted the electronic transition mechanism of ions, crystal transparency, cut-off wavelength and band gap energy of the grown crystal. The laser damage threshold of grown crystal was found and those results were mutually related with specific heat capacity of the grown crystal. The third-order nonlinear optical parameters estimated for grown crystal by Z-scan technique could be useful for optical applications.

References [1] K. Sathishkumar, J. Chandrasekaran, B. Babu, C. I. Sathish, Y. Matsushita, Synthesis, growth and characterization of bis (potassium) 2, 4-dinitrophenolate monohydrate (BPDNP): a new third harmonic generation material. Appl. Phys. A, Vol. 119, pp. 1355-1364, 2015, DOI: 10.1007/s00339015-9103-6.

[2] I. P. Bincy, R. Gopalakrishnan, Synthesis, growth and characterization of new organic crystal: 2Aminopyridinium p-Toluenesulfonate for third order nonlinear optical applications, J. Cryst.

Growth, Vol. 402, pp. 22-31, 2014 DOI: 1016/j.jcrysgro.2014.03.024.

[3] S. Reena Devi, R. Akilan, R. Mohan Kumar, T. Ganesh, G. Chakkaravarthi. 2-Aminopyridinium2, 4-dinitrophenolate, IUCr Data, Vol. 9, pp. 1,x161489, 2016, DOI: org/10.1107/S2414314616014899.

[4] B.W. Betterman, H. Cole, Dynamical diffraction of X-rays by perfect crystals, Rev. Mod. Phys., Vol. 36, pp. 681-717, 1964, DOI: org/10.1103/RevModPhys.36.681.

[5] P. Nagapandiselvi, C. Baby, R. Gopalakrishnan, Self-assembled supramolecular structure of N,N, N′, N′-tetramethylethylenediammonium-bis-(4-nitrophenolate): synthesis, single crystal growth and photo physical properties, RSC Adv., Vol. 4, PP. 22350-22358, 2014, DOI: 10.1039/C4RA02393E. Cite the paper S. Reena Devi, B. Valarmathi, R. Mohan Kumar, (2017). Growth Aspects, Structural and Optical Properties of 2-aminopyridinium 2,4 Dinitrophenolate Single Crystal. Mechanics, Materials Science & Engineering, Vol 9. doi 10.2412/mmse.6.55.34 MMSE Journal. Open Access www.mmse.xyz

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