Effects of Manganese (Ii) Sulphate on Structural, Spectral, Optical, Thermal

Mechanics, Materials Science & Engineering, May 2017

ISSN 2412-5954

Effects of Manganese (Ii) Sulphate on Structural, Spectral, Optical, Thermal and Mechanical Properties of L-Alanine Sodium Sulphate Single Crystals19 F. Praveena1, S.L. Rayar2 1

Department of physics, M.E.T.Engineering College, chenbagaramanputhoor, Tamilnadu, India

2 DOI 10.2412/mmse.56.71.446 provided by Seo4U.link

Keywords: LASS, FT-IR, TG-DTA, sodium sulphate single crystals.

ABSTRACT. New Non-linear Optical materials have been attracting in the research world for their potential applications in emerging opto-electronic technology. The dipolar nature of amino acid leads to peculiar physical and chemical properties, thus making a good candidate for NLO applications. Single crystals of manganese (II) sulphate doped LAlanine sodium sulphate(LASS) has been synthesized by slow evaporation technique. Structural property of the grown crystals are characterized by X-ray powder diffraction,FT-IR spectral analysis conforms all the functional groups.Thermogravity(TG) and differential themogravimetric(DTA) analysis have been performed to study the thermal stability of the crystals. The second harmonic generation efficiency was measured by Kurtz-Perry powder technique. The transmission and absorption of electromagnetic radiation is analysed through UV-VIS spectrum. Microhardness was measured at different applied load to understand the mechanical stability of the crystal.

Introduction. Non-linear optical materials are used in several practical applications in telecommunication, optical computing, optical data storage and processing, laser technology and in many other fields. Today research is focused on searching new semi organic nonlinear optical (NLO) materials, as they share the advantages of both inorganic (high thermal and mechanical stability) and organic (broad optical frequency range and second harmonic conversion efficiency) materials.

Alanine is an amino acid, which is an important source of energy for muscle tissue, the brain and central nervous system. L-alanine is an isomer of alanine with the chemical formula CH3CHNH2COOH next to glycine. L-alanine molecule can exist in zwitterionic form and it can form novel nonlinear optical (NLO) compounds [1-2].They contain proton donar carboxyl acid (-COO) group and the proton acceptor amino (NH2) group in them [3]. These versatile behaviours of amino acid based organic crystal attract the researchers towards crystal growth of NLO crystals. The complexes of amino acids and salts are promising materials for optical second harmonic generation (SHG) [4]. Recently also optical, spectral and second harmonic generation studies were carried out on L-Alanine based materials [5-8]. In this work, the manganese (II) sulphate is introduced into the lattice of L-alanine sodium sulphate crystals to alter the structural, spectral, thermal, optical and mechanical properties of LASS crystal and analysed. Characterization studies such as powder XRD, EDAX, FTIR were done. Kurtz and Perry SHG test confirms the NLO property of the grown crystals.Hardness values are found out by Vickers hardness test.

Synthesis and growth of the crystal. Analytical reagent (AR) grade L-alanine, sodium sulphate(Na2SO4) and manganese(II) sulphate monohydrate (MnSO4.H2O) were used along with double distilled water (as a solvent) for the growth of single crystals by the slow evaporation method.

L-alanine and Sodium sulphate mixed in 1:1 molar ratio were dissolved in double distilled water and stirred for four hours to obtain a homogeneous solution. The solutiobn was filtered and kept in a dust free environment. Transparent and colorless single crystals of L-alanine sodium sulphate (LASS) 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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Mechanics, Materials Science & Engineering, May 2017

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with dimenions13.5x11x6 mm3 were formed at room temperature in a period of about 30 days as per the reaction. LASS was added with MnSo4.H2O in the molar ratio 1:0.01. Mn2+ doped LASS crystals of 11x8x4 mm3 were grown in a period of about 27 days similarly under identical conditions with the pure LASS crystal growth. Fig. 1 (a), 1 (b) shows the photographs of pure and Mn2+ doped LASS crystals respectively.

Fig. 1. (a) Photograph of pure LASS, (b) photograph of Mn2+ doped LASS. Structural analysis

(110)

(04

(142) (251) (043)

(140)

(120)

(131)

Powder XRD. The purified samples of grown LASS crystals are crushed to a uniform powder and subjected to a powder X-ray diffraction using a Bruker AXS D8 advance powder X-ray Diffractometer. T studies. The powdered sample is scanned in the range 10 defined sharp peaks reveals the good crystalline nature of pure and doped LASS crystals.The position of the peaks are slightly shifted and the intensity varied due to the dopant. The XRD pattern of the grown LASS crystal and Mn2+ doped LASS crytals are shown in fig. 2 (a) and fig. 2 (b).

20

30

40

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60

70

80 0 20

30

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60

70

80

Fig. 2. (a): powder XRD pattern of pure LASS, (b): powder XRD pattern of Mn2+ doped LASS. Ft-ir spectral analysis. The FT-IR spectrum of undoped and Mn2+doped L-alanine sodium sulphate was recorded using FT-IR spectrometer in the region 4000-400cm-1.From the spectra,the Intensity of bands have been altered and slightly shifted..It is due to the presence of Mn2+ ions in the lattice of doped crystal. It is found that the N-H Streching vibration in the amine group is assigned wave number of 3087cm-1. The transmission due to the O-H bond in the carboxylate group is observed in the region MMSE Journal. Open Access www.mmse.xyz

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2730cm-1for LASS , whereas in the case of doped LASS, the peak is shifted to 2810 cm-1. The peaks at 1359 cm-1 and 1360 cm-1 due to S=O stretching in sulphate groups of pure and doped LASS repectively. Metal bondings are assigned the wave numbers 539 cm-1 and 540 cm-1 for pure and doped LASS crystals[9-10].Thus all the molecular groups presents in the Mn2+ doped LASS crystals could be identified. The FTIR spectra of pure and doped LASS crystals are shown in Fig.3(a) and fig.

3(b).

100.0 95 90

3981

774

100.0 95 90

772

85 80 75

1960

70

1237

85 80

1013 646 1113 540

75 6

70

65

65 410 .59

60

2108

60 55

55

%T

2601

45 40

50

1235

50

1360

%T 45 40

2605 2810 3081

35

647

35

30 25

2109

20

20 15

539

1603 1359

2730

5

25

1010

15 10

30

10

4000 .0

0.0

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3200

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5 0.0

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cm-1

Fig. 3. (a) The FTIR spectra of pure LASS, (b) The FTIR spectra of Mn2+ doped LASS. Optical Analysis Non-linear optical analysis. The NLO property of the crystal is confirmed by the Kurtz and Perry technique.The fundamental beam of 1064nm from Qswitched Nd:YAG laser is used to test the second harmonic generation (SHG) property of the doped L-alanine sodium sulphate crystals. The output power from the pure LASS and Mn2+ Doped LASS crystals were compared to that of KDP crystal and the results are presented in table1.

Table 1. SHG efficiency of pure LASS and doped LASS crystal.

Sl. No. Name of the crystal

Output Energy

Input Energy (joule)

SHG efficiency (compared with KDP)

6.81

0.68

0.87

10.01

0.68

1.28

(milli joule) 1

LASS

2

Mn2+ LASS(0.01)

doped

The result obtained for Mn2+ doped LASS shows that SHG efficiency is about 1.28 times that of KDP crystal. When compared with LASS crystal, it is found that the SHG efficiency of Mn2+ doped LASS crystal is high. This increase in the efficiency indicates that the crystals can be used for applications in non-linear optical devices. (ii) UV-VIS analysis. The UV - visible spectrum was recorded for the powdered sample of the crystals. This study was carried out in the spectral range 190-800 nm for the grown LASS and MnSO4 doped LASS crystal. The recorded optical absorption spectrum of the grown single crystals are shown in fig. 4(a), 4(b).

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Fig. 4. (a), (b) Recorded optical absorption spectrum.

It is observed from the spectrum that the lower cut-off wavelength is 204 nm for doped LASS and the transmittance of 97%, which proves the good optical quality.Using the formula: (1) The optical band gap (Eg) was determined to be 6.05 eV for the grown manganese (II) sulphate doped LASS crystal.The transmittance is decreased by adding dopant. The reduction of transmittance is expected due to the incorporation of cations into the superficial crystal lattice and forming defects centers.

Thermal Analysis. Thermogravimetry (TG) and differential thermogravimetric (DTA) analysis are carried out for L-alanine sodium sulphate crystal using Perkin Elmer, Diamond TG/DTA instrument .

Fig. 5. (a) Thermo gravimetric curve of pure LASS, (b) Thermo gravimetric curve of Mn2+ doped LASS. The figures 5 (a) and 5 (b) represents TGA trace of undoped and doped L-alanine sodium sulphate.

For pure LASS the decomposition point occurs at the temperature 294.5 the carbon dioxide (CO2) sulpur dioxide (SO2), and NH2 gases are expected to be liberated from LASS sample.

In Mn2+ doped LASS,a tiny endothermic peak around 235 to 255 decomposition of metal ions Mn2+. The sharp endothermic peak around 255 to 340 matches the onset decomposition of LASS and it is stable up to 296 . The slight increment in temperature is evident for the doped crystals suggesting that the substitution of dopant.

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Mechanics, Materials Science & Engineering, May 2017

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Mechanical analysis The mechanical property of grown crystals were studied by Vickers hardness test. The applied loads were 25, 50 and 100 grams. The measurement was done at different points on the crystal surface and the average value was taken as Hv micro hardness was calculated using the relation, Hv = 1.8544 P / d2

(2)

where P is the applied load; d

is the diagonal length of the indentation impression.

Fig. 6 (a) shows that the plots of the load p and Hv values.It is observed that the Vickers hardness number increases with increasing load. Above 100g, cracks developed on the surface of the crystals due to the to increase the hardness value. Fig. 6(b) shows that the plots of log d against log P for the pure and Mn2+ doped LASS crystals. The work hardening exponents were calculated from the slopes of the straight lines. The work hardening coefficients are found to be 4.4 and 3.07 respectively for pure and Mn2+ doped LASS crystals. According to Onitsch, 1.0 n 1.6 for hard materials and n > material category [11-12].

1.75 1.7 1.65 1.6 1.55 1.5 1.45 1.4 1.35

100 80 60

HV

40

LASS Mn2+ Doped LASS

20 0 0

50

100

LASS Mn 2+ Doped LASS

Log d

120

1.3979 1.4644

2

Load P Log P Fig. 6. (a) Hardness behavior of pure and Mn2+ doped LASS, (b) plots of log d verses log P of pure and Mn2+ doped LASS. Summary. Good optical quantity of NLO transparent crystals of pure and doped L-Alanine sodium sulphate are successfully grown by slow evaporation technique. Structural Characterization was carried out by Powder X-ray diffraction. The FT-IR analysis shows the bands belonging to spectrum of pure and Mn2+ doped L-Alanine sodium sulphate.All the functional groups are identified by this analysis.From Optical absorption studies the value of bandgap is determined as 6.05eV for Mn2+ doped LASS. From SHG test, it is clear that the efficiency of the crystal is increased when Mn2+ is doped with pure crystal.The SHG efficiency of doped L-Alanine sodium sulphate was found to be 1.2 times greater than that of KDP crystal. The good second harmonic generation efficiency indicates that the doped L-Alanine sodium sulphate crystals can be used for various applications in nonlinear optical devices. The Mn2+ doped LASS crystal is thermally stable upto 296 and was confirmed by TG-DTA studies.The slight increment in temperature is evident for the doped crystal suggesting that the substitution of Mn2+ the grown crystals increases with load and the work hardening coefficients are found to be 4.4 and 3.07 respectively for pure and Mn2+ doped MMSE Journal. Open Access www.mmse.xyz

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References [1] K. Seethalakshmi, S. Perumal. Recent Research in Science and Technology 2012, 4(6):13-16.

[2] K.K Hema Durga, P. Selvarajanj, D Shanthi, Int. J. Curr. Res. Rev., 2012, 4(14), 68-77.

[3]S.Gokul Raj, G. Ramesh Kumar, Adv. Mat. Lett. 2011, Vol. 2 (3), 176-182. DOI 10.5185/amlett.2011.1219 [4] K.D. Parikh, B.B. Parekh, D.J. Dave, M.J. Joshi, Journal of Crystallization Process and Technology, 2013, 3, 92-96, DOI10.4236/jcpt.2013.33015 [5] T.G. Jayanalina, S. Rajarajan, S. Parthiban, C. Mojumdar, J Therm Anal Calorim. 2013. DOI 10.1007/s10973-013-3058-7 [6] D. Balaubrmanian, R. Jayavel, P. Murugakoothan, Journal of natural science, Vol. 1. No. 3, 216221, 2009. DOI:10.4236/ns.2009.13029.

[7] C. Ramachandra Raja, G. Gokila, A. Antony Joseph, Spectrochim. Acta A 72-753, 2009.

[8] M. Vimalan, T. Rajesh Kumar, S. Tamilselvan, P. Sagayaraj, C.K. Mahadevan, Physica B Condensed Matter 405-65, 2010.

[9] P. Shanmugam, S. Pari, Journal of Chemical and Pharmaceutical Research, 7(5):44-53, 2015.

[10] Clothup N.B., Introduction to infrared and Raman spectroscopy, London: AcademicPress II ed.

1975.

[11] E.M. Onitsch, Mikroskopie 2, 1941, 135 p.

[12] G.Prabagaran, M.Victor Antony Raj, S. Arulmozhi, J. Madhavan,Der Pharma chemica,3(6): 43 650, 2011.

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