Structural, Optical and Magnetic Properties of α-Fe2O3 Nanoparticles

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

Structural, Optical and Magnetic Properties of α-Fe2O3 Nanoparticles31 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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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954

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, 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 α-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

2 (degrees)

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

The crystallite size (G) was calculated by using the Debye-Scherer formula,

=

(1)

where k - particle geometry dependent constant (for spherical shape k ~1),  - wavelength of used ( = 1.5406 Å),  - full width-at-half maximum (FWHM) and  - 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 α-Fe2O3 nanoparticles. From the optical absorbance and reflectance data, the optical band gap of the nanoparticles was estimated.

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

The optical bang gap Eg was obtained by plotting (αhυ)2 versus the photon energy (hυ) and by extrapolating the linear region (α = 0). The optical band gap was estimated using the Tauc equation

ℎ = (

− hν)

(2)

where hν – the photon energy, α – 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 α-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 α-Fe2O3 nanoparticles.

Magnetic Properties. Fig.3 shows the magnetization versus magnetic field curve of the α-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 α-Fe2O3 antiferromagnetic core [18].

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Mechanics, Materials Science & Engineering, April 2017 – ISSN 2412-5954 Fe2O3-100 K

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-Fe2 O3 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.

References [1] M. Abaker, U. Ahmad, S. Baskoutas, G.N. Dar, S.A. Zaidi, S.A. Al-Sayari, A. Al-Hajry, S.H. Kim, S.W. Hwang, A highly sensitive ammonia chemical sensor based on α-Fe 2 O 3 nanoellipsoids, Journal of Physics D: Applied Physics, 44 (2011) 425401, DOI: 10.1088/00223727/44/42/425401/meta.

[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.

MMSE Journal. Open Access www.mmse.xyz 135

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

[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.

[7] Q.A. Pankhurst, J. Connolly, S.K. Jones, J. Dobson, Applications of magnetic nanoparticles in biomedicine, Journal of Physics D: Applied Physics, 36 (2003) R167, DOI: 10.1088/00223727/36/13/201.

[8] T. Sugimoto, A. Muramatsu, K. Sakata, D. Shindo, Characterization of Hematite Particles of Different Shapes, Journal of Colloid and Interface Science, 158 (1993) 420-428, DOI : 10.1006/jcis.1993.1274.

[9] A.S. Teja, P.-Y. Koh, Synthesis, properties and applications of magnetic iron oxide nanoparticles, Progress in Crystal Growth and Characterization of Materials, 55 (2009) 22-45, DOI : 10.1016/j.pcrysgrow.2008.08.003.

[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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