Ferromagnetic and Photoluminescence Properties of Fe doped Indium-Tin- Oxide Nanoparticles

Mechanics, Materials Science & Engineering, April 2017

ISSN 2412-5954

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]. 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

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, April 2017

ISSN 2412-5954

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 This is less than the lattice constant of In2O3, as reported in literature as 1 crystallite size of (Fe:Sn) codoped In2O3 is determined as 41 nm by using the Debye-Scherrer formula.

9000

(Fe:Sn)In 2O3

7500

6000

4500

3000

1500

0 20

30

40

2

50

60

(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.

1800

In 2O3

1600

ITO (Fe:Sn) In2O 3

1400

SnO2

1200 1000 800 600 400 200 0 200

400

600

800

1000

-1

Raman Shift (cm )

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 (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.

References

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Mechanics, Materials Science & Engineering, April 2017

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Mechanics, Materials Science & Engineering, April 2017

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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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