SHORT RESEARCH COMMUNICATION The effects of lithium and yttrium substitution on the optical and structural properties of cobalt ferrites M K Shobana 1 *, H-S Nam 2 and H Choe 2 1 Department of Physics, School of Advanced Science, VIT University, Vellore, Tamil Nadu 632014, India 2 School of Materials Science and Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea Received: 13 December 2017 / Accepted: 22 May 2018 Abstract: Known as a hard magnetic material, cobalt ferrite belongs to one of the most attractive classes of materials owing to its diverse technical applicability such as in catalysis, sensors, batteries. In this study, we synthesized Li- and Y-substituted cobalt ferrite nanoparticles using a sol–gel combustion method. Their mean crystallite sizes with spinel structures were calculated as 15–19 and 2–5 nm and their lattice constant values were 7.8 ± 0.02 and 8.5 ± 0.3 A ˚ , respectively. The results also revealed that the band gap energy values of the prepared Li- and Y-doped cobalt ferrites decreased after doping compared with that of pure cobalt ferrite, and thus they appear to be promising for energy generation and storage applications. Keywords: Nanostructures; X-ray diffraction; Optical properties; Ferrite PAC Nos.: 75.75.Lf; 73.63.-b; 75.50.Gg; 78.67.Bf; 61.46.Df 1. Introduction Presently, spinel-structured nanometal oxides with one or more substituted metal ions are considered to belong to one of the most promising emerging classes of materials owing to their remarkable properties such as low melting tem- perature, high specific heating, large expansion coefficient, low saturation magnetic moment, and low magnetic tran- sition temperature [19, 32]. Based on these excellent properties, spinel nanoferrites have numerous technical applications in a number of different areas, such as catal- ysis, sensors, and batteries [5, 7, 8, 10, 12, 15, 21]. More specifically, numerous researchers have demonstrated the characteristics of several substituted cobalt ferrites for different applications [1, 2, 4, 6, 9, 18, 20, 23, 28]. How- ever, little attention has been paid to the analysis of some of the important properties of cobalt ferrites (CoFe 2 O 4 ), such as their structural and optical characteristics, espe- cially since those containing Li or Y have exhibited such interesting ones. Given that there is a strong correlation between the functional properties of substituted cobalt ferrites and their microstructures, composition, and particle/crystal sizes, the selection of the applied synthesis method plays a vital role in obtaining excellent functional properties. For example, substituted ions in ferrites are stabilized in octahedral sites, thereby giving rise to a degenerate or near-degenerate orbital ground state and thus different performances. Therefore, in the present study, we synthesized and mod- ified the structural and optical properties of cobalt ferrites by doping them with Li or Y through a sol–gel auto- combustion method. Additionally, we examined the struc- tural and optical properties of the Li- and Y-doped cobalt ferrites using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) and ultraviolet (UV) spectroscopy studies. Their average crystallite size, lattice constant values, and band gap energy values were calculated based on the XRD and UV results according to the varied amounts of Li or Y. *Corresponding author, E-mail: [email protected]Indian J Phys https://doi.org/10.1007/s12648-018-1292-3 Ó 2018 IACS
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SHORT RESEARCH COMMUNICATION
The effects of lithium and yttrium substitution on the opticaland structural properties of cobalt ferrites
M K Shobana1*, H-S Nam2 and H Choe2
1Department of Physics, School of Advanced Science, VIT University, Vellore, Tamil Nadu 632014, India
2School of Materials Science and Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 02707, Republic of Korea
Received: 13 December 2017 / Accepted: 22 May 2018
Abstract: Known as a hard magnetic material, cobalt ferrite belongs to one of the most attractive classes of materials
owing to its diverse technical applicability such as in catalysis, sensors, batteries. In this study, we synthesized Li- and
Y-substituted cobalt ferrite nanoparticles using a sol–gel combustion method. Their mean crystallite sizes with spinel
structures were calculated as 15–19 and 2–5 nm and their lattice constant values were 7.8 ± 0.02 and 8.5 ± 0.3 A,
respectively. The results also revealed that the band gap energy values of the prepared Li- and Y-doped cobalt ferrites
decreased after doping compared with that of pure cobalt ferrite, and thus they appear to be promising for energy