Effect of Ni2+ substitution on structural,magnetic, dielectric and optical properties of mixed spinel CoFe2O4 nanoparticles |
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| Affiliation: | 1. Department of Physics, Nanotechnology Laboratory, SRMV College of Arts and Science, Coimbatore-641020, Tamil Nadu, India;2. Department of Science and Humanities, Tamilnadu College of Engineering, Karumathampatti, Coimbatore-641 659, Tamil Nadu, India;1. Department of Physics, The University of Burdwan, Burdwan 713 104, India;2. CSIR-Central Glass and Ceramic Research Institute, Kolkata 700 032, India;1. Department of Physics, J B Campus, Bangalore University, Bengaluru 560056, India;2. Department of Physics, Surana College, Peenya Campus, Bengaluru 560022, India;3. Department of Condensed Matter Physics & Materials Sciences, TIFR, Mumbai 400005, India;4. Materials Research Center, IISc, Bengaluru 560012, India;1. Technical University of Cluj-Napoca, North University Center of Baia Mare, Department of Chemistry and Biology, 76 Victoriei Street, Baia Mare, 430122, Romania;2. INCDO-INOE 2000, Research Institute for Analytical Instrumentation, 67 Donath Street, Cluj-Napoca, 400293, Romania;3. Babes-Bolyai University, Faculty of Physics, 1 Kogalniceanu Street, Cluj-Napoca, 400084, Romania;4. Babes-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, Cluj-Napoca, 400028, Romania |
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| Abstract: | Nanoparticles of Co1?xNixFe2O4 with x=0.0, 0.10, 0.20, 0.30, 0.40 and 0.50 were synthesized by co-precipitation method. The structural analysis reveals the formation of single phase cubic spinel structure with a narrow size distribution between 13–17 nm. Transmission electron microscope images are in agreement with size of nanoparticles calculated from XRD. The field emission scanning electron microscope images confirmed the presence of nano-sized grains with porous morphology. The X-ray photoelectron spectroscopy analysis confirmed the presence of Fe2+ ions with Fe3+. Room temperature magnetic measurements showed the strong influence of Ni2+ doping on saturation magnetization and coercivity. The saturation magnetization decreases from 91 emu/gm to 44 emu/gm for x=0.0–0.50 samples. Lower magnetic moment of Ni2+ (2 µB) ions in comparison to that of Co2+ (3 µB) ions is responsible for this reduction. Similarly, overall coercivity decreased from 1010 Oe to 832 Oe for x=0.0–0.50 samples and depends on crystallite size. Cation distribution has been proposed from XRD analysis and magnetization data. Electron spin resonance spectra suggested the dominancy of superexchange interactions in Co1?xNixFe2O4 samples. The optical analysis indicates that Co1?xNixFe2O4 is an indirect band gap material and band gap increases with increasing Ni2+ concentration. Dispersion behavior with increasing frequency is observed for both dielectric constant and loss tangent. The conduction process predominantly takes place through grain boundary volume. Grain boundary resistance increases with Ni2+ ion concentration. |
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| Keywords: | Nanoparticles Optical properties Magnetic properties Dielectric properties XPS ESR |
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