Fabrication and Characterization of Indium Doped Nanaocrystalline Soft Ferrites

Abstract

In this dissertation impact of In3+ ions substitution on thermal, structural, spectral, dielectric and magnetic properties of Cu0.5M0.5InxFe2-xO4 (M: Ni and Zn), CuInxFe2O4 and Li0.5InxFe2.5-xO4 (Where x = 0.00, 0.08, 0.16, 0.24 and 0.32) spinel nanoferrites was studied and these were synthesized by sol-gel auto-combustion route. Thermal analysis of as obtained samples was performed to estimate the complete decomposition and formation of spinel phase. X-ray diffraction analysis revealed spinel crystal structure of all synthesized nanoferrites. A nonlinear behavior of lattice constant was evidenced from the synthesized samples. The crystallite size was calculated from Scherrer‟s formula and this indicates the nano-regime size of all the synthesized samples (9.37-33.21 nm). The X-ray density was increased in all four series by the incorporation of In3+ ions. The behavior of tetrahedral and octahedral radii as well as hopping lengths was analogous to the lattice constant. Fourier transform infrared spectra indicated two absorption bands υ1 and υ2 due to stretching vibrations of tetrahedral and octahedral metals complexes. The characteristic bands of spinel structure were observed in all the samples. Dielectric constant possessed smaller value for all the compositions of prepared nanoferrites and exhibited Debye type relaxation at high frequency. Dielectric loss and tan loss were found to decrease with the increase in frequency. Both types of losses showed resonance peaks at high frequency. AC conductivity of indium incorporated Cu-Ni, Cu-Zn and lithium nanoferrites was increased while for copper ferrites, it decreased. The grains and grain boundaries contribution in dielectric behavior was investigated from complex modulus spectroscopy. The magnetic study was carried out by vibrating sample magnetometer (VSM) and various magnetic parameters were calculated. Saturation magnetization (Ms) and coercivity (Hc) were decreased by incorporation of In3+ cations. Anisotropy constant (K1) and Bohr‟s magneton (μB) was found to decrease with the substitution of indium ions. The results of dielectric and magnetic properties proposed that synthesized nanoferrites are potential candidates for switching and high frequency applications.