Investigation on impedance response and dielectric relaxation of Ni-Zn ferrites prepared by self-combustion technique

Nanocrystalline mixed Ni1-xZnx Fe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1) have been achieved by low temperature self-combustion technique using oxylyldehydrazide (ODH) as fuel. The structural, morphological and dielectric properties were studied using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman Spectroscopy and frequency dependant impedance spectroscopy with frequency range from 1 Hz to 10(7) Hz. The XRD analyses of as prepared samples show single phase cubic spinel structure with Fd-3m space group. The average crystallite size was estimated using Debye-Scherer's formula and was found to be in the range 15-30 nm. FTIR spectra shows two prominent absorption bands, the higher band at tetrahedral (A) sites and the lower band at octahedral (B) site. The Raman peaks above 600 cm(-1) correspond to A(1g) type, involving motions of O atoms in the tetrahedral group (A-site) and the other low frequency peak 241, 335 and 480 represent the characteristics of the octahedral group (B-site) of ferrites. SEM images shows that all the samples have nano crystalline behavior with spherical shape. EDX confirms the constitutional distribution of prepared samples. The dielectric properties such as dielectric constant epsilon', dielectric loss tangent and ac conductivity were found to be lowest for x = 0.8. The grain and grain boundary contributions in nano ferrites have been explained using Nyquist plot. The prepared mixed ferrites are good material for frequency dependent applications. (C) 2017 Elsevier B. V. All rights reserved.