Structural, dielectric and impedance spectroscopic studies of Ni0.5Zn0.5−xLixFe2O4 nanocrystalline ferrites

Abstract

Nanocrystalline lithium substituted Ni–Zn ferrites with composition Ni[Formula: see text]Zn[Formula: see text]Li[Formula: see text]Fe2O4 ([Formula: see text] = 0.00–0.25 in steps of 0.05) were synthesized by the citrate gel auto-combustion method and were sintered at 1000[Formula: see text]C for 4 h in air atmosphere. The structural, dielectric, impedance spectroscopic and magnetic properties were studied by using X-ray diffraction, impedance analyzer and vibrating sample magnetometer respectively. The X-ray diffraction patterns confirm that all samples exhibit a single phase cubic spinel structure. Suitable cation distribution for all compositions has been proposed by using the X-ray diffraction line intensity calculations and the theoretical lattice parameter for each composition was observed in close agreement with the experimental ones and thereby supporting the proposed distribution. An increase in the saturation magnetization was observed up to [Formula: see text] = 0.10 level of Li[Formula: see text] substitution and thereafter magnetization reduced for higher concentrations to the highest level of Li[Formula: see text] substitution. The dielectric constant and the DC resistivity of Ni–Zn–Li ferrites were noticed to decrease with increase in the Li[Formula: see text] ion concentration. The impedance spectroscopic studies by using the Cole–Cole plots were studied in order to obtain the relaxation time, grain resistance and grain capacitance. AC conductivity initially remained almost independent of frequency for lower frequencies and thereafter for higher frequencies the AC conductivity increased with increase of Lithium concentration.