Abstract:
Pure Ni-Zn ferrites were prepared by the precursor-combustion method using Ni sub(1-x)Zn sub(x)Fe sub(2)(C sub(4)H sub(4)O sub(4)) sub(3).6N sub(2)H sub(4) (x=0.1, 0.3, 0.5, 0.7, 0.9) precursors. The fascinating property of this synthesis route is that when a small portion of the precursor is ignited, the bulk rapidly undergoes catalytic auto-decomposition forming nanoferrites. The chemical analysis of precursors confirms the presence of expected elements with desired stoichiometric ratio and thermal analysis helped to fix the formula of the precursors. The powder X-ray diffraction (XRD) studies indicated an increase in the lattice parameter (a) and a decrease in porosity (percent P), with the rise in zinc substitution. The crystallite size varied from 31 to 42 nm. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) images displayed particles having cuboidal geometry. The synthesized semiconducting ferrites demonstrated an increase in resistivity with an increase in zinc content. Dielectric studies showed a significant influence of frequency and temperature on the dielectric properties with the addition of zinc. AC susceptibility studies showed particle domains changing from single domain-superparamagnetic to superparamagnetic type with the rise in zinc content. Vibrating magnetometer sample (VSM) measurements reveal an increase in the saturation magnetization (M sub(s)) and remanent magnetization (M sub(r)) up to x=0.5 and x=0.3, respectively, followed by a decrease however coercivity (H sub(c)) showed a continuous decrease with zinc addition. The blocking temperature (T sub(B)) depicted a decline with an increase in the zinc concentration. The electrochemical analysis exhibited the highest specific capacitance (C sub(sp)) of 67.1 F/g for the composition x=0.3 at the lowest scan rate.
