Structural, dielectric properties and AC conductivity of Ni(1−x)ZnxFe2O4 spinel ferrites

The powders of Ni–Zn ferrite having the chemical formula Ni(1−x)ZnxFe2O4, where x varies as 0, 0.1, 0.2, 0.3, 0.4, and 0.5, were synthesized using solid state reaction method. The X-ray diffraction (XRD) studies confirmed the formation of spinel cubic structure. The average crystallite size was calculated using line broadening in XRD patterns. Also structural parameters like lattice constant (a), jump rate (L), polaron radius (rp), bond lengths (RA, RB) and porosity (P) were determined from XRD data. The micro-structural features of the samples were studied using scanning electron microscopy (SEM) techniques. The variation of dielectric constant (έ), loss tangent (tan δ) and AC conductivity (σac) as a function of frequency in range of 100 Hz to 5 MHz was studied. Also the variation of dielectric constant and loss tangent as function of temperature was studied at fixed frequencies. The DC resistivity measurements of the samples were performed using two probe methods. The activation energies were computed from the plots of log ρdc versus 1000/T.