Temperature dependence of electrical properties of nickel-zinc ferrites processed by the citrate precursor technique

Temperature dependence of resistivity, dielectric constant and dielectric loss have been investigated for four different compositions of nickel-zinc ferrites, Ni1−xZnxFe2O4 (x = 0.2, 0.35, 0.5 and 0.6), prepared by the citrate precursor technique. Activation energies calculated from the resistivity versus temperature curves for the compositions sintered at 1200 °C and 1300 °C range from 0.55 eV to 0.73 eV. Samples sintered at 1200 °C exhibit higher activation energies and low dielectric losses compared to those sintered at 1300 °C. Samples of the composition with x = 0.6 show low dielectric losses up to a measurement temperature of around 200 °C at higher frequencies as compared to samples of other compositions. The variations in activation energy with composition and sintering temperature have been explained on the basis of the site occupancy in ferrites and the atomic radii of the constituent metal ions.