SYNTHESIS, MICROSTRUCTURE AND AC ELECTRICAL CONDUCTIVITY OF COPPER SUBSTITUTED NICKEL-ZINC FERRITES

Abstract

A series of nickel-zinc ferrites with composition Cu_xNi­_0.3-xZn_0.7Fe₂O₄, with x=0.00, 0.05, 0.15 and 0.25 have been synthesized via the solid state ceramic route in order to carry out ac electrical measurement. Formation of single phase spinel structure have been confirmed by using X-ray diffraction. Microstructural features of sintered samples were obtained with scanning electron microscope. The micrographs showed that increasing copper substitution in nickel–zinc ferrite increased grain growth. The bulk density of these samples also increased as the copper content increased. AC conductivity, s_ac has been measured in the temperature range 300 K – 473 K and frequency range 10^-2Hz to 1MHz and discussed as a function of frequency and temperature. Analysis of the results shows that ac conductivity increases as the temperature of the sample and frequency of the applied ac electric field increase, but the dispersion of ac conductivity decreases with increasing the temperature for all the samples.