Electrical properties of Cu substituted Ni-Al Ferrite Oxides Ni1-xCuxAlFeO4

Electrical properties of Ni1-xCuxAlFeO4 spinel ferrites with (0.25<x<0.75) are investigated in the frequency rage (5 Hz up to 13 MHz) and over the temperature range(239-873 K). Obtained results reveal semiconducting behavior at lower copper content. As copper content increased in these compounds semiconducting to metallic-like behavior transition is observed. All studied compositions exhibit a transition with change in the slope of conductivity versus temperature curve. This transition temperature is found to decrease linearly with increasing copper content x. Results are explained in the light of cation-anion-cation and cation cation interactions at the octahedral site in the spinel unit cell. Impedance spectra of the conductivity display low grain boundary resistance which agrees with the grain gross appeared in the microstructure investigation of the scanning electron microscope micrographs of these samples .