Structural and electrical properties of Cd-substituted Li–Ni ferrites

Ferrites with general formula Li0.5Ni0.75−x/2Cdx/2Fe2O4 (where x = 0, 0.1, 0.3, 0.5, 0.7 and 0.9) were prepared by the standard sintering ceramic method. X-ray diffraction analysis confirmed the single-phase spinel structure of the samples. SEM micrographs were taken to study the microstructure. The average grain diameter is found to increase with the cadmium content. The dc resistivity measured as a function of temperature shows that conduction takes place by hopping mechanism. The room temperature dc resistivity decreases with Cd content up to 0.3 and then it increases with further increase in Cd content. The Curie temperature is found to decrease linearly with addition of Cadmium. The variation of Seebeck coefficient with temperature indicates that the samples with x = 0.1, 0.3 and 0.9 show transition from n-type to p-type charge carriers whereas those with x = 0, 0.5 and 0.7 show p-type conduction.