Preparation and electrical properties of sintered oxides composed of Mn1.5Co(0.25+X)Ni(1.25-X)O4 ( 05X50:75) with a cubic spinel structure

Monophase cubic spinel-type oxides of Mn1.5Co(0.25+X)Ni(1.25-X)O4 ( 05X51) were prepared through the oxidation of specimens sintered at 1400 C. The oxides with 05X50:75 composition are focused on in this study, as the oxides with 0:75\X51 composition did not convert into a monophase cubic spinel structure. The electrical conductivity of the sintered bodies was confirmed to increase exponentially with increasing temperature. In the composition range of 05X50:75, both the electrical conductivity and the Seebeck coefficient increased with increasing X. The oxides with composition between 05X\0:57 were n-type semiconductors, whereas those with 0:57\X50:75 were p-type. It was concluded that electrical conduction in the specimens is controlled by small polaron hopping.