Comparative study on structure, dielectric and electrical properties of cobalt- and zinc-substituted Mn3O4 spinels

In this paper, we report the comparative study of single-phase crystalline Mn3O4, CoMn2O4, and ZnMn2O4 spinels prepared by a wet chemical co-precipitation technique. The absence of impurity peaks in the X-ray diffraction pattern of all prepared spinels endorses the formation of highly pure and single-phase spinels with the tetragonal crystal structure. The highest intensity peak for Mn3O4 was observed at (211) direction plane, and the same was followed by CoMn2O4 and ZnMn2O4 with a slight decrease in the angle of diffraction. The microstructure features observed from scanning electron micrographs reveal irregular-shaped nanosized grains with an average grain size of ~ 100 nm. The dielectric studies carried out from room temperature to 500 °C show high dielectric loss at elevated temperatures endorsing better conducting behavior. The DC-conductivity measurement substantiates the negative temperature coefficient of resistance behavior where resistivity decreases with an increase in temperature. The activation energy calculated using Arrhenius relation was 0.58 eV for Mn3O4, whereas it is 1.1 and 1.4 eV for Co- and Zn-substituted Mn3O4 confirming semiconducting nature of substituted spinels at higher temperature region.