Fabrication and Measurement of the Physical and Thermoelectric properties of Ca_3-xDy_xCo_4-yFe_yO_9+ρ systems

The properties and performance of Cobalt oxide material as a p-type semiconductor for commercial use depends on its stability at high temperature region and its excellent physical and thermoelectric properties. Here in, we substitute (dope) and study the effects of magnetic ions (Dy, Fe) for (Ca, Co) in polycrystalline Ca₃Co₄O_9+ρ. A series of Ca_3-xDy_xCo_4-yFe_yO_9+ρ samples was synthesized using the sol-gel combustion method. After preparations, the samples were subjected to heat treatment at different temperature. X-ray diffraction analysis indicates the partial substitution of Dy in the Ca site and Fe in the Co site. It also confirmed the formation of single phase compounds, as well as changes in the structure of the materials depending on the sintering temperature. The obtained values of the electrical resistivity for all samples falls within the range of a semiconductor. The thermopower values are all positive, indicating that the majority carrier are holes.