Influence of Sr and Ce Codoping on Structural, Electrical and Thermoelectric Properties of CaMnO3

Polycrystalline samples of CaMnO3 and Ca1-x-ySrxCeyMnO3 with Ce/Sr double substitution (x = 0.02, 0.04, 0.06; y = 0.02) were prepared by citrate sol-gel route. The samples' phase was confirmed using the X-ray diffraction (XRD) technique, revealing that they only contain a single phase with an orthorhombic perovskite structure and no impurity phases. Also, the increase in lattice parameters with Sr2+ doping was observed. Rietveld refinement was done on the X-ray pattern using Fullprof software to find parameters. Using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), analyses of morphology and elemental compositions were performed. On sintered samples, electrical resistivity measurements were made using DC four-probe techniques. And conduction mechanism was explained based on a small polaron hopping mechanism. Between 308 K and 673 K, thermoelectric characteristics were studied. Ca(0.9)4Sr(0.04)Ce(0.02)MnO(3) has the highest power factor of all the prepared co-doped Ce/Sr samples.