Effects of Dy and Yb co-doping on thermoelectric properties of CaMnO3 ceramics

Perovskite-type Ca1−2xDyxYbxMnO3 (0≤x≤0.10) ceramics were synthesized by solid state reaction. Microstructures were characterized and thermoelectric properties were evaluated between 300 K and 1100 K. The samples obtained in this work have high relative densities with compact grains. The electrical resistivity shows a typical metallic conductivity behavior, and decreases with substitution. The Seebeck coefficients are negative, indicating n-type conduction, and the largest value is obtained −181 μV/K at x=0.02. The highest power factor 415 μW/(K2m) and the highest figure of merit 0.27 are both obtained for x=0.02 sample, and the ZT is about five times as much as un-doped CaMnO3 sample.