2017 Volume 125 Issue 4 Pages 308-312
The thermoelectric properties of Ca1−xBixMnO3−δ sintered bodies prepared by the electrostatic spray deposition method and sintering technology were evaluated. Ca0.95Bi0.05MnO3−δ showed the maximum power factor value of 230 µW·m−1·K−2 among Ca1−xBixMnO3−δ compounds at room temperature. From Seebeck coefficient, Hall coefficient and power generation efficiency measurements on CaMnO3−δ and Ca0.95Bi0.05MnO3−δ under high temperature, it was found that the power factor value of Ca0.95Bi0.05MnO3−δ increased with temperature in the range of 300–873 K, and was 2 to 5 times higher than that of CaMnO3−δ. The carrier concentration (n = 5.9 × 1020 cm−3) of Ca0.95Bi0.05MnO3−δ is two orders of magnitude higher than CaMnO3−δ (n = 7.1 × 1018 cm−3) at 300 K. The increase in carrier concentration contributed to higher conductivity, power factor and power generation density in the Bi-substituted compound. In thermoelectric performance evaluations, the power density reached 625 mW·cm−2 for Ca0.95Bi0.05MnO3−δ with a temperature difference of 444 K, an 11-fold increase compared to the parent compound CaMnO3−δ (57 mW·cm−2).