High-temperature Thermoelectric Properties of Cu-substituted Bi2Ba2Co2-xCuxOy Oxides

Cu-substituted Bi2Ba2Co2-xCuxOy (0.0 <= x <= 0.4) samples were prepared by conventional solid-state reaction method and the effect of Cu substitution on the microstructure and thermoelectric properties were investigated. The partial substitution of Cu for Co in Bi2Ba2Co2-xCuxOy led to an increase in the electrical conductivity because of an increase in the hole concentration and grain size of sintered bodies. In addition, Cu substitution led to an increase in Seebeck coefficients while kept the thermal conductivity unchanged. The highest thermoelectric figure of merit (ZT value) was obtained in x=0.4 sample and the value was 1.5 times as large as that of Cu-free sample at 873 K.