A promising oxide material for high-temperature thermoelectric energy conversion: Ba1−xSrxPbO3 solid solution system

Thermoelectric properties and figure of merit for Ba1−xSrxPbO3 solid solution were investigated in a temperature range of 320–1073 K. The electrical conductivity (σ) and the Seebeck coefficient (S<0) decreased with increasing Sr concentration, and their temperature dependence showed semimetallic behavior over the whole Sr concentration, i.e. metallic at lower temperatures and semiconducting at higher temperatures, suggesting the mixed conduction of the free electrons and the thermally activated (bound) holes. Thermal conductivity (κ) continuously decreased with a gradual change in temperature gradient from the positive to the negative with increasing Sr concentration. The maximal figure of merit was about 2×10−4 K−1 at 673 K for the sample with x=0.6, which was an exceedingly high value of the oxides. The present results suggest that the Ba1−xSrxPbO3 solid solution is a potential oxide for high-temperature thermoelectric energy conversion.