High temperature thermoelectric properties of Ba1-xSrxPbO3 (0≤x≤1.0)

Recently, some metal oxides are noted as new candidate materials for high-temperature thermoelectric applications. It has been known that a perovskite-type oxide, Ba1-xSrxPbO3, changes from a semimetal to a narrow-gap semiconductor with increasing Sr content. In this work, thermoelectric properties of Ba1-xSrxPbO3 (0 less than or equal to x less than or equal to 1.0) were investigated in a temperature range of 320-1073 K. The electrical conductivity (sigma) decreased with increasing Sr content. The seebeck coefficient (S) was negative (n-type), and took a minimum value around 650 K. This result suggests that carriers consist of free electrons and thermally activated holes. The thermal conductivity (lambda) decreased with increasing Sr content. The value of lambda increased with increasing temperatue for the samples with x less than or equal to 0.4, whereas decreased with increasing temperature for the samples with x greater than or equal to 0.6. The values of sigma, S, lambda of the sample with x=0.6 were 2.8x10(4) S/m, -120 mu V/K and 2.0 W/mK, respectively, at 673 K. The figure of merit was 2.0x10(-4) /K. The optimum temperature for a power factor (sigma S-2) increased with increasing Sr content. The power factor of the sample with x=1.0 was 4x10(-4) W/mK(2) at 1000 K. The figure of merit was estimated to be about 3.0x10(-4) /K at 1000 K, using a measured value of lambda at 673 K.