High temperature thermoelectric properties of Ba1-xSr xPbO3 (0⩽x⩽1.0)

Recently, some metal oxides have been noted as new candidate materials for high-temperature thermoelectric applications. It is known that a perovskite-type oxide, Ba_1-xSr_xPbO₃ , changes from a semimetal to a narrow-gap semiconductor with increasing Sr content. In this work, thermoelectric properties of Ba_1-xSr_xPbO₃ (0⩽x⩽0) were investigated in a temperature range of 320-1073 K. The electrical conductivity (σ) 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 (λ) decreased with increasing Sr content. The value of λ increased with increasing temperature for the samples with x⩽0.4, whereas it decreased with increasing temperature for the samples with x⩾0.6. The values of σ, S, λ of the sample with x=0.6 were 2.8×10⁴ S/m, -120 μV/K and 2.0 W/mK, respectively, at 673 K. The figure of merit was 2.0×10^-4/K. The optimum temperature for a power factor (σS²) increased with increasing Sr content. The power factor of the sample with x=1.0 was 4×10^-4 W/mK² at 1000 K. The figure of merit was estimated to be about 3.0×10^-4/K at 1000 K, using a measured value of λ at 673 K