High-temperature thermoelectric properties of La-doped BaSnO3 ceramics

To elucidate the thermoelectric properties at high temperatures, perovskite-type La-doped BaSnO3 ceramics were fabricated by a polymerized complex (PC) method and subsequent spark plasma sintering (SPS) technique. Fine powders of Ba1−xLaxSnO3 (x = 0.00–0.07) were prepared by the PC method using citrate complexes, and SPS treatment converted the powders into dense ceramics with relative densities of 93–97%. The La content dependence of the lattice parameter suggested that the solubility of La for Ba sites was approximately x = 0.03. The temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each La-doped ceramic was an n-type degenerate semiconductor in the measured temperature range of 373–1073 K. The La content dependence of the S values indicated that the electron carrier concentration increased successively up to x = 0.03, which was the solubility limit of the La atoms. The thermoelectric power factors S2σ increased drastically with La doping, and reached a maximum for x = 0.01 with values of 0.8 × 10−4 W m−1 K−2 at 373 K to 2.8 × 10−4 W m−1 K−2 at 1073 K.