Preparation of dense BaPbO3-based ceramics by a coprecipitation and their thermoelectric properties

Dense ceramics of BaPbO3 with a perovskite-type structure were prepared via a modified oxalate coprecipitation method, controlling the starting molar ratio of Pb/Ba. Oxalate coprecipitation from a mixed nitrate solution with molar ratio of Pb/Ba ≥ 1.05 led to dense BaPbO3 ceramics with relative density higher than 90%. This densification was due to liquid phase sintering of fine particles of BaPbO3 with the aid of a small amount of coexisting PbO, formed by calcination of the oxalate. The coprecipitation method was also used to prepare dense Ba1−xLaxPbO3 ceramics, and their electrical conductivity and Seebeck coefficient were measured at high temperatures to evaluate their thermoelectric power factors. The power factor for the BaPbO3 ceramic was comparable to that for the material prepared by a press–sintering method, indicating that the present coprecipitation method is a convenient way to prepare dense BaPbO3-based ceramics for exploring the thermoelectric properties.