Preparation and Thermoelectric Properties of LaCoO3 Ceramics

LaCoO(3) ceramics were prepared by conventional solid state reaction and normal sintering at the temperatures ranging from 1373 to 1523 K. The sintered densities increased with increasing sintering temperature and exceeded 90% of the theoretical values when sintered above 1473 K. The thermoelectric properties of the samples sintered at different temperatures were investigated from 323 to 673 K. The LaCoO(3) samples showed a negative Seebeck coefficient, whose absolute values decreased dramatically with increasing temperature in the range of 323 to 460 K, then changed to a positive value and lightly decreased above 460 K. The electrical conductivity increased with increasing temperature, indicating a semiconducting behavior. The Seebeck coefficients showed little difference between the samples sintered at different temperatures, but the power factor of the sample sintered at a higher temperature was larger because of the higher electrical conductivity.