Synthesis and thermoelectric power factor of (Ca0.95Bi0.05)3Co4O9/Ag composites

(Ca0.95Bi0.05)3Co4O9/Ag composite powders were synthesized rapidly by a polyacrylamide gel method and then the dense ceramic samples were prepared using a Spark plasma sintering technique. The effects of the Bi substitution and Ag addition on the microstructure and thermoelectric properties of the Ca3Co4O9 based ceramics were evaluated. Analysis of the microstructure and the composition indicated that Ag precipitated as the second phase on the grain boundaries. Addition of Ag decreased the densification and texture development of the composites. However, the electrical measurement showed that the electrical conductivity increased while the Seebeck coefficient decreased with increasing Ag contents. The power factor P of (Ca0.95Bi0.05)3Co4O9/Ag composites were improved due to the obvious increase in electrical conductivity.