Effect of sintering temperature on the thermoelectric properties of NaxCo2O4

Polycrystalline samples of NaxCo2O4 were synthesized by a conventional solid-state reaction (SSR) method by sintering at various temperatures in the range 1173–1293 K. The thermoelectric properties of the obtained samples, the electrical resistivity, Seebeck coefficient and thermal conductivity, increase with increasing sintering temperature. The dimensionless figure of merit decreased with increasing sintering temperature, and the sample sintered at 1173 K has the maximum value, ZT ∼ 0.11 at 973 K.