Pb-for-Bi substitution for enhancing thermoelectric characteristics of (Bi,Pb)sub 2Basub 2Osub 4±omegasub 0.5CoOsub 2

摘要

We report strongly enhanced thermoelectric characteristics for a misfit-layered oxide, [Bi2Ba2O4±omega]0.5CoO2, in a wide temperature range, as achieved through substituting up to 20% of Bi by Pb. The Pb substitution kept the thermal conductivity(κ) unchanged but decreased the electrical resistivity(ρ) and increased the Seebeck coefficient (S) simultaneously, such that a three-fold enhancement in the thermoelectric figure of merit, Z (≡S2/ρκ), was realized. At the same time x-rayabsorption near-edge structure data indicated that the valence and spin states of Co are not affected by the Pb-for-Bi substitution.