Oxide-based thermoelectric materials that exhibit a high figure of merit are promising because of their good chemical and thermal stabilities and their relative harmlessness compared with chalcogenide-based state-of-the-art thermoelectric materials. The layered barium-cobalt oxide (Ba1/3CoO2) exhibits a record-high ZT of 0.55 at 600 °C in air. The increase in ZT is directly originated by the decreased thermal conductivity of Ba1/3CoO2. As we hypothesized, the greater the atomic mass, the lower the thermal conductivity, resulting in higher ZT. The ZT is reliable and the highest among thermoelectric oxides. Moreover, this value is comparable to those of p-type PbTe and p-type SiGe.
- Yuqiao Zhang
- Hiromichi Ohta
