Thermal stability and oxidation resistance of BiCuSeO based thermoelectric ceramics

BiCuSeO-based oxyselenide compounds show promising thermoelectric properties, but its thermal stability and oxidation behavior are unknown, which were investigated in the present work with a PbTe-based thermoelectric alloy as a comparison. It was revealed that the BiCuSeO polycrystalline materials displayed much better thermal stability in air than the PbTe-based alloys that were severely oxidized at 573 K, resulting in a decreased density and significantly reduced electrical conductivity. Nevertheless, it was found that the BiCuSeO-based thermoelectric materials could not be used in air for a long time as a conventional oxide at high temperatures; apparent decomposition occurred in the BiCuSeO samples when heated at 773 K, although at 573 K the oxidation was limited to the surface accompanied by the formation of bismuth oxide.