Electrical and thermal transport behaviours of high-entropy perovskite thermoelectric oxides

Oxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature. However, their mediocre electrical conductivity or high thermal conductivity is still a challenge for the use in commercial devices. Here, we report significantly suppressed thermal conductivity in SrTiO3-based thermoelectric ceramics via high-entropy strategy for the first time, and optimized electrical conductivity by defect engineering. In high-entropy (Ca0.2Sr0.2Ba0.2Pb0.2La0.2)TiO3 bulks, the minimum thermal conductivity can be 1.17 W/(m center dot K) at 923 K, which should be ascribed to the large lattice distortion and the huge mass fluctuation effect. The power factor can reach about 295 mu W/(m center dot K-2) by inducing oxygen vacancies. Finally, the ZT value of 0.2 can be realized at 873 K in this bulk sample. This approach proposed a new concept of high entropy into thermoelectric oxides, which could be generalized for designing high-performance thermoelectric oxides with low thermal conductivity.

Automated summary

High-entropy strategy and defect engineering were used to significantly suppress thermal conductivity and optimize electrical conductivity in SrTiO3-based thermoelectric ceramics. The minimum thermal conductivity in high-entropy TiO3 bulks can be reduced to 1.17 W/(m • K), with a power factor of 295μW/(m • K-2), and a ZT value of 0.2 at 873K.