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

TLDR

Oxide ceramics are promising thermoelectrics for high‑temperature applications because of their thermal and chemical stability, yet their performance is limited by low electrical conductivity and high thermal conductivity. The study introduces a high‑entropy strategy to suppress thermal conductivity and defect engineering to improve electrical conductivity in SrTiO₃‑based ceramics, proposing a generalizable concept for high‑performance thermoelectric oxides. High‑entropy Ca₀.₂Sr₀.₂Ba₀.₂Pb₀.₂La₀.₂TiO₃ bulk achieves a minimum thermal conductivity of 1.17 W m⁻¹ K⁻¹ at 923 K, a power factor of ~295 μW m⁻¹ K⁻², and a ZT of 0.2 at 873 K, demonstrating the effectiveness of lattice distortion, mass fluctuation, and oxygen‑vacancy engineering.

Abstract

Abstract 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 SrTiO 3 -based thermoelectric ceramics via high-entropy strategy for the first time, and optimized electrical conductivity by defect engineering. In high-entropy (Ca 0.2 Sr 0.2 Ba 0.2 Pb 0.2 La 0.2 )TiO 3 bulks, the minimum thermal conductivity can be 1.17 W/(m·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 μW/(m·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.