Regulating the thermophysical properties of rare earth cerates through high entropy design and substitute

Abstract

Cerate ceramics are considered promising candidates for the new generation of thermal barrier coatings. However, in the middle temperature area (473-673K), the CTE mismatch due to the thermal contraction often results in coating failure. The aim of this work is to develop an innovative component regulation method that significantly reduces the thermal conductivity and alleviates the thermal contraction. Cerates exhibit a low thermal diffusion coefficient, primarily attributed to the impact of extrinsic phonon scattering mechanisms. Our comprehensive analysis encompassed various factors such as point defects, the degree of size and mass disorder, grain interfaces, and lattice distortion. By employing high entropy design and doping strategies, we have successfully alleviated the thermal contraction phenomenon in cerates, while maintaining their high CTE. Furthermore, an in-depth investigation of the valence states of elements and lattice energy was conducted to elucidate the thermal contraction mechanism of cerates in the middle temperature area.