First principle study on high-entropy perovskites Ca(Ti0.25Zr0.25Hf0.25Sn0.25)O3 and Ca(Ti0.25Zr0.25Hf0.25Ce0.25)O3 as thermal barrier coatings

Abstract

High-entropy ceramic materials attract widespread attention in thermal barrier coating applications due to their lower thermal conductivity. This work adopts the first-principle method to investigate the mechanical properties, thermal properties and electronic structures of cubic phase high-entropy perovskites Ca(Ti0·25Zr0.25Hf0.25Sn0.25)O3 and Ca(Ti0·25Zr0.25Hf0.25Ce0.25)O3. The calculated results show that both high-entropy perovskites are mechanically stable, and Ca(Ti0·25Zr0.25Hf0.25Ce0.25)O3 has a lower Young's modulus (187.07 GPa) than CaZrO3. As for thermal properties, the high-entropy effect enables both high-entropy perovskites to have lower Debye temperatures. The thermal conductivity of Ca(Ti0·25Zr0.25Hf0.25Ce0.25)O3 obtained by Clarke's model is only 1.290 W m−1 K−1, which is much lower than that of CaZrO3. It is noted that the narrower bandgaps and smaller average Bader charges of B-site, related to the local lattice distortion in high-entropy perovskites, should be responsible for their thermo-mechanical properties. This study demonstrates that Ca(Ti0·25Zr0.25Hf0.25Ce0.25)O3 will exhibit outstanding performance as a thermal barrier coating material.