A novel dual-phase high-entropy (La0.2Sm0.2Gd0.2Y0.2Yb0.2)2Zr2O7 ceramic with glass-like thermal conductivity prepared by ultrafast high-temperature sintering

Dual-phase high-entropy rare-earth zirconates (RE2Zr2O7) have become an important development direction of new thermal barrier coating materials due to their excellent properties. Currently, dual-phase high-entropy RE2Zr2O7 is mainly prepared by conventional solid-state sintering. In contrast, little research has been reported on the rapid sintering of dual-phase high-entropy RE2Zr2O7 using ultrafast high-temperature sintering (UHS). Therefore, in this work, a novel dual-phase high-entropy (La0.2Sm0.2Gd0.2Y0.2Yb0.2)2Zr2O7 (LSGYY) ceramic was designed and prepared by UHS at 1700?C for 5 min. Structural analysis showed that LSGYY consisted of both pyrochlore and defective fluorite structures, and the rare-earth cations were uniformly distributed without segregation. Compared with Gd2Zr2O7 and La2Zr2O7, LSGYY exhibited excellent mechanical and thermal properties, including higher hardness (11.73 ? 0.58 GPa), higher fracture toughness (1.55 ? 0.26 MPa?m1/2), glass-like thermal conductivity (1.37 - 1.45 W?m-1?K-1), and higher coefficient of thermal expansion (11.67 ? 10-6 K-1), suggesting that LSGYY is a promising candidate for application as a novel thermal barrier coating material.