A novel dual-phase high-entropy (La_0.2Nd_0.2Gd_0.2Er_0.2Yb _0.2)₂Zr₂O₇ ceramic for thermal barrier coatings applications: Preparation, microstructure, and thermo-physical properties

High-entropy rare earth zirconates (RE2Zr2O7) have attracted significant research attention for thermal barrier coatings (TBCs) application due to their superior performance. However, currently used high-entropy RE2Zr2O7 shows only the modest improvements, thus limiting their overall performance enhancement. Therefore, novel high-entropy RE2Zr2O7 (La0.2Nd0.2Gd0.2Er0.2Yb0.2)(2)Zr2O7 (HEC) was synthesized in this study by chemical co-precipitation method, which was characterized by dual-phase and significant differences in ionic radius and atomic mass. Compared with single-component RE2Zr2O7 (RE = La, Nd, Gd, Er, and Yb) ceramics, HEC demonstrates significantly superior performance, including higher hardness (11.705 GPa), fracture toughness (1.693 MPa m(1/2)), and thermal expansion coefficient (11.1926 x 10(-6)/K, 1400 degrees C), and lower thermal conductivity (1.33-1.43 W/(m center dot K), 26-1000 degrees C). The comprehensive performance improvement can be attributed to the high-entropy effect, dual-phase nature, and significant differences in ionic radius and atomic mass. This study provides valuable insight into the development of high-entropy RE2Zr2O7 and suggests their significant potential in TBCs.