Synthesis, microstructure and thermophysical properties of (La0.2Y0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 high-entropy oxide ceramic

In this study, a dense high-entropy oxide ceramic (La0.2Y0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 with a relative density of 93.7 %RD was synthesized by cold isostatic pressing, coupled with the pressureless sintering method. The microstructure and physical properties were characterized systematically, revealing an intrinsic hardness of 7.9 GPa and flexural strength of 187.9 MPa. Moreover, the elastic and shear moduli decreased from 148.05 to 56.68 GPa at 25 °C to 117.44 and 44.63 GPa at 1200 °C, respectively. The thermal diffusivity in the temperature range of 25–1200 °C decreased from 0.0053 to 0.0041 cm3/s, and the thermal expansion coefficient was 11.0 × 10−6 K−1. The excellent thermal insulation performance of the high-entropy oxide ceramic (La0.2Y0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 and its similar thermal expansion coefficient to those of Ni-based superalloys demonstrate that the material has broad application prospects in the field of thermal barrier coatings.