Preparation and Thermophysical Properties of Dual-phase High-Entropy Ceramics (La_0.2Eu_0.2Gd_0.2Y_0.2Yb_0.2)₂Zr₂O₇

High-Entropy ceramics (La_0.2Eu_0.2Gd_0.2Y_0.2Yb_0.2)₂Zr₂O₇ were prepared by high-temperature solid state reaction method with La₂O₃, Eu₂O₃, Gd₂O₃,Y₂O₃, Yb₂O₃ and ZrO₂ powder as raw materials. The preparation process was determined and the microstructure, phase composition, thermophysical properties of the high-entropy ceramics were studied. The high temperature thermal stability was analyzed. The results show that the dual-phase high-entropy ceramics with complete solid solution were obtained by sintering at 1 500 ℃ for 5h followed under furnace cooling. The high-entropy ceramics presented the dual-phase coexistence characteristics of pyrochlore/fluorite with grain size of 200—800 nm; the element distribution was uniform. The thermal conductivity at 800 ℃ of the high-entropy ceramics was 50% of currently used 8YSZ ceramics, and the thermal expansion coefficient was equivalent to that of 8YSZ ceramics. the high-entropy ceramics also showed excellent high temperature thermal stability.