Influence of size disorder parameter on the thermophysical properties of rare‐earth‐zirconate medium‐entropy ceramics

Abstract Inspired by the concept of entropy stabilization, a series of rare‐earth‐zirconate medium‐entropy ceramics were designed. The influence of size disorder parameter on the mechanical and thermophysical properties of rare‐earth‐zirconate medium‐entropy ceramics was investigated. The results show that the prepared rare‐earth‐zirconate medium‐entropy ceramics exhibit single pyrochlore structure, and the lattice constant is linearly related to the average doped rare‐earth ionic radius. The scanning electron microscope‐energy‐dispersive spectroscopy results indicate the uniform distribution of doped rare‐earth elements. The rare‐earth‐zirconate medium‐entropy ceramics have relative density above 98.1% with high mechanical properties ( H V ∼ 10.0 GPa, K Ⅰ ∼ 2.50 MPa m 0.5 , and E 0 ∼ 220 GPa). (La 1/3 Eu 1/3 Gd 1/3 ) 2 Zr 2 O 7 medium‐entropy ceramics with a larger (4.36%) present relatively high thermal expansion coefficients (10.93 ×310 −6 K −1 , 1200°C) and low thermal conductivity (1.57–1.58 W/(m K), 100–500°C). These results suggest that the prepared rare‐earth‐zirconate medium‐entropy ceramics can be used as a new type of thermal insulation materials.