The order-disorder transition(ODT)of A2B2O7 compounds obtained enormous attention owing to the potential application for thermal barrier coating(TBC)design.In this work,the influence of ODT on the mechanical and thermophysical properties of dual-phase A2B2O7 high-entropy ceramics was investigated by substituting Ce4+and Hf4+with different ionic radii on B-sites(Zr4+).The X-ray diffraction(XRD),Raman,and transmission electron microscopy(TEM)results show that rA3+/rB4+=1.47 is the critical value of ODT phase boundary with different doping B-site ion contents,and the energy dispersive spectroscopy(EDS)results further indicate the uniform distribution of elements.Interestingly,owing to the high intrinsic disorder derived from high-entropy effect,the A2B2O7 high-entropy ceramics exhibit unreduced modulus(E0 ≈ 230 GPa)and enhanced mechanical properties(HV≈ 10 GPa,KIC ≈ 2.3 MPa·m0.5).A2B2O7 high-entropy ceramics exhibit excellent thermal stability with relatively high thermal expansion coefficients(TECs)(Hf0.25,11.20×10-6 K-1,1000℃).Moreover,the matching calculation implied that the ODT further enhances the phonon scattering coefficient,leading to a relatively lower thermal conductivity of(La0.25Eu0.25Gd0.25Yb0.25)2(Zr0.85Ce0.15)2O7(1.48-1.51 W/(m-K),100-500℃)compared with other components.This present work provides a novel composition design principle for high-entropy ceramics,as well as a material selection rule for high-temperature insulation applications.

Jiatong ZHU;Mingyue WEI;Jie XU;Runwu YANG;Xuanyu MENG;Ping ZHANG;Jinlong YANG;Guangzhong LI;Feng GAO

State Key Laboratory of Solidification Processing,MIIT Key Laboratory of Radiation Detection Materials and Devices,School of Materials Science and Engineering,Northwestern Polytechnical University,Xi'an 710072,China;NPU-QMUL Joint Research Institute of Advanced Materials and Structure,Northwestern Polytechnical University,Xi'an 710072,China;State Key Laboratory of New Ceramics and Fine Processing,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China;State Key Laboratory of Porous Metal Materials,Northwest Institute for Nonferrous Metal Research,Xi'an 710016,China

先进陶瓷（英文版）

[1]Jiatong ZHU;Mingyue WEI;Jie XU;Runwu YANG;Xuanyu MENG;Ping ZHANG;Jinlong YANG;Guangzhong LI;Feng GAO-.Influence of order-disorder transition on the mechanical and thermophysical properties of A2B2O7 high-entropy ceramics)[J].先进陶瓷（英文版）,2022(08):1222-1234

A2B2O7,Ce4+and,Hf4+with,rA3+,rB4+,unreduced,25Eu0,25Gd0,25Yb0,85Ce0

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