(La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)₂Zr₂O₇:A novel high-entropy ceramic with low thermal conductivity and sluggish grain growth rate

Zifan Zhao^1,2，Huimin Xiang²，Fu-Zhi Dai²，Zhijian Peng¹，Yanchun Zhou²

1. School of Engineering and Technology,China University of Geosciences2. Science and Technology on Advanced Functional Composite Laboratory,Aerospace Research Institute of Materials & Processing Technology

摘 要：Fine grains and slow grain growth rate are beneficial to preventing the thermal stress-induced cracking and thermal conductivity increase of thermal barrier coatings.Inspired by the sluggish diffusion effect of high-entropy materials,a novel high-entropy（HE） rare-earth zirconate solid solution(La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)2 Zr₂ O₇ was designed and successfully synthesized in this work.The as-synthesized(La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)₂ Zr₂ O₇ is phase-pure with homogeneous rare-earth element distribution.The thermal conductivity of as-synthesized(La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)₂ Zr₂ O₇ at room temperature is as low as 0.76 W m-1 K-1.Moreover,after being heated at 1500 ℃ for 1-18 h,the average grain size of(La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)₂ Zr₂ O₇ only increases from 1.69 μm to 3.92 μm,while the average grain size of La₂Zr₂O₇ increases from 1.96 μm to 8.89 μm.Low thermal conductivity and sluggish grain growth rate indicate that high-entropy(La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)₂Zr₂O₇ is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance.

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