(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7: A novel high-entropy ceramic with low thermal conductivity and sluggish grain growth rate

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 (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)(2)Zr(2)O(7 )was designed and successfully synthesized in this work. The as-synthesized (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)(2)Zr2O7 is phase-pure with homogeneous rare-earth element distribution. The thermal conductivity of as-synthesized (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)(2)Zr(2)O(7 )at room temperature is as low as 0.76 W m-1 K-1. Moreover, after being heated at 1500 degrees C for 1-18h, the average grain size of (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)(2)Zr2O7) only increases from 1.69 mu m to 3.92 mu m, while the average grain size of La2Zr2O7 increases from 1.96 mu m to 8.89 mu m. Low thermal conductivity and sluggish grain growth rate indicate that high-entropy (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)(2)Zr2O7 is suitable for application as a thermal barrier coating material and it may possess good thermal stress-induced cracking resistance. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.