(La0.2 Ce0.2 Nd0.2 Sm0.2 Eu0.2)PO4: A high-entropy rare-earth phosphate monazite ceramic with low thermal conductivity and good compatibility with Al2O3

• 来源期刊: 材料科学技术（英文版）
• 年，卷（期）: 2019,（12）
• 页码范围: 2892-2896
• 页数: 5页
• 语种: 英文

摘要

Low thermal conductivity,matched thermal expansion coefficient and good compatibility are general requirements for the environmental/thermal barrier coatings (EBCs/TBCs) and interphases for Al2O3f/Al2O3 composites.In this work,a novel high-entropy (HE) rare-earth phosphate monazite ceramic (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 is designed and successfully synthesized.This new type of HE rare-earth phosphate monazite exhibits good chemical compatibility with Al2O3,without reaction with Al2O3 as high as 1600 ℃ in air.Moreover,the thermal expansion coefficient (TEC) of HE (La0.2Ce0.2Nd0.2Sm0.2Eu0.2)PO4 (8.9 × 10-6/℃ at 300-1000 ℃) is close to that of Al2O3.The thermal conductivity of HE (La0.2 Ce0.2 Nd0.2 Sm0.2 Eu0.2)PO4 at room temperature is as low as 2.08 W·m-1·K-1,which is about 42％ lower than that of LaPO4.Good chemical compatibility,close TEC to that of Al2O3,and low thermal conductivity indicate that HE (La0.2Ce0.2 Nd0.2 Sm0.2 Eu0.2)PO4 is suitable as a candidate EBC/TBC material and an interphase for Al2O3f/Al2O3 composites.