Thermophysical Properties of a Novel High-Entropy Niobate Oxide as a Potential Thermal Barrier Coating Material
High-entropy(La0.2Ho0.2Er0.2Y0.2Yb0.2)NbO4 ceramics were successfully prepared by the solid-state reac-tion method.The microstructure,thermal expansion coefficient,and thermal conductivity of high entropy nio-bate and rare earth niobates were characterized.The results show that the high-entropy niobate has a single-phase monoclinic structure with obvious ferroelastic domains,the doped rare earth elements are uniformly dis-tributed,and the volume expansion caused by the ferroelastic phase transformation can be ignored.Compared with the thermal expansion coefficient(10.60×10-6 K-1,829 ℃)and thermal conductivity(3.12 W·m-1·K-1,100 ℃)of YNbO4,high entropy ceramic(La0.2Ho0.2Er0.2Y0.2Yb02)NbO4 has higher thermal expansion coefficient(11.19x1 0-6 K-1,686 ℃)and lower thermal conductivity(2.34 W·m-1·K-1,100 ℃),which is a potential novel candidate material for thermal barrier coatings.
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