In this paper,(Sm0.5Yb0.5)3TaO7 was prepared via solid-reaction method in order to develop a novel ceramic layer material with excellent performance for thermal barrier coating and explore the influence of Yb addition on thermophysical performances of Sm3TaO7.Its crystal structure,microstructure,element composition,thermophysical performances and phase-stability at high temperatures were investigated.The final results indicate that the synthesized(Sm0.5Yb0.5)3TaO7 is of single pyrochlore-type lattice-structure,and compact microstructure,no element loss is found in the synthesis procedure.Owing to phonon scattering caused by doping cations,the thermal conductivity of(Sm0.5Yb0.5)3TaO7 reduces.Its thermal conductivity at high-temperature is about 1.02 W/(m·K),which is less than that of Sm3TaO7(1.31 W/(m·K))and Yb3TaO7(1.14 W/(m·K)).Because of low electronegativity of Yb3+,its thermal expansion coefficient at 1 300 ℃ is about 9.92 × 1 0-6 K-1.Its thermal expansion coefficient is higher than that of Sm3TaO7 and lies in the same order with that of YSZ and La2Zr2O7.The thermal conductivity and expansion coefficient of synthesized(Sm0.5Yb0.5)3TaO7 meet the requirements for thermal barrier coatings.This oxide also shows excellent phase-stability up to 1 300 ℃.
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