Thermal Conductivity and Sintering Behavior of Sm2Zr2O7 Ceramics with Y3+ Substitution for Different Lattices

Abstract Sm2Zr2O7 is one of the most promising candidate materials for ultra-high temperature thermal barrier coatings. In this paper, a series of (Sm1-x1Yx1)2(Zr1-x2Yx2)2O7-x2 ceramics with different lattice sites replaced by Y3+ ions were successfully prepared by the high-temperature solid-phase sintering method. The effect of Y3+ doping on microstructure, phase composition, thermal conductivity and sintering behavior of modified Sm2Zr2O7 ceramics were investigated, respectively. The results showed that (Sm1-x1Yx1)2(Zr1-x2Yx2)2O7-x2 were composed of a single pyrochlore crystal phase within 20% Y3+ ions doping concentration. Compared with pure Sm2Zr2O7, the fracture toughness of each (Sm1-x1Yx1)2(Zr1-x2Yx2)2O7-x2 ceramic was significantly reduced. In terms of reducing the thermal conductivity of Sm2Zr2O7, the substitution of Y3+ ion for Zr4+ was more obvious than the substitution of Y3+ for Sm3+. Thermal conductivity of Sm2(Zr0.9Y0.1)2O6.9 was 1.315 W·m-1·K-1 at 1200 °C, which was the lowest among the studied ceramics.. Sm2(Zr0.9Y0.1)2O6.9 ceramic exhibited a lower grain growth rate at 1400 °C, and still remained a single pyrochlore crystal phase after sintering for 100 h, indicating that Sm2(Zr0.9Y0.1)2O6.9 had good high-temperature stability at 1400 °C.