Effect of Ta2O5 addition on thermophysical and mechanical properties of (Sm0.5Gd0.3Yb0.2)2Ce2O7 compounds

Abstract

In this study, the (Sm0.5Gd0.3Yb0.2)2(Ce1−xTax)2O7+x oxides were obtained by high-temperature solid-state sintering. The phase lattice, micro-structure, thermal-physical and mechanical performances of samples were examined. The synthesised compounds exhibit a single fluorite-type lattice, and they also have relatively dense microscopic structures. The differences in atomic weight and ionic radius between the solute and host kations enable a reduction of thermal conductivity of bulk samples. The reduced thermal expansion coefficient and the elevated elastic modulus are ascribed to the lower ion-radius of Ta5+ compared to Ce4+. The addition of “soft” Ta2O5 reduces the micro-hardness and increases the fracture toughness. The presented results herein provide an effective approach to ameliorate the fracture toughness of ceramics for thermal barrier coatings.