Effect of cation substitution on thermophysical properties of fluorite A3BO7 ceramics

Abstract The effects of substituting A and B cations in A3BO7 compounds on their thermophysical properties were studied by imposing a significant mass difference on the substituents. Specifically, (Yb1−xYx)3(Nb1−yTay)O7 (YYNT) ceramics were synthesized, and their structural characteristics were investigated. All the YYNT ceramics had defective fluorite structures and exhibited glass-like low thermal conductivity (1.19 W/m K at 25 °C), which was derived from the highly distorted crystal structure and cation substitution. In addition, their excellent thermophysical properties, such as compatible thermal expansion, high elastic modulus, and hardness, make them promising candidates for new thermal barrier materials.