Effect of Ta5+ doping on the thermal physical properties of defective fluorite Y3NbO7 ceramics

The effects of substituting the B cation in A(3)BO(7) ceramics on their thermal physical properties were investigated by applying a large mass difference. Y-3(Nb1-xTax)O-7 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized, and their structural characteristics were determined. All the fabricated Y-3(Nb1-xTax)O-7 ceramics showed defective fluorite structures and glass-like low thermal conductivity (1.18-2.04 W/m center dot K at 25 degrees C) because of the highly distorted crystal structure and significant mass difference. Substitution with Ta5+ enhanced the sintering resistance, leading to superior thermal-insulating performance via grain boundary scattering. Furthermore, the ceramics exhibited excellent coefficients of thermal expansion, implying the promising applicability of Y-3(Nb1-xTax)O-7 as new thermal barrier materials. The effect of mass difference on the thermomechanical properties of the ceramics was examined, suggesting a simple strategy for engineering the chemical composition of new thermal barrier materials.