Influence of Yb Substitution for La on Thermophysical Property of La2AlTaO7 Ceramics

The (La1−xYbx)2AlTaO7 ceramics were synthesized by pressureless sintering process at 1600 °C for 10 h in air. The crystal phase, microstructure and thermophysical properties were investigated. Results show that pure (La1−xYbx)2AlTaO7 cermics with single weberite structure are prepared successfully. Owing to the reduction of crystal-lattice tolerance-factor, the thermal conductivity of (La1−xYbx)2AlTaO7 (x>0) ceramics increases with increasing Yb2O3 fraction at identical temperatures, which is lower than that of La2AlTaO7. Due to the relatively high electro-negativity of Yb element, the addition of Yb2O3 increases the thermal expansion coefficient of (La1−xYbx)2AlTaO7 ceramics.