文摘
The La3TaO7 and La2AlTaO7 oxides were prepared by solid state reaction method. The phase composition, microstructure and thermal properties were examined. Results show that pure La3TaO7 and La2AlTaO7 oxides are prepared successfully. From 20 °C to 1200 °C, the average thermal conductivities of La3TaO7 and La2AlTaO7 ceramics are 1.12 W/m K and 1.71 W/m K, respectively, which are much lower than that of YSZ. Compared to La2AlTaO7, La3TaO7 has lower thermal conductivity due to its higher atom-mass difference between the substituting and the substituted atoms. The thermal expansion coefficient of La3TaO7 is higher than that of YSZ, and the thermal expansion coefficient of La2AlTaO7 is close to that of YSZ. As compared with La2AlTaO7, the higher thermal expansion coefficient of La3TaO7 can be ascribed to its lower electro-negativity difference between ions at sites A and B. The La3TaO7 and La2AlTaO7 oxides can be explored as potential ceramic materials for thermal barrier coatings.