以高纯度La₂O₃、MgO、SrCO₃、CeO₂和Ta₂O₅为原材料，采用多步高温固相烧结法制备了Sr₃La₃Ce₇Ta₂O_26.5和Mg₃La₃Ce₇Ta₂O_26.5氧化物，研究了其晶体结构、微观形貌和热物理性能。结果表明：所合成的氧化物具有单一焦绿石结构，其显微组织致密，晶界清晰，元素种类和原子比与化学式基本一致；Sr₃La₃Ce₇Ta₂O_26.5的热膨胀系数大于Mg₃La₃Ce₇Ta₂O_26.5，二者在1 000℃时的热膨胀系数分别是11.6×10^-6，11.37×10^-6 K^-1，明显大于7YSZ的9×10^-6 K，并且二者在高温下均具有良好的晶体结构稳定性；Sr₃La₃Ce₇Ta₂O_26.5和Mg₃La₃Ce₇Ta₂O_26.5在1 200℃时的热导率分别为1.68，1.87 W·m^-1·K^-1，均低于7YSZ的2 W·m^-1·K^-1；Sr²⁺较大的离子半径和原子质量导致Sr₃La₃Ce₇Ta₂O_26.5的热导率低于Mg₃La₃Ce₇Ta₂O_26.5；合成氧化物的热导率和热膨胀系数均满足热障涂层的要求。

Taking La₂O₃, MgO, SrCO₃, CeO₂ and Ta₂O₅ with high purity as raw reactants, the Sr₃La₃Ce₇Ta₂O_26.5 and Mg₃La₃Ce₇Ta₂O_26.5 oxides were synthesized by multi-step high temperature sintering, and the crystal structure, microstructure and thermophysical properties were investigated. The results show that the obtained oxides exhibited a single pyroxhlore crystal structure; the microstructure was very dense, and the grain boundaries were very clear; the element composition and the corresponding mole ratio were consistent with the corresponding chemical formula. The thermal expansion coefficient of Sr₃La₃Ce₇Ta₂O_26.5 was larger than that of Mg₃La₃Ce₇Ta₂O_26.5, and the thermal expansion coefficients at 1 000℃ were 11.6×10^-6, 11.37×10^-6 K^-1, respectively, which were obviously larger than 9×10^-6 K of 7YSZ; the two oxides had good crystal structure stability at high temperature. The thermal conductivity at 1 200℃ of Sr₃La₃Ce₇Ta₂O_26.5 and Mg₃La₃Ce₇Ta₂O_26.5 were 1.68,1.87 W·m^-1·K^-1, respectively, which were smaller than 2 W·m^-1·K^-1 of 7YSZ; the large ionic radius and atomic mass of Sr²⁺ resulted in the lower thermal conductivity of Sr₃La₃Ce₇Ta₂O_26.5 than Mg₃La₃Ce₇Ta₂O_26.5. The thermal conductivity and expansion coefficient of the synthesized oxides both satisfied the requirements for thermal barrier coating.