中文摘要：

以Sm2O3、Gd2O3、Yb2O3和硝酸铈为原料,采用溶胶凝胶法和固相反应法制备了（Sm0.5Gd0.3Yb0.2）2Ce2O7陶瓷,用X射线衍射法分析了其相组成,用扫描电镜观察了其显微形貌,用激光脉冲法和推杆法测试了其热扩散系数及热膨胀系数.结果表明,合成的纯净的具有萤石结构的（Sm0.5Gd0.3Yb0.2）2Ce2O7陶瓷,其显微组织致密,晶界清晰干净.掺杂原子与基质原子之间质量及离子半径的差别增加了声子散射程度,从而使其热导率显著降低.同时因Gd^3＋、Yb^3＋引入而导致的氧空位有序度下降使得（Sm0.5Gd0.3Yb0.2）2Ce2O7具有较低的热膨胀系数,但仍满足热障涂层的要求,所合成的（Sm0.5Gd0.3Yb0.2）2Ce2O7陶瓷可用作新型热障涂层材料.

英文摘要：

Using Sm2O3, Gd2O3, Yb2O3 and Ce（NO3） · 6H2O as reactants, （Sm0.5Gd0.3Yb0.2）2Ce2O7 ceramic was prepared by sol-gel and solid reaction methods. Its phase composition was determined by X-ray diffraction, the microstructure was observed by scanning electronic microscope, and the thermal diffusivity and thermal expansion coeffcient were measured by laser-fash method and pushing-rod method respectively. Results show that pure （Sm0.5Gd0.3Yb0.2）2Ce2O7 ceramic with fluorite structure is synthesized successfully, it has a dense microstructure and the grain boundaries are very clean. The differences in mass and ionic radius between substituting atoms and substituted ions lead to the lower thermal conductivity of （Sm0.5Gd0.3Yb0.2）2Ce2O7 as compared to Sm2Ce2O7, and its lower thermal expansion coeffcient can also be attributed to the confused distribution of oxygen vacancies.