High density La_9.33Si₆O₂₆ polycrystals were fabricated by conventional and spark plasma sintering starting from nanopowders synthesized by freeze-drying. The materials exhibit a homogeneous microstructure formed by equiaxed grains with average sizes of 1.1 μm and 0.2 μm-diameter depending on the sintering route. Compressive mechanical tests were performed in air at constant strain rate between 900 and 1300 °C. A gradual brittle-to-ductile transition was found with increasing temperature and/or decreasing strain rate. Grain boundary sliding is the main deformation mechanism in the ductile region, characterized by a stress exponent n = 1 for the conventional sintered (large-grained) material and n = 2 for the spark plasma sintered (fine-grained) material; in both cases, the activation energy for creep was 360 kJ/mol. Effective cation diffusivities have been derived from mechanical data by comparison with appropriate models. The creep properties of lanthanum silicates are reported here for the first time.

高密度La _9.33 Si ₆ O ₂₆通过常规和火花等离子体烧结，从通过冷冻干燥合成的纳米粉末开始，制备多晶。这些材料表现出由等轴晶粒形成的均匀微观结构，这些晶粒的平均尺寸取决于烧结路径，平均直径为1.1μm，直径为0.2μm。在空气中以900至1300°C的恒定应变率进行压缩机械测试。发现随着温度的升高和/或应变速率的降低，脆性至韧性逐渐过渡。晶界滑动是延性区域的主要变形机制，其特征在于，传统烧结（大晶粒）材料的应力指数为n = 1，而火花等离子烧结（细晶粒）材料的应力指数为n = 2。在这两种情况下，蠕变的活化能均为360 kJ / mol。通过与适当的模型进行比较，可以从力学数据得出有效的阳离子扩散系数。首次报道了硅酸镧的蠕变特性。