La掺杂BaTiO_3陶瓷的制备与性质(Ⅱ)——金属有机盐表面包覆法

Preparation and Properties of La-doped BaTiO_3 Ceramics (Ⅱ): By a Surface-Coating Technique of Metal-Organic Compound

根据超薄介质层MLCCs等片式元件对高介电系数和细晶结构介质陶瓷材料的需求,采用金属有机盐前驱物表面包覆法实现氧化镧对水热钛酸钡粉体的均匀表面包覆和改性.试验发现:包覆物有机成分在650℃下已经完全热解,改性氧化物包覆粉体烧结后形成(Ba(1-x)La2x/3 )TiO3 单一固溶体;随着镧掺量的增加,介电峰值明显降低,介电峰展宽并移向低温,平均居里温度tav与La掺杂量几乎呈线性关系;烧成升温速率对瓷料的晶粒尺寸和介电特性有明显的影响.

In order to satisfy the need for thin layer of dielectric ceramics with small-size grains and high dielectric constant in MLCCs applications, the surface-coating technique was utilized to modify hydrothermal-synthesized BaTiO 3 (BT) with La-organic compound as the precursor, which was coated on the powders uniformly. It is found from experiments that the organic component completely decomposes at 650℃ and a single-phase solid solution Ba (1-x) La 2x/3 )TiO 3 forms after sintering. It is also found that, with the increase in La content, the peak of temperature-dependence of dielectric constant of La-doped Si-BT ceramics is compressed and moves to a low-temperature region, that the average Curie temperature t av decreases linearly with La content, and that the grain size and dielectric properties of the ceramics are greatly influenced by the increasing rate of sintering temperature.