粒度对纳米掺杂BaTiO3陶瓷结构和性能的影响

制备了纳米掺杂BaTiO3陶瓷，研究了纳米掺杂剂和BaTiO3的粒度对BaTiO3陶瓷的微观结构和介电性能的影响．结果表明，小粒度、高分散的纳米掺杂剂更易对BaTiO3颗粒实现均匀包裹，有效地抑制晶粒生长并形成更多的壳-芯晶粒，大比表面积使更多高活性的表面原子与BaTiO3发生原子输运形成传质，导致晶粒壳／芯比增大，从而提高其介电性能．纳米掺杂陶瓷的平均晶粒尺寸和四方率与BaTiO3粒度几乎成正比．随着BaTiO3粒度的减小，立方晶粒壳增大而四方晶粒芯减小，陶瓷由四方晶相向赝立方晶相转变，居里峰被显著压制，从而改善介电温度特性．同时，晶粒的壳与芯之间失配产生的内应力随之增加，使居里点向高温方向移动．

Effect of particle size on microstructure and properties of nano-doped BaTiO3 ceramics

The nano-doped BaTiO3 ceramics was prepared and the effect of particle size of nanodopant and BaTiO3 on the microstructure and dielectric properties of nano-doped BaTiO3 was investigated. The results show that the well dispersive nano powders calcined at lower temperature with small particle size prefer to coat BaTiO3 particles uniformly and form the core-shell grains. The nano-dopant can inhibit grain growth efficiently and form fine-grained structure. The average grain size and tetragonality of sintered ceramics is almost proportional to the particle size of BaTiO3. With decreasing of the particle size of BaTiO3, the crystal structure transforms from tetragonal phase to pseudocubic and the volume fraction of grain core decreases and that of grain shell increases, consequently dielectric temperature characteristic is improved dramatically. Furthermore Curie point shifts to higher temperature gradually when the particle size of BaTiO3 decreases, owing to an increase in the internal stress produced by the mismatch between the grain core and shell.