SrTiO_3基BLC二次烧成过程中显微结构的观察与分析

利用高温金相显微镜、SEM/EDAX和反光显微镜对以SrTiO_3为基的边界层陶瓷电容器(BLC)的烧结过程和绝缘化以后的晶粒和晶界结构进行了观察和分析。研究结果表明,掺有CuO和GeO_2的SrTiO_3的烧结过程为有液相参加的反应液相烧结,半导化以后的陶瓷的绝缘可以通过气相扩散和液相扩散的方式进行。气相扩散绝缘化过程是以离子扩散为主的沿晶界的扩散,金属离子和氧气同时向晶界扩散,氧的扩散使晶界区域发生氧化而绝缘,金属离子的扩散有利于晶界阻挡层的形成。液相扩散绝缘化过程与R.Wernicke提出的选择熔化理论相符,但晶界不一定要富钛。

THE OBSERVATION AND ANALYSIS OF MICROSTRUCTURE OF SrTiO_3-BASED BLC DURING PROCESSES OF SEMICONDUCTING AND INSULATION

The microstructure of SrTiO_2-based BLC during sintering and after insulating were observed and ana- lyzed by using high temperature microscope, SEM / EDAX and optical microscope. The experiments showed that the sintering process of SrTiO_3-based BLC doped whth CuO and GeO_2 was the liquid sintering The grain boundary of semiconducting SrTiO_3ceramics could be insulated by vapor-diffusion or by liquid-diffu- sion. The vapor-diffusion insulating process was mainly the diffusion of metal ions and oxygen along grain boundary areas The diffused oxygen made ceramics insulating by oxidizing the grain boundary areas The diffused metal ions formed insulating layer in the grain boundary areas The liquid-diffusion insulating pro- cess was similar to the mechanism of the selective melting of grain boundary Second phase proposed by R Wernicke but it was unnecessary for the grain boundary second phase to have excessive TiO_2.