晶粒尺寸对Ba$lt;sub$gt;0.70$lt;/sub$gt;Sr$lt;sub$gt;0.30$lt;/sub$gt;TiO$lt;sub$gt;3$lt;/sub$gt;陶瓷介电性能的影响规律及机理研究

通过制备晶粒尺寸处于0.1—10 μm之间的致密Ba_0.70Sr_0.30TiO₃陶瓷，系统研究了晶粒尺寸对居里温度T_C、铁电相介电常数ε_F、峰值介电常数ε_M的影响规律，并深入分析了其内在的影响机理.研究表明：晶粒尺寸减小时，T_C刚开始基本不变，直到晶粒尺寸小到一定程度时才开始降低，此变化规律可由Buesseum的内应力模型解释；随晶粒尺寸的增加，ε_F先增加后减小，此变化规律可由Shaikh的串并联模型来解释，主要影响因素有内应力、畴、晶界；ε_M随晶粒尺寸的增加，在晶粒尺寸较小时先增加后减小，晶粒尺寸较大时略有增加，此变化规律可由弥散相变理论和串并联模型共同解释，在晶粒尺寸较小时主要影响因素为内应力、微畴和晶界，晶粒尺寸较大时主要影响因素为晶界. 关键词： 0.70Sr_0.30TiO₃陶瓷')" href="#">Ba_0.70Sr_0.30TiO₃陶瓷 介电常数 居里温度 晶粒尺寸

Grain size dependence of the dielectric properties of Ba0.70Sr0.30TiO3 ceramics and its mechanisms

By successfully fabricating dense Ba_0.70Sr_0.30TiO₃ ceramics in the size range of 0.1—10 μm，the grain size dependence of the Curie temperature T_C，dielectric constant in ferroelectric phase ε_F and in peak ε_M were systematically investigated. The results show that T_C will not decrease considerably until the grain size becomes small enough. This can be explained by Buesseums internal stress model. As the grain size increases，ε_F increases first and decreases afterward，which can be interpreted by Shaikhs series-parallel model. The main active factors are internal stress，domain and grain boundary. On the other hand，if the grain size is small，ε_M increases first and decreases afterward as the grain size increases. If the grain size is bigger，ε_M increases slightly. This can be explained by the diffuse phase transition theory and series-paralled model. The main active factors are grain boundary，internal stress，for small grain sizes, and domain and grain boundary for bigger grain sizes，respectively.