(Ba0.9Sr0.1)(Ti0.999Nb0.001)O3陶瓷晶粒生长的动力学因子

研究了半导化（Ba0.9Sr0.1)(Ti0.999Nb0.001)O3陶瓷晶粒生长的动力学因子，采用固相反应法工艺制备该陶瓷样品，化学原材料方纯度高于99%的BaCO3,SrCO3,TiO2和Nb2O5等，并用到微量原料Al2O3和MnSi3以改善陶瓷的电学性能，同样化学配方的8种样品在1300℃中保温时间分别为1，3，6，10，30，60，100和300，以获得晶粒生长不同程度的块状陶瓷，利用扫描电子显微技术分析发现，随着保温时间的延长样品的平均晶粒尺寸变大，经自动图像处理技术发现，晶粒生长的动力学因子不是常数；在烧结初期大致为1.5，而在烧结后期为3.5，主与大多数报道的实验和模拟结果一致。

KINETIC EXPONENTS OF GRAIN GROWTH IN (Ba0.9Sr0. 1) (Ti0.999Nb0.001)O3 CERAMICS

In this work, the kinetic exponents of grain growth in (Ba0.9Sr0. 1) (Ti0.999Nb0. 001)O3 ceramics were investigated. The samples of BST ceramics were produced by the conventional ceramic processing, the solid-state reaction method. Raw materials, BaCO3, SrCO3, TiO2 and Nb2O5, are used, with chemical purity of higher than 99 % (in mass). In addition, two minor chemicals, Al2O3 and MnSiO3, are incorporated to enhance the electrical properties of resulting ceramics. After weighed according to a required composition, the chemicals were ball-milled with purified water for about 20 h and calcined at 1 200 ℃ for 2 h. They are then ground and milled again with polyvinyl alcohol (PVA) solution binder, and, spray-dried for granulating. The dried powders are hydropressed into pellets and sintered at 1 300 ℃ for different holding times, to obtain bulk ceramics with different degrees of grain growth. It was observed by SEM that the average grain diameters became larger with the increasing of soaking time. It is found that the kinetic exponents, obtained by an automatic image processing technique, are not a constant, about 1.5 at the early stage and 3.5 at the later period of grain growth. This is in good agreement with most of experimental and simulated results reported.