论文部分内容阅读
BaTiO_3的微波合成在中间相、产物形貌、颗粒上元素浓度等方面与常规合成均不相同,从实验上说明了微波合成中有非热效应的存在。在微波场中Ba~(2+),Ti~(4+)的扩散都得到很大的增强,由常规合成中基本为Ba~(2+)扩散转化为Ba~(2+),Ti~(4+)相互扩散,尽管仍然是以Ba~(2+)扩散为主,但Ti~(4+)的扩散不能忽略。微波合成反应中扩散过程的增强作用主要表现在对扩散系数指前因子及扩散推动力的影响。微波合成过程中没有Ba_2TiO_4中间相的出现,与常规合成有较大的差别,反应的动力学过程分析表明该反应符合Carter方程。在X射线衍射定量分析结果基础上计算微波合成BaTiO_3表观反应活化能为42.26kj/mol,仅为常规反应的1/5。
The microwave synthesis of BaTiO_3 is different from the conventional synthesis in the aspects of mesophase, product morphology and elemental concentration on particles. The experiment shows that there is non-thermal effect in microwave synthesis. In the microwave field, the diffusion of Ba ~ (2 +) and Ti ~ (4 +) in the microwave field is greatly enhanced. The diffusion from Ba ~ (2+) to Ba ~ (4+) diffuse into each other. Although the diffusion of Ba ~ (2+) is still dominant, the diffusion of Ti ~ (4 +) can not be neglected. The enhancement of the diffusion process in the microwave synthesis reaction is mainly reflected in the influence of the pre-exponential factor of diffusion coefficient and the driving force of diffusion. There was no appearance of Ba_2TiO_4 mesophase in the microwave synthesis process, which was different from the conventional synthesis. The kinetic process analysis showed that the reaction was in accordance with the Carter equation. Based on the quantitative analysis results of X-ray diffraction, the apparent activation energy of microwave synthesis of BaTiO 3 was calculated to be 42.26 kj / mol, which is only 1/5 of that of conventional reaction.