微波合成SrTiO~3的反应机理

研究了微波合成SrTiO~3的合成过程,XRD及电子探针的结果表明这一反应过程是由扩散控制,微波场的存在使扩散过程明显增强,存在有Sr和Ti元素的相互扩散,与常规合成有较大不同。从微波合成和常规合成反应产物的组成及显微结构等方面说明微波合成与常规合成具有不同的反应机理,微波合成在反应过程中没有出现其他的中间相,反应动力学计算表明反应过程的动力学符合Carter方程,反应的活化能为129kJ/mol,约为常规合成的1/2～1/3。

The mechanism of microwave synthesis for SrTiO~3

The difference of intermediate products, microstructure and element concentration in the particles between microwave synthesized samples and conventional samples were responsible for the exiting of non - thermal effect in the microwave field. The diffusions of ionic in the microwave field were enhanced so that the diffusion of Ti4 could not be neglected as in the conventional solid state reactions. The influence of the microwave field was mainly expressed as diffusion coefficient and the driving force of ionic motion. The intermediate phase which occurred in the conventional solid reaction was not found during microwavesyntheses. The quantitative analysis based on XRD experimental data shows that the reaction dynamics in microwave is suitable for the Carter equation. The activation energy for reaction of SrCO3 and TiO2 in the microwave field is 129kJ/mol, which is only about one third of that of conventional reaction.