固相反应合成SrTiO_3的反应动力学

SOLID STATE REACTION KINETICS OF SrCO_3 AND TiO_2

用X射线衍射定量分析测定了等摩尔SrCO3和TiO2 (锐钛矿 )粉体在 780～ 950℃恒流氩气氛下形成SrTiO3的摩尔分数 ,将其用常用固 /固反应动力学模型进行线性拟合 .结果表明 :Ginstling -Brounshtein方程和Carter方程均能较好地描述该反应的动力学 ;相应的表观反应活化能分别为 2 71kJ/mol和 2 68kJ/mol,表观频率因子分别为 1 .4 5× 1 0 11h- 1和 1 .2 6× 1 0 11h- 1;反应为金属离子扩散控速 .

The formation of SrTiO 3 from equimolar SrCO 3 and TiO 2(anatase) powders in the temperature range from 780 ℃ to 950 ℃ in argon was followed by X -ray diffraction quantitative measurements. The data are fitted to various equations commonly used in kinetic analyses of isothermal solid_state reactions. It is found that the kinetics of the reaction can be described fairly well both by Ginstling-Brounshtein equation and Carter equation in the temperature range. The corresponding apparent activation energies evaluated on the basis of the two models were respectively 271 kJ/mol and 268 kJ/mol, and similarly, the apparent frequency factors are 1.45×10 11 h -1 and 1.26×10 11 h -1 . The reaction rate is controlled by the diffusion of metallic cations.