溶胶-凝胶法制备的二氧化锆粉中t-ZrO_2的稳定性

Stability of t-ZrO_2 in zirconia powder prepared by solgel process

为研究溶胶凝胶法制备的二氧化锆粉中 t- Zr O2 在低温稳定存在的原因 ,该文采用 X射线衍射仪和差热分析仪对二氧化锆凝胶粉的晶体结构及动力学参数进行了分析。结果表明 ,低温时凝胶粉中的非晶态二氧化锆近程有序结构更接近 t- Zr O2 的晶体结构 ;在 6 0 0～ 80 0℃温区内 ,t- Zr O2的晶粒尺寸小于 30 nm,处于表面能起决定作用的稳定区间内 ;t- Zr O2 的析晶活化能 (5 6 .5 k J.mol- 1 )低于 m- Zr O2 析晶活化能 (10 9.2 k J.m ol- 1 )。晶体结构、表面能及析晶活化能诸方面均显示出有利于凝胶粉中的亚稳 t- Zr O2

The crystalline structure and dynamics of zirconia gel powder were measured with Xray diffractometer (XRD) and differential thermal analysis (DTA) to understand the steady existence of tZrO 2 in zirconia powder prepared by solgel method. The results showed that the shortrange order structure of the amorphous powder is close to that of tZrO 2. Between 600 and 800℃, the grain size (<30nm) of tZrO 2 remained in a steady range due to great surface energy. The activation energy for crystallization of tZrO 2 is lower than that of mZrO 2 (which is 56.5 and 109.2kJ·mol -1 respectively). The crystalline structure, the surface energy and the activation energy for crystallization all favor the stability of tZrO 2 in zirconia powder.