Pechini法制备的CeO_2纳米晶的晶化动力学  

Kinetics for crystallization of nanoscale cerium dioxide preparedby sol-gel process

作　　者：张腾[1] 唐电[1] 张琼[1] 邵艳群[1] Y.LEE 

机构地区：[1]福州大学材料研究所,福州350002 [2]美国密苏里罗拉大学材料研究中心,罗拉mo65401

出　　处：《中国有色金属学报》2004年第6期1053-1057,共5页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(59682006)

摘　　要：通过Pechini法制备CeO2粉末。XRD分析表明,该粉末在300℃下煅烧1h后成为纳米晶体。用DT 40热分析仪研究其晶化过程,在热分析过程中,CeO2的晶化过程符合Kissinger方程,计算得到其相变激活能为86.42kJ/mol,且其晶化过程所需能量比固相法的晶化过程所需能量显著降低。根据Qzawa方程得到,在250℃下Avrami指数n为1.5,频率因子为1.75×108。并由此推断该反应机理的形核过程为长程扩散控制型生长(初期阶段),从小尺寸开始的各种形状的生长形核率随时间下降。Nanosized CeO_2 particles were prepared by Pechini method. Using XRD method, it is demonstrated that nanoscale CeO_2 crystal is prepared after CeO_2 particles being heat-treated at 300 ℃ for 1 h. The crystallization process was investigated by deferential scanning calorimetry(DSC). The crystallization process is conformed to Kissinger (equation.) The activation energy of crystallization calculated by Kissinger equation is 86.42 kJ/mol, which is much lower than that of solid state reaction. The Avrami index and frequency factor calculated by Ozawa equation are 1.5 and (1.75×10~8,) respectively. From above results, a mechanism of kinetics for the process was deduced. The nucleation process is controlled by long range diffusion in early stage, and the tiny sized nuclei grow up to form various kinds of shapes, and the nucleation rate declines as the reaction proceeding.

关 键 词：纳米颗粒 二氧化铈 晶化 动力学 

分 类 号：TF123[冶金工程—粉末冶金]