【摘要】 使用场发射透射电镜及其扫描透射装置(STEM)和高角环形暗场像(HAADF)装置及EDS能谱仪研究了溶胶凝胶法制备的TiO2纳米微粒在电子束照射下晶体结构发生变化的现象,在200kV电子束照射下,经过不同时间的原位观察发现,纳米TiO2颗粒由开始的体心正方I41/amd(141)锐钛矿TiO2晶型转变为非晶体,随后又在电子束的照射下晶化为简单正方P42/mnm(136)金红石TiO2单晶,随后转变为尺寸更小的金红石TiO2纳米多晶体。HADDF图可以看到最后的晶粒细化过程中,原子有选择的进行迁移,使晶化区域的样品厚度不均匀化,能谱分析证明样品中只有TiO2存在。更多还原

【Abstract】 In situ observation of crystal structure variations induced by electron-beam irradiation in nanometer-sized titania prepared by sol-gel method was performed using high-resolution electron microscopy.The results show that amorphous region formed at the edge of anatase titania grain during the initial irradiation,and then the grain changes to entire amorphous structure.With the irradiation time increase,crystallization occurrs in the amorphous titania grain and rutile titania crystal forms,and one rutile titania grain changes to several rutile titania grains.More fine rutile titania crystal grains form at the end of irradiation.The HAADF image shows that these thinned grains have asymmetrical thickness after irradiation more than 20 min.The composition of the specimen is analyzed by EDS.更多还原