【摘要】 用溶胶 -凝胶法 (sol -gel)制备了纳米TiO2 微粉。应用正电子湮没寿命谱 (PAT)研究了纳米TiO2 的界面结构。PAT研究表明 ,sol-gel法制备的纳米TiO2 微粉中只存在两类缺陷 ,即与短寿命成分τ1对应的单空位尺寸的自由体积缺陷 ,以及与中等寿命成分τ2 对应的微孔洞缺陷。其缺陷数目及浓度随着粒子尺寸的改变有着显著的改变 ,表现出尺寸效应。更多还原

【Abstract】 Nanocrystalline TiO 2 was prepared by sol-gel process.The interfacial structures of nanocrystalline TiO 2 powder were studied by positron-annihilation technique (PAT).The investigation of PAT showed there were two defects in the TiO 2 powder prepared by sol-gel process:the lifetime τ 1 is attributed to positron trapping in vacancy-size volumes defect in the crystalline interfaces and the lifetime τ 2 is attributed to positron annihilation in microvoids defect at the intersections of interfaces.The number and density of defects changed with the annealing temperatures and grain-size of TiO 2 powder.That showed size effect.更多还原