氧化硅对二氧化钛纳米晶相变和晶粒生长的抑制作用

Retarding Effect of Silica on the Growth and Anatase-to-Rutile Transformation of TiO2 Nanocrystals

通过让正硅酸乙酯先水解,用溶胶－凝胶法制备了织构均匀的二氧化硅/二氧化钛复合粉体．用紫外－可见吸收光谱、傅里叶红外、透射电镜、Ｘ射线衍射和比表面仪对复合粉体进行了表征．发现添加少量的二氧化硅有效地抑制了二氧化钛晶粒生长和锐钛矿向金红石的相变．选择性溶解能除去复合粉体中９０%以上的氧化硅,得到高比表面积、骨架为锐钛矿相的介孔二氧化钛．复合粉体中二氧化硅主要形成了连通的网络结构,这种网络结构在８００℃仍有很好的稳定性．

By pre-hydrolysis of TEOS, Ti02/SiO2 composites with homogeneous texture were prepared by a sol-gel process. These composite powders were characterized by UV/Vis spectra, FT-IR, TEM, XRD, and BET techniques. It was found that the growth and anatase-to-rutile transformation of titania nanocrystals in the composite were retarded significantly in the presence of small amount of silica. Mesoporous TiO2 with high specific surface area and crystalline framework was obtained by selective dissolving of silica in composite. The fact that more than 90% of silica was removed after selective dissolving and the resulting TiO2 was mesoporous with mean pore size about 4nm suggested the network of ultrafine silica was continuous and uniform.