溶胶-凝胶法制备准晶型纳米TiO_2及其光致发光特性研究

Study on Standard Crystal Nano-TiOZ_2 Preparation and Its Photoluminescence Characteristics by Sol-gel Technique

采用溶胶凝胶法制备出了锐钛和金红石型两种准晶型纳米TiO2颗粒，ESEM结合XRD显示，锐钛型近似呈球状，粒径约30～40 nm；金红石型呈圆棒状，粒径约40～50 nm，两种粒径分布均匀，单分散性好，无团聚现象。FTIR分析表明硬脂肪和其它溶剂加入并不会改变纳米TiO2形成的晶型结构，但煅烧温度对TiO2晶型结构产生较大影响，450～600 ℃之间产物为锐钛型（最佳温度550 ℃），650～750 ℃之间为锐钛型向金红石型转变，750 ℃时已完全转化成金红石晶型。光催化实验表明，锐钛型催化活性大于金红石型。荧光光谱分析表明，锐钛型纳米TiO2在λ=414 nm处有一个特征激发峰，这是因为纳米TiO2中O空位Ti填隙缔合缺陷能级向价带跃迁可能参与了激发光形成过程而导致的。

Sol-gel technique is employed to prepare standard anatase and rutile crystal nanometer TiO2, ESEM coupled with XRD analyses show that anatase TiO2 is sphericity-like with 30-40 nm diameter, while rutile structure is columnlike with 40-50 nm diameter, two size distribution are narrow, dispersion is good with no reuniting phenomena. FT-IR results show that the crystals are not changed by stearic acid and other solvent additions, however, the calcination tempera- ture has a prodigious effect on the crystal form, the product is anatase TiO2 under 450~600 ℃ temperature, （the optimal temperature is 550℃ ）. When temperature is 650-750℃, anatase TiO2 begins to transform into rutile structure, crystals transformation is over under temperature is equal to 750℃. Photocatalysis shows that anatase TiO2 catalysis activity is stronger than rutile structure. Spectrofluorimetry identify that there is a characteristic excitated peak at λ=414 nm, which is launched by O space Ti interstitial associating defect to price jumps. That is an important foundation that anatase nano- TiO2 nanocrystals have photoluminescence effect.