溶胶-凝胶法制备纳米氧化钛及其相变机理的研究

Preparation of Nano-TiO_2 by Sol-Gel Method and Its Phase Transformation

以钛酸四丁酯为前驱物,用溶胶-凝胶方法制得了纳米氧化钛(TiO2)粒子,并采用紫外拉曼光谱,可见拉曼光谱以及XRD进行表征,并计算了不同焙烧温度时TiO2表面和体相的晶相组成,以此为基础研究了TiO2的相变机理。XRD与可见拉曼光谱的结果一致,均表明体相区锐钛矿在600℃时开始向金红石转变。然而紫外拉曼光谱的结果却表明,焙烧温度高达765℃时,表面区锐钛矿才开始发生相变,即从锐钛矿到金红石的相变过程中存在体相和表面相变不同步的现象,金红石相是从相互接触的锐钛矿粒子的界面开始生成的。

TiO2 nanoparticle was prepared by sol-gel method using Ti（OBu）4 as precursor.Phase transformation of TiO2 from anatase to rutile was studied by UV Raman spectroscopy,visible Raman spectroscopy,X-ray diffraction（XRD）.The results from visible Raman spectroscopy are in good agreement with those of XRD patterns.It was observed that anatase in the bulk region starts to change into rutile at 600 ℃.However,from UV Raman spectra,the anatase in the surface region transformed into the rutile phase until the calcination temperature was up to 765 ℃.The inconsistency in the results from the above three techniques suggests that the anatase phase of TiO2 at surface region can remain at relatively higher calcination temperatures than that in bulk during the phase transformation.It was suggested that the rutile phase starts to form at the interfaces between the anatase particles of the agglomerated TiO2 particles.