TiO_2/SiO_2复合薄膜的晶型和晶粒尺寸研究

PHASE STRUCTURE AND AVERAGE CRYSTALLINE SIZE OF TiO_2/SiO_2 COMPOSITE THIN FILMS

通过溶胶 -凝胶工艺在普通钠钙玻璃表面制备了均匀透明的TiO2 /SiO2 复合薄膜 .由紫外可见光谱发现 :在TiO2 薄膜中添加SiO2后 ,薄膜中TiO2 晶粒尺寸变小 ,TiO2 /SiO2 复合薄膜的吸收边缘波长发生了明显的“蓝移” .进一步用X射线衍射 (XRD)和透射电镜 (TEM )表征了TiO2 /SiO2 复合粉末和TiO2 粉末的晶型和晶粒尺寸 ,结果发现 :在TiO2 凝胶粉末中添加少量SiO2 (如摩尔分数为 5 % )后 ,TiO2 的晶粒生长受到明显抑制 ,晶粒尺寸明显变小 ,为 6～ 7nm ;当TiO2 凝胶粉末中添加的SiO2 量较高时 ,随热处理温度升高 ,TiO2 的晶型转变和晶粒生长受到更大抑制 。

The uniform transparent TiO2/SiO2 composite thin films were prepared via sol-gel process on the soda lime glass substrates. The effect of the addition amount of SiO2 on the structural phase transition and the crystal growth of TiO2 thin films was investigated by X-ray diffraction and transmission electron microscopy. It is found that the addition of SiO2 to TiO2 thin films suppresses the structural phase transition and the crystal growth of TiO2 crystal in the TiO2 thin films. The average crystalline size of TiO2 decreases and the absorption edge wavelength of TiO2/SiO2 composite thin films becomes less with the increase of SiO2 content. The average crystalline size becomes 6-7 nm with the addition of 5% SiO2 (in mole) and at the temperature of 500°C. With the increase of the SiO2 content, the temperature of the structural phase transition from anatase phase to rutile phase obviously increases and the crystal growth speed of TiO2 thin films is greatly suppressed.