二氧化钛溶胶凝胶的光致变色

通过钛酸丁酯在酸性醇溶液中的水解制备二氧化钛溶胶和凝胶。在中压汞灯的照射下，溶胶和凝胶由浅黄色变成蓝紫色。电子自旋共振谱(ESR)表明，变色的原因是由于…Ti－O－Ti－O…网络中Ti^4^+离子被还原成Ti^3^+离子。Ti^3^+离子又会被空气中的氧所氧化成Ti^4^+离子，个人成分吏家产凝胶由蓝紫色褪为浅黄色。和变色溶胶的吸收光谱不同，在变色凝胶的吸收光谱上出现了四个明显的吸收峰，这些吸收峰是由于处于一定结构中的Ti^3^+离子的3d轨道上电子的跃迁所引起。

Photochromism of titania sol and gel

titania sol and gel were prepared through the hydrolysis of Ti (OC~4H~9)~4 in acidic water solution. The sol and gel are sensitive to UV ilght and turn into blue-purple on irradiation. electron spin resonance (ESR) measurement showed that the photochromism was due to the presence of titanium (Ⅲ) ions in the …Ti－O－Ti－O… networks. The titanium (Ⅲ) ions could be oxidized by the oxygen in the atmosphere, and cause the slow color fading. The absorption peaks in the optical absorption spectra of the titania gel were attributed to the transition of 3d electron of a trivalent titanium in certain environment.