溶胶-凝胶法制备高折射率TiO2薄膜

 采用溶胶- 凝胶法制备了TiO₂纳米晶溶胶，并以旋涂法（spin-coating）镀制了高折射率光学薄膜。借助光散射技术和透射电镜研究了溶胶的微结构。采用原子力显微镜、场发射扫描电镜、紫外-可见-近红外光谱仪、椭偏仪、漫反射吸收光谱及强激光辐照实验，对膜层的结构、光学性能及抗激光损伤性能进行了系统的表征。结果显示:纳米晶薄膜的折射率达到了1.9，而传统的溶胶-凝胶薄膜折射率只有1.6；同时纳米晶薄膜的抗激光损伤阈值与传统的溶胶-凝胶薄膜相差不大，在1 064 nm处分别为16.3 J/cm²(3 ns脉冲) 和16.6 J/cm²(3 ns脉冲);纳米晶溶胶薄膜可以在保持较高抗激光损伤阈值情况下，大幅度提高薄膜折射率。

Preparation of high refractive index TiO2 thin film via sol-gel process

A simple sol-gel method was applied to prepare high refractive index thin film used in antilaser optical area. The method composed of two steps employing a complete hydrolysis and a restrained polycondensation at low temperature. The morphology of the resulting sol was determined by dynamic light scattering(DLS) techniques and was characterized as anatase by highresolution transmission electron microscopy(HRTEM). The thin optical films were deposited on K9 glass by a sol-gel spin-coating method. The film shows the presence of nanocrystalline anatase phase by X-ray diffraction(XRD) analysis. The film surface examined by atomic force microscopy(AFM) shows a mean square roughness of 7.5 nm. The transmission spectra of the film were measured using a UV-Vis-NIR spectrometer,and the refractive index,absorption coefficient of the film were calculated by ellipsometer. The refractive index of the films was about 1.91,much larger than other sol-gel films (about 1.6). The average laser induced damage threshold is 16.3J·cm－2(3 ns pulse) ,close to that of amorphous sol-gel films (16.6 J·cm－2,3 ns pulse) and much larger than that of physical films (10.8 J·cm－2,3 ns pulse).