Abstract
The alumina thin films were prepared by the sol-gel method using aluminium nitrate dissolved in 1, 3butanediol solution. The thin films usually had a homogeneous and flat surface structure. However, the surface structure of the films obtained after the immersion in an ethylene glycol and water mixed solution at 100°C changed to the sponge-like surface texture which was composed of fibrillar particle. The Al/Si intensity ratio of the thin films on a glass substrate measured by XRFS increased with the concentration of an ethylene glycol in immersion solution and reached to an approximately constant value above 22 mol%. The crystal structure of alumina after immersion changed into the amorphous from boehmite with an increase in ethylene glycol concentration. The addition of ethylene glycol has an effect upon the growth of the fibrillar particle which composes thin films. Therefore, ethylene glycol in the immersion solution restrains the peptisation of alumina particle and the production of boehmite by the hydration and enhances the growth of fibrillar particle. It was found that the vacant size in the thin films could be controlled by the ethylene glycol concentration in the immersion solution.
