Control of film thickness in the preparation of titania thin films

A titania coating solution was prepared by dissolving amorphous titania powders in 31 % hydrogen peroxide solution. Transparent titania thin films were prepared by dip-coating them on glass plates. The titania film was found to be uniform in thickness, when prepared using this solution with viscosity of 1 mPa.s. The refractive index of the film was estimated to be d = 2.3, which is slightly lower than that of pure anatase powders (d = 2.5). The film thickness was found to be directly proportional to the withdrawal speed of V-2/3. It was also found that the absorption edge of the UV-vis spectra shifts to a longer wavelength with increasing film thickness. Film thickness was easily estimated from the value of the wavelength at the absorption edge.