A SOL-GEL DERIVED YELLOW-TRANSMITTING COATING ON GLASS

Bright yellow, transparent coatings were deposited on sheet glass by the sol-gel dip coating process. Sols were prepared from titanium tetraethoxide, ferric nitrate nonahydrate and a mixture of 1-propanol and 2-butanol. Advantage was taken of the absorption of Fe3+ and Fe2+ (a part of the ferric ion being reduced to ferrous ion during baking of the film, as confirmed by Mössbauer and UV-VIS-NIR spectroscopy) in the UV and near-IR regions, respectively, and of the absorption of Ti4+ in the UV range. The coatings show a distinct transmission maximum which shifted in position depending on the physical thickness; this indicated the role of interference in monitoring the exact yellow shade of the transmitting color. Specular reflectance and transmission spectra of the coatings were examined to elucidate their optical behavior. The coating material was used in a multilayer design to obtain selective transmission behavior. © 1990.