Alkali Passivation Mechanism of Sol-Gel Derived TiO₂-SiO₂ Films Coated on Soda-Lime-Silica Glass Substrates

Abstract

Alkali passivation mechanism of sol-gel derived TiO₂-SiO₂ glass films with different TiO₂ contents coated on a soda-lime-silica glass substrate has been studied by SIMS and XPS analyses, and compared with the results of a sol-gel derived pure SiO₂ film. An increase in TiO₂ content in the TiO₂-SiO₂ film increased the sodium concentration in the film, which was induced by sodium migration from the glass substrate during the heat-treatment. It was also found that the chemical state of sodium ions in the TiO₂-SiO₂ films was different from the state of those either in the glass substrate or in the sol-gel derived pure SiO₂ film. It is thus concluded that the TiO₂-SiO₂ films serve not as a barrier but as an effective getter of alkli ions and thereby effectively improve the weathering resistance of the glass substrate.