ALKALI PASSIVATION MECHANISM OF SOL-GEL DERIVED TIO2-SIO2 FILMS COATED ON SODA-LIME-SILICA GLASS SUBSTRATES

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.