Alkali ion diffusion and structure of chemically strengthened TiO2 doped soda-lime silicate glass

Abstract

Diffusion kinetics and structural properties of chemically strengthened titania-doped soda-lime silicate glasses were studied by depth-resolved X-ray photoelectron spectroscopy, Raman spectroscopy and spectrophotometry. The glasses were ion exchanged, whereby Na+ in the glass was replaced by K+ in a molten salt bath, at four different treatment temperatures between 350 and 500 °C. The alkali diffusion coefficient, DK-Na, and corresponding activation energy were calculated to be between 3.26×10−12 and 4.47×10−11 cm2s−1 and between 101.1 kJmol−1 and 105.6 kJmol−1, respectively. DK-Na was observed to decrease as the TiO2 concentration was increased. Raman analysis showed Q3-silicate species with different bond lengths, which was attributed to surface compressive stresses, and increasing Si-O-Si bond angle with increasing ion exchange temperature. Ti3+ ions exist as a minor species in the glasses and its concentration depends on the TiO2 content. Deconvolution of the optical absorption spectra reveals Jahn-Teller compressive distortion of the Ti3+ octahedral coordination.