Abstract

Potassium and oxygen concentration profiles in soda-lime- silica glass subjected to an ion exchange in molten potassium nitrate at a temperature below the strain point of the glass were obtained by Auger electron spectroscopy. Measurement showed the excess of oxygen in the modified layer of glass and the similarity of the shapes of potassium and oxygen concentration profiles in the most part of the modified layer. Consequently, the replacement of smaller sodium ions by larger potassium ions is accompanied by oxygen diffusion from molten salt into glass. On the basis of these results, a microscopic model of ion-exchange processes in silicate glasses, including mixed alkali effect, was proposed.

© 1997 Optical Society of America