Diffusion of water in silica glasses containing different amounts of chlorine

The diffusion of water into silica glasses containing different amounts of chlorine was studied at 350°C and 825°C. Chlorine concentration in the silica glass ranged from less than 50 ppm to as much as 1000 parts per million (ppm). The silica glass samples were heat-treated in the presence of water vapor at a pressure of 355 Torr and the amount of water absorbed as a function of the heat-treatment time was determined by infrared spectroscopy. It was found that both the water diffusion coefficient and the solubility of water were not affected by the chlorine content within experimental error at either heat-treatment temperature. However, chlorine and hydrogen-bonded molecular water appear to interact with one another to form an IR band located at 2810 cm−1. This IR band became more intense as the amount of chlorine or molecular water was increased.