An infrared spectroscopic study of water-related species in silica glasses

Infrared (IR) spectroscopic measurements were made on types I, III and IV silica glass specimens before and after they were subjected to heat treatments at 80-1150 degrees C in low-pressure steam, ambient air and dry air. In addition to the standard silanol band at 3672 cm(-1), IR features attributed to free, hydrogen-bonded and structurally bound molecular water and to silanol which is hydrogen-bonded to neighboring silanol groups, water molecules and chlorine impurities were found to exist even in glasses with maximum total water concentrations of less than approximately 500 ppm H2O by weight. The existence of these species and their behaviors during heat treatments suggest a specific mechanism for the reaction between silica glass and molecular water. In addition, it is shown that the glass-water reaction does not attain equilibrium instantaneously at temperatures below 750 degrees C.