Water in Silicate Glass: 17O NMR of Hydrous Silica, Albite, and Na2Si4O9 Glasses

Abstract

The mechanism of incorporation of water in silica (SiO2), albite (NaAlSi3O8), and Na2Si4O9 composition glass has been studied by 1H, 17O, 23Na, 27Al, and 29Si NMR spectroscopy. Hydrated samples were prepared by quenching the melt from high pressure and high temperature with use of solid-media apparatus with a 17O-enriched starting material. Water content of the hydrated glasses was estimated from 1H NMR peak intensities compared with reference materials. For SiO2 glass, the 17O NMR spectrum has a sharp resonance line at the position corresponding to the chemical shift of molecular water. 17O NMR of both dry and hydrous (50 mol % H2O) albite glasses shows two environments with peaks for Si−O−Si and Si−O−Al. No significant difference was seen between dry and hydrated glasses. For the Na2Si4O9 glass, 1H and 29Si NMR results are consistent with each other and suggest the formation of Si−OH and molecular water in this glass. 17O NMR of this glass shows significant differences between dry and hydrated glass. Th...