Multinuclear NMR spectroscopic studies of structure and dynamics in hydrous NaAlSi3O8 and Ca0.5AlSi3O8 glasses

We studied the local structure and dynamics of dissolved water in hydrous aluminosilicate glasses with the compositions NaAlSi3O8·0.3H2O, NaAlSi3O8·1.3H2O and Ca0.5AlSi3O8·1.3H2O by using multinuclear NMR spectroscopy. Glasses were produced by melting glass powders with deuterium oxide under high pressure and the resulting 2H/(1H + 2H) ratio of the hydrous glasses was larger than 80%. NMR spectra reveal clear evidence for the presence of OH groups as well as of H2O molecules. The motion of these water species in the time range from some μs to some ms was studied by 1H NMR relaxation rates and the temperature dependence of the 2H NMR spectra. The motion is faster in the Ca-bearing glass than in the Na-bearing glass. The results are compared with those from quasi-elastic neutron scattering.