H NMR of Hydrous Glasses

The H2O/OH ratio has also been calculated for Si02 glass with H2O contents varying from 0.12 to 8.7 wt % from their MAS spectra acquired using 1-pulse sequences with 

Zeng et al. (1999) employed H- Al and H- Na TRAPDOR in combination with H mas to investigate the proton distribution in 4 hydrous aluminosilicate glasses. Peaks at 6 and 2.9 ppm correspond to 2 different water environments while others at 5-6, 3.5 and 1.5 ppm arise from 3 different hydroxyls. Rapid exchange occurs at room temperature between the 2 water environments. The data reveal the complexity of the proton speciation in these materials. All the resonances show a TRAPDOR effect to some extent. One of the groups identified is AlQ -OH, implying that the aluminosilicate framework is depolymerised by the water. This conclusion does not agree 

Interaction of water with inorganic materials at high pressure can result in sub-microscopic fluid water inclusions. In mineralogy it is important to know the pressure of the water to be able to determine its equation of state. If it is assumed that the molar magnetic susceptibility is a constant, the susceptibility is a function of the density (p) and hence the isotropic H chemical shift of the fluid in the inclusions can be used as an extremely accurate measure of its density (Withers et al. 2000). The relationship between these 2 parameters has been determined as 

This approach has greatly extended the pressure range that can be determined in fluid inclusions. 

Glasses prepared by sol-gel methods may be regarded as examples of hydrous glasses since they can retain significant proton levels when the gel is dried and vitrified. 

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