Abstract
Through a combination of 1H MAS NMR, 1H → 29Si → 1H double cross-polarization (CP) MAS NMR and 27Al → 1H CP MAS NMR, different OH species [SiOH, AlOH, and (Ca,Mg)OH (free OH)] have been unambiguously identified for hydrous Ca,Mg-(alumino)silicate glasses. This confirms my earlier speciation assignments made partially on the basis of 1H chemical shift arguments. The dissolution mechanisms of water in both Al-free silicate and aluminosilicate glasses (quenched melts) are fundamentally similar. For relatively polymerized compositions, it involves dominantly the formation of TOH species (T: Si, Al) through the rupture of T-O-T linkages, in addition to molecular H2O; for more depolymerized compositions containing network-modifying cations of large field strength (e.g., Ca, Mg), free OH species are also important.
Original language | English |
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Pages (from-to) | 395-398 |
Number of pages | 4 |
Journal | American Mineralogist |
Volume | 94 |
Issue number | 2-3 |
DOIs | |
Publication status | Published - Feb 1 2009 |
Keywords
- Aluminosilicate
- Glass
- Melt
- NMR
- Silicate
- Structure
- Water speciation
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology