Depolymerization effect of water in aluminosilicate glasses: Direct evidence from 1H-27Al heteronuclear correlation NMR

• DOI: 10.2138/am.2006.2365
• Publication Date: 2006-11-13T19:37:47Z
• Authors: X. Xue; M. Kanzaki
• Keywords: Heteronuclear molecule; Depolymerization; Proton NMR; Chemical shift

We have applied one-dimensional (1D) 1H MAS NMR, 27Al → CP as well 2D triple-quantum (3Q) heteronuclear correlation (HETCOR) and high-resolution 3QMAS/HETCOR NMR techniques to KAlSi3O8 (Or), NaAlSi3O8 (Ab) NaAlSiO4 (Ne) glasses containing 0~2 wt% H2O shed light on the dissolution mechanisms of water in aluminosilicate melts (glasses). An Al Q3-OH group, characterized by chemical shifts 1.3-1.9 ppm, was identified for all hydrous glasses. Its abundance increases with bulk Al/Si ratio. The (δiAl) this species are 64-68 larger than those Q4 3-6 ppm. Despite difference, it is only through HETCOR 3QMAS/HETCOR, but not or 3QMAS that peaks resolved. This study has demonstrated depolymerization formation AlOH/SiOH a general mechanism polymerized (glasses), experiments involving key its revelation.