Structure of hydrous aluminosilicate glasses along the diopside-anorthite join: A comprehensive one- and two-dimensional 1H and 27Al NMR study

Aluminum is dominantly present in four coordination (AlIV), but a small amount of five-coordinate Al (AlV) is also observed in all the anhydrous and hydrous glasses. Furthermore, six-coordinate Al (AlVI) is also present in most of the hydrous glasses. As Al of higher coordinations are favored by high pressure, AlVIOH and AlVOH may become major water species at higher pressures corresponding to those of the Earth's mantle.