Effects of interstitial water on phase transition of forsterite glass

Structures and Dynamics of Forsterite and Its Interstitial Water

“…On the other hand, the number for water with forsterite glass decreases with the approach to the interface at <1.0 nm, although it increases at approximately 1.0–1.3 nm. The decrease at <1.0 nm results from the formation of covalent bonds with Mg atoms at the surface of forsterite glass . Due to the uneven structure of the surface, the water molecules in the cavities form covalent bonds with Mg. Consequently, the coordination numbers of oxygens in the cavities become small.…”

“…Under the assumption that the maximum length of hydrogen bonds is 0.2921 nm, 20 the coordination number was counted using the running coordination number between oxygen atoms in water molecules because no clear inflection point was observed in the radial distribution function of water at a high temperature. 12 Figure 2b shows the distribution of the mean value of coordination numbers as a function of distance from the interface. For water with the forsterite crystal, the number increases with the approach to the interface at distances of <0.7 nm.…”

“…The decrease at <1.0 nm results from the formation of covalent bonds with Mg atoms at the surface of forsterite glass. 12 Due to the uneven structure of the surface, the water molecules in the cavities form covalent bonds with Mg. Consequently, the coordination numbers of oxygens in the cavities become small. The increase observed at around 1.0−1.3 nm indicates that the structured bounded water exists outside the uneven surface of forsterite glass.…”

“…The surface of forsterite glass has an effect of an increase in reactivity because Mg in the surface layer has a low coordination number. 11 Furthermore, Kubo et al 12 revealed that the Mg(OH) 2 crystal (i.e., brucite crystal) is formed from dissolved magnesium in the interstitial water of forsterite glass.…”

“…The interstitial water has a unique high-density structure and can exist as a liquid state at temperatures above the boiling point without pressurization. 12 In this study, MD calculations were performed to investigate the effects of the thickness of the water layer on diffusive properties and structures of interstitial water of forsterite in crystalline and glassy states. In addition, the effects of interstitial water on the structures and diffusive properties of the coexisting forsterite with interstitial water were investigated.…”