Structure and dynamics of interface between forsterite glass and amorphous ice

Structures and Dynamics of Forsterite and Its Interstitial Water

“…In the case of amorphous ice in contact with forsterite glass at 10 K, the density of water decreases with the approach to the interface. 10 In contrast, the present result shows that the density of liquid water in the interface with forsterite glass is almost constant at 470 K. This suggests that the unevenness of the surface of forsterite glass decreases with heating. The average densities of the inner part of water with forsterite crystal and glass (0.87 and 0.88 g cm −3 , respectively) are slightly larger than that of pure water (0.86 g cm −3 ).…”

“…The MSD value increases significantly with increasing the d . The MSD value of Mg in forsterite in the interface with water is larger than that of the internal part . The present result suggests that the atomic mobility in the interface may propagate to the internal part of forsterite for both the crystal and glass.…”

“…For both crystal and glass, as shown in Figure a, the densities of forsterite coexisting with interstitial water are lower than that those of pure states. The decrease in density is attributed to the existence of a low-density layer of forsterite in the interface with water . Although the densities are almost constant without depending on d , the density of the crystal at d = 0.8 nm is slightly lower than the average.…”

“…The d values of the systems (i) with 1.0−6.0 nm at 10 K were 0.8−7.6 nm at 470 K. Figure 1 shows the snapshots of the systems (i) with d = 0.8, 3.1, and 7.6 nm and the systems (ii) with d = 0.8, 3.1, and 7.8 nm at 470 K. All snapshots here were drawn with VESTA. 19 To prepare the two-phase system of water and forsterite crystal (i.e., system i), a fundamental orthorhombic cell of the forsterite crystal consisting of 1176 Mg 2 SiO 4 in 294 unit cells 10 was used as the initial structure. The infinite (010) surface (i.e., the b plane in Figure 1) of the forsterite crystal with Mg as the outmost atoms was constructed by breaking Mg−O covalent bonds and applying the two-dimensional periodic boundary conditions.…”

“…The potential parameters used in the present study were listed in our previous paper. 10 The values were empirically determined by constraining the model to reproduce the experimental results of the density, thermal expansion coefficient, and bulk modulus for forsterite and ice in the crystal and amorphous states. 13−15 2.2.…”