Structure and decompression melting of a novel, high-pressure nanoconfined 2-D ice
Molecular dynamics (MD) simulations of water confined in nanospaces between layers of talc (system composition Mg 3Si 4O 10(OH) 2 + 2H 2O) at 300 K and pressures of approximately 0.45 GPa show the presence of a novel 2-D ice structure, and the simulation results at lower pressures provide insight into the mechanisms of its decompression melting. Talc is hydrophobic at ambient pressure and temperature, but weak hydrogen bonding between the talc surface and the water molecules plays an important role in stabilizing the hydrated structure at high pressure. The simulation results suggest that experimentally accessible elevated pressures may cause formation of a wide range of previously unknown water structures in nanoconfinement. In the talc 2-D ice, each water molecule is coordinated by six Ob atoms of one basal siloxane sheet and three water molecules. The water molecules are arranged in a buckled hexagonal array in the a-b crystallographic plane with two sublayers along. Each H 2O molecule has four H-bonds, accepting one from the talc OH group and one from another water molecule and donating one to an Ob and one to another water molecule. In plan view, the molecules are arranged in six-member rings reflecting the substrate talc structure. Decompression melting occurs by migration of water molecules to interstitial sites in the centers of six-member rings and eventual formation of separate empty and water-filled regions. © 2005 American Chemical Society.
Publication Source (Journal or Book title)
Journal of Physical Chemistry B
Wang, J., Kalinichev, A., & Kirkpatrick, R. (2005). Structure and decompression melting of a novel, high-pressure nanoconfined 2-D ice. Journal of Physical Chemistry B, 109 (30), 14308-14313. https://doi.org/10.1021/jp045297s