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| - Structure and Decompression Melting of a Novel, High-Pressure Nanoconfined 2-D Ice
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| - Molecular dynamics (MD) simulations of water confined in nanospaces between layers of talc (systemcomposition Mg3Si4O10(OH)2 + 2H2O) at 300 K and pressures of approximately 0.45 GPa show the presenceof a novel 2-D ice structure, and the simulation results at lower pressures provide insight into the mechanismsof its decompression melting. Talc is hydrophobic at ambient pressure and temperature, but weak hydrogenbonding between the talc surface and the water molecules plays an important role in stabilizing the hydratedstructure at high pressure. The simulation results suggest that experimentally accessible elevated pressuresmay cause formation of a wide range of previously unknown water structures in nanoconfinement. In the talc2-D ice, each water molecule is coordinated by six Ob atoms of one basal siloxane sheet and three watermolecules. The water molecules are arranged in a buckled hexagonal array in the a−b crystallographic planewith two sublayers along [001]. Each H2O molecule has four H-bonds, accepting one from the talc OH groupand one from another water molecule and donating one to an Ob and one to another water molecule. In planview, the molecules are arranged in six-member rings reflecting the substrate talc structure. Decompressionmelting occurs by migration of water molecules to interstitial sites in the centers of six-member rings andeventual formation of separate empty and water-filled regions.
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