Koga K, Tanaka H, Zeng X C
Department of Chemistry, Fukuoka University of Education, Japan.
Nature. 2000 Nov 30;408(6812):564-7. doi: 10.1038/35046035.
Supercooled water and amorphous ice have a rich metastable phase behaviour. In addition to transitions between high- and low-density amorphous solids, and between high- and low-density liquids, a fragile-to-strong liquid transition has recently been proposed, and supported by evidence from the behaviour of deeply supercooled bilayer water confined in hydrophilic slit pores. Here we report evidence from molecular dynamics simulations for another type of first-order phase transition--a liquid-to-bilayer amorphous transition--above the freezing temperature of bulk water at atmospheric pressure. This transition occurs only when water is confined in a hydrophobic slit pore with a width of less than one nanometre. On cooling, the confined water, which has an imperfect random hydrogen-bonded network, transforms into a bilayer amorphous phase with a perfect network (owing to the formation of various hydrogen-bonded polygons) but no long-range order. The transition shares some characteristics with those observed in tetrahedrally coordinated substances such as liquid silicon, liquid carbon and liquid phosphorus.
过冷水和非晶冰具有丰富的亚稳相行为。除了高密度和低密度非晶态固体之间以及高密度和低密度液体之间的转变外，最近还提出了一种从脆性液体到强液体的转变，并得到了在亲水性狭缝孔中深度过冷的双层水行为证据的支持。在此，我们报告分子动力学模拟的证据，表明在大气压下高于 bulk 水的冻结温度时存在另一种一级相变——从液体到双层非晶态的转变。这种转变仅在水被限制在宽度小于一纳米的疏水性狭缝孔中时发生。冷却时，具有不完美随机氢键网络的受限水转变为具有完美网络（由于形成了各种氢键多边形）但无长程有序的双层非晶相。该转变与在四面体配位物质（如液态硅、液态碳和液态磷）中观察到的转变具有一些共同特征。
