The structure of a new phase of ice
The structure of a new phase of ice
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作者：
Lobban, C;Finney, JL;Kuhs, WF
冰有十一种已知的晶相（图1），其中水分子通过氢键连接成四面体框架（1）。这种不寻常的大量不同的固相证明了水分子的结构多样性，在这里，我们报告了一个新的，第十二阶段的结晶冰的压力范围为0.2-0.6 GPa的识别。这个相的拓扑结构不同于任何已知的相，并且包含水分子的五元环和七元环的混合物。它有一个类似的冰IV的密度，这也发生在这个压力范围内的稳定区域的冰V.这两个阶段都可能是亚稳态相对于密度较小的冰V.该区域的水相图，从而提供了一个潜在的模型系统的亚稳态的实验和理论研究。
Ice has eleven known crystalline phases (Fig. 1), in which the water molecules are linked through hydrogen bonds into tetrahedral frameworks(1). This uncommonly large number of different solid phases attests to the structural versatility of the water molecule, Here we report the identification of a new, twelfth phase of crystalline ice in the pressure range 0.2-0.6 GPa. The topology of this phase is unlike that of any of the known phases, and contains a mixture of five-and seven-membered rings of water molecules. It has a density similar to that of ice IV, which also occurs in this pressure range within the stability region of ice V. Both phases are likely to be metastable with respect to the less-dense ice V. This region of the water phase diagram thus provides a potential model system for experimental and theoretical studies of metastability.