HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA.
Nat Commun. 2017 Jan 23;8:14260. doi: 10.1038/ncomms14260.
A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid-solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure-temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought.
亚稳液相可能在过冷状态下存在，使液体维持在熔点以下，如过冷水和硅。它也可能作为固态-固态转变的瞬态存在，如最近对胶体颗粒和玻璃形成金属系统的研究所示。一个重要的问题是，晶体固体是否可以直接熔化成可持续的亚稳液体。通过热加热，晶体固体总是会在熔点以上熔化成液体。在这里，我们报告说，通过减压过程，铋的高压晶相可以在熔点线以下熔化成亚稳液体。在静态条件下，减压诱导的亚稳液体可以维持数小时，并且当施加外部干扰（如加热和冷却）时，它会转变成晶体相。它发生在类似于观察到过冷液体 Bi 的压力-温度区域。类似于过冷液体，压力诱导的亚稳液体可能比我们想象的更为普遍。
