冰在低温下压缩时没有无形形态
Chris A Tulk1, Jamie J Molaison2, Adam R Makhluf3
1Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN, USA. tulkca@ornl.gov.
Nature
|May 24, 2019
概括
压缩动力学影响无形冰的形成. 冰I在100K的缓慢压缩产生晶体相,而不是高密度无形冰 (HDA),挑战了无形冰的两液体水模型.
科学领域:
- 材料科学
- 物理化学
- 凝聚物质物理学
背景情况:
- 无形水冰存在多种形式,缺乏晶体秩序.
- 高密度无形冰 (HDA) 以前被认为是玻璃状,影响了超冷水异常的双液体水模型.
- 其他理论认为HDA是由于机械不稳定性和运动缓慢而形成的.
研究的目的:
- 研究动力学在无形冰相形成中的作用.
- 挑战现有的理论, 将无形冰与超冷液体水联系起来.
- 在不同的动力条件下探索冰的压缩路径.
主要方法:
- 在控制的,缓慢的运动条件下,冰的压缩I在100克尔文.
- 缓慢与快速压缩协议的结果比较.
- 由此产生的冰相的结构分析,包括质子排序和相互透.
主要成果:
- 冰I在100K的缓慢压缩产生了结晶阶段:冰IX',冰XV'和冰VIII'.
- 100K的快速压缩产生了高密度无形冰 (HDA),而不是冰IX'.
- 发现冰I直接转化为冰XV'在结构上受到抑制.
结论:
- 无形冰形成是低密度冰I和高密度冰XV'之间的动态停止转变.
- 这项研究挑战了无形冰相与超冷水的双液体模型之间的联系.
- 动力学,而不是热力学化,对于确定无形与晶体冰结构的形成至关重要.
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