PRESSURE-INDUCED PHASE-TRANSITIONS IN CLATHRATE HYDRATES
PRESSURE-INDUCED PHASE-TRANSITIONS IN CLATHRATE HYDRATES
复制标题
DOI：
10.1063/1.460329
复制
发表时间：
1991-01-01
影响因子：
4.4
通讯作者：
WHALLEY, E
中科院分区：
文献类型：
--
作者：
HANDA, YP;TSE, JS;WHALLEY, E
当在 77 K 下加压至 10 kbar 时，Ice I 转变为高密度非晶相。通过在活塞缸装置中压制样品并通过分子动力学模拟，研究了结构 I 和结构 II 笼形水合物的类似转变。 还对结构 I 和 II 空晶格进行了模拟。 发现水合物和空晶格在 77 K 压力下转变为高密度相。空晶格的高密度相可以在零压力下恢复，就像冰的高密度非晶相的情况一样。 然而，不可能在零压力下回收水合物的高密度相。 相反，当压力释放时，它们恢复到原来的晶体结构。 分子动力学结果表明，在压力下，水合物中的水分子在客体分子周围塌陷，客体和水分子之间的排斥力主要是在压力释放时向原始结构可逆转变的原因。
Ice I transforms to a high-density amorphous phase when pressed to 10 kbar at 77 K. Similar transformations in structure I and structure II clathrate hydrates have been studied by pressing samples in a piston-cylinder apparatus and by molecular dynamics simulations. The simulations were also carried out on structure I and II empty lattices. The hydrates and the empty lattices were found to transform to high-density phases under pressure at 77 K. The high-density phases of the empty lattices could be recovered at zero pressure, as is possible in the case of high-density amorphous phase of ice. However, it was not possible to recover the high-density phases of the hydrates at zero pressure. Instead, they reverted back to their original crystalline structures when the pressure was released. The molecular dynamics results suggest that under pressure the water molecules in the hydrates collapse around the guest molecules, and the repulsive forces between the guest and the water molecules are mainly responsible for the reversible transition to the original structure when the pressure is released.