Kinetics of the ordering transition in ice Ih; crystal structure and thermal expansion of ice XI

Below 80 K ordinary water ice (ice Ih) undergoes a phase transition in which the randomly oriented molecules in the crystal adopt an ordered orientation. This ordered form of ice is known as ice XI. In pure ice, the transition is expected to require ~ 100 kyr to complete. In planetary environments, such as the outer solar system, time is no issue, so it is likely that ice XI is very abundant in space. However, the transformation can be sped up with a molecular 'lubricant', such as KOH, which at low concentrations acts to catalyse the ice Ih to ice XI reaction. Even so, on the timescales of typical neutron diffraction studies, the transformation usually around half complete after 5 days. I propose a long-duration experiment (1-2 months) to prepare the most completely transformed ice XI specimen, which is essential for accurate characterisation of the structure and properties.

当温度低于80开尔文时，普通水冰（ice Ih）会发生相变，其晶体内部原本随机取向的水分子将呈现有序排列。这种有序态的冰被称为冰XI（ice XI）。在纯冰体系中，该相变的完全完成预计需要约10万年。在诸如外太阳系的行星环境中，时间并非限制条件，因此冰XI在宇宙中可能分布极为广泛。不过，可通过添加分子‘润滑剂’加速该相变过程，例如氢氧化钾（KOH）：在低浓度下，它可催化冰Ih向冰XI的相变反应。即便如此，在典型的中子衍射（neutron diffraction）研究的时间尺度下，该相变通常在5天后仅完成约一半。我提议开展一项为期1至2个月的长期实验，以制备相变完成度最高的冰XI样品，这对于精准表征其结构与物理性质至关重要。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于冰Ih向冰XI的相变动力学，以及冰XI的晶体结构和热膨胀性质。它通过长期中子衍射实验（使用HRPD仪器），在催化条件下加速相变过程，旨在制备完全转化的冰XI样本，以提供精确的结构和性质表征。数据集来自ISIS中子与μ子源，包含多个数据发布条目，适用于冰相变和行星科学领域的研究。