Effect of pressure on the ice XII to ice XIV phase transition

Water ice displays a remarkably complex phase diagram containing pairs of hydrogen-ordered / disordered phases. Ice XII is a hydrogen-disordered phase and ice XIV is its hydrogen-ordered counterpart, which was discovered by our group. A recent article has claimed that ice XIV can be fully hydrogen-ordered. However, this claim turned out to be the result of an integration error. In fact, only 60% ordering has been achieved so far. Following this, we have systematically explored the effect pressure has on the formation of ice XIV using in-situ pressure neutron diffraction. This has shown some remarkably complex and unexpected behaviour for deuterated ice. However, to really finish the ice XIV story, we now need to measure the corresponding protiated samples with neutron diffraction.

水冰（water ice）的相图（phase diagram）极为复杂，其中包含多组氢有序/氢无序相（hydrogen-ordered / disordered phases）。冰XII（ice XII）属于氢无序相（hydrogen-disordered phase），而冰XIV（ice XIV）是其对应的氢有序相（hydrogen-ordered counterpart），该相由我们研究团队首次发现。近期有一篇学术文章声称冰XIV可实现完全氢有序，但该结论实为积分误差（integration error）所致。事实上，截至目前仅实现了60%的氢有序化。在此之后，我们通过原位高压中子衍射（in-situ pressure neutron diffraction）系统探究了压力对冰XIV形成过程的影响，实验结果在氘代冰（deuterated ice）体系中展现出异常复杂且出乎意料的行为。然而，若要完整厘清冰XIV的相关研究全貌，我们还需利用中子衍射（neutron diffraction）对对应的氕代样品（protiated samples）开展测量工作。