Hydrostatic equation of state of H₂O and D₂O ices up to 120 GPa in helium.

The equation of state (EOS) of H₂O ice at high pressure is of utmost importance in high-pressure science, as ice is an archetypal H-bonded system and a key component of giant planetary interiors. To date, all ice EOS were measured without pressure-transmitting medium (PTM). This approach has led to significant deviatoric stresses in ice crystals, resulting in large dispersion of data points and anomalies in the measured compression curves. In this proposal, we aim to accurately measure the EOS of H₂O and D₂O ice crystals embedded in helium, allowing for the most hydrostatic compression possible. Studying H₂O and D₂O single-crystals under quasi-hydrostatic compression within helium will enable to better constrain the intrinsic EOS, shed light on the symmetrization mechanism to ice X, and elucidate the role of quantum effects for comparison with calculations. This proposal leverage on our recently developped loading technique of H₂O in helium.

高压下水冰的状态方程（Equation of State, EOS）在高压科学领域具有至关重要的意义，这是因为冰是典型的氢键缔合体系，同时也是巨型行星内部的关键组成成分。迄今为止，所有已测得的冰态状态方程均未采用传压介质（pressure-transmitting medium, PTM）。这种未使用传压介质的测量方案会在冰晶体中引发显著的偏应力，进而导致实验数据点离散度偏高，且实测压缩曲线出现异常。在本项目申请中，我们旨在精准测量封装于氦气中的H₂O与D₂O冰晶体的状态方程，以实现最接近理想状态的静水压压缩环境。通过研究氦气环境下H₂O与D₂O单晶的准静水压压缩行为，我们能够更精准地限定本征状态方程，揭示冰X相（ice X）的对称化机制，并厘清量子效应的作用规律，以便与理论计算结果开展对比验证。本项目将依托我们近期开发的将H₂O封装于氦气中的样品加载技术。