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.