Suppressive Crystallization of Water Confined in Hydrophobic Sub-nanometer Pores under Multi-GPa-Range High Pressures

Water in nanospaces exhibits unique physical properties which are different from those of bulk water. In this study, we focused on the phase behavior of the confined water within activated carbon pores under high pressure (< 7 GPa) by performing in-situ X-ray scattering measurements using a diamond anvil cell. The results reveal that the confined water densifies continuously under compression, and does not crystallize even at the phase transition pressure (∼ 2 GPa) at which water transforms high-pressure ice-VII in bulk.