Like the relationship between diamond and graphite, ice has several different crystal structures, even though it has the same chemical composition.Among them, in high-pressure ice called Ice III, which is formed by freezing water due to low temperature and high pressure, we have discovered a previously unknown layer of "new water" at the interface with water.

　This research group produces high-pressure ice in water by applying pressure to water using an anvil-type high-pressure generator, and polarizes the process of growth and melting of ice III induced by pressurization and depressurization of water. It is said that it was observed on the spot using a microscope.Then, it was found that a liquid having a fluidity different from that of the surrounding water was formed at the interface of ice III that grows under pressure and the interface of ice III that melts under reduced pressure.

　From the wettability and surface pattern on the ice surface, this "new water" was presumed to be a liquid with a different structure, which has a higher density than normal water and is immiscible with normal water.In the past, it was thought that the structure of water changed continuously from ice to water at the water / ice interface, but in this study, we overturned that myth, and the surface of ice has normal water and structure. Direct observations showed that different "new waters" existed forming distinct interfaces.

　This result paves the way for the verification of the hypothesis that "the existence of water has a structure different from that of water that we know", which has been discussed for a long time to explain the peculiar physical properties of water. It is expected to contribute to elucidation and elucidation of natural phenomena related to water.

Paper information:[The Journal of Physical Chemistry Letters] High-Density Liquid Water at a Water–Ice Interface