Water’s premelting state observed, blurring ice and liquid behavior

A research team from Tokyo University of Science has directly observed a novel “premelting” phase of water confined within nanoscale pores, using advanced nuclear magnetic resonance (NMR) spectroscopy. In this state, water molecules are simultaneously frozen in place yet rotate like a liquid, blurring the traditional distinction between solid and liquid phases. By studying heavy water (D₂O) inside 1.6-nanometer-wide channels of hexagonal rod-like crystals, the researchers identified a three-layered molecular structure where incompletely hydrogen-bonded water begins melting before the fully frozen ice structure melts, confirming the coexistence of solid-like and liquid-like behaviors during the premelting phase. This discovery provides new insights into the structural and dynamic properties of confined water, which behaves differently from bulk ice and liquid water. The premelting state features water molecules locked in solid positions but rotating at speeds comparable to liquid water, highlighting unique molecular mobility under confinement. Beyond advancing fundamental understanding, these findings have potential applications in developing novel