KRISS Team Identifies Ice XXI, a New Room-Temperature High-Pressure Phase of Water

Overview

• Experiments pushed water above 2 gigapascals at room temperature, producing a supercompressed liquid before it crystallized.
• The KRISS-built dynamic diamond anvil cell shortened pressure ramps to about 10 milliseconds, reducing nucleation artifacts seen in conventional cells.
• Microsecond-resolution measurements at the European XFEL recorded multiple freezing–melting routes that culminated in Ice XXI.
• Structural analysis found an unusually large unit cell with a flattened rectangular geometry, distinguishing Ice XXI from known ice phases.
• The peer-reviewed work, led by KRISS with 33 collaborators and support from European XFEL and DESY, was published in Nature Materials in October and suggests relevance to high-pressure ice layers inside icy moons.