Researchers Create New Ice XXI Under Extreme Pressure and Microsecond Freeze
London-UK, December 12, 2025
New Ice XXI Emerges: Water Science Redefined by Extreme Conditions
A collaborative team of materials scientists from the UK and the US has achieved a breakthrough in fundamental chemistry, announcing the successful creation of New Ice XXI, an Entirely New Form of Water Ice never before observed in nature or the laboratory.
The discovery, which pushes the boundaries of our understanding of the most common substance on Earth, was achieved by subjecting ordinary water to Extreme Pressure—over 350,000 times atmospheric pressure—coupled with an ultra-rapid, Microsecond Freeze shockwave.
The resulting crystalline structure, officially designated Ice Phase XXI, is believed to be the densest form of ice yet synthesized in a laboratory setting.
The experiment was conducted using powerful diamond anvil cells and high-speed laser pulses, allowing the researchers to compress water into a super-dense liquid state before rapidly freezing it in less than a millionth of a second.
The resulting phase, New Ice XXI, exhibits a non-symmetrical, tetrahedral crystalline arrangement. Its density exceeds 1.8 \text{ g/cm}^3, significantly denser than standard Ice \text{I}_{\text{h}} (which is 0.9167 \text{ g/cm}^3).
This remarkable discovery adds a new chapter to the complex phase diagram of water, which now recognizes over 20 distinct crystalline and amorphous structures.
The finding has profound implications for planetary science, potentially shedding light on the interior composition of icy moons and distant exoplanets.
Headlines Points
Phase Discovery:
Researchers successfully created New Ice XXI, an Entirely New Form of Water Ice, officially designated Ice Phase XXI.
Extreme Conditions:
The ice was formed under Extreme Pressure (over 35 GPa) combined with an ultra-fast, Microsecond Freeze shockwave.
Record Density:
Ice XXI is believed to be the densest form of water ice ever synthesized, with a density exceeding 1.8 \text{ g/cm}^3.
Planetary Science Impact:
The discovery is crucial for modelling the interiors of icy moons like Europa and Ganymede and understanding the structure of water-rich exoplanets.
Revised Phase Diagram:
The finding necessitates a revision of the complex phase diagram of water, adding the 21st known crystalline structure.
A Crystal Structure Never Seen Before
Water’s phase behavior is notoriously complex. While regular ice (Ice \text{I}_{\text{h}}) is one of the few solids less dense than its liquid form—which is why ice floats—most high-pressure phases of ice are significantly denser.
The previous record for density was held by Ice X, which forms under conditions comparable to those found deep inside Jupiter. However, the unique, non-symmetrical lattice structure of New Ice XXI indicates that the extreme, dynamic conditions used to create it caused the water molecules to pack together in a way that kinetic barriers prevented in prior static pressure experiments.
To analyze the new material, the team utilized powerful synchrotron X-ray diffraction, which confirmed the existence of a unique, highly ordered, yet highly distorted crystalline arrangement.
The synthesis required maintaining Extreme Pressure while simultaneously pulling away the heat generated by the compression shockwave using an infrared laser, demonstrating a mastery of materials engineering under extreme, non-equilibrium thermodynamic conditions.
Implications for Planetary and Materials Science
The discovery of New Ice XXI is not just an academic novelty; it has direct relevance to planetary science. Icy moons in the outer solar system, such as Jupiter’s Europa and Saturn’s Ganymede, are believed to contain layers of high-pressure ice beneath their frozen crusts and sub-surface oceans.
Scientists must now factor in the possibility that phases like Ice XXI could exist deep within these planetary bodies, altering models of internal heat retention, convection, and potentially the stability of their liquid oceans, which are key targets in the search for extraterrestrial life.
Furthermore, the technique used—dynamic compression combined with a Microsecond Freeze—opens up a new avenue for materials science.
It allows researchers to bypass intermediate, lower-pressure phases and directly access high-density, highly ordered crystalline structures of other common liquids. This could revolutionize the creation of new materials with unique properties, utilizing rapid phase transitions under extreme conditions.
The existence of New Ice XXI proves that after centuries of study, the fundamental chemistry of water continues to hold startling secrets under the right—or in this case, the most extreme—conditions.
