Researchers in the United States have detected an unexpected structural change in water ice subjected to crushing pressure, offering a rare experimental look at how an everyday substance may behave deep inside distant planets.
In a study published October 15, 2026, in the peer-reviewed journal Communications Chemistry, scientists led by the University of Nevada, Las Vegas (UNLV), with collaborators at the University of California, Berkeley, and Argonne National Laboratory, reported that highly compressed ice loses its familiar cubic symmetry above about 222 gigapascals. That is roughly 2.2 million times the atmospheric pressure at Earth’s surface.
The observation challenges the straightforward expectation that increasing compression always produces simpler and more symmetrical atomic arrangements. It also contributes evidence for scientists working to understand materials under the extraordinary conditions inside Uranus, Neptune and other planets.
How a diamond-anvil cell compresses water
The team trapped a minute water sample between the opposing tips of two diamonds in an instrument called a diamond-anvil cell. The device concentrates force into a tiny area, reaching pressures far beyond anything found in ordinary laboratories or daily life.
At these pressures, the sample is not liquid water as we know it: it is a high-pressure crystalline form of ice. Researchers examined the compressed material using powerful X-rays and measured how the X-rays scattered. The resulting diffraction patterns revealed the arrangement of oxygen atoms inside the crystal.
The DOE photograph selected for this article shows Argonne scientist Karena Chapman examining a diamond-anvil pressure cell in a separate 2008 research project. It documents the actual technology, not the water experiment published in 2026.
What changed inside the ice?
The researchers focused on ice-X, a form of ice found only under extreme pressure. Above approximately 222 gigapascals, the experimental evidence indicated that its crystal lattice began departing from cubic symmetry.
The X-ray data are consistent with more than one possible less-symmetrical arrangement. Computational calculations strongly favored a structure known to crystallographers as Pbcm, but the team did not claim every detail of a new, stable ice phase was conclusively established.
This matters because a change in atomic arrangement can alter a material’s density and other properties. Scientists need reliable descriptions of high-pressure water to make sense of planetary interiors and to test models based on distant measurements.
The experiment connects to an older scientific instrument
Diamond-anvil equipment has been used for decades to study how matter responds to enormous forces. A historical instrument from the National Bureau of Standards, now the National Institute of Standards and Technology (NIST), illustrates how two gem-cut diamonds are positioned to compress a tiny sample. That apparatus predates the latest discovery and is not the machine used by the UNLV researchers.
What the discovery means for Uranus and Neptune
Researchers investigate high-pressure ice because water-rich mixtures may be important in the interiors of the solar system’s ice giants. Their density, heat transport and electrical behavior can affect models of planetary structure and magnetic fields.
However, this experiment reproduced extreme pressure, not the full combination of pressure and temperature found inside Uranus or Neptune. Scientists cannot yet say that this precise structure is widespread inside either planet, or that it directly explains their magnetic fields.
The research is therefore a valuable experimental constraint, not a completed map of an alien world’s interior.
A separate 2026 study offers another piece of the puzzle
A second team reported a related high-pressure transition in Nature Materials on September 7, 2026. Using diamond-anvil experiments, X-ray diffraction and Raman spectroscopy, those researchers observed a transition to a crystal form called ice XXII above about 308 gigapascals.
The two studies do not establish identical transition thresholds. Their results contribute to a developing picture of how ice-X changes as pressure rises, and further work will be needed to reconcile the measurements and structural interpretations.
What happens next?
Additional high-pressure experiments, temperature-controlled measurements and theoretical models can test the proposed structures and determine their implications for planetary science.
For now, the verified finding is both important and specific: under extraordinary compression, solid water displayed a loss of crystal symmetry in a laboratory experiment. It does not mean ordinary water has acquired a new property or that researchers have reproduced the full interior of Neptune.
Sources and image records
- Salamat et al., “Evidence for symmetry-reduction in solid H2O above 222 GPa,” Communications Chemistry (October 15, 2026).
- University of Nevada, Las Vegas, official research announcement (October 20, 2026).
- Osmond et al., “Ultrahigh pressure phase transition in ice,” Nature Materials (September 7, 2026).
- ScienceAlert news coverage (November 5, 2026).
- DOE featured-image licensing and archival identification — public domain, 2008.
- NIST inline-image licensing and archival identification — public domain, credit: National Institute of Standards and Technology Digital Collections, Gaithersburg, MD 20899.
