An international team of physicists has confirmed the existence of a new hexagonal phase of superionic ice, generated under extreme pressures reaching 229 gigapascals—approximately 2.3 million times Earth’s atmospheric pressure—and laser-heated temperatures exceeding 2,000 degrees Celsius.
Diamond Anvil Cells and Synchrotron X-Ray Probes
Led by physicist Alexis Forestier of the French Alternative Energies and Energy Commission (CEA), researchers subjected microscopic water samples to immense physical stress inside diamond anvil cell devices. According to findings published in Physical Review Letters, the team simultaneously blasted the samples with infrared laser heating to hit conditions around 2,630 Kelvin, or roughly 2,357 degrees Celsius.
Trapped Between Solid Crystals and Flowing Liquid
Under these brutal conditions, standard vaporization is entirely suppressed. The molecules cannot break apart into gas. Instead, the matter forms a hybrid state of matter known as superionic ice.
In this phase, oxygen atoms lock into a rigid crystal lattice while hydrogen protons stream freely through the structure like a liquid.
Using tiny beams of synchrotron X-ray diffraction, the research team monitored the lattice restructuring in real time. They observed the structural transition shift into a hexagonally closed-packed (hcp) arrangement. Measurements confirmed that this hcp phase becomes the dominant, most stable structure at pressures topping 200 gigapascals and temperatures above 1,800 Kelvin.
Revising the Interior Mechanics of Ice Giants
This newly mapped phase changes how scientists model planetary interiors.
The mobile protons moving through the solid oxygen lattice generate high electrical conductivity. This internal dynamo effect directly influences planetary magnetic fields.
Uranus and Neptune possess notably strange magnetic fields that tilt sharply against their rotational axes and sit heavily offset from their planetary centers. If this newly isolated hexagonal ice phase exhibits distinct mechanical elasticity and conductivity profiles compared to previously studied cubic (fcc) variants, planetary scientists must fundamentally update current models of mantle convection and fluid circulation.
Closing the Gap Between Theory and Reality
The discovery has nothing to do with terrestrial ice found on Earth’s surface. It remains strictly bound to extreme laboratory setups and deep-space conditions.
