Observation of a strange form of super-ionic hot ice
This material that was thought to be found only in the depths of Neptune and Uranus has been observed on Earth.
From left to right, in this artistic rendering, high-powered lasers are focused on the surface of a diamond, generating a sequence of shock waves propagating through a water sample, simultaneously compressing and heating the sample initially liquid and freezing it in superionic mode.
From the seas of Antarctica to the depths of your freezer, most of the ice on Earth is relatively tame by humans. But across the solar system and beyond, extreme temperatures and conditions can crush frozen stuff into bizarre varieties, to say the least.
Researchers recently took X-ray pictures of what may be the most recently discovered state of ice : a highly electrically conductive material called ice Observation of a strange form of super-ionic hot ice. As the research team reports today in the journal Nature , this ice has a pressure between one and four million times that of sea level and a temperature half as hot as the surface of the Sun.
“Yes, we are talking about ice,” says Marius Millot , study director and physicist at the Lawrence Livermore National Laboratory in California. “But the sample is several thousand degrees away. »
Although normally unobservable on Earth, such conditions are thought to be present on planets like Uranus and Neptune , which could help explain how these distant worlds work, including the origins of their unusual magnetic fields.
BEYOND SCIENCE FICTION
Scientists already know of 17 varieties of crystalline ice ( Kurt Vonnegut fans will be relieved to learn that Ice IX is relatively harmless compared to its fictional counterpart). More than 30 years ago, physicists already predicted that crushing pressure could cause water to Observation of a strange form of super-ionic hot ice.
The materials Observation of a strange form of super-ionic hot ice are twofold, both solid and liquid. At the microscopic level, we observe a crystal lattice impregnated with floating atomic nuclei that can carry an electrical charge. In water, or H2O, the oxygen atoms turned into a solidified crystal, while the hydrogen protons were in liquid form. (Recently, another team of scientists working on potassium confirmed the existence of both a solid and a liquid state of matter .)
"It's a pretty exotic state of matter," says co-author Federica Coppari, who also works at the Livermore lab.
In this image of an X-ray diffraction experiment, giant lasers are focused on the water sample, which rests on the faceplate of the diagnostic tool used to record diffraction patterns. Additional laser beams generate an X-ray on an iron sheet, allowing researchers to take a snapshot of the compressed and heated layer of water.
Last year, Millot, Coppari and their colleagues discovered the first evidence of ice Observation of a strange form of super-ionic hot ice, using laser-induced shock waves to compress liquid water to such an extent that it turned into solid ice for a few billionths of a second. The team's measurements showed that the ice had briefly become hundreds of times more conductive than it had been before, suggesting that it had become Observation of a strange form of super-ionic hot ice .
In their latest tests, the researchers used six giant laser beams to generate a sequence of shock waves that turned a thin layer of liquid water into solidified ice at millions of times the pressure of Earth's surface and between 3,000 and 5,000 degrees Fahrenheit. Perfectly timed X-ray flashes probed the configuration, which lasted only a few billionths of a second, and revealed that the oxygen atoms had indeed taken on a crystalline form.
The researchers found that the oxygen was concentrated in small, cube-like spaces, occupied by one atom at each corner and one in the center on each side. Coppari explains that this is the first time that solidified water has appeared in such a way. The team proposed to call this new formation Ice XVIII.
Although there was some overlap between the two experiments, further research will be needed to definitively prove that ice can be Observation of a strange form of super-ionic hot ice, as confirmed by Roberto Car , physicist from the Princeton University which did not take part in the work. Nevertheless, he considers the study to be an important illustration of the variability of water.
"The fact that matter can organize itself in such a variety of forms is quite amazing," he says.
MAGNETIC MYSTERIES
The team's results already tell us about the patterns of planets such as Uranus and Neptune. Often known as ice giants, these massive worlds are about 65% water, with added ammonia and methane forming layers similar to the surface, mantle, and terrestrial rocky core.
The new experiments indicate that Uranus and Neptune should have an ice sheet Observation of a strange form of super-ionic hot ice that acts as the mantle of our planet, made up of solid rock that always flows on extremely geological time scales long. And that could help explain why these planets have such peculiar magnetic fields.
The magnetic fields of Earth, Jupiter, and Saturn are thought to have been created by internal dynamics near their cores. The fields of these planets align quite closely with their axes, as if following magnetic bars through their center.
Neptune's magnetic field, on the other hand, appears to follow an inner bar that has drifted to one side, its ends emerging from points halfway the equator. Stranger still is Uranus, as if the same bar magnet flipped over, meaning its south pole juts out into the planet's northern hemisphere. The magnetic fields of the two ice giants are thought to be unstable.
Millot suggests that there could be a liquid layer at the upper edge of the ice sheet Observation of a strange super-ionic hot ice form of Uranus and Neptune, but that it is also a phase highly electrically conductive water. The magnetic fields of these planets could find their origin there, much closer to the surface than the magnetic fields of other worlds, which could explain their singularities. And since astronomers have discovered many exoplanets the size of Neptune and Uranus, the results of this research could potentially apply to regions very far from our solar system.
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