May 22, 2022

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They may be common on distant, water-rich planets.

They may be common on distant, water-rich planets.

The findings could have implications for our understanding of distant, water-rich planets.

NLV researchers have discovered a new form of ice, redefining the properties of high-pressure water.

Solid water, or ice, is like many other substances in that it can form different solids based on changing conditions of temperature and pressure, such as the formation of carbon from diamond or graphite. However, water is exceptional in this respect, as we know of at least 20 solid forms of ice.

A team of scientists working at the UNLV Extreme Conditions Laboratory in Nevada has devised a new method for measuring the properties of high-pressure water. The water sample was first squeezed between opposite ends of the diamond and frozen into several mixed ice crystals. The ice was then subjected to a laser heating technique that caused it to temporarily melt before rapidly re-forming into a group of tiny micro-crystals.

By gradually increasing the pressure and releasing it periodically with a laser beam, the team observed that water ice had transitioned from the familiar cubic phase, Ice-VII, to the newly discovered intermediate and quadrupole phase, Ice-VIIt, before settling. to another well-known stage, Ice-X.

Zach Grande, Ph.D. at UNLV. Taleb, who led work that also showed that the transition to Ice-X, when water solidifies, occurs at much lower pressures than previously thought.

While it is unlikely that we will find this new phase of ice anywhere on Earth, it is likely to be a common component within the Earth’s mantle, as well as on large moons and water-rich planets outside our solar system.

The team’s results were announced in the March 17, 2022 issue of the magazine. physical examination b.

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The research team has been working to understand the behavior of high-pressure water that may be present in the interiors of distant planets.

To do this, Grandi and UNLV physicist Ashkan Salameh placed a sample of water between the ends of two circular-cut diamonds known as diamond anvil cells, a standard feature in the field of high-pressure physics. Applying a little force to the diamond allowed the researchers to recreate pressures as high as those at the center of the Earth.

By compressing a sample of water between these diamonds, the scientists arranged the oxygen and hydrogen atoms in a variety of different arrangements, including the newly discovered arrangement, Ice-VIIt.

Not only did the first-of-its-kind laser heating technique allow scientists to observe a new phase of water ice, the team also found that the transition to Ice-X occurred at pressures nearly three times lower than previously thought: 300,000 atmospheres instead of 1 million. This transition has been a hotly debated topic in society for several decades.

“Zach’s work showed that this transition to the ionic state occurs at much lower pressures than previously thought,” Salamat said. “It’s the missing piece and the most accurate measurement on the water in these conditions.”

Salamat added that the work is also working to reset our understanding of the formation of exoplanets. The researchers hypothesize that the Ice-VIIt phase could be found abundantly in the crust and upper mantle of water-rich planets projected outside our solar system, meaning it could have habitable conditions.

Reference: “Pressure-driven symmetry transitions in dense HtwoO ice” by Zachary M. Grande, Si Hoy Pham, Dean Smith, John H. Boisfert, Qinliang Huang, and Jesse S. Mar 17, 2022 Available here physical examination b.
DOI: 10.1103/ PhysRevB.105.104109

Collaborators at Lawrence Livermore National Laboratory used a large supercomputer to simulate bond rearrangements, and they predicted that the phase shifts should occur exactly where they were measured by experiments.

Additional collaborators include UNLV physicists Jason Stephen and John Boasvert, UNLV mineralogist Oliver Chuner, and scientists from Argonne National Laboratory and the University of Arizona.

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