UNLV physicists pioneered a new method of laser heating in a diamond anvil cell (shown here) as part of their discovery of a new form of ice. Credit: Chris Higgins NLV researchers have discovered a new form of ice that redefines the properties of water at high pressure. Solid water or ice, like many other materials, can form various solid materials under various conditions of temperature and pressure, for example: B. carbon forming diamond or graphite. However, water is an exception in this regard, as at least 20 solid forms of ice are known. A team of scientists working at UNLV’s Extreme Conditions Laboratory in Nevada has developed a new way to measure the properties of water under high pressure. The water sample was first sandwiched between the tips of two opposite diamonds and solidified into several mixed ice crystals. The ice was then subjected to laser heating, which temporarily melted it before quickly turning it back into a clump of tiny, powdery crystals. By gradually increasing the pressure and periodically irradiating the laser beam, the team observed the transition of water ice from the known cubic phase, Ice-VII, to the newly discovered intermediate and tetragonal phase, Ice-VII, before settling. in another known phase, Ice-X. Zach Grande, UNLV Ph.D. student, led the work, which also showed that as the water becomes aggressively steep, the transition to Ice-X occurs at much lower pressures than previously thought. While it’s unlikely we’ll find this new phase of ice anywhere on Earth’s surface, it’s most likely a common component of Earth’s mantle, as well as large moons and rich planets in waters outside our solar system. The group’s findings were published in the March 17, 2022 issue of the journal. Physical examination B. The research team has been working to understand the behavior of high-pressure water that could exist inside distant planets. To do this, Grande and UNLV physicist Ashkan Salamat placed a water sample between the tips of two round diamonds, known as diamond anvil cells, a standard feature in high-pressure physics. Applying a small force to the diamonds allowed the researchers to recreate a pressure as high as at the center of the Earth. By pressing a sample of water between these diamonds, the scientists arranged the oxygen and hydrogen atoms into various configurations, including the recently discovered Ice-VIIt configuration. The laser heating technique, the first of its kind, not only allowed scientists to observe a new phase of water ice, but the team also found that the transition to Ice-X occurred at a pressure nearly three times lower than previously thought, at 300,000 atmospheres. instead of 1 million This transition has been the subject of heated discussion in the community for several decades. “Zack’s work showed that this conversion to an ionic state occurs at a much lower pressure than previously thought,” Salamat said. “This is the missing piece and the most accurate measurement ever taken on the water in these conditions.” The work also redefines our understanding of exoplanet composition, Salamat added. The researchers speculate that the Ice VIIt phase may be abundant in the crust and upper mantle of expected water-rich planets outside our solar system, meaning they may have habitable conditions for life. Reference: “Symmetry Transitions Induced by H2O Pressure in Dense Ice”, Zachary M. Grande, C. Hai Pham, Dean Smith, John H. Boiswerth, Chenliang Huang, Jesse S. Smith, Nir Goldman, Jonathan L. Belof, Oliver Chauner by Jason H. Steffen and Ashkan Salamat, March 17, 2022 Physical examination B.The results could have implications for our understanding of distant water-rich planets.
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Researchers at Lawrence Livermore National Laboratory used a large supercomputer to model bond rearrangements and predicted that phase transitions should occur exactly where the experiments measured them.
Other collaborators include UNLV physicists Jason Steffen and John Boyswerth, UNLV mineralogist Oliver Chauner, and scientists from Argonne National Laboratory and the University of Arizona.
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