During high-pressure experiments, researchers from the University of Nevada in Las Vegas (UNLV) have identified a completely new type of ice, which could notably exist in the bowels of our planet.
High pressure experiments
If the ice cubes you put in your glass are probably the shape of ice cream the most evocative, there are actually at least 20 different ones, characterized by unique crystal structures and appearing when water or ice is subjected to different combinations of temperatures and pressures.
In the context of work published in the journal Physical Review Bthe scientists of theUNLV have developed a new method for measuring the properties of water under high pressure. A water sample is first placed in a diamond anvil cell, where the intense pressure forces the oxygen and hydrogen atoms to arrange themselves differently. The resulting ice is then briefly struck by a laser so that it melts and refreezes into another form, similar to a powder of tiny crystals.
By testing different pressures, the researchers discovered an entirely new type of ice, constituting a transitional stage between two known forms. At around 5.1 gigapascalsice VIIhaving a cubic structure, turned into ice VIItconsisting of symmetrical tetragonal crystals, having then stabilized in ice X.
Potentially common ice on some exoplanets
Given the high pressure needed to produce it, the team says the ice VIIt could be common in the Earth’s mantle, that of other exoplanets, and even near the surface of water-rich worlds.
During these experiments, the team also discovered that X ice was forming under three times lower pressure than expected (about 300,000 times greater than that measured on the surface of our planet), calling into question the potential of habitability of certain extrasolar planets.