To better understand the physics of materials under high pressure and therefore the interior of planets, and now exoplanets, physicists have for decades been refining techniques to go well beyond atmospheric pressure. They passed the threshold of two million atmospheres, even reaching almost 10 million atmospheres for the first time, as in the center of the planet Uranus.
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[EN VIDÉO] Uranus, the first planet discovered by telescope Discover Uranus, an ice giant located three billion kilometers from Earth. A cold and strange mode of which we are just beginning to understand its history and its composition.
A research team from the University of Bayreuth, in collaboration with international partners, has just announced via an article published in the prestigious journal Nature that she had broken a record in the field of physical tall pressures. The physicists have thus for the first time begun to explore the territory of the behavior of the matter in the center ofstarsas Uranus in the Solar systemor some super-earths in the kingdom of exoplanets, almost reaching in the laboratory the pressure of a terapascal, or 1,000 gigapascals. For the record, the Earth’s atmosphere is at an average pressure of about 100,000 pascals, so one terapascal is about 1012 Pa, or about 10 millionatmospheres !
” The method we have developed allows us for the first time to synthesize new material structures in the terapascal range and analyze them in situ — that is, while the experiment is still in progress. In this way, we discover previously unknown states, properties and structures of crystals and we can significantly deepen our understanding of matter in general. Valuable information can be acquired for the exploration of telluric planets and the synthesis of functional materials used in innovative technologies “, explains in a press release the physicist Leonid Dubrovinsky of the Bavarian Geoinstitute (BGI) of the University of Bayreuth, first author of the publication.
From Bridgman to Dubrovinsky
These results are undoubtedly part of the trajectory opened a long time ago by the Nobel Prize in Physics Percy Williams Bridgmanand especially to his pupil Francis Birch who, in 1952, demonstrated that the coat of the Earth is mainly composed of silicatesand that our Planet also has an outer core liquid and an inner core solidboth consisting of iron.
Indeed, Bridgman was one of the pioneers of high pressure physics that we find at great depth, in the mantle or in the heart of the Earth, even in the center of giant planets as Jupiter. For this, he invented and developed the technique for subjecting samples of matter to pressures exceeding 100,000 atmospheres by means of diamond anvil cells.
To recreate the conditions prevailing in the depths of the planets, samples of matter can be placed between the tips of two diamonds. The diamonds are then pressed against each other to produce very high pressures. An infrared laser beam can then heat the sample up to 1,000°C and more. Translation into French by clicking on the white rectangle at the bottom right, then on the nut, then on “Subtitles” and “Translate automatically”. © Carnegie Science
The physics of high pressures as found inside giant planets has been the subject of work that has been in the news regularly for a decade. This is due in particular to the fact that we have developed algorithms that can be implemented on computers powerful enough to be able to predict the existence of new materials with new structures, such as the algorithm named Uspex (Universal Structure Predictor: Evolutionary Xtallography) developed by the great Russian physicist and crystallographer Artem Oganovbut also new technologies and methods to do ever more extreme experiments in the laboratory like those exposed in Nature by Leonid Dubrovinsky and colleagues, edited by Natalia Dubrovinskaiafrom the Laboratory of Crystallography from the University of Bayreuth. The researcher is famous for obtaining a material made of boron nitride almost as hard as diamond.
Today, by exceeding 10 million atmospheres, it is a new nitride of rhenium (Re₇N₃) and a alloy rhenium-nitrogen which were obtained as bonuses. Their crystalline structure has been characterized by experiments of diffraction of X-rays.
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