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Scientists at the University of Chicago are part of an international research team that discovered superconductivity – the ability to conduct electricity perfectly – at the highest temperatures ever recorded.
With the help of advanced technology from Argonne National Laboratory, affiliated with UChicago, the team studied a class of materials in which it observed superconductivity at temperatures of about 23 degrees Celsius (minus 9 degrees Fahrenheit), a jump of about 50 degrees compared to previous confirmed record.
Although superconductivity has occurred under extremely high pressure, the result still represents a major step forward in the creation of room temperature superconductivity – the ultimate goal of scientists being to be able to use this phenomenon for advanced technologies. The results were published on May 23 in the journal Nature; Vitali Prakapenka, a research professor at the University of Chicago, and Eran Greenberg, a postdoctoral researcher at the University of Chicago, are co-authors of the research.
Just as a copper wire conducts electricity better than a rubber tube, some types of materials are more apt to become superconductors, a state defined by two main properties: The material provides zero resistance to electrical current and can not be penetrated by magnetic fields. Potential uses are as vast as they are exciting: electrical wires with decreasing currents, extremely fast supercomputers and efficient magnetic levitation trains.
But scientists had previously been able to create superconducting materials only when they were cooled to extremely cold temperatures: at first, it was minus 240 degrees Celsius and more recently at minus 73 degrees Celsius. Since this cooling is expensive, its applications are limited worldwide.
Recent theoretical predictions have shown that a new class of materials based on superconducting hydrides could pave the way for higher temperature superconductivity. Researchers at the Max Planck Institute of Chemistry in Germany have teamed up with researchers at the University of Chicago to create one of these materials, lanthanum superhydrides, to test their superconductivity and determine its structure and structure. composition.
The only problem was that the material had to be subjected to extremely high pressure – between 150 and 170 gigapascals, or more than a million and a half of the pressure at sea level. That's only in these High pressure conditions that the material – a tiny sample of only a few microns – exhibited superconductivity at the new record temperature.
In fact, the material had three of the four characteristics necessary to prove superconductivity: it lost its electrical resistance, decreased its critical temperature under an external magnetic field and showed a change of temperature when certain elements were replaced by different isotopes. The fourth characteristic, called the Meissner effect, in which the material expels any magnetic field, has not been detected. This is because the material is so small that this effect could not be observed, researchers said.
They used the advanced photon source of the Argonne National Laboratory, which provides ultra-bright and high-energy X-ray beams that have made breakthroughs in many areas, from the best batteries to understanding the 39 deep inside the Earth, to analyze the material. As part of the experiment, researchers at the Center for Advanced Radiation Sources at the University of Chicago pressed a small sample of the material between two tiny diamonds to exert the necessary pressure and then used the X-rays of the beam line to probe its structure and composition.
Since the temperatures used to conduct the experiment are in the normal range of many places in the world, the ultimate goal of ambient temperature – ie, at least 0 ° C – seems within our reach.
The team is already pursuing its collaboration to find new materials capable of creating superconductivity under more reasonable conditions.
"Our next goal is to reduce the pressure needed to synthesize samples, bring the critical temperature closer to room temperature, and perhaps even create samples that can be synthesized at high pressures, but still superconducting at normal pressures." said Prakapenka. "We continue to search for new and interesting compounds that will bring us new discoveries, often unexpected."
Source of the story:
Material provided by University of Chicago. Original written by Emily Ayshford. Note: Content can be changed for style and length.
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