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Researchers synthesize the superconducting material at room temperature

Magnetic levitation

The goal of a new research led by Ranga Dias, assistant professor of mechanical engineering and physics and astronomy, is to develop superconducting materials at room temperature. Currently, extreme cold is required to achieve superconductivity, as demonstrated in this photo by Dias̵

7;s lab, where a magnet floats atop a liquid nitrogen-cooled superconductor. Credit: University of Rochester photo / J. Adam Fenster

By compressing simple molecular solids with hydrogen at extremely high pressures, engineers and physicists at the University of Rochester have, for the first time, created superconducting material at room temperature.

Featured as a cover story in the diary Nature, the work was conducted by the laboratory of Ranga Dias, assistant professor of physics and mechanical engineering.

Dias says that the development of superconducting materials – without electrical resistance and magnetic field ejection at room temperature – is the “Holy Grail” of condensed matter physics. Sought after for more than a century, these materials “can definitely change the world as we know it,” says Dias.

In setting the new record, Dias and his research team combined hydrogen with carbon and sulfur to synthesize photochemically simple organically-derived carbonaceous sulfur hydride in a diamond anvil cell, a research device used to examine minute quantities. of materials under extraordinarily high pressure.

The carbonaceous sulfur hydride showed superconductivity at approximately 58 degrees Fahrenheit and a pressure of approximately 39 million psi. This is the first time that superconducting material has been observed at room temperature.

“Due to the limitations of low temperatures, materials with such extraordinary properties have not completely transformed the world in the way many might have imagined. However, our discovery will break down these barriers and open the door to many potential applications, ”says Dias, who is also affiliated with the University’s High Energy Density Physics and Materials Science programs.

Applications include:

  • Electric grids that transmit electricity without the loss of up to 200 million megawatt hours (MWh) of energy that now occurs due to resistance in the wires.
  • A new way to push levitated trains and other forms of transport.
  • Medical imaging and scanning techniques such as magnetic resonance and magnetocardiography
  • Faster and more efficient electronics for digital logic and memory device technology.

“We live in a semiconductor company and with this type of technology, you can take society into a superconducting society where you’ll never need things like batteries again,” says Ashkan Salamat of the University of Nevada Las Vegas, co-author of the discovery. .

The amount of superconducting material created by the diamond anvil cells is measured in picoliters, about the size of a single inkjet particle.

The next challenge, says Dias, is to find ways to create superconducting materials at room temperature at lower pressures, so that they are economical to produce in larger volumes. Compared to the millions of pounds of pressure created in diamond anvil cells, the Earth’s atmospheric pressure at sea level is about 15 PSI.

Because the ambient temperature is important

First discovered in 1911, superconductivity gives materials two key properties. The electrical resistance vanishes. And any semblance of a magnetic field is expelled, due to a phenomenon called the Meissner effect. The magnetic field lines must pass around the superconducting material, making levitation of such materials possible, something that could be used for frictionless high-speed trains, known as magnetic levitation trains.

Powerful superconducting electromagnets are already critical components of maglav trains, magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) machines, particle accelerators and other advanced technologies, including the first quantum supercomputers.

But the superconducting materials used in devices usually only work at extremely low temperatures, lower than any natural temperature on Earth. This restriction makes them expensive to maintain and too expensive to extend to other potential applications. “The cost of keeping these materials at cryogenic temperatures is so high that you can’t really take full advantage of them,” says Dias.

Previously, the highest temperature for a superconducting material was reached last year in Mikhail Eremets’ laboratory at the Max Planck Institute for Chemistry in Mainz, Germany, and the Russell Hemley group at the University of Illinois at Chicago. That team reported superconductivity from -10 to 8 degrees Fahrenheit using lanthanum superhydride.

In recent years, researchers have also explored copper oxides and iron-based chemicals as potential candidates for high-temperature superconductors. However, hydrogen, the most abundant element in the universe, also offers a promising building block.

“To have a high temperature superconductor, you want stronger bonds and lighter elements. These are the two fundamental criteria, “says Dias.” Hydrogen is the lightest material and the hydrogen bond is one of the strongest.

“Solid metallic hydrogen is theorized to have a high Debye temperature and strong electron-phonon coupling, which is required for superconductivity at room temperature,” says Dias.

However, extraordinarily high pressures are needed just to bring pure hydrogen into a metallic state, which was first obtained in a laboratory in 2017 by Harvard University professor Isaac Silvera and Dias, then a postdoc in the laboratory of Silvera.

A “paradigm shift”

And so, Dias’s lab in Rochester pursued a “paradigm shift” in its approach, using hydrogen-rich materials as an alternative that mimic the elusive superconducting phase of pure hydrogen and can be metallized at much lower pressures.

First, the lab combined yttrium and hydrogen. The resulting yttrium superhydride showed superconductivity at what was then a record temperature of around 12 degrees Fahrenheit and a pressure of around 26 million pounds per square inch.

Subsequently the lab explored covalent hydrogen-rich organically derived materials.

This work led to carbonaceous sulfur hydride. “This presence of carbon is of paramount importance here,” the researchers report. Further “compositional tuning” of this combination of elements could be the key to achieving superconductivity at even higher temperatures, they add.

Reference: “Superconductivity at Room Temperature in a Carbonaceous Sulfur Hydride” by Elliot Snider, Nathan Dasenbrock-Gammon, Raymond McBride, Mathew Debessai, Hiranya Vindana, Kevin Vencatasamy, Keith V. Lawler, Ashkan Salamat and Ranga P. Dias, October 14 2020, Nature.
DOI: 10.1038 / s41586-020-2801-z

Other co-authors on the article include lead author Elliot Snider ’19 (MS), Nathan Dasenbrock-Gammon ’18 (MA), Raymond McBride ’20 (MS), Kevin Vencatasamy ’21, and Hiranya Vindana (MS), all Dias laboratory; Mathew Debessai (Ph.D) of Intel Corporation and Keith Lawlor (Ph.D) of the University of Nevada Las Vegas.

The project was supported with funding from the National Science Foundation and the US Department of Energy’s Academic Inventory Management Alliance Program and its Office of Science, Fusion Energy Sciences. The preparation of the diamond surfaces was performed in part at the Integrated Nanosystems Center (URnano) of the University of Rochester.

Dias and Salamat have started a new company, Unearthly Materials to find a path to room temperature superconductors that can be scalable at room pressure.

I am patent pending. Anyone interested in licensing the technology can contact Curtis Broadbent, licensing manager at URVentures.

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