Researchers synthesize superconducting material at room temperature

Engineers and physicists at the University of Rochester have compressed simple molecular solids with hydrogen at extremely high pressures and, for the first time, created material that is superconducting at room temperature.

Listed as the cover story in the diary natureThe work was carried out by the laboratory of Ranga Dias, an assistant professor of physics and mechanical engineering.

According to Dias, the development of superconducting materials – without electrical resistance and emission of the magnetic field at room temperature – is the “holy grail” of condensed matter physics. Searched for more than a century, such materials can “definitely change the world as we know it,” says Dias.

To set the new record, Dias and his research team combined hydrogen with carbon and sulfur to photochemically synthesize simple carbon-containing sulfur hydride from organic production in a diamond anvil cell, a research device used to study tiny amounts of material under extremely high pressure.

The carbonaceous sulfur hydride showed superconductivity at about 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 limits of low temperatures, materials with such extraordinary properties have not changed the world in the way many imagined. However, our discovery will break down those barriers and open the door to many potential applications, ”says Dias, who is also involved in the university’s materials science and high-energy physics programs.

Applications include:

• Power grids that transmit electricity without losing up to 200 million megawatt hours (MWh) of energy that is now created due to the resistance in the wires.
• A new way to power floating trains and other means of transport.
• Medical imaging and scanning techniques such as MRI and magnetocardiography
• Faster, more efficient electronics for digital logic and storage device technology.

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

The amount of superconducting material produced by the diamond anvil cells is measured in picoliters – roughly the size of a single inkjet particle.

The next challenge, says Dias, is to find ways to produce the superconducting materials at room temperature at lower pressures so that they can be economically produced 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.

Why room temperature is important

Superconductivity was first discovered in 1911 and gives materials two key properties. The electrical resistance disappears. And any semblance of a magnetic field is expelled due to a phenomenon called the Meissner effect. The magnetic field lines must run around the superconducting material, which makes it possible to levitate such materials, which could be used for smooth high-speed trains, so-called magnetic levitation trains.

Powerful superconducting electromagnets are already important parts of Maglav trains, magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) machines, particle accelerators, and other advanced technologies, including early quantum supercomputers.

However, the superconducting materials used in the devices usually only work at extremely low temperatures – lower than all natural temperatures on earth. This limitation makes it costly to maintain – and too costly to extend to other potential applications. “The cost of keeping these materials at cryogenic temperatures is so high that you can’t really get the full benefit from them,” says Dias.

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

Researchers have also examined copper oxides and iron-based chemicals as potential candidates for high temperature superconductors in recent years. 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 light elements. Those are the two basic criteria, ”says Dias. “Hydrogen is the lightest material and hydrogen bonding is one of the strongest.

“It is believed that solid metallic hydrogen has a high Debye temperature and strong electron-phonon coupling, which is required for superconductivity at room temperature,” says Dias.

However, extremely high pressures are required to bring pure hydrogen into a metallic state. This was first achieved in 2017 in a laboratory by Isaac Silvera and Dias, professor at Harvard University, and subsequently as a postdoc in Silvera’s laboratory.

A “paradigm shift”

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

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

Next, the lab examined covalent hydrogen-rich organic materials.

This work resulted in the carbonaceous sulfur hydride. “This presence of carbon is extremely important here,” the researchers report. Another “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 of the paper are the lead author Elliot Snider ’19 (MS), Nathan Dasenbrock-Gammon ’18 (MA), Raymond McBride ’20 (MS), Kevin Vencatasamy ’21 and Hiranya Vindana (MS), all slide laboratory; Mathew Debessai (Ph.D.) from Intel Corporation and Keith Lawlor (Ph.D.) from the University of Nevada in Las Vegas.

The project received funding from the National Science Foundation and the US Department of Energy’s Stockpile Stewardship Academic Alliance program and the Office of Science, Fusion Energy Sciences. The preparation of the diamond surfaces was partially carried out at the Integrated Nanosystems Center (URnano) at Rochester University.

Dias and Salamat have founded a new company called Unearthly Materials to find a way to produce superconductors at room temperature that can be manufactured in a scalable manner at ambient pressure.

Patents are pending. Anyone interested in licensing the technology can contact Curtis Broadbent, License Manager at URVentures.