Physicists advance in race for room-temperature superconductivity

Diamond Anvil Cell
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Diamond Anvil Cell

A team of physicists from UNLV’s Nevada Extreme Conditions Lab (NEXCL) used a diamond anvil cell, a research device similar to the one pictured, in their research to lower the pressure needed to observe a material capable of superconductivity at room temperature . Photo credit: Image courtesy of NEXCL

Less than two years ago, the scientific world was shocked by the discovery of a material capable of superconductivity at room temperature. Now a team of physicists from the University of Nevada Las Vegas (UNLV) have upped the ante by reproducing the feat using the lowest pressures ever recorded.

To be clear, science is closer than ever to a usable, replicable material that could one day revolutionize energy transport.

The discovery made international headlines in 2020 first superconductivity at room temperature by UNLV physicist Ashkan Salamat and his colleague Ranga Dias, a physicist at the University of Rochester. To achieve the feat, the scientists chemically synthesized a mixture of carbon, sulfur and hydrogen, first into a metallic state and then even further into a superconducting state at room temperature, using extremely high pressure — 267 gigapascals — conditions that one finds nature near the center of the earth only under conditions.

Fast forward less than two years, and researchers are now able to complete the feat at just 91 GPa — about a third of the pressure originally reported. The new findings were published as a preliminary article in the journal chemical communication this month.

And Super Discovery

By fine-tuning the compositions of carbon, sulfur and hydrogen used in the original breakthrough, researchers are now able to produce a material at a lower pressure that retains its superconducting state.

“These are pressures at levels that are difficult to understand and evaluate outside of the laboratory, but our current development shows that it is possible to achieve relatively high superconducting temperatures at consistently lower pressures – which is our ultimate goal,” said the The study’s lead author, Gregory Alexander Smith, a graduate student researcher at UNLV’s Nevada Extreme Conditions Laboratory (NEXCL). “Ultimately, if we want to make devices useful for societal needs, we need to reduce the pressure required to produce them.”

Although the pressure is still very high – about a thousand times higher than at the bottom of the Mariana Trench in the Pacific Ocean – they continue to race toward a near-zero target. It’s a race that’s gaining exponential momentum at UNLV as researchers gain a better understanding of the chemical relationship between the carbon, sulfur and hydrogen that make up the material.

“Our knowledge of the relationship between carbon and sulfur is advancing rapidly, and we are finding ratios that result in remarkably different and more efficient reactions than originally observed,” said Salamat, who leads UNLV’s NEXCL and has contributed to the latest learning. ÔÇťObserving such different phenomena in a similar system only shows the richness of Mother Nature. There is so much more to understand, and each new advance brings us closer to the abyss of everyday superconducting devices.”

The holy grail of energy efficiency

Superconductivity is a remarkable phenomenon, first observed more than a century ago, but only at remarkably low temperatures that foreshadowed any thought of practical application. It wasn’t until the 1960s that scientists theorized that the feat might be possible at higher temperatures. The 2020 discovery of a room-temperature superconductor by Salamat and colleagues excited the scientific world in part because the technology supports the flow of electricity without resistance, meaning that energy flowing through a circuit can be conducted indefinitely and without loss of performance. This could have significant implications for energy storage and transmission, supporting everything from better cell phone batteries to a more efficient energy grid.

“The global energy crisis shows no signs of slowing, and costs are rising in part because of a US energy grid that loses about $30 billion annually due to the inefficiency of current technology,” Salamat said. “Societal change requires us to be at the forefront of technology, and I believe today’s work is at the forefront of tomorrow’s solutions.”

According to Salamat, the properties of superconductors can support a new generation of materials that could fundamentally transform the energy infrastructure of the US and beyond.

“Imagine taking energy in Nevada and sending it across the country with no energy loss,” he said. “This technology could make it possible one day.”

References: “Carbon content drives high-temperature superconductivity in a carbonaceous sulfur hydride below 100 GPa” by G. Alexander Smith, Ines E. Collings, Elliot Snider, Dean Smith, Sylvain Petitgirard, Jesse S. Smith, Melanie White, Elyse Jones, Paul Ellison, Keith V Lawler, Ranga P Dias, and Ashkan Salamat, July 7, 2022, chemical communication.
DOI: 10.1039/D2CC03170A

Smith, the lead author, is a former UNLV student researcher in Salamat’s lab and is currently a PhD student in chemistry and research at NEXCL. Additional study authors include UNLV’s Salamat, Dean Smith, Paul Ellison, Melanie White and Keith Lawler; Ranga Dias, Elliot Snider and Elyse Jones from the University of Rochester; Ines E. Collings from the Swiss Federal Laboratories for Materials Testing and Research, Sylvain Petitgirard from ETH Zurich; and Jesse S. Smith of Argonne National Laboratory.

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