Physicists advance in the race for room-temperature superconductivity

A team of physicists from the Nevada Extreme Conditions Lab (NEXCL) at UNLV used a diamond anvil cell, a research device similar to the one pictured, in their research to lower the pressure needed to observe material capable of superconductivity at ambient temperature. 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 yet again by replicating the feat at the lowest pressure ever recorded.

To be clear, this means science is closer than ever to a usable, repeatable material that could one day revolutionize the way energy is transported.

International headlines were in 2020 with the discovery of room temperature superconductivity for the first time by UNLV physicist Ashkan Salamat and his colleague Ranga Dias, a physicist from the University of Rochester. To achieve the feat, 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 you would only find in nature near the center of the Earth.

Less than two years later, researchers are now able to achieve the feat at just 91 GPa, about a third of the pressure originally reported. The new findings were published in a preliminary article in the journal Chemical communications this month.

A great discovery

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

“These are pressures at a level that is difficult to understand and assess outside of the lab, but our current trajectory shows that it is possible to achieve relatively high superconducting temperatures at consistently lower pressures – which is our ultimate goal. “said 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 society’s needs, we need to reduce the pressure to create them.”

Although the pressures are still very high – about a thousand times higher than what you would feel at the bottom of the Pacific Ocean’s Mariana Trench – they continue to rush towards a near-zero goal. It’s a race that’s growing exponentially 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 lead to remarkably different and more efficient responses than what was initially observed,” said Salamat, who leads the NEXCL at the UNLV and contributed to the latest study. “Observing such different phenomena in a similar system shows the richness of Mother Nature. There’s so much more to understand, and each new advance brings us closer to the precipice 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 preempted any idea of ​​practical application. It wasn’t until the 1960s that scientists speculated that the feat might be possible at higher temperatures. The 2020 discovery by Salamat and his colleagues of a room-temperature superconductor has the scientific world excited in part because the technology supports electrical flow with zero resistance, which means energy flowing through a circuit could be infinite driving without loss of power. This could have major implications for energy storage and transmission, supporting everything from better cellphone batteries to a more efficient energy grid.

“The global energy crisis shows no signs of abating and costs are rising in part because of a US energy grid that is losing an estimated $30 billion a year due to inefficiencies in current technology,” Salamat said. “For societal change, we need to be at the forefront of technology, and the work that is being done today is, I believe, at the forefront of tomorrow’s solutions.”

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

“Imagine harnessing energy in Nevada and sending it across the country without any loss of energy,” he said. “This technology could one day make that possible.”

Reference: “Carbon Content Drives High Temperature Superconductivity in 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 communications.
DOI: 10.1039/D2CC03170A

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

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