Low pressure, high effort: physicists win in the race for superconductivity at room temperature

Less than two years after shocking the scientific world with the discovery of a material capable of superconductivity at room temperature, a team of UNLV physicists have upped the ante by reproducing the performance at the lowest pressure ever recorded.

In other words, science is closer than ever to a usable, replicable material that could one day revolutionize energy transport. UNLV physicist Ashkan Salamat and his colleague Ranga Dias, a physicist at the University of Rochester, made international headlines in 2020 by reporting room-temperature superconductivity for the first time. 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 extreme pressure — 267 gigapascals — conditions that were man only found in nature near the center of the earth. Fast forwarding less than two years, the team is 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 pre-article in the journal this month chemical communication.

A great discovery

By fine-tuning the compositions of carbon, sulfur and hydrogen used in the original breakthrough, scientists are 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 Lead author of the study, 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 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 scientists 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. “To observe such different phenomena in a similar system simply 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 community 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.”