Materials known as cubic rare earth hydrides have the potential to act as superconductors under normal conditions.
Researchers at the University of Illinois Chicago have developed innovative materials that could help tackle a significant modern problem: creating superconductors that function at typical temperature and pressure levels.
Superconductors play a crucial role in many common technologies, such as MRI machines and power transmission systems, but they currently require chilling to extremely low temperatures to operate. This limitation curtails their broader applications. Scientists around the globe are seeking materials that could achieve superconductivity at “high” temperatures, meaning temperatures approaching room temperature, without the need for extreme cooling.
Adam Denchfield, along with a team of scientists from UIC, presented three new designs for superconducting materials in a paper published in the Proceedings of the National Academy of Sciences. Their computer simulations suggest these designs exhibit key characteristics necessary for achieving superconductivity at very high temperatures.
Denchfield, a PhD student in physics, collaborated with Hyowon Park, an associate professor of physics, and Russell Hemley, a professor of both physics and chemistry, on this research.
For years, researchers have sought materials that enable superconductivity — which allows electric current to flow without resistance — at higher temperatures, potentially at room temperature. This advancement could lead to the development of advanced power grids, improved electric motors, and more sophisticated magnetically levitated trains.
In 2023, a contentious study was released regarding a superconducting material made from the rare earth element lutetium, which claimed to work at nearly normal temperature and pressure conditions. This sparked skepticism in the scientific community, which motivated Denchfield to delve into previous research on similar materials known as rare earth trihydrides.
“Initially, I shared the skepticism many felt within the field,” Denchfield stated. “This led me to review earlier studies from the late 1960s that investigated rare earth trihydrides.”
These historical studies revealed unusual alterations in the electrical conductivity of the materials when cooled, phenomena that are not yet fully comprehended. Denchfield discovered that specific configurations of lutetium atoms, when combined with hydrogen and nitrogen, could produce interesting properties, including high-temperature superconductivity.
His research culminated in a focus on a promising compound made of lutetium, hydrogen, and nitrogen, which exhibited results aligning with superconductivity. Hemley’s team’s work even gained attention from the New York Times.
However, Denchfield did not stop there; he sought to determine if other combinations and structures of rare earth hydrides, such as substituting lutetium with yttrium or scandium, might perform better. Aiming to maximize the superconducting temperature, he identified three cubic structures in simulations that could yield the desired properties.
“We essentially proposed three increasingly complex template structures that we hope others can modify and explore further,” Denchfield explained. “I see this as an exploratory paper intended to motivate and inspire the search for entirely new classes of structures with potential for high-temperature superconductivity.”
The material designs presented in the paper indicate that they could achieve critical temperatures exceeding 200 degrees Kelvin, approximately -100 degrees Fahrenheit. Denchfield mentioned that some designs may even reach the “holy grail” of attaining superconductivity at normal pressure and room temperature. Nevertheless, laboratory synthesis and testing of these new designs are necessary to confirm the predictions.
“Adam’s study expands on our group’s previous achievements: first discovering a nearly room-temperature superconductor in another rare earth hydride when subjected to pressure, followed by intriguing evidence of similar high-temperature superconductivity in the lutetium-based material,” Hemley remarked. “The possibility of finding new classes of related materials with various compositions represents an exciting new chapter in our ongoing mission to identify and create novel materials capable of potentially transforming energy technologies.”
