Reviewed by Lexie CornerNov 6 2024
A graduate student at the University of Illinois Chicago has developed new materials that could help scientists tackle one of the most challenging problems of our time: creating superconductors that function at standard pressures and temperatures. The study was published in the Proceedings of the National Academy of Sciences.
A rare earth hydride structure that may achieve high-temperature superconductivity. Image Credit: Adam Denchfield
Superconductors are commonly used in everyday applications, such as power transmission and MRI equipment. However, their potential is limited because they need to be cooled to extremely low temperatures to operate effectively.
Researchers worldwide are searching for materials that could exhibit superconductivity at “very high” temperatures—specifically, closer to room temperature—without the need for supercooling.
Adam Denchfield and a team of researchers from UIC have proposed three intriguing new designs for superconducting materials. These designs demonstrate some characteristics necessary for very high-temperature superconductivity in computer simulations.
Denchfield, a Physics Ph.D. candidate at UIC, co-authored the study with Associate Professor of Physics Hyowon Park and Professor of Physics and Chemistry Russell Hemley.
For decades, scientists have sought materials that would enable superconductivity—or the lossless transfer of electricity—at higher temperatures, such as room temperature. Achieving this would facilitate the development of more sophisticated magnetically levitated trains, more efficient electric motors, and advanced power grids.
In 2023, a contentious study was released by a team of scientists regarding a superconducting material that operates at temperatures and air pressures around ambient conditions. This material contains the rare earth element lutetium. Denchfield was inspired by the controversy surrounding this research to review earlier studies on rare earth trihydrides, the type of substance they investigated.
I looked at the results, and I was just as skeptical as many others in the field. So I set out to look into the literature to seek alternate explanations and found studies from the late 1960s studying rare earth trihydrides.
Adam Denchfield, Graduate Student, University of Illinois Chicago
These earlier investigations revealed unusual, yet-to-be-understood changes in the materials' electrical conductivity upon cooling. Denchfield found that the arrangement of lutetium atoms with hydrogen and nitrogen can lead to intriguing properties, including high-temperature superconductivity.
Ultimately, his work produced experimental results that supported the presence of superconductivity, culminating in a report on a promising lutetium-hydrogen-nitrogen combination. The New York Times featured an article about the group's findings.
Denchfield's efforts did not stop there; he began exploring whether alternative rare earth hydride configurations and structures could yield better results, such as substituting lutetium with its periodic-table counterparts, scandium and yttrium.
In his simulations, he identified three different types of cubic structures that could produce the desired properties, aiming to raise the superconducting temperature as high as possible.
We basically put forward three template structures of increasing complexity that we want other people to be able to take and mess with, plug and play different elements. I would describe this as an exploratory paper, a motivational and inspirational work that should inspire the search for a whole new class of structures that could be very high-temperature superconductors.
Adam Denchfield, Graduate Student, University of Illinois Chicago
The paper's material designs achieve a critical temperature exceeding 200 ºK, or approximately -100 ºF, where superconductive properties begin to manifest. According to Denchfield, certain designs may be capable of achieving the “holy grail” of superconductivity at room temperature and pressure. To validate these predictions, materials with the new designs will need to be produced and tested in a laboratory setting.
The new study led by Adam builds on the previous milestones of our group: the discovery of the first near-room-temperature superconductor in another rare earth hydride under pressure, then the tantalizing evidence for similar high-temperature superconductivity in the lutetium-based material. The prospects for new classes of related materials with different compositions is the latest chapter in our exciting efforts to discover and create new materials that could one day revolutionize energy technologies.
Russell Hemley, Associate Professor, University of Illinois Chicago
Journal Reference:
Denchfield, A., et al. (2024) Electronic structure of nitrogen-doped lutetium hydrides. Physical Review Materials. doi.org/10.1103/physrevmaterials.8.l021801.