New materials designed by a University of Illinois Chicago graduate student may help scientists tackle the challenge of building superconductors that operate at normal temperatures and pressures. Superconductors, essential in applications like MRI machines and power transmission, currently require extremely low temperatures to function, limiting their potential. Scientists worldwide are seeking materials that exhibit superconductivity at much higher temperatures, closer to room temperature, without super-cooling. Adam Denchfield and a team of UIC scientists have proposed three promising new designs for superconducting materials, which, in computer simulations, demonstrate some of the properties needed for very high-temperature superconductivity.
For decades, scientists have looked for materials that could make superconductivity—the lossless transmission of electricity—possible at higher temperatures, such as room temperature. This would allow the use of superconductors for advanced power grids, more efficient electric motors and more advanced magnetically levitated trains.
In 2023, a group of scientists published a controversial paper on a superconducting material containing a rare earth element called lutetium that works at close to ambient temperature and air pressure. The controversy inspired Denchfield to explore past literature on the type of material they described, called rare earth trihydrides.
“I looked at the results, and I was just as skeptical as many others in the field,” Denchfield said. “So I set out to look into the literature to seek alternate explanations and found studies from the late 1960s studying rare earth trihydrides.”
These older studies showed very strange changes in the electrical conductivity of the materials when cooled, which are still not fully understood. Denchfield found that special arrangements of the lutetium atoms in combination with hydrogen and nitrogen can cause the material to exhibit intriguing properties, including high-temperature superconductivity.
His research eventually led to a paper on a promising lutetium-hydrogen-nitrogen compound and experimental results that were consistent with superconductivity.
But Denchfield didn’t stop there. He explored whether other rare earth hydride combinations and structures, such as replacing lutetium with its periodic-table cousins yttrium and scandium, could work even better. Intending to increase the superconducting temperature as much as possible, he landed on three types of cubic structures that could produce the desired properties in simulations.
“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,” Denchfield said. “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.”
Material designs described in the paper achieve critical temperature — the point where superconductive properties appear — above 200 degrees Kelvin, roughly equivalent to -100 degrees Fahrenheit. Denchfield said some designs could achieve the “holy grail” of superconductivity at ambient pressure and room temperatures. To verify the predictions, materials with the new designs will have to be synthesized and tested in the laboratory.
For more information: Proceedings of the National Academy of Sciences
Image: A rare earth hydride structure that may achieve high-temperature superconductivity. (Graphic: Adam Denchfield)
