Published October 20, 2020
After decades of hunting, scientists recently announced the discovery of a room-temperature superconductor — an elusive material that conveys electricity with no loss of energy at everyday temperatures.
Eva Zurek professor of chemistry, College of Arts and Sciences, spoke with UBNow about why researchers around the world are celebrating this extraordinary milestone, and what work remains to be done in this fascinating field.
Zurek was not an author of the Oct. 14 paper in Nature that announced the creation of the room-temperature superconductor, a compound made from carbon, sulfur and hydrogen that superconducts at temperatures of up to 58 degrees Fahrenheit. That study was led by Ranga P. Dias at the University of Rochester. But Zurek is part of a team that previously used numerical calculations to explore the potential for superconductivity in a carbon-sulfur-hydrogen system.
A theoretical chemist, Zurek uses supercomputers to predict the structures and properties of superconductors, superhard materials and other novel materials. She is also an expert in high-pressure chemistry.
She notes that while exciting, the recent breakthrough will not lead to immediate technological advances, as the material only superconducts under enormous pressures equivalent to those found deep in the Earth’s interior.
Electricity passes throughout a superconducting material without resistance. Superconductors also expel magnetic fields (the Meissner effect). Moreover, a superconductor can maintain an electric current even when a voltage is not applied. Each superconducting material has an associated critical temperature below which the superconducting state is maintained. Above the critical temperature, the superconducting properties are destroyed.
A room-temperature superconductor would revolutionize technology. A superconducting power grid would not lose energy via resistance, so it would result in tremendous energy savings compared with the technology we have today. Superconducting magnets are used in MRI machines, particle accelerators and in magnetic levitation trains.
The first superconductor discovered in 1911 by Kamerlingh Onnes had an extremely low critical temperature, only a few degrees above absolute zero. Ever since this discovery, scientists have dreamt of room-temperature superconductivity. However, raising the critical temperature turned out to be extremely challenging, and despite many advances (and several Nobel Prizes) over the years, the materials known would need to be cooled by liquid helium or liquid nitrogen until very recently.
This is the first material that can exhibit superconductivity at room temperature (a chilly room, but still). The experiment illustrates that room-temperature superconductivity — one of the Holy Grails of materials research — is possible. Understanding what the chemical structure of the material is, and the reason why it is a superconductor, will hopefully yield design principles that can be used to engineer or synthesize a material that has a similar critical temperature, but at lower pressures.
This will be very hard to do and would undoubtedly warrant a Nobel Prize. In the last five to 10 years, we have discovered some of the design principles for synthesizing/designing high-temperature superconductors (hydrogen-rich materials under pressure are key). The next step is to discover design principles to bring down the pressure while keeping the good superconducting properties. At the moment, the way forward is not completely clear. However, introducing elements that can form strong bonds (that would not break apart when pressure is released) is one possibility. Carbon would form such strong bonds. Progress in this field is accelerating, so I am cautiously optimistic.
My group uses crystal structure prediction methods coupled with quantum mechanical calculations to try to predict chemical compounds that could be stable under pressure and superconducting. We also calculate their potential for superconductivity.
We actually looked at the carbon-sulfur-hydrogen system previously, but our results do not match up with Dias’. This could be because our calculations do not consider more complicated phenomena, such as quantum behavior of the protons, or because we looked at the wrong chemical composition. We are looking into these issues, and hopefully our calculations can explain Dias’ work and help characterize the material his team made.