Research Group Sets New Temperature Record For Superconductivity

An international team of scientists has built a superconductor that functions at 250 K, or -23 °C. At just -9 °F, this temperature is only a few degrees colder than the chilliest winter day in Florida history. However, it’s nearly 50 °C (84.6 °F) hotter than the previous record high for superconductivity—and it puts the “holy grail” of energy transmission almost within our reach.

First discovered in 1911, superconductors are devices that conduct electricity with zero resistance. Because none of the energy is lost during the transmission process, superconductors could allow us to generate electricity in one place—a solar farm in a sunny region of the US, for example—and send it all over without wasting any.

The problem is that scientists have yet to create a practical superconductor. Existing devices require extreme conditions, such as very low temperatures and incredibly high pressures, which limits their usefulness. That’s why scientists across the globe are on the hunt for a superconductor that works at room temperature, and this new study, published in the journal Nature, represents a giant leap forward in that effort.

The scientists created a type of material called a lanthanum superhydride. By placing enormous pressure—between 150 and 170 gigapascals, more than one-and-a-half-million times the pressure at sea level—on a sample of the material, they were able to coax it to act as a superconductor at this record-high temperature. Only under these high-pressure conditions did the material, a tiny sample only a few microns across, exhibit superconductivity at the new record temperature.

In fact, the material showed three of the four characteristics needed to prove superconductivity: It dropped its electrical resistance, decreased its critical temperature under an external magnetic field and showed a temperature change when some elements were replaced with different isotopes. The fourth characteristic, called the Meissner effect, in which the material expels any magnetic field, was not detected. That’s because the material is so small that this effect could not be observed, researchers said.

They used the Advanced Photon Source at Argonne National Laboratory (CSA CSM), which provides ultrabright, high-energy X-ray beams that have enabled breakthroughs in everything from better batteries to understanding the Earth’s deep interior, to analyze the material. In the experiment, researchers within University of Chicago’s Center for Advanced Radiation Sources squeezed a tiny sample of the material between two microscopic diamonds to exert the pressure needed, then used the beamline’s X-rays to probe its structure and composition.

University of Chicago researcher Vitali Prakapenka said, “Our next goal is to reduce the pressure needed to synthesize samples, to bring the critical temperature closer to ambient and perhaps even create samples that could be synthesized at high pressures, but still superconduct at normal pressures.”