Superconductive materials could transform electronics if they were less demanding. Achieving this state, where electrical currents move without resistance, typically needs either very low temperatures or very high pressures or both. Any real-world benefits, such as instantly recharging electric vehicles, would be reduced by requirements for cryogenic freezers or diamond anvil cells. Scientists have now moved closer to superconductive materials that function near ordinary temperatures and pressures. A team led by physicists at the University of Houston established a new record for superconductivity by reaching the highest temperature at ambient pressure. The temperature of -122.15 degrees Celsius may not seem elevated, yet it exceeds the usual requirement near absolute zero at -273.15 degrees Celsius. This advance also ends a long period of limited progress in superconductor studies. Hua Zhou, a physicist at Argonne National Laboratory, described it as a major step toward practical superconductors operating at room temperature and pressure. With the material remaining superconductive at normal pressure, researchers can examine it using common instruments and start creating technologies for everyday conditions. The material is a cuprate superconductor composed of copper oxide layers mixed with other metal oxides including mercury, barium, and calcium. Known as Hg1223, it has held the record since 1993 for the highest-temperature superconductor at ambient pressure, previously at -140.15 degrees Celsius. To raise this value, the team applied a pressure-quenching process. Hg1223 was first compressed in a diamond anvil cell to 30 gigapascals, nearly 300,000 times sea-level pressure. The pressure was then released rapidly, leaving the material in a metastable state that retains some quantum properties without sustained extreme pressure. Similar to how diamonds keep their structure after formation under Earth’s pressure, quick pressure release creates small defects in the material. These defects allow Hg1223 to stay superconductive at higher temperatures once pressure returns to normal levels. Confirmation came through analysis at the Advanced Photon Source, a high-powered X-ray facility at Argonne that tracks tiny material changes. Hg1223 is not the warmest superconductor created. A lanthanum decahydride sample remained superconductive up to -13.15 degrees Celsius but required 190 gigapascals of pressure, far above the 30 gigapascals used here. The goal remains room-temperature superconductivity at ambient pressure, which could benefit energy storage, electric vehicles, and magnetic levitation systems. The study appeared in Proceedings of the National Academy of Sciences.
