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Nickel superconductor works above -233°C threshold at normal pressure

A team of engineers and physicists at Southern University of Science and Technology, in China, has created a nickel-based material that behaves as a superconductor above the -233°C (40 K) threshold under ambient pressure. In their study in Nature, the researchers synthesized thin films of bilayer nickelate (La₂.₈₅Pr₀.₁₅Ni₂O₇) and found one that behaved as a high-temperature superconductor.

The -233°C threshold (40 K), often associated with the McMillan limit, marks a boundary beyond which conventional superconductivity theories become less predictive.

Scientists have been searching for a room-temperature superconductor that could revolutionize a wide range of technologies. The ability to achieve superconductivity without the need for costly and complex cooling systems would significantly reduce energy loss due to heat conversion in electrical transmission, leading to dramatic improvements in efficiency and cost reduction. This breakthrough could lead to advancements in numerous fields, including maglev trains, fusion reactors and MRI machine components. This new effort by the team in China represents another step in reaching the ultimate goal.

Until now, high-temperature superconductors have primarily been based on copper and iron compounds, while nickelate superconductors required high-pressure conditions to function.

The newly discovered high-temperature nickelate superconductor emerged from the team's experiments with epitaxially grown bilayer nickelate thin films. Their work was part of a long-term project geared toward finding high-temperature superconductors based on nickel. The current research had been running for three years and involved growing nickelates with controlled rare-earth metal substitutions and precise oxygen content.

For this latest successful effort, the team substituted a portion of lanthanum with praseodymium in the nickelate structure. Testing showed it transitioned to a superconductor at approximately -228°C.

The research team suggests their development of a nickel-based, high-temperature superconductor is likely to open the door to other possibilities, some nickel-based and others based on other metals. It might also help in research dedicated to understanding why some materials can transition into superconductors.