Researchers in Korea have published a paper that they say shows the first superconductor that operates at room temperature and pressure.
The paper on the room temperature superconductor material has been published on the pre-print server arxiv.org and still has to go through peer review, but it is struggling to gain traction among researchers. There is currently talk of retracting the paper before it goes through peer review.
“For the first time in the world, we succeeded in synthesizing the room-temperature superconductor (Tc≥400 K, 127∘C) working at ambient pressure with a modified lead-apatite (LK-99) structure,” said Sukbae Lee, CEO of the Quantum Energy Research Centre (Q-Centre) at Korea University along with colleagues Ji-Hoon Kim and Young-Wan Kwon.
Researchers at the University of Nevada developed a room temperature material back in 2020 and started a company called Unearthly Materials to develop it. Another material called Redmatter developed at the University of Rochester in the US also shows promise.
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The superconductivity of LK-99 is shown through the the Critical temperature (Tc), Zero-resistivity, Critical current (Ic), Critical magnetic field (Hc), and the Meissner effect and originates from minute structural distortion by a slight volume shrinkage (0.48 %), not by external factors such as temperature and pressure.
The unique structure of LK-99 that allows the minute distorted structure to be maintained in the interfaces is the most important factor that LK-99 maintains and exhibits superconductivity at room temperatures and ambient pressure.
The shrinkage is caused by Cu2+ substitution of Pb2+(2) ions in the insulating network of Pb(2)-phosphate and it generates the stress. The heat capacity results indicated that the new model is suitable for explaining the superconductivity of LK-99.
The LK-99 material is a modified-lead apatite crystal structure with the composition Pb10−xCux(PO4)6O (0.9<x<1.1) and was synthesized using a solid-state method and exhibits the Ohmic metal characteristic of Pb(6s1) above its superconducting critical temperature, Tc, and the levitation phenomenon as Meissner effect of a superconductor at room temperature and atmospheric pressure below Tc. A LK-99 sample shows Tc above 126.85∘C (400 K).
“We analyze that the possibility of room-temperature superconductivity in this material is attributed to two factors: the first being the volume contraction resulting from an insulator-metal transition achieved by substituting Pb with Cu, and the second being on-site repulsive Coulomb interaction enhanced by the structural deformation in the one-dimensional(D) chain (Pb2-O1/2-Pb2 along the c-axis) structure owing to superconducting condensation at Tc,” said Lee in a second paper on the structure of the material.
