Copper-substituted lead apatite, aka LK-99, was claimed to be room-temperature superconductor, but due to the complicated components and structures, the reproduction is still controversial. Chinese researchers have some replication of the Korean work and have extended with better procedures and research. They have updated a prior paper with new synthesis (instructions about how to make it) and better measurements.
They modified the synthetic procedure of SCCLA to codope both sulfur and copper into lead apatite, and the structural characterization reveals a directional stacking mechanism. The magnetic and electric properties of SCCLA have been comprehensively investigated. The hysteresis MH loops can be observed up to 250 K, and the ZFC–FC bifurcation occurs as well. The RT curve manifests that SCCLA possesses a strange-metal phase at large current and a second-order phase transition occurs at around 230 K during cooling. Further synthesis of lead-free sample is then performed which provides us even stronger diamagnetism and smaller resistance at low temperature. They therefore believe that they have made a substantial step towards room-temperature superconductivity.
The researchers on this paper are associated with 9 University departments or institutions (South China, Wuhan, Beijing, Japa, Fuzhou, Hefei).
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