A resistivity anomaly at 380 K in reproduced LK-99

To confirm the room-temperature superconductivity at ambient pressure as claimed in recent arXiv preprints by Lee et al., we followed the original authors’ systematic solid-state synthesis recipe to reproduce Cu-doped Pb-apatite, known as LK-99. Using X-ray diffraction and Raman spectroscopy, we identified inclusion of various impurities alongside the apatite phase in our sample. While the sample exhibited an overall semiconducting behavior in electrical transport, an intriguing resistivity anomaly at 380 K was observed, possibly originating from a structural phase transition of the Cu2-δS impurity. Based on the transport and magnetization measurements, we conclud that the sample is a non-magnetic semiconductor, with absence of superconductivity. KCI Citation Count: 0