Synthesis and characterisation of LK-99

Abstract

Recently, two arXiv preprints (arXiv:2307.12008, arXiv:2307.12037) reported signatures of superconductivity above room temperature (SART) and at ambient pressure, striking worldwide experimental research efforts in replicating the results3-6, as well as theoretical attempts to explain the purported superconductivity7-11. The material of interest has chemical formula Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O, where $x \approx 1$, and was named by the authors as LK-99. It belongs to lead apatite family, and was synthesised from two precursors, lanarkite (PbSO$_4\cdot$PbO) and copper phosphide (Cu$_3$P). Here we performed a systematic study on LK-99, starting from solid-state synthesis, followed by characterisation and transport measurements. We did not observe any signatures of superconductivity in our samples of LK-99.