Hydrothermal Synthesis and Magnetic Properties of Copper-doped Lead Apatite

his study synthesized copper-substituted lead apatite using the hydrothermal method, starting from hydroxyapatite precursors. For stability, it is recommended to maintain copper substitution below x=2 in the Pb10-xCux(PO4)O apatite. The introduction of copper appropriately reduces the lattice constant, in line with DFT theoretical calculations. Non-equilibrium heat treatment introduces additional charge carriers; oxygen-rich tempering shifts the sample to paramagnetism, while anaerobic tempering leads to complex and unique hysteresis loops. Non-equilibrium annealing can increase carrier concentration, but its efficacy is limited. Although some improvements have been observed, further exploration involving additional element doping or seeking interfaces with suitable conductive phases is needed to achieve superconductivity.