Incorporation and deposition behaviors of Cu and Ni ions into hydroxyapatite channels by heat treatment

The incorporation of multiple metals into hydroxyapatite was investigated using Cu and Ni. Both Cu and Ni were successfully incorporated into hydroxyapatite, forming Ca10(PO4)6CuxNiy(O, OH)2 by heat treatment under N2 at 900 °C after metal aqueous solution loading with x = 0–0.3 and y = 0–0.2. The Cu occupied the channel center site, whereas the Ni shifted from the center of the Ca10(PO4)6Cu0.3Ni0.2(O, OH)2. The environment surrounding Ni in this apatite was different from that in Ca10(PO4)6Ni0.2(O, OH)2, suggesting the influence of Cu incorporation in the channel. CuO and NiO were deposited from Ca10(PO4)6Cu0.3Ni0.2(O, OH)2 at 600–900 and 700–900 °C by heating under 10% H2O air, respectively. The NiO deposition temperature was lower than that of Ca10(PO4)6Ni0.2(O, OH)2, suggesting that the coexistence of Cu in the apatite channel facilitated the Ni deposition. •Both Cu and Ni were successfully incorporated into hydroxyapatite.•Cu and Ni occupied different sites in the apatite lattice.•Cu and Ni oxides were deposited on the apatite by heat treatment under a H2O-containing atmosphere.