Mechanochemical-hydrothermal synthesis and characterization of fluoridated hydroxyapatite

Fluoridated hydroxyapatite (FHAp) was successfully synthesized from the starting materials of CaCO₃, CaHPO₄·2H₂O, and CaF₂ via a mechanochemical-hydrothermal route. X-ray diffraction, infrared spectroscopy, surface area measurements, and scanning electron microscopy identified the resultant powders as FHAp nanocrystals with the specific surface areas of up to 114.72 m²/g. The mechanism study revealed that under such mechanochemical-hydrothermal conditions the formation reactions of FHAp were completed in two stages. The starting materials firstly reacted into a poorly crystallized calcium-deficient apatite and the complete incorporation of fluoride ions into apatite occurred in the second stage.