Mechanochemical–hydrothermal synthesis of carbonated apatite powders at room temperature

Crystalline carbonate- and sodium-and-carbonate-substituted hydroxyapatite (CO3HAp and NaCO3HAp) powders were prepared at room temperature via a heterogeneous reaction between Ca(OH)2/CaCO3/Na2CO3 and (NH4)2HPO4 aqueous solution using the mechanochemical–hydrothermal route. X-ray diffraction, infrared spectroscopy, thermogravimetry, and chemical analysis were performed. Room temperature products were phase-pure CO3HAp and NaCO3HAp containing 0.8–12 wt% of carbonate ions in the lattice. Dynamic light scattering revealed that the median agglomerate size of the room temperature CO3HAp and NaCO3HAp powders was in the range of 0.35–1.6 μm with a specific surface area between 82 and 121 m2/g. Scanning and transmission electron microscopy confirmed that the carbonated HAp powders consisted of mostly submicron aggregates of nanosized, ≈20 nm crystals. The synthesized carbonated apatite powders exhibit chemical compositions and crystallinities similar to those of mineral constituents of hard tissues and therefore are promising for fabrication of bone-resembling implants.