Fabrication of hydroxyapatite microspheres with poor crystallinity using a novel flame-drying method

Three kinds of hydroxyapatite (HA) microspheres were prepared using a flame-drying method. The morphologies and selected area diffraction of HA slurries were determined by TEM. The phase composition, and morphologies were studied by TEM, X-ray diffractometer (XRD), scanning electron microscope (microstructure, SEM), respectively. The TEM result shows that the slurries are composed of nano-particle HA. With the aging time of HA slurry prolonging, the morphology of HA particle changes from spherical ACP (amorphous calcium phosphate) to rod-like acicular nano-crystal morphology. Low temperature can also cause the crystallinity degree of HA slurry decrease obviously. The XRD result shows that the crystallinity of HA microspheres prepared from three kinds of HA slurry is consistent with its corresponding slurry. The SEM result shows that the sphericity of the microspheres prepared by pure HA slurry without ammonia water is the best among three kinds of microspheres, then the HA slurry containing ammonia solution forms the hollow microspheres with open pore, and ice-water mixture flurry.