Nanoparticle hydroxyapatite was prepared by a wet chemical precipitationmethod. The effects of different synthesis conditions, i.e. contents of reagents (0.2, 0.5 and 0.8mol/L), reaction temperatures (20, 37, 55 and 75 deg C) and reaction time (0-24 h), were studiedbased on crystallization process analysis and the effects of washing methods (with water or alcohol)were also studied. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD),transmission electron microscopy (TEM), electron diffraction (ED) and inductively coupled plasmaspectroscopy (ICP) were used to characterize the powders. Chemical analysis shows that the purity ofthe precipitated hydroxyapatite largely depends on reaction time. X-ray diffraction and TEMmicrographs results show that reaction temperature is a key factor affecting crystallinity,morphology and particle size. Degree of supersaturation and stirring also affects thecrystallization. Particles are in a shape of short rod and have a size of 20-40 nm in length at 20deg C and 37 deg C, but acicular morphology and a size of 150-170 nm in length at 75 deg C.Particles are monocrystalline at 20 deg C and 37 deg C, and are poly-crystalline at 55 deg C and 75deg C. The results show that stoichiometry hydroxyapatite with controlled particle size, morphologyand crystallinity can be obtained by carefully controlling the reaction conditions.
