Effects of solvents on properties of nanocrystalline hydroxyapatite produced from hydrothermal process

Hydroxyapatite (HA) particles have been synthesised in isopropanol–water solvent via hydrothermal process. The influences of isopropanol on crystallisation, such as phase evolution, crystallite size, crystallinity degree, chemical composition, and agglomeration of the HA nanoparticles have been investigated by using XRD, FTIR, TEM, BET, TG-DSC and laser diffraction method. All HA nanoparticles prepared in the water–isopropanol mixed solvent have been found to be carbonated HA, and the amount of carbonate increased with increase of alcohol in the solvent. However, the crystallite size and crystallinity degree of the HA nanoparticles decreased with the addition of isopropanol. In addition, there was little change in morphology of HA particles produced in different solvents, though the aspect ratio of the HA increased slightly with increasing concentration of alcohol. The agglomeration was found to be mainly controlled by the zeta-potential and not by the change of solvent.