PANG, Y. and BAO, X., 2003. Influence of temperature, ripening time and calcination on the morphology and crystallinity of hydroxyapatite nanoparticles. Journal of the European Ceramic Society, 23 (10), pp.1697-1704
Nano-sized hydroxyapatite (HA) particles were prepared by chemical precipitation through aqueous solutions of calcium
chloride and ammonium hydrogenphosphate. The influence of temperature, ripening time and calcination on the crystallinity
and morphology of the HA nanoparticles were investigated. It was found that the crystallinity and crystallite size increased
with the increase of synthetic temperature and ripening time. XRD and TEM results showed that the morphology change
of HA nanoparticles was related to their crystallinity. High crystallinity of HA led to regular shape and smooth surface of
the nanoparticles. The crystallinity of HA powders increased greatly after calcination at 650 C for 6 h but the change of
the crystallite size after calcination was dependent on the crystallinity and crystallite size of ‘‘as prepared’’ HA nanoparticles.