NANOSIZED BIOCERAMIC HYDROXYAPATITE POWDERS VIA SOL-GEL METHOD

High purity hydroxyapatite powders have been synthesized through sol-gel technique using calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate as the precursors for calcium and phosphorus, respectively. The monomers were heated in an 11 v/v% ammonium solution at 100˚ C until white gels of hydroxyapatite mixture were obtained. The obtained gel was then dried at ca. 350˚ C and subsequently subjected to calcination. XRD measurement shows that the powders contain hydroxyapatite crystals with β -TCP and calcium oxide as secondary phases. Hydroxyapatite powder of higher purity, i. e., the correct Ca/P ratio has been obtained, by adding an appropriate amount of diammonium hydrogen phosphate and heating with stirring. Morphological evaluation by SEM measurement shows that the particles of the HA are tightly agglomerated, globular in shape with an average size of 1-2 μm. The primary particulates have average diameters of 50-200 nm, as detected by SEM and nanoparticle sizer. Purity (almost 100%) of the obtained hydroxyapatite was confirmed by XRD analysis