Synthesis and characterization of nanocrystalline hydroxyapatite and biphasic calcium phosphate using Ca(OH)2 and (NH4)H2PO4

In this study, nanocrystalline hydroxyapatite and biphasic calcium phosphate prepared via wet chemical precipitation technique in an isolated N2 environment that utilizes calcium hydroxide and ammonium dihydrogenphosphate as main precursors, is presented. Formation of predominantly hydroxyapatite with increasing crystallinity from 39.6 to 88.3% with corresponding crystallite sizes of ∼20.6 and ∼46.6 nm were found for the as-grown and the annealed powders, respectively. Partly phase transition of hydroxyapatite to β-TCP phase forming biphasic calcium phosphate was observed in the 900 oC annealed powders. Aggregated structures with nanopores were depicted on the surface of the as-grown sample while interconnected worm-like structures with voids forming nanopores were found for the sample annealed at 900 oC. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)