Influence of precipitation conditions on the synthesis of hydroxyapatite

The goal of this study was to find suitable precipitation conditions (Ca/P ratio, pH and precipitation rate) for the synthesis of hydroxyapatite (HAP; Ca10(PO4)6(OH)2) and to determine the effect of precipitation conditions on the product properties. Hydroxyapatite was synthesized by precipitation. Three ratios of Ca/P (1; 1.67; 3) were selected for the synthesis, then two pH values (7 and 12) and two precipitation rates of ammonium dihydrogen phosphate (0.5 and 5 ml·min). The prepared powders were evaluated from the standpoint of particle size distribution, crystal size and morphology by optical and scanning electron microscope, and phase composition by X-ray diffraction analysis.