Characterization and thermal behavior of hydroxyapatite prepared by precipitation.

The aim of this study was to find appropriate 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 its thermal behavior. Hydroxyapatite was synthesized by precipitation. Three ratios of Ca/P (1; 1.67; 3) were selected for the synthesis, then pH 7 and 12 was selected, and the ammonium dihydrogen phosphate precipitation rate was set to 2 mL min−1. The prepared powders were studied from the standpoint of particle size distribution, crystal size and morphology (optical microscope, scanning electron microscope), phase composition (X-ray diffraction analysis) and thermal stability in relation to the Ca/P ratio. [ABSTRACT FROM AUTHOR]