Hydrothermal Synthesis of Hydroxyapatite Fibers Precipitated by Propionmide

Fibrous hydroxyapatite (HA) powder was successfully synthesized through hydrothermal method. Cal- cium nitrate tetrahydrate and diammonium hydrogen phosphate were added as precursors and propionamide (PA) as precipitant was used to control the degree of supersaturation of the reaction solution. XRD, FTIR, SEM and TEM were used to characterize the product. The synthesized HA powder was found to possess high crystallinity and regular morphology, as well as good dispersion. The effects of starting pH value and the concentration of precursors on the morphology, constitution, crystallinity and the growth characteristics of HA were investigated. The results show that the starting pH and concentration significantly affect the morphology at different extents, but not on the constitution and crystallinity. In fact, low starting pH controls orientation of fibrous HA while low concentration widens HA fibers.