Morphology and formation mechanism of hydroxyapatite whiskers from moderately acid solution

Abstract

Hydroxyapatite (HA) whiskers with uniform morphology and good crystallinity were successfully prepared by a precipitation-hydrolysis method in moderately acid solution at 85-95 °C for 48-120 h, their lengths were in the range of 50-150 mum and aspect ratios (length/diameter) in the range of 40-100. The precipitates formed at each stage of the synthesis were characterized by XRD, FTIR, TEM and SEM. The morphology and crystallinity of the precipitates depended on the synthesis temperature and time as well as the concentrations of soluble calcium and phosphate ions. The HA whiskers were formed by the hydrolysis of precursors produced during the reactions and took over the morphology of fibrous octacalcium phosphate (OCP). The stoichiometric HA whiskers were improved with the increase of pH value of solution, the synthetic temperature and the duration.

Keywords

• hydroxyapatite whiskers
• precipitation-hydrolysis
• morphology
• forming mechanism