Sol–gel synthesis and characterization of nanostructured hydroxyapatite powder

Nanocrystalline powders of hydroxyapatite (HAP) were prepared from Ca(NO3)2·4H2O and P2O5 using a simple sol–gel approach. The resultant gel precursors obtained based on the concentration of the starting solutions were either transparent or translucent. Fourier transform-infrared spectroscopy (FT-IR) result combined with the X-ray diffraction (XRD) indicates the presence of amorphous hydroxyapatite (HAP) in the as-dried gel precursor. X-ray patterns collected on the powder after heat-treatment at 900 °C for 12 h in air exhibits single phase of HAP. Scanning electron microscopy (SEM) shows that the powder obtained after heat-treatment at 900 °C is composed of nanocrystalline (50–150 nm) HAP particles.