Atomic environment in sol–gel derived nanocrystalline hydroxyapatite

Hydroxyapatite prepared by sol–gel route was investigated with respect to local structure changes induced by heat treatment. The X-ray diffraction analysis revealed the presence of nanocrystalline hydroxyapatite with significantly broadened reflections for the sample dried at 110 °C as compared with the samples heat treated at 900 °C and 1150 °C. Line broadenings for the nanocrystalline sample are evidenced also in the X-ray photoelectron spectroscopy and nuclear magnetic resonance spectra. By heat treatment at high temperatures the atomic environment is modified both around cations and oxygen. A higher bioactivity is expected from the nanocrystalline sample than from the high temperature heated samples with large sized crystals.