Nanocrystalline hydroxyapatite powders by a chitosan–polymer complex solution route: Synthesis and characterization

Nanocrystalline hydroxyapatite (HAp) powders were successfully synthesized by a simple method using chitosan–polymer complex solution. To obtain HAp nanopowders, the prepared precursor was calcined in air at 400–800 °C for 2 h. The phase composition of the calcined samples was studied by X-ray diffraction (XRD) technique. The XRD results confirmed the formation of HAp phase with a small trace of monotite phase. With increasing calcination temperature, the crystallinity of the HAp increased, showing the hexagonal structure of HAp with the lattice parameter a in a range of 0.94030–0.94308 nm and c of 0.68817–0.68948 nm. The particle sizes of the powder were found to be 55.02–73.36 nm as evaluated by the XRD line broadening method. The chemical composition of the calcined powders was characterized by FTIR spectroscopy. The peaks of the phosphate carbonate and hydroxyl vibration modes were observed in the FTIR spectra for all the calcined powders. TEM investigation revealed that the prepared HAP samples consisted of rod-like nanoparticles having the particle size in the range of 100–300 nm. The corresponding selected-area electron diffraction (SAED) analysis further confirmed the formation of hexagonal structure of HAp.

TEM images with corresponding selected-area electron diffraction (SAED) patterns of HAp powders calcined in air for 2 h at (a) 400 °C, (b) 500 °C, (c) 600 °C, (d) 700 °C and (e) 800 °C. The TEM results revealed that the prepared HAP samples consisted of rod-like nanoparticles having the crystalline size in the range of 100–300 nm. The corresponding selected-area electron diffraction (SAED) analysis further confirmed the formation of hexagonal structure of HAp.Figure optionsDownload as PowerPoint slide