Zinc containing calcium phosphates obtained via microwave irradiation of suspensions

Hydroxyapatite (HA) is a synthetic bio-ceramic very much like biological apatite which is the mineral constituent of bone. Biological apatite, however, varies in chemical composition with the presence of several additional ions such as Mg+2, Zn+2, Mn+2, Na+, K+, Sr+2, CO3-2, HPO4-2, F-1 and SiO4-4. These ions are responsible for specific biological functions; therefore, their substitution into the HA lattice is of interest. Zinc (Zn+2) is of interest due to its presence in all biological tissues and role in various biological functions. Traditional methods for synthesis of phase pure or substituted HA are either time consuming or require expensive methodologies. Traditional co-precipitation method often requires ageing time up to 24 h or more, in order to ensure that the precipitated amorphous apatitic phase attains stoichiometry ratio (i.e. Ca:P molar ratio of 1.67). Stochiometric ratio also plays an important role in thermal stability. It was envisaged that microwave irradiation of pre-precipitated suspensions can be used as a quick route for synthesis of zinc substituted calcium phosphates. This study, therefore, explores the possibility of incorporating zinc into the apatitic structure, the effect of zinc concentration and temperature on phase-purity and morphology. Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infra-Red Spectroscopy were used to characterize the materials. Increasing zinc content influenced phase-purity and thermal stability of the resulting material.