Effect of temperature on morphology of triethanolamine-assisted synthesized hydroxyapatite nanoparticles

Hydroxyapatite (HA) nanoparticles have been synthesized using ortho-phosphoric acid as the source of PO4 3 ions, and calcium chloride, suitably complexed with triethanolamine, as the calcium source. The effect of temperature on the morphology of the product has been investigated. The chemical compositions of the samples have been established through Fourier transform infrared spectroscopy. This study reveals that A-type and B-type carbonate substitution are present in HA samples and the concentration of carbonate ions decrease with rise in temperature. Morphological analyses by TEM studies suggest that the average lengths and widths of the needle-shaped particles size increases with temperature up to 50 °C, while a morphological change of the particles from needle to spherical shape is observed on raising the temperature above 50 °C. This change in morphology has been assigned to the apparent solubility of HA at these temperatures, which has been studied by the determination of thermochemical properties of the reaction system by endpoint conductivity and electrophoretic mobility measurements.