Synthesis and characterisation of iron substituted apatite

It is known that bones and teeth are composed mostly of hydroxyapatite (HAp), and that iron is present in them as a trace element. Crystal growth after the incorporation of Fe, however, has not been reported extensively yet. In this work, HAp particles doped with Fe ions were synthesised using hydrothermal method. The influence of Fe addition and pH values on the crystal growth of HAp was studied. It was shown that a higher pH will increase the crystal size and thereby increase the crystallinity of HAp. Fe2+/3+ has a smaller ionic radius than Ca2+ and can be incorporated directly, resulting in poor crystallinity and a concomitant reduction in crystal size. At an Fe concentration of 0.2, the rod-like Fe-HAp transformed to a spherical morphology. It suggests that Fe ions can affect the morphologies by the adsorption on specific crystal faces that inhibit growth.