Effect of zinc ions on the structural characteristics of hydroxyapatite bioceramics

Ionic substituted calcium phosphates have received much attention for their use as implant materials because of their ability to mimic natural hard tissues. In this work, the properties of hydroxyapatite ceramic doped with small amounts of zinc ions (5, 10, and 15 mol%) by using a wet chemical precipitation route were studied. XRD spectra revealed that adding zinc led to the development of a biphasic mixture composed of hydroxyapatite (HA) and beta-TCP phases, which affected the morphology, crystallinity, and crystallite size of the precipitates. With increasing zinc ion substitution in the HA lattices, the degree of crystallinity of the powders reduces due to the additional formation of beta-TCP phase. Slender, elongated, and highly agglomerated particles were observed for all synthesized powders. However, calcination at 700 degrees C caused the particles to become more spherical, having diameters ranging from 30 to 37 nm. An increase in the concentration of zinc ions promoted the beta-TCP phase, which ultimately altered the lattice parameters of the HA structure and suppressed the growth of particles.