Synthesis and mechanical behaviour of chlorapatite and chlorapatite/β-TCP composites

Chlorine substituted hydroxyapatite (HAP) and biphasic mixtures (HAP + β-TCP) were prepared through an aqueous precipitation method. Characterization studies using XRD, thermograms, elemental analysis and FT-IR spectra have confirmed the incorporation of added chlorine into the apatite structure forming a solid solution. Substitution of chlorine in the calcium deficient apatites tends to form biphasic mixtures of HAP and β-TCP and the proportions in the formed mixtures were dependent on the deficiency of calcium in the precursors used. The thermal stability of the chlorine substituted apatites was evident up to 1200 °C from the present results. The cell parameters for chlorine substituted apatite powders tend to follow significant expansion with respect to those of stoichiometric HAP, being always smaller than those of the stoichiometric chlorapatite sample. The mechanical properties of the solid solution of chlorapatites have shown promising features when compared to the pure stoichiometric chlorapatite sample.