High thermally stable Mg-substituted tricalcium phosphate via precipitation

Tricalcium phosphates incorporating small amounts of Mg show attractive biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation. A systematic investigation on Mg-stabilized β-TCP (β-tricalcium phosphate, β-Ca₃(PO₄)₂) is presented. Microstructure, composition and thermal behaviour were investigated by means of thermogravimetry and differential thermal analysis (TG-DTA), induced coupled plasma-atomic emission spectroscopy (ICP-AES), Fourier transform infrared spectroscopy (FT-IR), N₂ adsorption isotherms, X-ray diffraction (XRD and HT-XRD), and scanning electron microscopy (SEM). Pure and Mg-substituted tricalcium phosphate precursors consisted of calcium-deficient hydroxyapatite, the specific surface area being 128 m²/g and 87 m²/g, respectively. Tricalcium phosphate nanostructured powders were obtained by thermal treatment above 800 °C. The incorporation of Mg within the calcium phosphate lattice promoted the formation of the β-TCP phase at slightly lower temperature and resulted in the stabilization of the β-polymorph at high temperature (i.e. 1600 °C).