Synthesis and thermal stability of hydroxyapatite-β-tricalcium phosphate composites with cosubstituted sodium, magnesium, and fluorine

The preparation of biphasic mixtures (HAP + beta-TCP) of controlled ratios with the combined substitution of essential biocompatible trace elements (Na, Mg, and F) was carried out by an aqueous precipitation method. The results showed that incorporated elements have played a significant role in the thermal stability of the apatites up to 1400 degrees C, and that increased calcium deficiency in the apatites has led to the formation of a higher proportion of beta-TCP in the biphasic mixtures. However, minor discrepancies in the structural parameters due to the incorporated trace elements and the matching of phases of the synthesized powders with respect to the stoichiometric HAP were apparent from the present investigation.