The effect of triethanolamine on the formation of sol–gel derived fluoroapatite/hydroxyapatite solid solution

Fluoroapatite/hydroxyapatite (FA/HA) solid solution shows good bioactivity and stability, and is one of promising biomaterials. In this work, 1.67Ca(NO3)2–PO(OEt)x(OH)3−x ethanol solutions with different concentrations of trifluoroacetic acid and triethanolamine were mixed. The mixed solutions were transformed into the as-prepared powder on a hot plate. After the as-prepared powder was calcined at 500 or 900 °C, a pure FA/HA phase could be obtained. The fluorine contents in the FA/HA strongly depended on the ratios of triethanolamine/trifluoroacetic acid. The presence of triethanolamine in the mixed solutions enhances the dissociation of trifluoroacetic acid and accelerates the formation of unevaporable Ca(OOCF3C)x(NO3)2−x complex species, as a result, more fluorine could be incorporated into the apatite to form the solid solution.