Synthesis and characterization of carbonate hydroxyapatite

Substituted apatite ceramics are of clinical interest as they offer the pot ential to improve the bioactive properties of implants. Carbonate hydroxyap atite (CHA) has been synthesized by an aqueous precipitation method and pre cipitates with two different levels of carbonate, processed as powders. Sin tering experiments were performed to establish the influence of carbonate i n significantly reducing the temperature required to prepare high-density c eramics when compared with stoichiometric hydroxyapatite (HA). High-tempera ture X-ray diffraction was used to characterize the phase stability of the apatites on sintering. Increasing carbonate content was shown to reduce the temperature at which decomposition occurred, to phases of CaO and beta-TCP . Mechanical testing, performed using biaxial flexure, showed that the CHA specimens had strengths similar to stoichiometric HA. (C) 1998 Kluwer Acade mic Publishers.