Faster synthesis of A-type carbonated hydroxyapatite powders prepared by high-temperature reaction

Synthesis of A-type carbonated hydroxyapatite (CHA) materials has typically involved heating of a hydroxyapatite composition for 24 hours or greater. In this study, a hydroxyapatite powder was heated at 800, 900 or 1000°C for 1, 8 or 16 hours in dry CO2. Samples heated for 8 and 16 hours at 900/1000°C were fully-carbonated A-type CHAs. After only one hour at 1000°C, the carbonate content approached 95% of the theoretical maximum. Preparing compositions with more than 95% of the theoretical maximum with reduced thermal energy (1000°C for 1 hour, or 900°C for 8 hours) results in powders with higher surface areas and a reduced level of sintering, compared to powders prepared with typical thermal treatments reported for A-type CHAs, such as 1000°C for 16 hours. As far as the authors are aware, these are the shortest heating times reported for the preparation of fully-carbonated A-type CHAs which is significant for future applications of such powders, particularly in applications beyond medical devices such as chromatography, remediation and carbon capture.