An investigation of the chemical synthesis and high-temperature sintering behaviour of calcium hydroxyapatite (HA) and tricalcium phosphate (TCP) bioceramics

The experimental conditions for the synthesis of sub-micrometre,spherical particles of calcium hydroxyapatite[Ca10(PO4)6(OH)2] (HA) andtricalcium phosphate [Ca3(PO4)2] (TCP) areinvestigated through chemical coprecipitation from the aqueous solutions ofcalcium nitrate and di-ammonium hydrogen phosphate salts. The precipitationprocess employed was also found to be suitable for the production ofsub-micrometre HA/TCP composite powders in situ. The synthesized pureHA and TCP powders were found to be stable even at 1300°C in air forprolonged heating times. Bioceramic sample characterization was achieved bypowder X-ray diffraction (XRD), scanning electron microscopy (SEM), energydispersive X-ray spectroscopy (EDX), and density and surface area measurements.Crystallographic analyses of HA powders were performed by the Rietveld method onthe powder XRD data.