PREPARATION, ANALYSIS, AND CHARACTERIZATION OF CARBONATED APATITES

  • 1 January 1982
    • journal article
    • research article
    • Vol. 34, S69-S81
Abstract
A range of synthetic carbonated apatites were characterized using IR and Raman spectroscopy, X-ray diffraction and chemical analysis and compared to stoichiometric hydroxyapatite and [human] dental enamel. Synthetic apatites were prepared by aqueous precipitation and by solid-state reaction at high temperatures. A method is described for the carbonate determination of apatite samples using gas chromatography. Carbonate exists in 2 crystallographically distinct sites in the apatite crystal structure and is consistent with a carbonate-for-phosphate substitution mechanism, where 4 carbonate groups replace 3 phosphate groups. Na+ and OH- are involved with the substitution of carbonate ions in the apatite structure. Observed Na/carbonate and Cal/P molar ratios confirm this mechanism. Substitution of this type may explain the predominant mode of carbonate substitution in biological apatites.