Calcified Tissue International

, Volume 43, Issue 1, pp 33–40

Influence of preparation conditions on the composition of type B carbonated hydroxyapatite and on the localization of the carbonate ions

  • M. Vignoles
  • G. Bonel
  • D. W. Holcomb
  • R. A. Young
Laboratory Investigations

DOI: 10.1007/BF02555165

Cite this article as:
Vignoles, M., Bonel, G., Holcomb, D.W. et al. Calcif Tissue Int (1988) 43: 33. doi:10.1007/BF02555165

Summary

It is shown how certain aspects of the composition and structure of carbonated apatites depend strictly on preparation conditions, for example, excess of phosphate or calcium ions in the reaction medium, CO32− concentration, pH, ammonia added or not. Depending on those conditions, either one or the other of the two proposed mechanisms of introduction of carbonate ions into the B sites is dominant. The mechanisms are (1) replacement of a phosphate ion by a carbonate ion with the formation of three vacancies, one in a phosphate oxygen site and one each in the neigh-boring Ca2+ and OH sites; and (2) replacement of a phosphate ion by a carbonate accompanied by a hydroxyl ion. Whether mechanism (1) is observed to dominate over mechanism (2), or vice versa, is accounted for by the relative concentrations of the various ions in the reaction medium. The number of vacancies is decreased by the presence of either, or both, excess calcium ions or ammonia in the reaction medium. A structural-chemical mechanism is advanced for the view that, with the smallest CO32− content, the A sites are favored but with increasing carbonate content the B sites become favored and the A-site content becomes less than it is when the total carbonate content is less.

Key words

Preparation conditions Type B carbonated hydroxyapatite Phosphate ion Composition and structure 

Copyright information

© Springer-Verlag New York Inc. 1988

Authors and Affiliations

  • M. Vignoles
    • 1
  • G. Bonel
    • 1
  • D. W. Holcomb
    • 2
  • R. A. Young
    • 2
  1. 1.Laboratoire de Physico-Chimie des Solides U.A.C.N.R.S.ToulouseFrance
  2. 2.School of PhysicsGeorgia Institute of TechnologyAtlantaUSA