Journal of Dental Research, Vol 61, 429-434, Copyright © 1982 by International & American Associations for Dental Research Online Journals
Carbonate apatites from aqueous and non-aqueous media studied by ESR, IR, and X-ray diffraction: effect of NH4+ ions on crystallographic parameters
Y. Doi, Y. Moriwaki, T. Aoba, M. Okazaki, J. Takahashi and K. Joshin
Carbonate-containing apatites prepared from aqueous and non-aqueous media
were investigated by ESR, IR, and X-ray diffraction. A typical asymmetric
signal at g = 2.0, which many workers have observed in irradiated calcified
tissues, is interpreted in terms of CO3(3)- and Co-2 and the trapped
electron center, The CO3(3)- and CO2- ions originated from the carbonate
which substitutes for the phosphate ion in the apatite crystalline
structure. From the comparison of the data between the carbonate apatites
prepared under the presence of Na+ and NH4+ ions, it is suggested that NH4+
ions contribute to the crystallographic parameters, either by substituting
in the structure or by suppressing the CO3 incorporation into the
structure, or by both. The production of the CO2- radical ion could be
accounted for based on the concept of hydrogen bond between the oxygen atom
of CO2(3)- and the hydrogen atom of NH4+.
