Effect of carbonate content on the ESR spectrum near g=2 of carbonated calciumapatites synthesized from aqueous media
- 1 March 1989
- journal article
- research article
- Published by Springer Nature in Calcified Tissue International
- Vol. 44 (2), 114-124
- https://doi.org/10.1007/bf02556470
Abstract
The ESR spectrum of X-irradiated carbonated apatites synthesized at low temperature was studied as a function of their carbonate content. Using13C-enriched samples, four different carbonate-derived radicals and a surface O− ion could be identified. Isotropic CO 3 − and CO 2 − ions are present at a B site in the apatite lattice, and anisotropic CO 3 − and CO 2 − radicals are located at the surface of the crystallites. Only the isotropic ESR signals increase with increasing carbonate content. The anisotropic signal ascribed to a surface CO 2 − radical is mainly responsible for the so-called asymmetric ESR signal near g=2. It is argued that this surface signal may still be composite and caused by several very similar CO 2 − ions. The consequences for phenomenological ESR studies of calcified tissues are discussed.Keywords
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