Carbonate Incorporation in Apatite
Carbonate incorporation in apatite occurs via both A-type carbonate substitution, where carbonate substitutes for an anion within the apatite channels, and B-type carbonate substitution, where carbonate substitutes for a phosphate in the apatite lattice. Though these two forms are generally accepted, there is debate over the existence of multiple orientations within A-type and B-type substitution, referred to as Al/A2 and Bl/B2, respectively. Specifics of these orientations, as well as the experimental evidence for each, will be discussed. Special attention will be given to C-13 NMR which has indicated anywhere from two to four different peaks that could be attributed to two to four different forms of carbonate incorporation. Although it is generally accepted that the peak at 166.Spprn is attributed to A-type carbonate incorporation and the peak at 170.2 ppm is attributed to B-type carbonate incorporation, multiple authors have noted other peaks with different chemical shifts and have assigned the peaks to either multiple types of A-type incorporation, multiple types of B-type incorporation, or the presence of amorphous carbonate. Currently, there is no way to decipher which of these theories is correct and all must be considered. Lastly, measurements of the distances between various ions in apatite lattice and the incorporated carbonate will be used to discuss the stability of A-type and B-type carbonate incorporation.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2016
- F&M Theses Collection