@article{PAR00010634,
  title = {{A} carbonate-fluoride defect model for carbonate-rich fluorapatite},
  author = {{Y}i, {H}.{H}. and {B}alan, {E}tienne and {G}ervais, {C}. and {S}egalen, {L}. and {F}ayon, {F}. and {R}oche, {D}. and {P}erson, {A}. and {M}orin, {G}. and {G}uillaumet, {M}. and {B}lanchard, {M}. and {L}azzeri, {M}. and {B}abonneau, {F}.},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e propose a microscopic model of the dominant carbonate for phosphate substitution in fluorapatite. {A} well-crystallized sedimentary fluorapatite sample containing similar to 2.3 +/- 0.8 wt% of carbonate was investigated using {F}ourier transform infrared spectroscopy ({FTIR}) and {C}-13 and {F}-19 magic angle spinning nuclear magnetic resonance ({MAS} {NMR}). {A}bout 75% of the carbonate groups replace the phosphate group ("{B}-site"), whereas a lesser contribution from carbonate groups located in the structural channels ("{A}-site") is observed. {B}eside the dominant {F}-19 {NMR} signal of channel ions at similar to-102 ppm, an additional signal corresponding to similar to 8% of fluoride ions is observed at -88 ppm. {F}-19 double quantum-single quantum ({DQ}-{SQ}) {MAS} {NMR} and {C}-13 {{F}-19} frequency-selective {R}otational {E}cho {DO}uble {R}esonance ({REDOR}) experiments prove that this additional signal corresponds to isolated fluoride ions in the apatite structure, located in close proximity of substituted carbonate groups. {D}ensity functional theory ({DFT}) calculations allow us to propose a composite carbonate-fluoride tetrahedron defect model accounting for these experimental observations. {T}he planar carbonate ion lies in the sloping face of the tetrahedron opposite a fluoride ion occupying the remaining vertex, together replacing the tetrahedral phosphate ion. {T}his "francolite-type" defect leads to a diagnostic narrow {IR} absorption band at 864 cm(-1) that could be used as a guide to, e.g., detect the incipient transformation of fossil bone and teeth samples.},
  keywords = {{A}patite ; {NMR} ; first-principles calculation ; carbonate ; {FTIR}},
  booktitle = {},
  journal = {{A}merican {M}ineralogist},
  volume = {98},
  numero = {5-6},
  pages = {1066--1069},
  ISSN = {0003-004{X}},
  year = {2013},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00010634},
}