Crystallinity and compositional changes in carbonated apatites: Evidence from 31P solid-state NMR, Raman, and AFM analysis

John David P. McElderry, Peizhi Zhu, Kamal H. Mroue, Jiadi Xu, Barbara Pavan, Ming Fang, Guisheng Zhao, Erin McNerny, David H. Kohn, Renny T. Franceschi, Mark M.Banaszak Holl, Mary M.J. Tecklenburg, Ayyalusamy Ramamoorthy, Michael D. Morris

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO 43- ν1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3-10.3 wt% CO3 2- range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ν1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals.

Original languageEnglish
Pages (from-to)192-198
Number of pages7
JournalJournal of Solid State Chemistry
StatePublished - 2013


  • Bone mineral
  • Carbonated apatite
  • Crystallinity
  • MAS
  • NMR
  • Raman spectroscopy


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