A DFT, X- and W-band EPR and ENDOR Study of Nitrogen-Centered Species in (Nano)Hydroxyapatite

作者:Gafurov Marat; Biktagirov Timur*; Mamin Georgy; Orlinskii Sergei
来源:Applied Magnetic Resonance, 2014, 45(11): 1189-1203.
DOI:10.1007/s00723-014-0572-0

摘要

Incorporation of the nitrogen-containing impurities in hydroxyapatite (HAp) powders with the sizes of the crystallites of (20-50) nm was studied using first-principles modeling combined with the multi-frequency (9 and 94 GHz) electron paramagnetic resonance (EPR) methods. It is shown that the observed EPR spectra are undoubtedly due to the presence of the bulk radiation-induced NO3 (2-) radicals. This conclusion is based on spin-polarized density functional theory calculations of spectroscopic parameters within gauge-including projector augmented wave framework followed by the exact comparison of the simulated EPR and electron-nuclear double resonance spectra with the experimental findings. In addition, a comprehensive analysis of the simulated properties allows us to suggest that the paramagnetic centers preferably occupy PO4 (3-) sites in the HAp structure.

  • 出版日期2014-11

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