Paper Title:
A MAS-NMR and Combined Rietveldt Study of Mixed Calcium/Strontium Fluorapatite Glass-Ceramics
  Abstract

Strontium is one of the most common substituents in apatite crystals. The presence and behavior of Sr in apatite-group phases are of considerable significance in biology. The present paper investigates the substitution of strontium for calcium in a glass-ceramic of the following composition 4.5SiO23Al2O31.5P2O54CaO1CaF2. The glasses were characterized using Differential Thermal Analysis (DTA), X-ray powder diffraction (XRD), neutron diffraction (ND) and 19F Resonance Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The all calcium glass crystallized to calcium fluorapatite (Ca5(PO4)3F). Substituting strontium partially for calcium resulted in the formation of a mixed strontium/calcium fluorapatites. In contrast complete substitution resulted in the formation of strontium fluorapatite. MAS-NMR showed the the F to be present as F-Ca(3) representing a fluoride ion surrounded by three Ca2+ ions in the all calcium glass and was present as F-Sr(3) in the all strontium glass. In the mixed glasses fluorine was present as FCa( 3), F-Ca(2)Sr, F-CaSr(2) and F-Sr(3). Ca had a higher tendency to occupy the F-M(3) sites than Sr which may reflect the higher charge to size ratio of Ca2+ relative to Sr2+ and its greater affinity for F- ions.

  Info
Periodical
Key Engineering Materials (Volumes 309-311)
Main Theme
Edited by
Takashi Nakamura, Kimihiro Yamashita and Masashi Neo
Pages
305-308
DOI
10.4028/www.scientific.net/KEM.309-311.305
Citation
R. G. Hill, A. Calver, S. Skinner, A. Stamboulis, R. V. Law, "A MAS-NMR and Combined Rietveldt Study of Mixed Calcium/Strontium Fluorapatite Glass-Ceramics", Key Engineering Materials, Vols. 309-311, pp. 305-308, 2006
Online since
May 2006
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$32.00
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