Article,
Micro-Raman and FTIR studies of synthetic and natural apatites
Biomaterials, 28 (19): 3043--3054 (July 2007)
DOI: 10.1016/j.biomaterials.2007.02.028
Abstract
B-type synthetic carbonate hydroxyapatite (CHAp), natural carbonate
fluorapatite (CFAp) and silicon-substituted hydroxyapatite (SiHAp)
have been studied by using micro-Raman and infrared (IR) spectroscopy.
It was found that while B-type carbonate substitution predominates
in carbonate apatites (CAps), A-type is also detected. B-type carbonate
substitution causes a broadening of the v(1) P-O stretching mode
that is associated with the atomic disorder and lowering of the local
symmetry in CAps from C-6h(2) to C-3h. An similar to 15 cm(-1) shift
of the v(3c) PO4 stretching IR mode was observed upon decarbonation
of the CFAp. Such shift which was confirmed by lattice dynamics calculations
points out that the P-O bond lengths on the,mirror plane increase
when carbonate leaves the apatite structure. The present results
support the substitution mechanism proposed on the basis of neutron
powder diffraction studies of the same samples whereby carbonate
substitutes on the mirror plane of the phosphate tetrahedron. The
intensity ratios of the v(2) IR CO3 and v(1) PO4 bands in samples
of various carbonate contents provide a measure of the degree of
carbonation for CAps. (C) 2007 Elsevier Ltd. All rights reserved.
Tags
- b
- bone;
- carbonate;
- carbonated
- crystal-structure;
- dentin;
- diffraction;
- enamel
- fluorapatite;
- hydroxyapatite;
- neutron
- powder
- silicon-substituted
- spectroscopy;
