title: FT-IR spectroscopy of fluoro-substituted hydroxyapatite: strengths and limitations.
abstract: Fluoro substituted hydroxyapatite (FHAp) samples were prepared by a cyclic pH method. Both calcined and uncalcined samples were subjected to elemental analysis (F, Ca, P) and X-ray diffraction (XRD) analysis to verify composition and phase purity. Good correlation between a-axis parameters and fluoride ion content was found for calcined samples, however, for uncalcined samples the fluoride ion content was higher than estimated from the a-axis values. Fourier transform infra red (FT-IR) spectroscopy analysis of the calcined samples showed OH band shifts and splitting in accordance with F-HO interactions affecting the OH vibration. We conclude that the OH libration (620-780 cm(-1) range) is more suited for estimation of fluoride ion content than the OH stretching. In contrast, uncalcined samples all displayed FT-IR spectra similar to that of hydroxyapatite (HAp) despite the presence of fluoride ions (18-73%). FT-IR emission spectroscopy was used to probe the changes occurring in the FT-IR spectra of HAp and FHAp samples upon heating. Interpretation of the spectral changes occurring during heating to 1,000 degrees C and subsequent cooling is given. Room temperature spectra of samples heated to various temperatures was used to determine the temperature necessary to produce FT-IR spectra displaying the expected OH bands. A model accounting for the combined observations is proposed.
authors.affiliation: Tissue BioRegeneration and Integration Program, Science Research Centre, Queensland University of Technology, Brisbane, QLD, Australia.
authors.forename: Llew
authors.initials: L
authors.lastname: Rintoul
authors.forename: Edeline
authors.initials: E
authors.lastname: Wentrup-Byrne
authors.forename: Shuko
authors.initials: S
authors.lastname: Suzuki
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Grøndahl
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry; D006358:Hot Temperature; D006882:Hydroxyapatites / Q000138:chemical synthesis / Q000737:chemistry*; D008422:Materials Testing; D015394:Molecular Structure; D033362:Powder Diffraction; D017550:Spectroscopy, Fourier Transform Infrared; D023822:Tissue Engineering
chemical_list: D001672:Biocompatible Materials; D006882:Hydroxyapatites; D005459:Fluorides