Determination of OH ions in hydroxyfluorapatites by infrared spectroscopy

Baumer, A.; Ganteaume, Max; Klee, W. E.

doi:10.3406/bulmi.1985.7864

Cited by 26 publications

(21 citation statements)

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“…The hydroxy endmembers display a unique sharp band at 3573 cm -1 that is replaced by a second absorption at around 3545 cm -1 as F replaces OH in apatite. For F contents > 50 mol%, only a rather broad absorption at 3541 cm -1 is present in the spectrum, which vanishes for higher F concentrations (Baumer et al 1985). The anion composition of sample CAPR (Table 6) is F 1.77 OH 0.23 .…”

Section: Infrared Spectroscopymentioning

confidence: 96%

On the symmetry and crystal chemistry of britholite: New structural and microanalytical data

Oberti¹,

Ottolini²,

Ventura

et al. 2001

American Mineralogist

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We provide in this paper complete structural and micro-chemical characterization of two britholite samples with compositions (Mn 0.(from Los Islands, Guinea). The crystal-chemical formulae were calculated by combining electron-microprobe analyses for intermediate-Z elements (Na, Ca, Mn, Si, P), ion-microprobe analyses for low-Z (H, Li, Be, B, F) and high-Z elements (Ba, Y, REE and actinides), and high-quality (R obs 1.2-2.6) single-crystal structure refinements. Structure refinements indicate that the best approximation to the real symmetry is the P6 3 space group. In britholite, the lowering of symmetry with respect to the P6 3 /m space group of apatite means that the O3 and O3a atoms are no longer equivalent and allows the tetrahedron to rotate up to ~4° around the Si-O1 bond. Consequently, the O3a atom moves closer to the REE1a site, whereas the O3 atom moves farther from the REE1 site and closer to the REE2 site, which thus assumes a [7+1] coordination. The infrared spectrum of britholite from Latium shows a unique and very broad band in the OH-stretching region at 3437 cm -1 , which is consistent with the ordering of trivalent REE cations at the REE2 site. The calculated integral molar absorptivity ε i is 23600 L⋅mol -1 ⋅cm -2 . A remarkable constancy in the unit-cell volume along the whole apatite-britholite compositional range is observed for values of the aggregate ionic radius at the REE sites shorter than 1.12 and longer than 1.15 Å, whereas large variations are observed for intermediate values; this behavior suggests constraints due to the rigidity of the tetrahedral group, that are further enhanced at high symmetry.

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Section: Infrared Spectroscopymentioning

confidence: 96%

On the symmetry and crystal chemistry of britholite: New structural and microanalytical data

Oberti¹,

Ottolini²,

Ventura

et al. 2001

American Mineralogist

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“…According to Baumer et al, 31 the position, the number (one or two) and relative integrated intensity of OH stretching band(s) in the 3480-3650 cm 21 region can be used to estimate the amount of fluoride ions in FHA samples. A signal band present at 3750 cm 21 indicates that less than 5% of the hydroxyl ions in HA have been substituted with fluoride ions, whereas, for example, a signal band at 3538 cm 21 indicates that at least 75% of the hydroxyl ions have been substituted with fluoride ions.…”

Section: Fourier Transform Infrared Analysismentioning

confidence: 99%

RETRACTED: Effect of fluorine ion addition on structural, thermal, mechanical, solubility and biocompatibility characteristics of hydroxyapatite nanopowders

Eslami

Solati‐Hashjin

Tahriri

2010

Advances in Applied Ceramics

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In this study, the effect of fluorine ion addition on the structural, thermal, mechanical and solubility characteristics of hydroxyapatite nanopowders was investigated. The fluorine substituted hydroxyapatite powders with compositions of Ca 5 (PO 4 ) 3 (OH) 12x F x [x50 (hydroxyapatite), x50?68 (fluorhydroxyapatite) and x50?97 (fluorapatite)] were prepared. The powders were uniaxially pressed and were formed as disc shape. Subsequently, sinterability and thermal stability of disc samples were compared together. Also the effects simultaneously of fluoride content and temperature on the lattice parameters, crystallites size, microstrain and microstructure of the samples were examined. The sintering density and flexural strength of these samples were evaluated with the sintering temperature. Finally, the in vitro dissolution studies of the apatite samples were performed at osteoclastic resorption conditions. The above mentioned experimental results showed that the fluorine content had significant impact on the sintering behaviour, densification and mechanical properties of the hydroxyapatite nanopowders.

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“…Different methods have been used to determine the OH − ion content in biological calcified tissues: chemical analysis [1], vibrational spectroscopy [11], inelastic neutron scattering [8] and solid-state NMR [5,6,10,12]. However, many methods suffer from drawbacks when applied to the dental tissues because large amounts of visible light fluorescence hinder the Raman spectra and the F − ions, abundantly present in human tooth enamel, affect the OH stretching modes in the IR spectra [13]. Although solid-state NMR has been successfully applied to count OH − ions [14] in synthetic hydroxyapatite (HAp) [15] provided by separation of the OH − ion and water resonances in the 1 H magic angle spinning (MAS) NMR spectra, this approach fails to quantify OH − content in biological hard tissues, because loss of crystallinity and interference from the organic matrix lead to significant line broadening and manifold overlapping 1 H NMR signals [5,10,16].…”

Section: Introductionmentioning

confidence: 99%