Compositional Analyses of F, Cl and OH by Raman Spectroscopy in Apatite from Mafic-Ultramafic Pipes of the Ivrea Verbano Zone (NW Italy) (original) (raw)
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Micro-Raman and FTIR studies of synthetic and natural apatites
Biomaterials, 2007
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 2 6h to C 3h . An $15 cm À1 shift of the v 3c PO 4 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 CO 3 and v 1 PO 4 bands in samples of various carbonate contents provide a measure of the degree of carbonation for CAps. r
BioMed research international, 2013
Calcium phosphate apatites are inorganic compounds encountered in many different mineralized tissues. Bone mineral, for example, is constituted of nanocrystalline nonstoichiometric apatite, and the production of "analogs" through a variety of methods is frequently reported. In another context, the ability of solid surfaces to favor the nucleation and growth of "bone-like" apatite upon immersion in supersaturated fluids such as SFB is commonly used as one evaluation index of the "bioactivity" of such surfaces. Yet, the compounds or deposits obtained are not always thoroughly characterized, and their apatitic nature is sometimes not firmly assessed by appropriate physicochemical analyses. Of particular importance are the "actual" conditions in which the precipitation takes place. The precipitation of a white solid does not automatically indicate the formation of a "bone-like carbonate apatite layer" as is sometimes too hastily concluded: "all that glitters is not gold. " The identification of an apatite phase should be carefully demonstrated by appropriate characterization, preferably using complementary techniques. This review considers the fundamentals of calcium phosphate apatite characterization discussing several techniques: electron microscopy/EDX, XRD, FTIR/Raman spectroscopies, chemical analyses, and solid state NMR. It also underlines frequent problems that should be kept in mind when making "bone-like apatites. "
Journal of Solid State Chemistry, 2013
Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomiclevel. Raman and 31 P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31 P NMR linewidth and inverse Raman PO 4 3− 1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3-10.3 wt% CO 3 2− range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31 P NMR chemical shift frequency and the Raman phosphate 1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals.
Raman spectroscopic studies of O–H stretching vibration in Mn-rich apatites: A structural approach
American Mineralogist, 2020
The O-H stretching vibration mode in crystals of (Mn,Cl)-rich and F-poor minerals of the apatite-supergroup has been studied by micro-Raman spectroscopy. The main purpose was to check if such an analysis can provide a quick and simple method to assess the distribution of Ca This is a preprint, the final version is subject to change, of the American Mineralogist (MSA) Cite as Authors (Year) Title. American Mineralogist, in press.
American Mineralogist
The O–H stretching vibration mode in crystals of (Mn,Cl)-rich and F-poor minerals of the apatite-supergroup has been studied by micro-Raman spectroscopy. The main purpose was to check if such an analysis can provide a quick and simple method to assess the distribution of Ca and Mn together with traces of Fe + Mg (= Mn*) on nonequivalent cationic sites in the apatite structure, especially in small and strongly heterogeneous crystals directly in thin sections. The O–H stretching vibration mode can then be treated as a useful structural probe giving information on the M2 occupants bonded to XOH. Pieczkaite, with the empirical formula (Mn4.49Fe0.47Ca0.05Mg0.01)Σ5.01P2.99O12[Cl0.83(OH)0.17], displays the O–H stretching mode centered at ~3380 cm–1, which shows that the complete replacement of Ca by Mn* at the M2 site is connected with a shift of the O–H stretching band ~192 cm–1 toward lower wavenumbers in relation to the O–H Raman band position reported for hydroxylapatite. The value is ...
Chemical Geology, 2007
Compositional control on the annealing kinetics of fission-tracks (FT) in apatite requires routine measurement of sample grain composition. However, for practical reasons the bulk composition of analysed grains is not routinely measured and instead grain chlorine content or etch-pit dimensions are used to characterise a samples annealing behaviour. A more desirable approach is to measure crystallographic parameters (i.e. unit cell dimension) of a grain as these represent the summed effect of all substitutions and crystal defects. We show how Raman microspectrometry can be used as a routine non-destructive tool to obtain rapid measurement of the crystallographic structure of apatite grains etched for FT analysis. Variations of unit cell parameter a are found to correspond to a systematic variation of Raman shift in the range of 452-440 cm − 1 for measurements made on c-parallel sections of apatite where the direction of the polarized incident beam is parallel to the c axis.
Geochimica et Cosmochimica Acta, 1999
Major, minor, and trace element abundances in apatites from various I-and S-type (igneous and sedimentary) granites of the Lachlan Fold Belt have been determined using electron microprobe and laser ablation inductively coupled plasma mass spectrometer. The results show that apatite can accommodate many minor and trace elements, whose concentrations and ratios are relatively sensitive to factors controlling many of the fundamental differences between I-and S-type granites. Apatites from S-type granites generally have higher F but lower Cl contents than those from I-type granites, which is ascribed mainly to the loss of Cl during the weathering processes forming the source rocks of S-type granites, although fractional crystallisation can cause significant enrichment in F as well. High Mn and Fe contents in apatites from S-type granites, and high S and As abundances in apatites from mafic I-type granites, result from different oxygen fugacities and degrees of Al saturation (or aluminosity) between metaluminous mafic I-type magmas and peraluminous S-type and felsic I-type magmas. There are systematic and distinctive differences in absolute rare-earth element (REE) abundances, REE distribution patterns, and element ratios (e.g., La/Y, Sm/Nd, etc.) between apatites from different types of granite. The strong Eu depletion that characterises apatites from S-and felsic I-type granites is interpreted here to be a result of the uniqueness of crystal chemistry of apatite and high Eu 2ϩ /Eu 3ϩ ratios in S-type and felsic I-type magmas, which are more reduced and peraluminous than mafic I-type magmas. Strong REE (La to Eu) and Th enrichment in apatites from mafic I-type granites and marked Nd depletion in apatites from most S-type and felsic I-type granites are caused by the precipitation and fractionation of monazite in the parental magmas of the latter rocks. Substitution mechanisms are responsible for high Na in apatites from S-type and felsic I-type granites, and for high Si in apatites from mafic I-type granites, and may also have important effects on REE partitioning between apatite and melt. Thus, apatite chemistry can be used as an excellent indicator of granite petrogenesis. The results have important implications for identifying different types of granite and are potentially significant for determining the provenance of sedimentary rocks.
Can crystallinity be used to determine the degree of chemical alteration of biogenic apatites?
Chemical Geology, 2004
A new Raman spectroscopic technique has been refined to more efficiently determine the crystallinity indices of biogenic apatites. We investigate the possible relationships between the structure (crystallinity) and geochemistry (rare earth element (REE), d 18 O) of biogenic apatites. A selection of phosphatic remains dated from present to about 510 Ma (Late Cambrian), for most of which either the oxygen isotope compositions or REE patterns are available, has been characterized for crystallinity using Raman spectroscopy. We define a new crystallinity index (CI Raman ) from the ratio of the full width at half maximum (FWHM) of the intense peak of the PO 4 symmetric stretching mode in the sample and a reference magmatic apatite. In order to compare our crystallinity index with CI used in previously published studies, we also analyzed part of our sample set with FT-IR spectroscopy and X-ray diffractometry. A detailed study of natural samples demonstrates that crystallinity index is a poor criterion for determining if a sample has been altered since deposition. This result is based on three major observations: (1) independently of the CI Raman , the original geochemical signatures of the biogenic apatites can be preserved over a long period, (2) strong geochemical perturbations (lowering of d 18 O values and of La/Sm ratios) may occur without detectable recrystallization, and (3) alteration by heating, marked by the transformation of organic matter into graphite, produces REE fractionations and limited oxygen isotope exchange with crustal aqueous fluids. D
Minerals, 2016
Calcium phosphate apatites offer outstanding biological adaptability that can be attributed to their specific physico-chemical and structural properties. The aim of this review is to summarize and discuss the specific characteristics of calcium phosphate apatite biominerals in vertebrate hard tissues (bone, dentine and enamel). Firstly, the structural, elemental and chemical compositions of apatite biominerals will be summarized, followed by the presentation of the actual conception of the fine structure of synthetic and biological apatites, which is essentially based on the existence of a hydrated layer at the surface of the nanocrystals. The conditions of the formation of these biominerals and the hypothesis of the existence of apatite precursors will be discussed. Then, we will examine the evolution of apatite biominerals, especially during bone and enamel aging and also focus on the adaptability of apatite biominerals to the biological function of their related hard tissues. Finally, the diagenetic evolution of apatite fossils will be analyzed.
Structural properties of apatites from Finland studied by FTIR spectroscopy
Bulletin of the Geological Society of Finland, 1998
Studies by XRD and FTIR analyses of the structure of Sokli and Siilinjärvi apatites and a comparison with the Kola and Kovdor apatites are presented. In the structure of apatites from Finland the occurrence of F...OH and F...OH...F bonds and the incorporation of CO, 2 ions into A and B positions were established.