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XANES
About: XANES is a research topic. Over the lifetime, 7737 publications have been published within this topic receiving 188032 citations.
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TL;DR: High-spatial-resolution XANES maps for the different S species across adjacent calcite prisms confirm their distinctive distributions in the molluscan shells and illustrate the presence of narrow, submicron transverse growth features.
Abstract: The microstructure and composition, including chemical speciation of sulphur (S), of two mollusc shells were investigated using a combination of scanning electron microscopy, X-ray absorption near-edge structure spectroscopy (XANES) and electron probe microanalysis (EPMA). The shell of Pinna is composed of monocrystalline, and Pinctada, of polycrystalline, calcite prisms separated by organic-rich walls. Sulphur speciation information from XANES spectra using a scanning X-ray microscope showed that the protein S content of the interprismatic walls is higher than the SO4 content, whereas the reverse is true for the intraprismatic structures. High-spatial-resolution XANES maps for the different S species across adjacent calcite prisms confirm their distinctive distributions in the molluscan shells and illustrate the presence of narrow, submicron transverse growth features. On a larger scale, a series of wider growth zones, incorporating the submicron zones, are aligned parallel to each other and cross-cut many calcite prisms. EPMA element maps for magnesium (Mg) and S demonstrate that these growth increments are compositionally zoned, comprising alternating layers of high mineral (Mg-rich) and high organic (S-rich) components. Additionally, these maps confirm that the organic interprismatic walls have lower Mg and higher S than the intraprismatic structures.
78 citations
TL;DR: In this article, the electrochemical mechanism of the cathode material Li2FeSiO4 with reversible extraction/insertion of more than one Li+ from/into the structure has been studied by techniques of in situ synchrotron X-ray absorption near edge structure (XANES) and Xray diffraction (XRD).
Abstract: The electrochemical mechanism of the cathode material Li2FeSiO4 with reversible extraction/insertion of more than one Li+ from/into the structure has been studied by techniques of in situ synchrotron X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD). These advanced techniques provide effective solutions to address the limitations of characterization by traditional ex situ methods. The study of in situ Fe K-edge XANES indicates that the Fe ion in the Li2FeSiO4 is oxidized continuously to high valence during the charging process from open circuit potential to 4.8 V, which contributes to the high reversible capacities of the materials. In situ XRD and theoretical study from first-principles calculations have been employed to reveal the structural evolution of the Li2FeSiO4 underlying the high capacity during the charge/discharge process. The results of both experimental and theoretical studies are consistent and indicate that Li2FeSiO4 undergoes two two-phase reactions when the electro...
78 citations
TL;DR: In this article, a-C:H films with a hydrogen content varying from 29 to 47 1.5 µm have been synthesized by electron cyclotron resonance chemical vapor deposition at low substrate temperatures (<120 ǫ°C) applying a wide range of bias voltage.
Abstract: In this study, we have employed infrared (IR) absorption spectroscopy, visible Raman spectroscopy, and x-ray absorption near edge structure (XANES) to quantify the hydrogen (H) content in hydrogenated amorphous carbon (a-C:H) films. a-C:H films with a hydrogen content varying from 29 to 47 at. % have been synthesized by electron cyclotron resonance chemical vapor deposition at low substrate temperatures (<120 °C) applying a wide range of bias voltage, Vb, (−300 V
78 citations
TL;DR: Inverse spinel cobalt ferrite (CoFe2O4) nanoparticles were synthesized by a polymer pyrolysis method and calcined at various temperatures from 800 to 1000°C as mentioned in this paper.
78 citations
TL;DR: In this paper, the structure of iron-bearing sodium borosilicate glasses with up to 10mol% "FeO" has been investigated in the range 0.15 -0.95.
Abstract: The structure of iron-bearing sodium borosilicate glasses with up to 10 mol% “FeO” has been investigated in the range 0.15 < Fe3+/ΣFe < 0.95. According to Mossbauer spectroscopy, Fe3+ and Fe2+ are mainly in tetrahedral and octahedral coordination, respectively, although other coordination states exist for both cations. From XANES experiments, we conclude that increasing Fe content and varying redox states have only a minor effect on the relative proportions of BO3 and BO4 units. In Raman spectra, a decrease of the proportion of BO4 species present in danburite-like units (Na2O·B2O3·2SiO2) is found upon increasing iron content and oxidizing state. Whereas the insensitivity of the overall boron speciation to iron content and redox state points to weak interactions between boron and iron, the changes affecting BO4 species do indicate a more subtle interplay between Fe3+ and the other tetrahedrally coordinated cations (Si,B) because of the competition between tetrahedral Fe3+ and B3+ for charge compensation by Na+.
78 citations