Topic
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: A novel approach, which allows a refinement of 3D local structure of materials without long-range order, based on the quantitative analysis of X-ray absorption near edge structure (XANES) using multi-dimensional interpolation of spectra as a function of structural parameters.
77 citations
TL;DR: In this paper, the authors used X-ray absorption near edge structure (XANES) and high concentration chemical sorption experiments, as well as very low concentration tracer experiments, to determine I2, I(V) and I (-I) in supernatant solutions and slurries of minerals.
77 citations
TL;DR: A facile synthesis method is reported for nanosized V2O5/C composite cathodes and their electrochemical performance as well as energy storage mechanism and results suggest that the charge compensation during de/sodiation process accompanied by the reversible changes in the oxidation state of vanadium is suggested.
Abstract: There is a significant interest to develop high-performance and cost-effective electrode materials for next-generation sodium ion batteries. Herein, we report a facile synthesis method for nanosized V2O5/C composite cathodes and their electrochemical performance as well as energy storage mechanism. The composite exhibits a discharge capacity of 255 mAh g(-1) at a current density of 0.05 C, which surpasses that of previously reported layered oxide materials. Furthermore, the electrode shows good rate capability; discharge capacity of 160 mAh g(-1) at a current density of 1 C. The reaction mechanism of V2O5 upon sodium insertion/extraction is investigated using ex situ X-ray diffraction (XRD) and synchrotron based near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Ex situ XRD result of the fully discharged state reveals the appearance of NaV2O5 as a major phase with minor Na2V2O5 phase. Upon insertion of sodium into the array of parallel ladders of V2O5, it was confirmed that lattice parameter of c is increased by 9.09%, corresponding to the increase in the unit-cell volume of 9.2%. NEXAFS results suggest that the charge compensation during de/sodiation process accompanied by the reversible changes in the oxidation state of vanadium (V(4+) ↔ V(5+)).
76 citations
TL;DR: In this paper, a structural analysis of Mo−Mg binary oxides in oxidized/reduced states was carried out and it was concluded that MoO4 tetrahedra are the main component in the near-surface region for samples of x (Mo/(Mo + Mg)) ≤ 0.7 in the oxidized state, while the reduced Mo ions including MoO2 species are also formed.
Abstract: Mo L3-edge XANES and diffuse reflectance UV−vis spectra have been recorded for structural studies of Mo−Mg binary oxides which catalyze metathesis reactions of olefins after pretreatment with H2 at 773 K. The XANES of reference compounds revealed that the local symmetry around the Mo ion as well as the valence state affects the spectral features. From the XANES of Mo−Mg binary oxides in oxidized/reduced states, it is concluded that MoO4 tetrahedra are the main component in the near-surface region for samples of x (Mo/(Mo + Mg)) ≤ 0.7 in the oxidized state. For samples in the reduced state, the tetrahedral species remain, but reduced Mo ions including MoO2 species are also formed, while the MoO2 phase is formed in the bulk phase at x = 0.5−0.8. In the latter samples, Mo ions are easily reduced by treatment with H2. The active species for metathesis reactions relates to formation of the MoO2 phase not only in the bulk but also in the near-surface region.
76 citations
TL;DR: In this article, X-ray absorption fine structure (XAFS) spectroscopy was used to determine the stability and structures of AuIII and AuI chloride complexes at elevated temperatures and pressures (T-P) typical of natural hydrothermal conditions.
76 citations