Local structure and oxidation state of uranium in some ternary oxides: X-ray absorption analysis

2007 ◽  
Vol 180 (1) ◽  
pp. 54-61 ◽  
Author(s):  
A.V. Soldatov ◽  
D. Lamoen ◽  
M.J. Konstantinović ◽  
S. Van den Berghe ◽  
A.C. Scheinost ◽  
...  
Keyword(s):  
Oxidation State ◽  
Local Structure ◽  
Absorption Analysis ◽  
X Ray ◽  
X Ray Absorption ◽  
Ternary Oxides

scholarly journals Time-Resolved X-ray Absorption Spectroscopy in (Photo)Electrochemistry

Surfaces ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 138-150 ◽  
Author(s):  
Martina Fracchia ◽  
Paolo Ghigna ◽  
Alberto Vertova ◽  
Sandra Rondinini ◽  
Alessandro Minguzzi
Keyword(s):  
Oxidation State ◽  
Absorption Spectroscopy ◽  
Time Resolution ◽  
Local Structure ◽  
Future Perspectives ◽  
Time Resolved ◽  
X Ray ◽  
Fixed Energy ◽  
Complete Survey ◽  
X Ray Absorption

This minireview aims at providing a complete survey concerning the use of X-ray absorption spectroscopy (XAS) for time-resolved studies of electrochemical and photoelectrochemical phenomena. We will see that time resolution can range from the femto-picosecond to the second (or more) scale and that this joins the valuable throughput typical of XAS, which allows for determining the oxidation state of the investigated element, together with its local structure. We will analyze four different techniques that use different approaches to exploit the in real time capabilities of XAS. These are quick-XAS, energy dispersive XAS, pump & probe XAS and fixed-energy X-ray absorption voltammetry. In the conclusions, we will analyze possible future perspectives for these techniques.

scholarly journals Local Structure and Magnetism of LiFeSi0.01P0.99O4/C as a Cathode Material on Lithium-Ion Battery

2021 ◽  
Vol 1 (1) ◽  
pp. 1-4
Author(s):  
Vera Laviara Maghfirohtuzzoimah ◽  
Sahara Hamas Intifadhah ◽  
Pelangi Az-zahra ◽  
Wantana Klysubun ◽  
Dita Puspita Sari ◽  
...  
Keyword(s):  
Lithium Ion Battery ◽  
Oxidation State ◽  
Local Structure ◽  
Lithium Ion ◽  
Antiferromagnetic Order ◽  
Main Peak ◽  
X Ray ◽  
State And Local ◽  
Silicon Doped ◽  
X Ray Absorption

The oxidation state and local structure of LiFeSi0.01P0.99O4/C composites as a cathode on lithium-ion battery were investigated by Fe K-edge X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). The LiFeSi0.01P0.99O4/C sample was prepared by solid-state reaction process. Based on the XANES analysis, the absorption of edge energy (E0) of the sample was 7124.92 eV. In addition, linear combination fitting (LCF) analysis of XANES confirmed the oxidation state of iron mixture of 2+ and 3+ as the effect of silicon doped in LiFePO4. The Fourier Transform (FT) of the Fe K-edge EXAFS fitting analysis showed that the nearest neighbors surrounding atom Fe were the main peak with high intensity that confirmed Fe-O bond; the second and third peak with lower intensity confirmed Fe-P and Fe-Fe bonds, respectively. In addition, the SQUID magnetometer result of LiFeSi0.01P0.99O4/C indicated the antiferromagnetic order temperature of LiFeSi0.01P0.99O4/C at ~51 K with the indication of the presence of impurity and structural distortion.

X-Ray Absorption Analysis of Ge and Ga Environments in Ba-Gallogermante Glasses

1993 ◽  
Vol 307 ◽  
Author(s):  
Celia I. Merzbacher ◽  
David A. McKeown
Keyword(s):  
Bond Length ◽  
Absorption Spectroscopy ◽  
Local Structure ◽  
Octahedral Coordination ◽  
Absorption Analysis ◽  
Tetrahedral Coordination ◽  
X Ray ◽  
X Ray Absorption ◽  
Absorption Edges

ABSTRACTX-ray absorption spectroscopy has been used to characterize the local structure surrounding Ga and Ge in BaO-Ga2O3-GeO2 glasses. Based on comparisons with results for crystalline standards of known structure, Ge and Ga in all of the glasses are primarily in tetrahedral coordination; no evidence for octahedral coordination is observed. Bond length and coordination values derived from fitting calculations are fairly uniform for all glasses, however disorder increases with increase in BaO and decrease in GeO2 content, especially in the second shell surrounding Ge and Ga. Ge absorption edges for all glasses resemble smoothed BGG-An or GeO2 [quartz] edges. Ga absorption edges of the glasses also resemble the BGG-An edge which has two edge maxima, but in the glasses the relative intensities of the two maxima vary with composition.

Study of the local structure and oxidation state of iron in complex oxide catalysts for propylene ammoxidation

2014 ◽  
Vol 4 (8) ◽  
pp. 2512-2519 ◽  
Author(s):  
Li-bin Wu ◽  
Liang-hua Wu ◽  
Wei-min Yang ◽  
Anatoly I. Frenkel
Keyword(s):  
Oxidation State ◽  
Local Structure ◽  
Redox Reactions ◽  
Complex Oxide ◽  
Oxide Catalysts ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Propylene Ammoxidation ◽  
Uv Visible ◽  
X Ray Absorption

A combination of X-ray absorption, Raman and UV-visible spectroscopy reveals the competing redox reactions during the deactivation of Fe-based complex catalysts.

Application of In Situ X-ray Absorption Spectroscopy to Study Dilute Chromium Ions in a Molten Chloride Salt

2019 ◽  
Author(s):  
Jisue Moon ◽  
Carter Abney ◽  
Dmitriy Dolzhnikov ◽  
James M. Kurley ◽  
Kevin A. Beyer ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Local Structure ◽  
Chloride Salt ◽  
X Ray ◽  
Molten Chloride ◽  
Stable Species ◽  
Higher Temperature ◽  
Cr Concentration ◽  
X Ray Absorption

The local structure of dilute CrCl<sub>3</sub> in a molten MgCl<sub>2</sub>:KCl salt was investigated by <i>in situ</i> x-ray absorption spectroscopy (XAS) at temperatures from room temperature to 800<sup>o</sup>C. This constitutes the first experiment where dilute Cr speciation is explored in a molten chloride salt, ostensibly due to the compounding challenges arising from a low Cr concentration in a matrix of heavy absorbers at extreme temperatures. CrCl<sub>3</sub> was confirmed to be the stable species between 200 and 500<sup>o</sup>C, while mobility of metal ions at higher temperature (>700<sup>o</sup>C) prevented confirmation of the local structure.

scholarly journals Local Structure and Dynamics of Functional Materials Studied by X-ray Absorption Fine Structure

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1315
Author(s):  
Takafumi Miyanaga
Keyword(s):  
Fine Structure ◽  
Local Structure ◽  
Chemical Reactivity ◽  
Functional Materials ◽  
X Ray ◽  
Structure And Dynamics ◽  
Absorption Fine ◽  
Structure Phase Transition ◽  
Local Electronic Structure ◽  
X Ray Absorption

X-ray absorption fine structure (XAFS) is a powerful technique used to analyze a local electronic structure, local atomic structure, and structural dynamics. In this review, I present examples of XAFS that apply to the local structure and dynamics of functional materials: (1) structure phase transition in perovskite PbTiO3 and magnetic FeRhPd alloys; (2) nano-scaled fluctuations related to their magnetic properties in Ni–Mn alloys and Fe/Cr thin films; and (3) the Debye–Waller factors related to the chemical reactivity for catalysis in polyanions and ligand exchange reaction. This study shows that the local structure and dynamics are related to the characteristic function of the materials.

scholarly journals Changes of Pd Oxidation State in Pd/Al2O3 Catalysts Using Modulated Excitation DRIFTS

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 116
Author(s):  
Gian Luca Chiarello ◽  
Ye Lu ◽  
Miren Agote-Arán ◽  
Riccardo Pellegrini ◽  
Davide Ferri
Keyword(s):  
Particle Size ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Oxidation State ◽  
Diffuse Reflectance ◽  
X Ray ◽  
Spectral Changes ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption ◽  
Reversible Reduction

Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.

scholarly journals The Study of Magnetic Properties for Non-Magnetic Ions Doped BiFeO3

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4061
Author(s):  
Yongtao Li ◽  
Liqing Liu ◽  
Dehao Wang ◽  
Hongguang Zhang ◽  
Xuemin He ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Local Structure ◽  
Metal Ion ◽  
Single Phase ◽  
Sol Gel ◽  
X Ray ◽  
Co Doping ◽  
Magnetic Ions ◽  
X Ray Absorption ◽  
Fe Ions

BiFeO3 is considered as a single phase multiferroic. However, its magnetism is very weak. We study the magnetic properties of BiFeO3 by Cu and (Cu, Zn). Polycrystalline samples Bi(Fe0.95Cu0.05)O3 and BiFe0.95(Zn0.025Cu0.025)O3 are prepared by the sol-gel method. The magnetic properties of BiFe0.95(Zn0.025Cu0.025)O3 are greater than that of BiFeO3 and Bi(Fe0.95Cu0.05)O3. The analyses of X-ray absorption fine structure data show that the doped Cu atoms well occupy the sites of the Fe atoms. X-ray absorption near edge spectra data confirm that the valence state of Fe ions does not change. Cu and Zn metal ion co-doping has no impact on the local structure of the Fe and Bi atoms. The modification of magnetism by doping Zn can be understood by the view of the occupation site of non-magnetically active Zn2+.

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