Characterization of Uranium Speciation in a Metallic Matrix

2002 ◽  
Vol 757 ◽  
Author(s):  
Gini Curran ◽  
Patrick G. Allen ◽  
Daniel F. Caputo ◽  
Ken R. Czerwinski
Keyword(s):  
Gamma Spectroscopy ◽  
Metallic Matrix ◽  
Elemental Content ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Uranium Speciation ◽  
Icp Ms ◽  
High Concentrations ◽  
X Ray Absorption

ABSTRACTThree metallic slag samples recovered from the site of their inadvertent creation several decades after the fact were sectioned and analyzed to determine uranium speciation to evaluate environmental behavior as well as assess proliferation resistance of the waste form. Uranium concentration in the highly inhomogeneous samples was up to 5% by weight as determined by gamma spectroscopy. Sample sections were milled in a hardened steel ball mill for x-ray absorption spectroscopy analysis (XAS). Powders were digested in a mixture of heated concentrated nitric acid and peroxide and analyzed for elemental content using ICP-AES and ICP-MS. Though elemental content of the samples varied widely, high concentrations of Al were consistently found. Other metals of significance were Ti, Fe, Ni, Cu, Zn, and Sn. High Pb concentrations were occasionally found. XAS analysis revealed the samples contained primarily uranyl and another phase identified as a uranium-aluminum melt.

scholarly journals A multi-method characterization of natural terrestrial birnessites

2020 ◽  
Vol 105 (6) ◽  
pp. 833-847
Author(s):  
Florence T. Ling ◽  
Jeffrey E. Post ◽  
Peter J. Heaney ◽  
Cara M. Santelli ◽  
Eugene S. Ilton ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Large Set ◽  
X Ray Diffraction ◽  
Full Spectrum ◽  
X Ray ◽  
High Concentrations ◽  
Diffraction Patterns ◽  
X Ray Absorption ◽  
Crystal Structure And Chemistry

Abstract With a focus on a large set of natural birnessites collected from terrestrial, freshwater systems, we applied and compared the capabilities of X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) to characterize crystal structure and chemistry. Using XRD, we successfully identified 3 of the 11 natural birnessite samples as hexagonal ranciéite-like phases, but the remaining samples yielded less interpretable “3-line” diffraction patterns with broad, asymmetrical peaks at d-spacings of ~7.2, ~2.4, and ~1.4 Å. EXAFS analysis suggested that many of these samples had characteristics of both triclinic and hexagonal birnessite. However, application of EXAFS to the ranciéite-like phases yielded unreasonably high concentrations of triclinic birnessite as an intergrowth, calling into question the use of synthetic hexagonal H-birnessite as an appropriate standard in the linear combination fitting of EXAFS data for natural birnessites. FTIR spectroscopy of the “3-line” birnessite samples successfully distinguished triclinic and hexagonal constituents, and analyses of peak positions suggested that natural birnessites occur as a full spectrum of triclinic and hexagonal intergrowths. XPS analysis of these samples revealed that higher Mn3+ concentrations relative to Mn2+ and Mn4+ are correlated to increased proportions of triclinic birnessite.

EXELFS Studies of Carbon Fibers

1990 ◽  
Vol 48 (2) ◽  
pp. 72-73
Author(s):  
V. Serin ◽  
K. Hssein ◽  
G. Zanchi ◽  
J. Sévely
Keyword(s):  
Carbon Fibers ◽  
Energy Analysis ◽  
Electron Excitation ◽  
Complex Structures ◽  
High Modulus ◽  
Promising Technique ◽  
X Ray ◽  
Fine Structures ◽  
X Ray Absorption

The present developments of electron energy analysis in the microscopes by E.E.L.S. allow an accurate recording of the spectra and of their different complex structures associated with the inner shell electron excitation by the incident electrons (1). Among these structures, the Extended Energy Loss Fine Structures (EXELFS) are of particular interest. They are equivalent to the well known EXAFS oscillations in X-ray absorption spectroscopy. Due to the EELS characteristic, the Fourier analysis of EXELFS oscillations appears as a promising technique for the characterization of composite materials, the major constituents of which are low Z elements. Using EXELFS, we have developed a microstructural study of carbon fibers. This analysis concerns the carbon K edge, which appears in the spectra at 285 eV. The purpose of the paper is to compare the local short range order, determined by this way in the case of Courtauld HTS and P100 ex-polyacrylonitrile carbon fibers, which are high tensile strength (HTS) and high modulus (HM) fibers respectively.

scholarly journals Database of ab initio L-edge X-ray absorption near edge structure

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yiming Chen ◽  
Chi Chen ◽  
Chen Zheng ◽  
Shyam Dwaraknath ◽  
Matthew K. Horton ◽  
...  
Keyword(s):  
High Throughput ◽  
Scattering Theory ◽  
Research Community ◽  
Metal Compounds ◽  
Edge Structure ◽  
X Ray ◽  
Initial Release ◽  
Computational Workflow ◽  
X Ray Absorption

AbstractThe L-edge X-ray Absorption Near Edge Structure (XANES) is widely used in the characterization of transition metal compounds. Here, we report the development of a database of computed L-edge XANES using the multiple scattering theory-based FEFF9 code. The initial release of the database contains more than 140,000 L-edge spectra for more than 22,000 structures generated using a high-throughput computational workflow. The data is disseminated through the Materials Project and addresses a critical need for L-edge XANES spectra among the research community.

Characterization of Silver Binding in Cryptomelane by X-ray Absorption Spectroscopy

1998 ◽  
Vol 524 ◽  
Author(s):  
R. Ravikumar ◽  
D. W. Fuerstenau ◽  
G. A. Waychunas
Keyword(s):  
Manganese Oxide ◽  
Silver Ions ◽  
Oxide Phase ◽  
Synthetic Sample ◽  
Temperature Spectrum ◽  
X Ray ◽  
Room Temperature Sample ◽  
X Ray Absorption ◽  
Temperature Sample

ABSTRACTUsing silver K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, two different samples of silver-containing manganese oxide were analyzed in the fluorescence mode. For the first sample, silver ions from solution were sorbed onto one synthetic manganese oxide phase, namely cryptomelane (KxMn8O16, where l<x<2). The second sample was a silvermanganese oxide from Colorado. From the EXAFS analysis, silver was found to occupy two different sites in the synthetic sample. The natural samples from Colorado also exhibited a very similar coordination distances as the synthetic samples. In the low temperature spectrum of the synthetic sample at 10 K, the Ag-O peak was found to be missing and the amplitude of the Ag- Ag peak was approximately three times larger than the corresponding room temperature sample.

Characterization of As-doped, p-type ZnO by x-ray absorption near-edge structure spectroscopy: Theory

2006 ◽  
Vol 89 (22) ◽  
pp. 222113 ◽  
Author(s):  
Sukit Limpijumnong ◽  
M. F. Smith ◽  
S. B. Zhang
Keyword(s):  
Edge Structure ◽  
X Ray ◽  
P Type ◽  
X Ray Absorption

Deposition of TRISO Particles With Superhard SiC Coatings and the Characterization of Anisotropy by Raman Spectroscopy

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
E. López-Honorato ◽  
P. J. Meadows ◽  
J. Tan ◽  
Y. Xiang ◽  
P. Xiao
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Pyrolytic Carbon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flat Substrate ◽  
High Concentrations ◽  
Triso Particles ◽  
Sic Coatings

In this work we have deposited silicon carbide (SiC) at 1300°C with the addition of small amounts of propylene. The use of propylene and high concentrations of methyltrichlorosilane (9 vol %) allowed the deposition of superhard SiC coatings (42 GPa). The superhard SiC could result from the presence of a SiC–C solid solution, undetectable by X-ray diffraction but visible by Raman spectroscopy. Another sample obtained by the use of 50 vol % Argon, also showed the formation of SiC with good properties. The use of a flat substrate together with the particles showed the importance of carrying out the analysis on actual particles rather than in flat substrates. We show that it is possible to characterize the anisotropy of pyrolytic carbon by Raman spectroscopy.

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