Journal ArticleDOI
Local Structure and Charge Distribution in the UO2−U4O9 System
Steven D. Conradson,Dario Manara,Franck Wastin,David Clark,Gerard H. Lander,Luis A. Morales,Jean Rebizant,Vincenzo V. Rondinella +7 more
TLDR
In this paper, X-ray absorption fine structure spectra of UO(2+x) for x = 0-0.74 A were analyzed and it was shown that the adventitious O atoms are incorporated as oxo groups with U--O distances of 1.20.Abstract:
Analysis of X-ray absorption fine structure spectra of UO(2+x) for x = 0-0.20 (UO(2)--U(4)O(9)) reveals that the adventitious O atoms are incorporated as oxo groups with U--O distances of 1.74 A, most likely associated with U(VI), that occur in clusters so that the UO(2) fraction of the material largely remains intact. In addition to the formation of some additional longer U--O bonds, the U sublattice consists of an ordered portion that displays the original U--U distance and a spectroscopically silent, glassy part. This is very different from previous models derived from neutron diffraction that maintained long U--O distances and high U--O coordination numbers. UO(2+x) also differs from PuO(2+x) in its substantially shorter An-oxo distances and no sign of stable coordination with H(2)O and its hydrolysis products.read more
Citations
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Journal ArticleDOI
Biogenic Uraninite Nanoparticles and Their Importance for Uranium Remediation
TL;DR: In this paper, the role of size as a moderator of nanoparticle aqueous reactivity and for the bioremediation of subsurface U(VI) contamination was investigated.
Journal ArticleDOI
Trends in covalency for d- and f-element metallocene dichlorides identified using chlorine K-edge X-ray absorption spectroscopy and time-dependent density functional theory.
Stosh A. Kozimor,Ping Yang,Enrique R. Batista,Kevin S. Boland,Carol J. Burns,David Clark,Steven D. Conradson,Richard L. Martin,Marianne P. Wilkerson,Laura E. Wolfsberg +9 more
TL;DR: Results show that the orbital mixing for the d-block compounds slightly decreases in covalency with increasing principal quantum number, in the order Ti > Zr approximately = Hf, and that uranium displays approximately half the covalent orbital mixing of transition elements.
Journal ArticleDOI
Products of abiotic U(VI) reduction by biogenic magnetite and vivianite
Harish Veeramani,Daniel S. Alessi,Elena I. Suvorova,Juan S. Lezama-Pacheco,Joanne E. Stubbs,Jonathan O. Sharp,Urs Dippon,Andreas Kappler,John R. Bargar,Rizlan Bernier-Latmani +9 more
TL;DR: In this article, the DMRB Shewanella putrefaciens strain CN32 was used to synthesize two biogenic Fe(II)-bearing minerals: magnetite and vivianite.
Journal ArticleDOI
Structure of biogenic uraninite produced by Shewanella oneidensis strain MR-1.
Eleanor J. Schofield,Harish Veeramani,Jonathan O. Sharp,Elena I. Suvorova,Rizlan Bernier-Latmani,Apurva Mehta,Jonathan Stahlman,Samuel M. Webb,David Clark,Steven D. Conradson,Eugene S. Ilton,John R. Bargar +11 more
TL;DR: The detailed structural analysis in this study provides an essential foundation for subsequent investigations of environmental samples and suggests that established thermodynamic parameters for the latter material are an appropriate starting point to model the behavior of nanobiogenic uraninite.
Journal ArticleDOI
Uranium Redox Transformations after U(VI) Coprecipitation with Magnetite Nanoparticles
I. Pidchenko,Kristina O. Kvashnina,Tadahiro Yokosawa,Nicolas Finck,S. Bahl,Dieter Schild,Robert Polly,Elke Bohnert,André Rossberg,Jörg Göttlicher,Kathy Dardenne,Jörg Rothe,Thorsten Schäfer,Horst Geckeis,Tonya Vitova +14 more
TL;DR: It is demonstrated that the U M4 high energy resolution X-ray absorption near edge structure (HR-XANES) method is capable to clearly characterize U(IV), U(V), and U(VI) existing simultaneously in the same sample.
References
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Book
EXAFS: Basic Principles and Data Analysis
TL;DR: In this article, the authors proposed a method for the generation of X-Rays and electrons using wave-particle duality of photons and wave-wave spectroscopy.
Journal ArticleDOI
Number of relevant independent points in x-ray-absorption fine-structure spectra
TL;DR: It is shown that the usual formulations of x-ray-absorption fine-structure spectra underestimate the degrees of freedom by at least one.
Journal ArticleDOI
Relativistic calculations of spin-dependent x-ray-absorption spectra
A. L. Ankudinov,John J. Rehr +1 more
TL;DR: In this article, an efficient interpolative approach is presented for relativistic calculations of polarized x-ray-absorption spectra (XAS) including spin and spin-orbit interactions, based on a spinor-relativistic Dirac-Fock treatment of atomic densities and dipole matrix elements.
Journal ArticleDOI
A review of the oxidation of uranium dioxide at temperatures below 400°C
TL;DR: A critical review of the extensive literature on the air oxidation of UO2 at temperatures below 400°C is presented in this article, where the key parameters that affect the rate of air oxidation are examined systematically and their importance to the reaction rate is evaluated.
Book ChapterDOI
Electronic structure and bonding in actinyl ions
TL;DR: In this paper, the Inverse trans influence is introduced in the context of the actinide-oxygen bond and the experimental energy level scheme is compared with the results of molecular orbital calculations of varying degrees of sophistication, the most successful being SCF calculations incorporating the effects of relativity.
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