A multimodal X-ray spectroscopy investigation of uranium speciation in ThTi 2 O 6 compounds with the brannerite structure.

Autor: Dixon Wilkins MC; Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.; School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USA., Townsend LT; Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK., Stennett MC; Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK., Kvashnina KO; The Rossendorf Beamline at ESRF, CS 40220, 38043, Grenoble Cedex 9, France.; Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328, Dresden, Germany., Corkhill CL; Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK. c.corkhill@sheffield.ac.uk.; School of Earth Sciences, The University of Bristol, Bristol, BS8 1RL, UK. c.corkhill@sheffield.ac.uk., Hyatt NC; Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.; School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USA.; School of Earth Sciences, The University of Bristol, Bristol, BS8 1RL, UK.
Jazyk: angličtina
Zdroj: Scientific reports [Sci Rep] 2023 Aug 07; Vol. 13 (1), pp. 12776. Date of Electronic Publication: 2023 Aug 07.
DOI: 10.1038/s41598-023-38912-1
Abstrakt: ThTi 2 O 6 derived compounds with the brannerite structure were designed, synthesised, and characterised with the aim of stabilising incorporation of U 5+ or U 6+ , at dilute concentration. Appropriate charge compensation was targeted by co-substitution of Gd 3+ , Ca 2+ , Al 3+ , or Cr 3+ , on the Th or Ti site. U L 3 edge X-ray Absorption Near Edge Spectroscopy (XANES) and High Energy Resolution Fluorescence Detected U M 4 edge XANES evidenced U 5+ as the major oxidation state in all compounds, with a minor fraction of U 6+ (2-13%). The balance of X-ray and Raman spectroscopy data support uranate, rather than uranyl, as the dominant U 6+ speciation in the reported brannerites. It is considered that the U 6+ concentration was limited by unfavourable electrostatic repulsion arising from substitution in the octahedral Th or Ti sites, which share two or three edges, respectively, with neighbouring polyhedra in the brannerite structure.
(© 2023. Springer Nature Limited.)
Databáze: MEDLINE
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