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Synthesis, characterization, and crystal structure of dominant uranium(V) brannerites in the UTi2–xAlxO6 system

DOI: 10.1021/acs.inorgchem.1c02733 DOI Help

Authors: Malin C. Dixon Wilkins (University of Sheffield) , Lucy M. Mottram (University of Sheffield) , Ewan R. Maddrell (National Nuclear Laboratory,) , Martin C. Stennett (University of Sheffield) , Claire L. Corkhill (University of Sheffield) , Kristina O. Kvashnina (European Synchrotron Radiation Facility (ESRF); Helmholtz-Zentrum Dresden-Rossendorf) , Neil C. Hyatt (University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Inorganic Chemistry , VOL 6

State: Published (Approved)
Published: November 2021
Diamond Proposal Number(s): 24074

Abstract: The synthesis, characterization, and crystal structure of a novel (dominant) uranium(V) brannerite of composition U1.09(6)Ti1.29(3)Al0.71(3)O6 is reported, as determined from Rietveld analysis of the high-resolution neutron powder diffraction data. Examination of the UTi2–xAlxO6 system demonstrated the formation of brannerite-structured compounds with varying Al3+ and U5+ contents, from U0.93(6)Ti1.64(3)Al0.36(3)O6 to U0.89(6)Ti1.00(3)Al1.00(3)O6. Substitution of Al3+ for Ti4+, with U5+ charge compensation, resulted in near-linear changes in the b and c unit cell parameters and the overall unit cell volume, as expected from ionic radii considerations. The presence of U5+ as the dominant oxidation state in near-single-phase brannerite compositions was evidenced by complementary laboratory U L3-edge and high-energy-resolution fluorescence-detected U M4-edge X-ray absorption near-edge spectroscopy. No brannerite phase was found for compositions with Al3+/Ti4+ > 1, which would require a U6+ contribution for charge compensation. These data expand the crystal chemistry of uranium brannerites to the stabilization of dominant uranium(V) brannerites by the substitution of trivalent cations, such as Al3+, on the Ti4+ site.

Journal Keywords: X-ray absorption near edge spectroscopy; Oxides; Oxidation state; Chemical structure; Materials

Subject Areas: Chemistry, Materials

Instruments: B18-Core EXAFS

Other Facilities: HRPD at ISIS; BM20 at ESRF

Added On: 19/11/2021 08:26

Discipline Tags:

Earth Sciences & Environment Radioactive Materials Chemistry Materials Science Nuclear Waste Inorganic Chemistry

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) X-ray Absorption Near Edge Structure (XANES)