Spectroscopic characterization of neptunium(VI), plutonium(VI), americium(VI) and neptunium(V) encapsulated in uranyl nitrate hexahydrate

Journal Article · 13 May 2021 · Physical Chemistry Chemical Physics. PCCP

DOI: https://doi.org/10.1039/D1CP01047 · OSTI ID:1798329

Yu, Xiaojuan ^[1]; Einkauf, Jeffrey ^[2]; Bryantsev, Vyacheslav S. ^[2]; Cheshire, Michael C. ^[2]; Reinhart, Benjamin J. ^[3]; Autschbach, Jochen ^[1]; Burns, Jonathan D. ^[4]

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1. State Univ. of New York (SUNY), Buffalo, NY (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Argonne National Lab. (ANL), Argonne, IL (United States)
4. Texas A & M Univ., College Station, TX (United States)

The coordination of crystalline products resulting from the co-crystallization of Np(VI), Pu(VI), Am(VI), and Np(V) with uranyl nitrate hexahydrate (UNH) has been revealed through solid-state spectroscopic characterization via diffuse reflectance UV-Vis-NIR spectroscopy, SEM-EDS, and extended X-ray absorption fine structure (EXAFS) spectroscopy. Density functional and multireference wavefunction calculations were performed to analyze the An(VI/V)O₂(NO₃)₂·2H₂O electronic structures and to help assign the observed transitions in the absorption spectra. EXAFS show a similar coordination between the U(VI) in UNH and Np(VI) and Pu(VI); while Am resulted in a similar coordination to Am(III), as reduction of Am(VI) occurred prior to EXAFS data being obtained. Finally, the co-crystallization of the oxidized transuranic species—penta- and hexavalent—with UNH, represents a significant advance from not only a practical standpoint in providing an elegant solution for used nuclear fuel recycle, but also as an avenue to expand the fundamental understanding of the 5f electronic behavior in the solid-state.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
• Grant/Contract Number: AC02-06CH11357; NE0008653; SC0001136
• OSTI ID: 1798329
• Journal Information: Physical Chemistry Chemical Physics. PCCP, Journal Name: Physical Chemistry Chemical Physics. PCCP Journal Issue: 23 Vol. 2021; ISSN 1463-9076
• Publisher: Royal Society of ChemistryCopyright Statement
• Country of Publication: United States
• Language: English

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