XPS spectra of uranyl minerals and synthetic uranyl compounds. I: The U 4f spectrum

Schindler, Michael; Hawthorne, Frank C.; Freund, Michael S.; Burns, Peter C.

doi:10.1016/j.gca.2008.10.042

Cited by 143 publications

(101 citation statements)

References 62 publications

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“…Important for this study is the observed chemical shift of the U 6+ band in U 4 f 7/2 spectra for uranyl-hydroxyhydrate minerals. Here, Schindler et al [27] showed that the U 6+ band for uranyl-hydroxy-hydrate compounds with no or small portions of monovalent interstitial cations occurs at 382.0-382.3 eV while the same band occurs at 381.0-381.6 eV in the spectra of uranyl-hydroxy-hydrate minerals with divalent interstitial cations.…”

Section: +mentioning

confidence: 83%

“…Previously reported binding energies for U 6+ , U 5+ and U 4+ in the U 4 f 7/2 peaks of uranyl minerals and mixed-valent U-compounds were used to identify the different U-bands. Separations between the bands are similar for many compounds and have average values of 0.9 for U 6+ -U 5+ and 0.6 eV for U 5+ -U 4+ [27]. Schindler et al [27] showed that the chemical shifts of the U 6+ and U 4+ bands in the U 4 f 7/2 peak for uranyl minerals are between 381.0-382.3 and 380.2-380.7 eV, respectively.…”

Section: General Composition Of the Surfacementioning

confidence: 99%

“…Separations between the bands are similar for many compounds and have average values of 0.9 for U 6+ -U 5+ and 0.6 eV for U 5+ -U 4+ [27]. Schindler et al [27] showed that the chemical shifts of the U 6+ and U 4+ bands in the U 4 f 7/2 peak for uranyl minerals are between 381.0-382.3 and 380.2-380.7 eV, respectively. Here, the average binding energies of the U 6+ and U…”

Section: General Composition Of the Surfacementioning

confidence: 99%

“…Spectra were recorded using 20 sweeps, scan rates per sweep of 200 ms with analyzer pass-energies of 80 and 160 eV and with an aperture size of 55 μm. Resolution for the different pass-energies and aperture and their effect on the FWHM values (FWHM = full width at half maximum) of the U 4 f and O 1s peaks are described in detail in Schindler et al [27,28]. Shirley background corrections [29], Gaussian-Lorentzian peak shapes and asymmetric peak shapes were used to fit the U 4 f and O 1s spectra, respectively.…”

Section: Surface Composition Analysis By X-ray Photoelectron Spectrosmentioning

confidence: 99%

“…They were constrained to be equal in each individual spectrum. Additional details on fitting procedure and characteristic binding energies for U 6+ bands in other uranyl minerals can be found in Schindler et al [27].…”

Section: +mentioning

confidence: 99%

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An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Schindler¹,

Hawthorne

Mandaliev

et al. 2011

Radiochimica Acta

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Summary.Understanding the mechanism(s) of uraniummineral dissolution is crucial for predictive modeling of U mobility in the subsurface. In order to understand how pH and type of cation in solution may affect dissolution, experiments were performed on mainly single crystals of curite, PbSolutions included: deionized water; aqueous HCl solutions at pH 3.5 and 2; 0.5 mol L −1 Pb(II)-, Ba-, Sr-, Ca-, Mg-, HCl solutions at pH 2; 1.0 mol L −1 Na-and K-HCl solutions at pH 2; and a 0.1 mol L −1 Na 2 CO 3 solution at pH 10.5. Uranyl mineral basal surface microtopography, micromorphology, and composition were examined prior to, and after dissolution experiments on micrometer scale specimens using atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Evolution of etch pit depth at different pH values and experimental durations can be explained using a stepwave dissolution model. Effects of the cation in solution on etch pit symmetry and morphology can be explained using an adsorption model involving specific surface sites. Surface precipitation of the following phases was observed: (a) a highly-hydrated uranyl-hydroxy-hydrate in ultrapure water (on all minerals), (b) a Na-uranyl-hydroxy-hydrate in Na 2 CO 3 solution of pH 10.5 (on uranyl-hydroxy-hydrate minerals), (c) a Na-uranyl-carbonate on zippeite, (d) Ba-and Pb-uranylhydroxy-hydrates in Ba-HCl and Pb-HCl solutions of pH 2 (on uranophane), (e) a (SiO x (OH) 4−2x ) phase in solutions of pH 2 (uranophane), and (f) sulfate-bearing phases in solutions of pH 2 and 3.5 (on zippeite).

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Section: +mentioning

confidence: 83%

Section: General Composition Of the Surfacementioning

confidence: 99%

Section: General Composition Of the Surfacementioning

confidence: 99%

Section: Surface Composition Analysis By X-ray Photoelectron Spectrosmentioning

confidence: 99%

Section: +mentioning

confidence: 99%

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An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Schindler¹,

Hawthorne

Mandaliev

et al. 2011

Radiochimica Acta

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Coordination‐Induced Magnetism Strategy for Highly Selective and Efficient Uranium Separation

Zhao,

Feng,

Zhang

et al. 2024

Advanced Science

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Highly efficient separation of dispersed uranium is important for the sustainable development of nuclear industry, and adsorption is the most recognized approach. However, there are many coexisting interfering metal ions that compete with uranyl ion for the chelating ligands in the adsorbents and lead to low separation selectivity and efficiency. Herein, a coordination‐induced magnetism strategy is presented for the separation of uranium based on the conversion of diamagnetic cyanoferrocene (Fc‐CN) nanocrystals to uranium‐containing magnetic recoverable ferromagnetic aggregates. Different from previous adsorption strategies, this strategy combines the mechanisms of photocatalytic uranium enrichment and chemical uranium adsorption. Under light irradiation, electron of Fe(II) in Fc‐CN is excited and transfers to uranyl ion via the cyano group to form tight coordination bond between N atom in cyano group and uranium. This phenomenon is unique for uranyl ion, and thus, a high uranium removal rate of 97.98% is achieved in simulated nuclear wastewater with the presence of tremendous interfering ions, proving its highly selective and efficient uranium separation performance. The ability to form highly stable magnetic aggregates via photoinduced interaction between Fc‐CN and uranium enriches the understanding on the chemical properties of Fc‐CN and uranium.

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Temperature‐dependent Variations of the Interface between UO₂ and Zr

Youn

Kim

Park

et al. 2015

Bulletin Korean Chem Soc

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Temperature‐dependent variations of the interface between uranium dioxide and zirconium in UO2 ‐Zr systems were studied using X‐ray photoelectron spectroscopy. The surface of the uranium dioxide sample was oxidized to hyperstoichiometric UO 2+x composed of U(IV), U(V), and U(VI) valence states at room temperature, whereas UO2 consisting of the only U(IV) oxidation state appeared after annealing with zirconium. In the zirconium sample, its surface was spontaneously oxidized to ZrO2 at room temperature, whereas it was variously changed after heating the UO2 ‐Zr sample. Furthermore, we observed a molten product composed of α‐Zr(O), (U,Zr)O2 , and ZrO2 when a UO2 ‐Zr sample was fully melted.

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XPS spectra of uranyl minerals and synthetic uranyl compounds. I: The U 4f spectrum

Cited by 143 publications

References 62 publications

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Coordination‐Induced Magnetism Strategy for Highly Selective and Efficient Uranium Separation

Temperature‐dependent Variations of the Interface between UO₂ and Zr

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XPS spectra of uranyl minerals and synthetic uranyl compounds. I: The U 4f spectrum

Cited by 143 publications

References 62 publications

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

An integrated study of uranyl mineral dissolution processes: etch pit formation, effects of cations in solution, and secondary precipitation

Coordination‐Induced Magnetism Strategy for Highly Selective and Efficient Uranium Separation

Temperature‐dependent Variations of the Interface between UO2 and Zr

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Temperature‐dependent Variations of the Interface between UO₂ and Zr