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Yu Y, Hao Y, Xiao B, Langer E, Novikov SA, Ramanantoanina H, Pidchenko I, Schild D, Albrecht-Schoenzart TE, Eichel RA, Vitova T, Alekseev EV. U(V) Stabilization via Aliovalent Incorporation of Ln(III) into Oxo-salt Framework. Chemistry 2024; 30:e202401033. [PMID: 38775406 DOI: 10.1002/chem.202401033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Indexed: 06/29/2024]
Abstract
Pentavalent uranium compounds are key components of uranium's redox chemistry and play important roles in environmental transport. Despite this, well-characterized U(V) compounds are scarce primarily because of their instability with respect to disproportionation to U(IV) and U(VI). In this work, we provide an alternate route to incorporation of U(V) into a crystalline lattice where different oxidation states of uranium can be stabilized through the incorporation of secondary cations with different sizes and charges. We show that iriginite-based crystalline layers allow for systematically replacing U(VI) with U(V) through aliovalent substitution of 2+ alkaline-earth or 3+ rare-earth cations as dopant ions under high-temperature conditions, specifically Ca(UVIO2)W4O14 and Ln(UVO2)W4O14 (Ln=Nd, Sm, Eu, Gd, Yb). Evidence for the existence of U(V) and U(VI) is supported by single-crystal X-ray diffraction, high energy resolution X-ray absorption near edge structure, X-ray photoelectron spectroscopy, and optical absorption spectroscopy. In contrast with other reported U(V) materials, the U(V) single crystals obtained using this route are relatively large (several centimeters) and easily reproducible, and thus provide a substantial improvement in the facile synthesis and stabilization of U(V).
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Affiliation(s)
- Yi Yu
- School of Physics and Electronics information, Gannan Normal University, Ganzhou, 341000, PR China
| | - Yucheng Hao
- School of Energy Materials and Chemical Engineering, Hefei University, Hefei, 230000, PR China
| | - Bin Xiao
- Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, D-52428, Jülich, Germany
| | - Eike Langer
- Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, D-52428, Jülich, Germany
| | - Sergei A Novikov
- Department of Chemistry, University of Georgia, 302 East Campus Road, Athens, GA 30602, USA
| | - Harry Ramanantoanina
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, D-76125, Karlsruhe, Germany g
| | - Ivan Pidchenko
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, D-76125, Karlsruhe, Germany g
| | - Dieter Schild
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, D-76125, Karlsruhe, Germany g
| | - Thomas E Albrecht-Schoenzart
- Department of Chemistry and Nuclear Science and Engineering Center, Colorado School of Mines, Golden, Colorado, 80401, USA
| | - Rüdiger-A Eichel
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, D-52428, Jülich, Germany
| | - Tonya Vitova
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, D-76125, Karlsruhe, Germany g
| | - Evgeny V Alekseev
- Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, D-52428, Jülich, Germany
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2
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Verma PK, Mahanty B, Bhattacharyya A, Matveev PI, Borisova NE, Kalmykov SN, Mohapatra PK. Pyridine Diphosphonate Ligand for Stabilization of Tetravalent Uranium and Neptunium in Aqueous Medium under Aerobic Conditions. Inorg Chem 2024; 63:3348-3358. [PMID: 38320960 DOI: 10.1021/acs.inorgchem.3c03840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Though uranium is usually present in its +6 oxidation state (as uranyl ion) in aqueous solutions, its conversion to oxidation states such as +4 or +5 is a challenging task. Electrochemical reduction and axial oxo activation are the preferred methods to get stable unusual oxidation states of uranium in an aqueous medium. In previous studies, dicarboxylic acid has been used to stabilize UO2+ in aqueous alkaline solutions. In the present work, a diphosphonate ligand was chosen due to its higher complexing ability compared to that of the carboxylate ligands. Neptunium complexation studies with 2,6-pyridinediphosphonic acid (PyPOH) indicated the formation of different species at different pH values and the complexation facilitates disproportionation of NpO2+ to Np4+ and NpO22+ at pH 2. Hexavalent actinides form insoluble complexes in aqueous media at pH = 2, as confirmed by UO22+ complexation studies. The in situ complexation-driven precipitation resulted in conversion to pure Np4+ in aqueous media as the Np4+-PyPOH complex. A strong complexing ability of the PyPOH ligand toward the Np4+ ion is also seen for the stabilization of the electrochemically generated U4+ in aqueous medium under aerobic conditions. The U4+-PyPOH complex was found to be stable for 3 months. Raman, UV-vis, fluorescence, and cyclic voltametric studies along with density functional theory (DFT) calculations were done to get structural insights into the PyPOH complexes of actinides in different oxidation states.
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Affiliation(s)
- Parveen Kumar Verma
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Bholanath Mahanty
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Arunasis Bhattacharyya
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Petr I Matveev
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia
| | - Nataliya E Borisova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia
| | - Stepan N Kalmykov
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991, Russia
| | - Prasanta Kumar Mohapatra
- Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
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3
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El Monjid A, Szenknect S, Mesbah A, Hunault MOJY, Menut D, Clavier N, Dacheux N. Incorporation of U(IV) in monazite-cheralite ceramics under oxidizing and inert atmospheres. Dalton Trans 2024; 53:2252-2264. [PMID: 38193888 DOI: 10.1039/d3dt03251e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
This work is the first attempt to prepare Nd1-xCaxUxPO4 monazite-cheralite with 0 < x ≤ 0.1 by a wet chemistry method. This method relies on the precipitation under hydrothermal conditions (T = 110 °C for four days) of the Nd1-xCaxUxPO4·nH2O rhabdophane precursor, followed by its thermal conversion for 6 h at 1100 °C in air or Ar atmosphere. The optimized synthesis protocol led to the incorporation of U and Ca in the rhabdophane structure. After heating at 1100 °C for 6 h in air, single-phase monazite-cheralite samples were obtained. However, α-UP2O7 was identified as a secondary minor phase in the samples heated under Ar atmosphere. The U speciation in the samples converted in an oxidising atmosphere was carefully characterized using synchrotron radiation by combining HERFD-XANES and XRD. These results showed the presence of a minor secondary phase containing hexavalent uranium and phosphate with a stoichiometry of U : P = 0.78. This highly labile uranyl phosphate phase incorporated 21 mol% of the uranium initially precipitated with the rhabdophane precursor. This phase was completely removed by a washing protocol. Thus, single-phase monazite-cheralite was obtained through the wet chemistry route described in this work with a maximum U loading of x = 0.08.
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Affiliation(s)
- Alison El Monjid
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
| | - Stéphanie Szenknect
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
| | - Adel Mesbah
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, France
| | | | - Denis Menut
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Nicolas Clavier
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
| | - Nicolas Dacheux
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
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Balhara A, Gupta SK, Modak B, Annadata HV, Patra GD, Tyagi D, Ghosh B. Local Structure and Speciation-Driven UO 22+ → Sm 3+ Energy Transfer for Enhanced Luminescence in Li 2B 4O 7. Inorg Chem 2023. [PMID: 38033302 DOI: 10.1021/acs.inorgchem.3c03202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Herein, we report the uranyl sensitization of Sm3+ emissions in uranium-codoped Li2B4O7:Sm3+ phosphor. The uranyl speciation in codoped [Sm, U] LTB samples was determined by synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy that revealed two coordination shells for U(VI) ions with bond distances of U-Oax (∼1.81 Å) and U-Oeq (∼2.30 Å). EXAFS fitting suggested that the uranyl moiety is present as pentagonal bipyramids (UO7) and hexagonal bipyramids (UO8) with five and six equatorial oxygen ligands, respectively. The alteration of the local structure of Sm3+ from [SmO4] to [SmO7] polyhedra and the changes in the coordination number of equatorial oxygen for uranyl were observed with different codoping concentrations of Sm3+ and uranium. Density functional theory (DFT) calculations suggested the lowering of defect formation energy for Li vacancies on codoping of Sm and U. Hence, we proposed the increase of the equatorial coordination number of UO22+ on the increase in the lithium vacancies in LTB. In addition, DFT supported the feasibility of efficient energy transfer (ET) due to the overlap of uranium and Sm3+ excited state levels. The influence of the same on the spectral features and UO22+ → Sm3+ energy transfer was investigated by time-resolved photoluminescence (PL) studies. The ET efficiency from the UO22+ to Sm3+ was 70.5% in 0.5 mol % codoped [Sm, U] LTB samples. The correlation of EXAFS and luminescence properties indicated a red shift in vibronic features of uranyl emission with increase in the equatorial coordination of the uranyl moiety from five to six. Additionally, a higher probability of ET was observed for uranyl speciation as UO8 hexagonal bipyramids. Temperature-dependent emissions and decay profiles were collected under uranyl excitation to investigate the thermal dependence of ET. A high energy barrier (Ea ∼ 4027 cm-1) was evaluated for the thermal quenching of Sm3+ emissions. This work provides insights into the modulation of luminescence and ET efficiency via structural changes in uranyl and Sm local environment in LTB phosphor.
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Affiliation(s)
- Annu Balhara
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Santosh K Gupta
- Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Brindaban Modak
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Harshini V Annadata
- Beamline Development & Application Section, Bhabha Atomic Research Center, Mumbai 400085, India
| | - Giri Dhari Patra
- Technical Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Deepak Tyagi
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
| | - Biplab Ghosh
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
- Beamline Development & Application Section, Bhabha Atomic Research Center, Mumbai 400085, India
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Dixon Wilkins MC, Townsend LT, Stennett MC, Kvashnina KO, Corkhill CL, Hyatt NC. A multimodal X-ray spectroscopy investigation of uranium speciation in ThTi 2O 6 compounds with the brannerite structure. Sci Rep 2023; 13:12776. [PMID: 37550380 PMCID: PMC10406819 DOI: 10.1038/s41598-023-38912-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 07/17/2023] [Indexed: 08/09/2023] Open
Abstract
ThTi2O6 derived compounds with the brannerite structure were designed, synthesised, and characterised with the aim of stabilising incorporation of U5+ or U6+, at dilute concentration. Appropriate charge compensation was targeted by co-substitution of Gd3+, Ca2+, Al3+, or Cr3+, on the Th or Ti site. U L3 edge X-ray Absorption Near Edge Spectroscopy (XANES) and High Energy Resolution Fluorescence Detected U M4 edge XANES evidenced U5+ as the major oxidation state in all compounds, with a minor fraction of U6+ (2-13%). The balance of X-ray and Raman spectroscopy data support uranate, rather than uranyl, as the dominant U6+ speciation in the reported brannerites. It is considered that the U6+ 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.
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Affiliation(s)
- Malin C Dixon Wilkins
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USA
| | - Luke T Townsend
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK
| | - Martin C Stennett
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK
| | - Kristina O Kvashnina
- 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
| | - Claire L Corkhill
- Department of Materials Science and Engineering, University of Sheffield, Sheffield, UK.
- School of Earth Sciences, The University of Bristol, Bristol, BS8 1RL, UK.
| | - Neil C Hyatt
- 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
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6
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Misael WA, Severo Pereira Gomes A. Core Excitations of Uranyl in Cs 2UO 2Cl 4 from Relativistic Embedded Damped Response Time-Dependent Density Functional Theory Calculations. Inorg Chem 2023; 62:11589-11601. [PMID: 37432868 DOI: 10.1021/acs.inorgchem.3c01302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
X-ray spectroscopies, by their high selectivity and sensitivity to the chemical environment around the atoms probed, provide significant insights into the electronic structures of molecules and materials. Interpreting experimental results requires reliable theoretical models, accounting for environmental, relativistic, electron correlation, and orbital relaxation effects in a balanced manner. In this work, we present a protocol for the simulation of core excited spectra with damped response time-dependent density functional theory based on the Dirac-Coulomb Hamiltonian (4c-DR-TD-DFT), in which environmental effects are accounted for through the frozen density embedding (FDE) method. We showcase this approach for the uranium M4- and L3-edges and oxygen K-edge of the uranyl tetrachloride (UO2Cl42-) unit as found in a host Cs2UO2Cl4 crystal. We have found that the 4c-DR-TD-DFT simulations yield excitation spectra that very closely match the experiment for the uranium M4-edge and the oxygen K-edge, with good agreement for the broad experimental spectra for the L3-edge. By decomposing the complex polarizability in terms of its components, we have been able to correlate our results with angle-resolved spectra. We have observed that for all edges, but in particular the uranium M4-edge, an embedded model in which the chloride ligands are replaced by an embedding potential reproduces rather well the spectral profile obtained for UO2Cl42-. Our results underscore the importance of the equatorial ligands to simulating core spectra at both uranium and oxygen edges.
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Affiliation(s)
- Wilken Aldair Misael
- Univ. Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France
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Kvashnina KO, Butorin SM. High-energy resolution X-ray spectroscopy at actinide M 4,5 and ligand K edges: what we know, what we want to know, and what we can know. Chem Commun (Camb) 2022; 58:327-342. [PMID: 34874022 PMCID: PMC8725612 DOI: 10.1039/d1cc04851a] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/15/2021] [Indexed: 12/20/2022]
Abstract
In recent years, scientists have progressively recognized the role of electronic structures in the characterization of chemical properties for actinide containing materials. High-energy resolution X-ray spectroscopy at the actinide M4,5 edges emerged as a promising direction because this method can probe actinide properties at the atomic level through the possibility of reducing the experimental spectral width below the natural core-hole lifetime broadening. Parallel to the technical developments of the X-ray method and experimental discoveries, theoretical models, describing the observed electronic structure phenomena, have also advanced. In this feature article, we describe the latest progress in the field of high-energy resolution X-ray spectroscopy at the actinide M4,5 and ligand K edges and we show that the methods are able to (a) provide fingerprint information on the actinide oxidation state and ground state characters (b) probe 5f occupancy, non-stoichiometry, defects, and ligand/metal ratio and (c) investigate the local symmetry and effects of the crystal field. We discuss the chemical aspects of the electronic structure in terms familiar to chemists and materials scientists and conclude with a brief description of new opportunities and approaches to improve the experimental methodology and theoretical analysis for f-electron systems.
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Affiliation(s)
- Kristina O Kvashnina
- The Rossendorf Beamline at ESRF, The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France.
- Institute of Resource Ecology, Helmholtz Zentrum Dresden-Rossendorf (HZDR), PO Box 510119, 01314 Dresden, Germany
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Sergei M Butorin
- Condensed Matter Physics of Energy Materials, X-ray Photon Science, Department of Physics and Astronomy, Uppsala University, P.O. Box 516, SE-751 20 Uppsala, Sweden.
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