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Murphy GL, Kegler P, Alekseev EV. Advances and perspectives of actinide chemistry from ex situ high pressure and high temperature chemical studies. Dalton Trans 2022; 51:7401-7415. [PMID: 35475437 DOI: 10.1039/d2dt00697a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High pressure high temperature (HP/HT) studies of actinide compounds allow the chemistry and bonding of among the most exotic elements in the periodic table to be examined under the conditions often only found in the severest environments of nature. Peering into this realm of physical extremity, chemists have extracted detailed knowledge of the fundamental chemistry of actinide elements and how they contribute to bonding, structure formation and intricate properties in compounds under such conditions. The last decade has resulted in some of the most significant contributions to actinide chemical science and this holds true for ex situ chemical studies of actinides resulting from HP/HT conditions of over 1 GPa and elevated temperature. Often conducted in tandem with ab initio calculations, HP/HT studies of actinides have further helped guide and develop theoretical modelling approaches and uncovered associated difficulties. Accordingly, this perspective article is devoted to reviewing the latest advancements made in actinide HP/HT ex situ chemical studies over the last decade, the state-of-the-art, challenges and discussing potential future directions of the science. The discussion is given with emphasis on thorium and uranium compounds due to the prevalence of their investigation but also highlights some of the latest advancements in high pressure chemical studies of transuranium compounds. The perspective also describes technical aspects involved in HP/HT investigation of actinide compounds.
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Affiliation(s)
- Gabriel L Murphy
- Institute of Energy and Climate Research, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
| | - Philip Kegler
- Institute of Energy and Climate Research, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
| | - Evgeny V Alekseev
- Institute of Energy and Climate Research, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany.
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2
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Estevenon P, Dumas T, Solari PL, Welcomme E, Szenknect S, Mesbah A, Kvashnina KO, Moisy P, Poinssot C, Dacheux N. Formation of plutonium(IV) silicate species in very alkaline reactive media. Dalton Trans 2021; 50:12528-12536. [PMID: 34545888 DOI: 10.1039/d1dt02248b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Studying the speciation of Pu(IV) in very alkaline and silicate ion rich reactive media allowed identification of the formation of plutonium(IV)-silicate colloidal suspensions which were stable for months. These colloids were stabilized in aqueous solution for pH > 13 and for concentrations around 10-2 mol L-1. Successive filtration processes allowed evaluation of their size, which was found to be smaller than 6 nm. Their structural characterization by XAS evidenced that their structure was similar to those identified for the other tetravalent actinide-silicate colloidal systems like thorium, uranium and neptunium. Their formation could explain the increase of plutonium solubility usually observed in alkaline silicate-rich solutions and could affect the plutonium mobility as a result in contaminated sites or in other environmental permeable media.
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Affiliation(s)
- Paul Estevenon
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France. .,ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Bagnols-sur-Cèze, France. .,The Rossendorf Beamline at the ESRF, CS40220, 38043 Grenoble Cedex 9, France.,Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, P.O. Box 510119, 01314, Dresden, Germany
| | - Thomas Dumas
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France.
| | - Pier Lorenzo Solari
- Synchrotron Soleil, L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | | | | | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Bagnols-sur-Cèze, France.
| | - Kristina O Kvashnina
- The Rossendorf Beamline at the ESRF, CS40220, 38043 Grenoble Cedex 9, France.,Helmholtz Zentrum Dresden-Rossendorf (HZDR), Institute of Resource Ecology, P.O. Box 510119, 01314, Dresden, Germany
| | - Philippe Moisy
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France.
| | | | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Bagnols-sur-Cèze, France.
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3
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Diagenetic formation of uranium-silica polymers in lake sediments over 3,300 years. Proc Natl Acad Sci U S A 2021; 118:2021844118. [PMID: 33479173 DOI: 10.1073/pnas.2021844118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The long-term fate of uranium-contaminated sediments, especially downstream former mining areas, is a widespread environmental challenge. Essential for their management is the proper understanding of uranium (U) immobilization mechanisms in reducing environments. In particular, the long-term behavior of noncrystalline U(IV) species and their possible evolution to more stable phases in subsurface conditions is poorly documented, which limits our ability to predict U long-term geochemical reactivity. Here, we report direct evidence for the evolution of U speciation over 3,300 y in naturally highly U-enriched sediments (350-760 µg ⋅ g-1 U) from Lake Nègre (Mercantour Massif, Mediterranean Alps, France) by combining U isotopic data (δ238U and (234U/238U)) with U L 3 -edge X-ray absorption fine structure spectroscopy. Constant isotopic ratios over the entire sediment core indicate stable U sources and accumulation modes, allowing for determination of the impact of aging on U speciation. We demonstrate that, after sediment deposition, mononuclear U(IV) species associated with organic matter transformed into authigenic polymeric U(IV)-silica species that might have partially converted to a nanocrystalline coffinite (UIVSiO4·nH2O)-like phase. This diagenetic transformation occurred in less than 700 y and is consistent with the high silica availability of sediments in which diatoms are abundant. It also yields consistency with laboratory studies that proposed the formation of colloidal polynuclear U(IV)-silica species, as precursors for coffinite formation. However, the incomplete transformation observed here only slightly reduces the potential lability of U, which could have important implications to evaluate the long-term management of U-contaminated sediments and, by extension, of U-bearing wastes in silica-rich subsurface environments.
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4
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Instability of U 3Si 2 in pressurized water media at elevated temperatures. Commun Chem 2021; 4:65. [PMID: 36697616 PMCID: PMC9814221 DOI: 10.1038/s42004-021-00504-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 03/31/2021] [Indexed: 01/28/2023] Open
Abstract
Following the Fukushima Daiichi accident, significant efforts from industry and the scientific community have been directed towards the development of alternative nuclear reactor fuels with enhanced accident tolerance. Among the proposed materials for such fuels is a uranium silicide compound (U3Si2), which has been selected for its enhanced thermal conductivity and high density of uranium compared to the reference commercial light water reactor (LWR) nuclear fuel, uranium oxide (UO2). To be a viable candidate LWR fuel, however, U3Si2 must also demonstrate that, in the event of this fuel coming in contact with aqueous media, it will not degrade rapidly. In this contribution, we report the results of experiments investigating the stability of U3Si2 in pressurized water at elevated temperatures and identify the mechanisms that control the interaction of U3Si2 under these conditions. Our data indicate that the stability of this material is primarily controlled by the formation of a layer of USiO4 (the mineral, coffinite) at the surface of U3Si2. The results also show that these layers are destabilized at T > 300 °C, leading to the complete decomposition of U3Si2 and its pulverization due to its full oxidation to UO2.
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5
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Strzelecki AC, Barral T, Estevenon P, Mesbah A, Goncharov V, Baker J, Bai J, Clavier N, Szenknect S, Migdisov A, Xu H, Ewing RC, Dacheux N, Guo X. The Role of Water and Hydroxyl Groups in the Structures of Stetindite and Coffinite, MSiO 4 (M = Ce, U). Inorg Chem 2021; 60:718-735. [PMID: 33393766 DOI: 10.1021/acs.inorgchem.0c02757] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Orthosilicates adopt the zircon structure types (I41/amd), consisting of isolated SiO4 tetrahedra joined by A-site metal cations, such as Ce and U. They are of significant interest in the fields of geochemistry, mineralogy, nuclear waste form development, and material science. Stetindite (CeSiO4) and coffinite (USiO4) can be formed under hydrothermal conditions despite both being thermodynamically metastable. Water has been hypothesized to play a significant role in stabilizing and forming these orthosilicate phases, though little experimental evidence exists. To understand the effects of hydration or hydroxylation on these orthosilicates, in situ high-temperature synchrotron and laboratory-based X-ray diffraction was conducted from 25 to ∼850 °C. Stetindite maintains its I41/amd symmetry with increasing temperature but exhibits a discontinuous expansion along the a-axis during heating, presumably due to the removal of water confined in the [001] channels, which shrink against thermal expansion along the a-axis. Additional in situ high-temperature Raman and Fourier transform infrared spectroscopy also confirmed the presence of the confined water. Coffinite was also found to expand nonlinearly up to 600 °C and then thermally decompose into a mixture of UO2 and SiO2. A combination of dehydration and dehydroxylation is proposed for explaining the thermal behavior of coffinite synthesized hydrothermally. Additionally, we investigated high-temperature structures of two coffinite-thorite solid solutions, uranothorite (UxTh1-xSiO4), which displayed complex variations in composition during heating that was attributed to the negative enthalpy of mixing. Lastly, for the first time, the coefficients of thermal expansion of CeSiO4, USiO4, U0.46Th0.54SiO4, and U0.9Th0.1SiO4 were determined to be αV = 14.49 × 10-6, 14.29 × 10-6, 17.21 × 10-6, and 17.23 × 10-6 °C-1, respectively.
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Affiliation(s)
- Andrew C Strzelecki
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,Materials Science and Engineering Program, Washington State University, Pullman 99164, Washington, United States
| | - Thomas Barral
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Paul Estevenon
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France.,CEA, DES, ISEC, DMRC, Univ Montpellier, Site de Marcoule 30207, France
| | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Vitaliy Goncharov
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,Materials Science and Engineering Program, Washington State University, Pullman 99164, Washington, United States.,Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Jason Baker
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Jianming Bai
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton 11973, New York, United States
| | - Nicolas Clavier
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Stephanie Szenknect
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Artaches Migdisov
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Hongwu Xu
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos 87545, New Mexico, United States
| | - Rodney C Ewing
- Department of Geological Sciences, Stanford University, Stanford 94305, California, United States
| | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule 30207, Bagnols sur Cèze, France
| | - Xiaofeng Guo
- Department of Chemistry, Washington State University, Pullman 99164, Washington, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman 99164, Washington, United States.,Materials Science and Engineering Program, Washington State University, Pullman 99164, Washington, United States
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6
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Strzelecki AC, Bourgeois C, Kriegsman KW, Estevenon P, Wei N, Szenknect S, Mesbah A, Wu D, Ewing RC, Dacheux N, Guo X. Thermodynamics of CeSiO 4: Implications for Actinide Orthosilicates. Inorg Chem 2020; 59:13174-13183. [PMID: 32871073 DOI: 10.1021/acs.inorgchem.0c01476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Zircon (ZrSiO4, I41/amd) can accommodate actinides, such as thorium, uranium, and plutonium. The zircon structure has been determined for several of the end-member compositions of other actinides, such as plutonium and neptunium. However, the thermodynamic properties of these actinide zircon structure types are largely unknown due to the difficulties in synthesizing these materials and handling transuranium actinides. Thus, we have completed a thermodynamic study of cerium orthosilicate, stetindite (CeSiO4), a surrogate of PuSiO4. For the first time, the standard enthalpy of formation of CeSiO4 was obtained by high temperature oxide melt solution calorimetry to be -1971.9 ± 3.6 kJ/mol. Stetindite is energetically metastable with respect to CeO2 and SiO2 by 27.5 ± 3.1 kJ/mol. The metastability explains the rarity of the natural occurrence of stetindite and the difficulty of its synthesis. Applying the obtained enthalpy of formation of CeSiO4 from this work, along with those previously reported for USiO4 and ThSiO4, we developed an empirical energetic relation for actinide orthosilicates. The predicted enthalpies of formation of AnSiO4 are then determined with a discussion of future strategies for efficiently immobilizing Pu or minor actinides in the zircon structure.
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Affiliation(s)
- Andrew C Strzelecki
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States.,Materials Science and Engineering, Washington State University, Pullman, Washington 99164, United States
| | - Clement Bourgeois
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States
| | - Kyle W Kriegsman
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States
| | - Paul Estevenon
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France.,CEA, DES, ISEC, DMRC, Univ Montpellier, Site de Marcoule 30207, France
| | - Nian Wei
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,College of Physical Science and Technology, Sichuan University, Chengdu 610065, People's Republic of China
| | - Stephanie Szenknect
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France
| | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France
| | - Di Wu
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States.,Materials Science and Engineering, Washington State University, Pullman, Washington 99164, United States.,The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, Washington 99164, United States
| | - Rodney C Ewing
- Department of Geological Sciences, Stanford University, Stanford, California 94305, United States
| | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols sur Cèze 30207, France
| | - Xiaofeng Guo
- Department of Chemistry, Washington State University, Pullman, Washington 99164, United States.,Alexandra Navrotsky Institute for Experimental Thermodynamics, Washington State University, Pullman, Washington 99164, United States.,Materials Science and Engineering, Washington State University, Pullman, Washington 99164, United States
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7
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Abstract
Most of the highly radioactive spent nuclear fuel (SNF) around the world is destined for final disposal in deep-mined geological repositories. At the end of the fuel's useful life in a reactor, about 96% of the SNF is still UO2. Thus, the behaviour of UO2 in SNF must be understood and evaluated under the weathering conditions of geologic disposal, which extend to periods of hundreds of thousands of years. There is ample evidence from nature that many uranium deposits have experienced conditions for which the formation of coffinite, USiO4, has been favoured over uraninite, UO2+x, during subsequent alteration events. Thus, coffinite is an important alteration product of the UO2 in SNF. Here, we present the first evidence of the formation of coffinite on the surface of UO2 at the time scale of laboratory experiments in a solution saturated with respect to amorphous silica at pH = 9, room temperature and under anoxic conditions.
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8
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Guo Z, Chu T. Extraction of tetravalent uranium by N,N,N',N'-tetramethylmalonamide in ionic liquid. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116629] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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9
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Estevenon P, Welcomme E, Tamain C, Jouan G, Szenknect S, Mesbah A, Poinssot C, Moisy P, Dacheux N. The formation of PuSiO 4 under hydrothermal conditions. Dalton Trans 2020; 49:6434-6445. [PMID: 32355939 DOI: 10.1039/d0dt01183e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Attempts to synthesize plutonium(iv) silicate, PuSiO4, have been made on the basis of results recently reported in the literature for CeSiO4, ThSiO4, and USiO4 under hydrothermal conditions. Although it was not possible to prepare PuSiO4via applying the conditions reported for thorium and uranium, an efficient method of PuSiO4 synthesis was established by applying the conditions optimized for the CeSiO4 system. This method was based on the slow oxidation of plutonium(iii) silicate reactants under hydrothermal conditions at 150 °C in hydrochloric acid (pH = 3-4). These results shed new light on the potential behavior of plutonium in reductive environments, highlighting the representative nature of cerium surrogates when studying plutonium under such conditions and providing some important pieces of information regarding plutonium chemistry in silicate solutions.
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Affiliation(s)
- Paul Estevenon
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France and ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
| | | | | | - Gauthier Jouan
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France
| | - Stephanie Szenknect
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
| | - Adel Mesbah
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
| | | | - Philippe Moisy
- CEA, DES, ISEC, DMRC, Univ Montpellier, Marcoule, France
| | - Nicolas Dacheux
- ICSM, Univ Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols-sur-Cèze, France.
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10
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Mondal SK, Das PK, Mandal N, Arya A. A novel approach to the structural distortions of U/Th snub-disphenoids and their control on zircon → reidite type phase transitions of U 1-x Th x SiO 4. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:145401. [PMID: 31825899 DOI: 10.1088/1361-648x/ab60e4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Coffinite (USiO4) and thorite (ThSiO4) are conspicuous radiogenic silicates in the geonomy. They form U1-x Th x SiO4 (uranothorite) solid solutions in zircon-type phase. Investigating the phase-evolution of these minerals is of utmost significance in realizing their applicability in the front-as well as at the back-end of nuclear industries. We carried out a systematic study of zircon- to reidite-type (tetragonal I41/amd to I41/a) structural transitions of U1-x Th x SiO4 solid solution, and investigated their mechanical behaviour. We found a unique behaviour of transition pressure with the change in U-Th concentration in the solid solution. The phase transition pressure (p t) is found to be minimum for x = 0.5. We develop the necessary formalism and present an efficient method to estimate the longitudinal and angular distortions of U/ThO8-triangular dodecahedra (snub-disphenoids). We have parameterized two new factors: δ (longitudinal distortions) and σ 2 (angular distortions) to quantify the polyhedral distortions. A detailed analysis of U/ThO8 snub-disphenoidal distortions is presented to address such variation of p t with U and Th concentration. We argue that our approach is independent of polyhedral volume and can be used for any AB8 (A: cation, B: anion) type snub-disphenoidal system.
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Affiliation(s)
- Sudip Kumar Mondal
- Department of Physics, Jadavpur University, Kolkata 700032, India. Faculty of Science, High Pressure and Temperature Laboratory, Jadavpur University, Kolkata 700032, India
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11
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Chukanov NV, Vigasina MF. Raman Spectra of Minerals. VIBRATIONAL (INFRARED AND RAMAN) SPECTRA OF MINERALS AND RELATED COMPOUNDS 2020. [DOI: 10.1007/978-3-030-26803-9_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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12
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Biswas S, Edwards SJ, Wang Z, Si H, Vintró LL, Twamley B, Kowalski PM, Baker RJ. Americium incorporation into studtite: a theoretical and experimental study. Dalton Trans 2019; 48:13057-13063. [PMID: 31407762 DOI: 10.1039/c9dt02848j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Studtite, [UO2(η2-O2)(H2O)2]·2H2O, and metastudtite, [UO2(η2-O2)(H2O)2], are important phase alterations of UO2 in a spent nuclear fuel repository and have previously been shown to react with Np(v). In this work we extend the study to Am(v) on a tracer scale and show spectroscopic evidence that the Am is incorporated into the structure of studtite as Am(iii). A computational study on the possible mechanisms for the incorporation of Np and Am shows that protonation of the -yl oxygen is the favoured route and the calculated incorporation energies are large and positive. The results suggest that Am is less favoured compared to Np but energetically more favoured to incorporate both actinide ions into metastudtite rather than studtite. Finally, we have shown that once incorporated, Am readily leaches into water but spectroscopic measurements suggest subtle changes in the structure of studtite.
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Affiliation(s)
- Saptarshi Biswas
- School of Chemistry, University of Dublin Trinity College, Dublin 2, Ireland.
| | - Samuel J Edwards
- School of Chemistry, University of Dublin Trinity College, Dublin 2, Ireland.
| | - Zheming Wang
- Pacific Northwest National Laboratory, MSIN K8-96, P.O. Box 999, Richland, WA 99352, USA
| | - Hang Si
- Institute of Energy and Climate Research, IEK-6: Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Strasse, 52428 Jülich, Germany.
| | - Luis León Vintró
- School of Physics, University College Dublin, Belfield, Dublin 4, Ireland
| | - Brendan Twamley
- School of Chemistry, University of Dublin Trinity College, Dublin 2, Ireland.
| | - Piotr M Kowalski
- Institute of Energy and Climate Research, IEK-6: Nuclear Waste Management and Reactor Safety, Forschungszentrum Jülich GmbH, Wilhelm-Johnen-Strasse, 52428 Jülich, Germany.
| | - Robert J Baker
- School of Chemistry, University of Dublin Trinity College, Dublin 2, Ireland.
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13
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Estevenon P, Welcomme E, Szenknect S, Mesbah A, Moisy P, Poinssot C, Dacheux N. Preparation of CeSiO 4 from aqueous precursors under soft hydrothermal conditions. Dalton Trans 2019; 48:7551-7559. [PMID: 31119248 DOI: 10.1039/c9dt01258c] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Even though CeSiO4 was synthesized one time through a hydrothermal treatment, the conditions leading to its formation remain largely unknown. In order to define the optimized conditions of synthesis, a multiparametric study was developed by varying the pH of the solution, the temperature, and the nature of the reactants and of the complexing ions in solution. This study highlighted that CeSiO4 could not be obtained starting from Ce(iv) reactants. An optimal set of conditions was defined to prepare single phase samples. Pure CeSiO4 was obtained through a hydrothermal treatment at 150 °C using a starting mixture of 1 mol L-1 Ce(iii) nitrate and Na2SiO3 solutions and by adjusting the initial pH to 8. The chemical limitations observed during the synthesis of CeSiO4 suggested that the formation of this phase may result from the slow in situ oxidation of a Ce(iii) silicate complex during the hydrothermal treatment.
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Affiliation(s)
- Paul Estevenon
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
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14
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Estevenon P, Kaczmarek T, Vadot F, Dumas T, Solari PL, Welcomme E, Szenknect S, Mesbah A, Moisy P, Poinssot C, Dacheux N. Formation of CeSiO 4 from cerium(iii) silicate precursors. Dalton Trans 2019; 48:10455-10463. [PMID: 31241109 DOI: 10.1039/c9dt01990a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although the preparation of CeSiO4 has been already reported, the formation of pure cerium silicate from aqueous precursors appears as a challenge. An innovative way of synthesis has been identified in this study, allowing the formation of CeSiO4 after hydrothermal treatment starting from Ce(iii) silicate precursors. Among the experimental parameters examined, significant effects were found according to the nature of the precursor and of the reactive media considered, the pH of the reactive media and the temperature of the hydrothermal process. This study allows the determination of optimized conditions for the hydrothermal synthesis of pure CeSiO4 (A-Ce2Si2O7 or Ce4.67(SiO4)3O as starting precursors, nitric medium, pH = 7, 7 days at 150 °C). The in situ low oxidation rate of Ce(iii) into Ce(iv) was a key parameter to consider in order to avoid the presence of CeO2 in the final mixtures.
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Affiliation(s)
- Paul Estevenon
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France and ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule - Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France.
| | - Thibault Kaczmarek
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France and ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule - Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France.
| | - Fabien Vadot
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France and ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule - Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France.
| | - Thomas Dumas
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Pier Lorenzo Solari
- Synchrotron SOLEIL L'Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
| | - Eleonore Welcomme
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Stephanie Szenknect
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule - Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France.
| | - Adel Mesbah
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule - Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France.
| | - Philippe Moisy
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Christophe Poinssot
- CEA, Nuclear Energy Division, CEA Marcoule Research Department of Mining and Fuel Recycling Processes, DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Nicolas Dacheux
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule - Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France.
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15
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Estevenon P, Welcomme E, Szenknect S, Mesbah A, Moisy P, Poinssot C, Dacheux N. Impact of Carbonate Ions on the Synthesis of ThSiO4 under Hydrothermal Conditions. Inorg Chem 2018; 57:12398-12408. [DOI: 10.1021/acs.inorgchem.8b02146] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Paul Estevenon
- CEA, Nuclear Energy Division, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, CEA Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule, Bât.
426, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Eleonore Welcomme
- CEA, Nuclear Energy Division, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, CEA Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Stephanie Szenknect
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule, Bât.
426, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Adel Mesbah
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule, Bât.
426, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Philippe Moisy
- CEA, Nuclear Energy Division, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, CEA Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Christophe Poinssot
- CEA, Nuclear Energy Division, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, CEA Marcoule, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Nicolas Dacheux
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule, Bât.
426, BP 17171, 30207 Bagnols-sur-Cèze, France
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16
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Neill TS, Morris K, Pearce CI, Sherriff NK, Burke MG, Chater PA, Janssen A, Natrajan L, Shaw S. Stability, Composition, and Core-Shell Particle Structure of Uranium(IV)-Silicate Colloids. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9118-9127. [PMID: 30001122 DOI: 10.1021/acs.est.8b01756] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Uranium is typically the most abundant radionuclide by mass in radioactive wastes and is a significant component of effluent streams at nuclear facilities. Actinide(IV) (An(IV)) colloids formed via various pathways, including corrosion of spent nuclear fuel, have the potential to greatly enhance the mobility of poorly soluble An(IV) forms, including uranium. This is particularly important in conditions relevant to decommissioning of nuclear facilities and the geological disposal of radioactive waste. Previous studies have suggested that silicate could stabilize U(IV) colloids. Here the formation, composition, and structure of U(IV)-silicate colloids under the alkaline conditions relevant to spent nuclear fuel storage and disposal were investigated using a range of state of the art techniques. The colloids are formed across a range of pH conditions (9-10.5) and silicate concentrations (2-4 mM) and have a primary particle size 1-10 nm, also forming suspended aggregates <220 nm. X-ray absorption spectroscopy, ultrafiltration, and scanning transmission electron microscopy confirm the particles are U(IV)-silicates. Additional evidence from X-ray diffraction and pair distribution function data suggests the primary particles are composed of a UO2-rich core and a U-silicate shell. U(IV)-silicate colloids formation correlates with the formation of U(OH)3(H3SiO4)32- complexes in solution indicating they are likely particle precursors. Finally, these colloids form under a range of conditions relevant to nuclear fuel storage and geological disposal of radioactive waste and represent a potential pathway for U mobility in these systems.
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Affiliation(s)
- Thomas S Neill
- Research Centre for Radwaste and Disposal, Williamson Research Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Katherine Morris
- Research Centre for Radwaste and Disposal, Williamson Research Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Carolyn I Pearce
- Pacific Northwest National Laboratory, Richland , Washington 99354 , United States
| | - Nicholas K Sherriff
- National Nuclear Laboratory, Chadwick House, Warrington Road , Birchwood Park, Warrington WA3 6AE , U.K
| | - M Grace Burke
- Materials Performance Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Philip A Chater
- Diamond Light Source, Harwell Campus , Didcot , Oxfordshire OX11 0DE , U.K
| | - Arne Janssen
- Materials Performance Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
- Diamond Light Source, Harwell Campus , Didcot , Oxfordshire OX11 0DE , U.K
| | - Louise Natrajan
- School of Chemistry , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Samuel Shaw
- Research Centre for Radwaste and Disposal, Williamson Research Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
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17
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Estevenon P, Welcomme E, Szenknect S, Mesbah A, Moisy P, Poinssot C, Dacheux N. Multiparametric Study of the Synthesis of ThSiO4 under Hydrothermal Conditions. Inorg Chem 2018; 57:9393-9402. [DOI: 10.1021/acs.inorgchem.8b01390] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Paul Estevenon
- CEA, Nuclear Energy Division, CEA Marcoule, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Eleonore Welcomme
- CEA, Nuclear Energy Division, CEA Marcoule, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Stephanie Szenknect
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule,
Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Adel Mesbah
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule,
Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Philippe Moisy
- CEA, Nuclear Energy Division, CEA Marcoule, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Christophe Poinssot
- CEA, Nuclear Energy Division, CEA Marcoule, Research Department of Mining and Fuel Recycling Processes, DEN/DMRC, BP 17171, 30207 Bagnols-sur-Cèze, France
| | - Nicolas Dacheux
- ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule,
Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze, France
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18
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Mesbah A, Clavier N, Lozano-Rodriguez MJ, Szenknect S, Dacheux N. Incorporation of Thorium in the Zircon Structure Type through the Th 1-xEr x(SiO 4) 1-x(PO 4) x Thorite-Xenotime Solid Solution. Inorg Chem 2016; 55:11273-11282. [PMID: 27749037 DOI: 10.1021/acs.inorgchem.6b01862] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pure powdered compounds with a general formula Th1-xErx(SiO4)1-x(PO4)x belonging to the zircon-xenotime family were successfully synthesized under hydrothermal conditions (250 °C, 7 days) as recently reported for the preparation of coffinite. Therefore, a thorough, combined PXRD, EDX, EXAFS, Raman, and FTIR analysis showed the formation of a solid solution in agreement with Vegard's law. Moreover, the examination of the local structure shows that the Th-O distances remain close to those found in ThSiO4, whereas the Er-O distances show a significant decrease from 2.38(14) to 2.34(7) Å when increasing the erbium content from x = 0.2 to x = 1. The variation of the local structure also affects the PO43- groups that are surely distorted in the structure.
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Affiliation(s)
- Adel Mesbah
- ICSM, UMR 5257 CEA/CNRS/ENSCM/University of Montpellier , Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex, France
| | - Nicolas Clavier
- ICSM, UMR 5257 CEA/CNRS/ENSCM/University of Montpellier , Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex, France
| | - M Janeth Lozano-Rodriguez
- HZDR, Institute of Resource Ecology, The Rossendorf Beamline at ESRF , P.O. Box 220, 38043 Grenoble, France
| | - Stephanie Szenknect
- ICSM, UMR 5257 CEA/CNRS/ENSCM/University of Montpellier , Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex, France
| | - Nicolas Dacheux
- ICSM, UMR 5257 CEA/CNRS/ENSCM/University of Montpellier , Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols-sur-Cèze cedex, France
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19
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Biswas S, Steudtner R, Schmidt M, McKenna C, León Vintró L, Twamley B, Baker RJ. An investigation of the interactions of Eu³⁺ and Am³⁺ with uranyl minerals: implications for the storage of spent nuclear fuel. Dalton Trans 2016; 45:6383-93. [PMID: 27028717 DOI: 10.1039/c6dt00199h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of a number of uranyl minerals of the (oxy)hydroxide, phosphate and carbonate types with Eu(iii), as a surrogate for Am(iii), have been investigated. A photoluminescence study shows that Eu(iii) can interact with the uranyl minerals Ca[(UO2)6(O)4(OH)6]·8H2O (becquerelite) and A[UO2(CO3)3]·xH2O (A/x = K3Na/1, grimselite; CaNa2/6, andersonite; and Ca2/11, liebigite). For the minerals [(UO2)8(O)2(OH)12]·12H2O (schoepite), K2[(UO2)6(O)4(OH)6]·7H2O (compreignacite), A[(UO2)2(PO4)2]·8H2O (A = Ca, meta-autunite; Cu, meta-torbernite) and Cu[(UO2)2(SiO3OH)2]·6H2O (cuprosklodowskite) no Eu(iii) emission was observed, indicating no incorporation into, or sorption onto the structure. In the examples with Eu(3+) incorporation, sensitized emission is seen and the lifetimes, hydration numbers and quantum yields have been determined. Time Resolved Laser Induced Fluroescence Spectroscpoy (TRLFS) at 10 K have also been measured and the resolution enhancements at these temperatures allow further information to be derived on the sites of Eu(iii) incorporation. Infrared and Raman spectra are recorded, and SEM analysis show significant morphology changes and the substitution of particularly Ca(2+) by Eu(3+) ions. Therefore, Eu(3+) can substitute Ca(2+) in the interlayers of becquerelite and liebigite and in the structure of andersonite, whilst in grimselite only sodium is exchanged. These results have guided an investigation into the reactions with (241)Am on a tracer scale and results from gamma-spectrometry show that becquerelite, andersonite, grimselite, liebigite and compreignacite can include americium in the structure. Shifts in the U[double bond, length as m-dash]O and C-O Raman active bands are similar to that observed in the Eu(iii) analogues and Am(iii) photoluminescence measurements are also reported on these phases; the Am(3+) ion quenches the emission from the uranyl ion.
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Affiliation(s)
- Saptarshi Biswas
- School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland.
| | - Robin Steudtner
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, P.O. Box 510119, D-01314 Dresden, Germany
| | - Moritz Schmidt
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, P.O. Box 510119, D-01314 Dresden, Germany
| | - Cora McKenna
- Department of Geology, School of Natural Sciences, University of Dublin, Trinity College, Dublin 2, Ireland
| | - Luis León Vintró
- School Of Physics, University College Dublin, Belfield, Dublin 4, Ireland
| | - Brendan Twamley
- School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland.
| | - Robert J Baker
- School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland.
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20
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Zänker H, Weiss S, Hennig C, Brendler V, Ikeda‐Ohno A. Oxyhydroxy Silicate Colloids: A New Type of Waterborne Actinide(IV) Colloids. ChemistryOpen 2016; 5:174-182. [PMID: 27957406 PMCID: PMC5130165 DOI: 10.1002/open.201500207] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/26/2016] [Indexed: 11/10/2022] Open
Abstract
At the near-neutral and reducing aquatic conditions expected in undisturbed ore deposits or in closed nuclear waste repositories, the actinides Th, U, Np, and Pu are primarily tetravalent. These tetravalent actinides (AnIV) are sparingly soluble in aquatic systems and, hence, are often assumed to be immobile. However, AnIV could become mobile if they occur as colloids. This review focuses on a new type of AnIV colloids, oxyhydroxy silicate colloids. We herein discuss the chemical characteristics of these colloids and the potential implication for their environmental behavior. The binary oxyhydroxy silicate colloids of AnIV could be potentially more mobile as a waterborne species than the well-known mono-component oxyhydroxide colloids.
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Affiliation(s)
- Harald Zänker
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Stephan Weiss
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Christoph Hennig
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Vinzenz Brendler
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Atsushi Ikeda‐Ohno
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
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