Synthesis and study of hydrated uranium(VI) oxides, UO3·nH2O

Нипрук, О. В.; Knyazev, A. V.; Chernorukov, G. N.; Pykhova, Yu. P.

doi:10.1134/s1066362211020044

Cited by 29 publications

(17 citation statements)

References 6 publications

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“…Four (oxy)hydroxide minerals namely Schoepite, [(UO 2 ) 8 O 2 (OH) 12 ] ⋅ 12H 2 O, Na‐Metaschoepite, Na[(UO 2 ) 4 O 2 (OH) 5 ] ⋅ 5H2O, Compreignacite, K 2 [(UO 2 ) 6 O 4 (OH) 6 ] ⋅ 7H 2 O, and Becquerelite, Ca[(UO 2 ) 6 O 4 (OH) 6 ] ⋅ 8H 2 O were synthesized according to the literature procedures and purity checked by powder X‐ray diffraction and vibrational spectroscopy (supporting information). All show similar structural features, namely 2D layered networks consisting of layers of edge‐sharing UO 7 pentagonal bipyramids, interspersed with hydrogen‐bonded water molecules and s‐block cations (Figure S1).…”

Section: Resultsmentioning

confidence: 99%

“…Experiments using uranium materials were carried out using pre−set radiological safety precautions in accordance with the local rules of Trinity College Dublin. Schoepite, Na‐Metaschoepite, Compreignacite and Becquerelite were synthesized according to the literature procedures and checked for purity using Raman and IR spectroscopy and Powder X‐Ray Diffraction (ESI). Powder diffraction was performed on a Siemens D500 diffractometer using Bragg‐Brentano geometry with step size of 0.02° at 16 s per step.…”

Section: Introductionmentioning

confidence: 99%

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Redox Processes in Solid‐State Uranyl (Oxy)hydroxide Minerals

et al. 2017

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The correlation between the structure of a series of uranyl minerals of the type [(UO2)8O2(OH)12] and M[(UO2)xOy(OH)z] (M=Na, x=4, y=2, z=5; M=K2, x=6, y=4, z=6; M=Ca, x=6, y=4, z=6), and their electrochemical properties have been investigated by using solid‐state cyclic voltammetry. Solid‐state electrochemical investigations at near‐neutral pH values reveal that all minerals undergo redox reactions in the potential range from −0.72 to −0.91 V vs. Ag/AgCl. This process is assigned to the U(VI)/U(V) redox couple and a further reduction, observed between −0.95 and −1.20 V, is associated with the U(V)/U(IV) reduction. The nature of the reduced products has been probed by using vibrational spectroscopy and SEM−EDX, and was found to be UO2+x. The mechanism of reduction has been elucidated and shown to be dominated by two independent one‐electron transfer reactions with disproportionation playing at most a minor role. The rate of charge propagation through the solid deposits, characterized by the homogeneous charge‐transport diffusion coefficient, DCT, is much lower in these minerals than structurally related systems with ion, rather than electron, transfer being rate limiting. Overall, the insights into the nature and rate of redox conversion suggest that the uranyl minerals formed by the oxidative corrosion of spent nuclear fuels are not electrochemically innocent.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Redox Processes in Solid‐State Uranyl (Oxy)hydroxide Minerals

et al. 2017

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“…Schoepite, 48 studtite and metastudtite 32 were prepared as described in the literature and purity was checked by powder X-ray diffraction (Fig. S7-9 †).…”

Section: Methodsmentioning

confidence: 99%

An EXAFS and HR-XANES study of the uranyl peroxides [UO₂(η²-O₂)(H₂O)₂]·nH₂O (n = 0, 2) and uranyl (oxy)hydroxide [(UO₂)₄O(OH)₆]·6H₂O

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Prüßmann²,

Vitova³

et al. 2014

Dalton Trans.

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The solid-sate structures of the two uranyl peroxides studtite, [UO2(η(2)-O2)(H2O)2]·2H2O, and metastudtite [UO2(η(2)-O2)(H2O)2] have been determined by U-L3 edge extended X-ray absorption fine structure (EXAFS) spectroscopy and show that upon removal of the interstitial water in studtite there are structural changes with a small shortening of the U-O(peroxo) and small lengthening of the U-O(yl) bonds. High-energy resolution X-Ray absorption near edge structure (HR-XANES) spectroscopy has been used to probe the differences in the local electronic structure and, supported by ab initio FEFF9.5.1 calculations, dehydration causes a shift to higher energies of the occupied O p-DOS and U d- and f-DOS of metastudtite. The HR-XANES spectrum of schoepite, [(UO2)4O(OH)6]·6H2O, has been measured as the White Line intensity can give information on the mixing of metal and ligand atomic orbitals. There is an indication for higher degree of ionicity for the U-OH bond in schoepite compared to the U-O2 bond in studtite.

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“…An analog of the hydroxy-hydrated uranyl oxide mineral schoepite ([(UO2)8O2(OH)12](H2O)12 [6,7]) was synthesized according to the procedure discussed in [9], and its purity was checked using powder XRD; H2SO4 (Sigma-Aldrich, 98%) and Cs2SO4 (Vekton, Russia, 99%) were used as received. The 0.2 g of synthetic schoepite (0.03 mmol), 0.12 g of cesium sulfate (0.33 mmol), and 0.01 (0.19 mmol) ml of sulfuric acid were dissolved in 10 ml of deionized water.…”

Section: Synthesismentioning

confidence: 99%

Crystallographic Insights into Uranyl Sulfate Minerals Formation: Synthesis and Crystal Structures of Three Novel Cesium Uranyl Sulfates

et al. 2019

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An alteration of the uranyl oxide hydroxy-hydrate mineral schoepite [(UO2)8O2(OH)12](H2O)12 at mild hydrothermal conditions was studied. As the result, four different crystalline phases Cs[(UO2)(SO4)(OH)](H2O)0.25 (1), Cs3[(UO2)4(SO4)2O3(OH)](H2O)3 (2), Cs6[(UO2)2(SO4)5](H2O)3 (3), and Cs2[(UO2)(SO4)2] (4) were obtained, including three novel compounds. The obtained Cs uranyl sulfate compounds 1, 3, and 4 were analyzed using single-crystal XRD, EDX, as well as topological analysis and information-based structural complexity measures. The crystal structure of 3 was based on the 1D complex, the topology of which was unprecedented for the structural chemistry of inorganic oxysalts. Crystal chemical analysis performed herein suggested that the majority of the uranyl sulfates minerals were grown from heated solutions, and the temperature range could be assumed from the manner of interpolyhedral linkage. The presence of edge-sharing uranyl bipyramids most likely pointed to the temperatures of higher than 100 °C. The linkage of sulfate tetrahedra with uranyl polyhedra through the common edges involved elevated temperatures but of lower values (~70–100 °C). Complexity parameters of the synthetic compounds were generally lower than that of uranyl sulfate minerals, whose structures were based on the complexes with the same or genetically similar topologies. The topological complexity of the uranyl sulfate structural units contributed the major portion to the overall complexity of the synthesized compounds, while the complexity of the respective minerals was largely governed by the interstitial structure and H-bonding system.

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Synthesis and study of hydrated uranium(VI) oxides, UO3·nH2O

Cited by 29 publications

References 6 publications

Redox Processes in Solid‐State Uranyl (Oxy)hydroxide Minerals

Redox Processes in Solid‐State Uranyl (Oxy)hydroxide Minerals

An EXAFS and HR-XANES study of the uranyl peroxides [UO₂(η²-O₂)(H₂O)₂]·nH₂O (n = 0, 2) and uranyl (oxy)hydroxide [(UO₂)₄O(OH)₆]·6H₂O

Crystallographic Insights into Uranyl Sulfate Minerals Formation: Synthesis and Crystal Structures of Three Novel Cesium Uranyl Sulfates

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Synthesis and study of hydrated uranium(VI) oxides, UO3·nH2O

Cited by 29 publications

References 6 publications

Redox Processes in Solid‐State Uranyl (Oxy)hydroxide Minerals

Redox Processes in Solid‐State Uranyl (Oxy)hydroxide Minerals

An EXAFS and HR-XANES study of the uranyl peroxides [UO2(η2-O2)(H2O)2]·nH2O (n = 0, 2) and uranyl (oxy)hydroxide [(UO2)4O(OH)6]·6H2O

Crystallographic Insights into Uranyl Sulfate Minerals Formation: Synthesis and Crystal Structures of Three Novel Cesium Uranyl Sulfates

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An EXAFS and HR-XANES study of the uranyl peroxides [UO₂(η²-O₂)(H₂O)₂]·nH₂O (n = 0, 2) and uranyl (oxy)hydroxide [(UO₂)₄O(OH)₆]·6H₂O