The Luminescence Spectra of UF<sub>4</sub> and UC<sub>14</sub>

Görller‐Walrand, Christiane; Gos, M. P.; D'Olieslager, W.

doi:10.1524/ract.1993.62.12.55

Cited by 8 publications

(6 citation statements)

References 7 publications

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“…1a, the energy gap of U 4+ in aqueous solution between 1 S 0 and 3 P 2 levels is so broad (about 17 400 cm −1 ) [7] that the deexcitation process from 1 S 0 may contain luminescence emissions. Moreover, several studies have reported the luminescence properties of U(IV) in solid phases such as U(HPO 4 ) 2 ·nH 2 O powder [6], UF 4 or UCl 4 powder [8], sulfate complexes in a frozen matrix [9] and U 4+ doped LiYF 4 single crystal [10], and the excitation spectra of U(HPO 4 ) 2 ·nH 2 O powder and U 4+ doped LiYF 4 have a characteristic peak in the 240-260 nm range. Based on these considerations, we have carried out spectroscopic experiments on U 4+ in aqueous solutions and discovered the emission spectrum.…”

Section: Introductionmentioning

confidence: 99%

Luminescence properties of tetravalent uranium in aqueous solution

Kirishima¹,

Kimura²,

Nagaishi³

et al. 2004

Radiochimica Acta

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The luminescence spectra of U 4+ in aqueous solutions were observed in the UV-VIS region at ambient and liquid nitrogen temperatures. The excitation spectrum indicates that the luminescence is arising from the deexcitation of a 5 f electron at the 1 S 0 level and no other emissions of U 4+ in aqueous solutions were detected for other f -f transitions. All the luminescence peaks were assigned to the transitions from 1 S 0 to lower 5 f levels. To estimate the luminescence lifetime, luminescence decay curves were measured using time-resolved laser-induced fluorescence spectroscopy. At room temperature, the decay curve indicated that the lifetime was shorter than 20 ns. On the other hand, the frozen sample of U 4+ in aqueous solution at liquid nitrogen temperature showed the same emission spectrum as at room temperature and its lifetime was 149 ns in H 2 O system and 198 ns in D 2 O system. The longer lifetime at liquid nitrogen temperature made it possible to measure the spectrum of U 4+ at the concentration as low as 10 −6 M. The difference in the anion species (ClO 4 − , Cl − , SO 4 2− ) affected the structure of the emission spectrum to some extent.

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Section: Introductionmentioning

confidence: 99%

Luminescence properties of tetravalent uranium in aqueous solution

Kirishima¹,

Kimura²,

Nagaishi³

et al. 2004

Radiochimica Acta

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“…Structural investigations of UF 4 using diffraction methods have extended over the past 75 years. The structure was first reported in 1949, and it was shown that UF 4 crystallized in the C 2/ c space group and was isostructural to MF 4 (M = Th, Np, Pu, Zr, Hf, and Ce) . At this time, the positions of the U atoms were deduced, while those of the F atoms were not determined.…”

Section: Introductionmentioning

confidence: 97%

“…Additionally, UF 4 is envisaged as a fuel for advanced nuclear reactors . The coordination chemistry of UF 4 has been well documented, and the material has been studied in the solid state by spectroscopic (EXAFS, 19 F NMR, , IR, Raman, XPS, absorption, and luminescence), X-ray − and neutron powder diffraction (NPD), and theoretical methods . Nevertheless, some physicochemical properties are still not well understood, one of them being the intrinsic negative thermal expansion (NTE) of the material below room temperature .…”

Section: Introductionmentioning

confidence: 99%

Digging into the Intrinsic Negative Thermal Expansion of Uranium Tetrafluoride

Louis-Jean,

Scott,

Jang

et al. 2024

ACS Omega

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The intrinsic negative thermal expansion of UF 4 below room temperature was examined. A redetermination of the structure of UF 4 by single-crystal X-ray diffraction at 100, 200, and 300 K accompanied by an evaluation of the atomic displacement parameters (ADPs) of the F atoms was performed. The structure of UF 4 was described as the stacking of two subnetworks, respectively, constituted by the U(1) and U(2) atoms. The subnetwork formed by the U(2) atoms consists of infinite layers that run parallel to the (b, c) plan. The layers are composed of infinite zigzag chains of corner-sharing U(2)F 8 polyhedra running along the c-axis. An increase of temperature from 100 to 300 K leads to a decrease of the unit cell volume and the a and c lattice parameters and an increase of the b lattice parameter. As the temperature increases, the intrachain, interchain, and interlayer U−U distances decrease. It is proposed that the decrease of the intrachain and interlayer U−U distances causes a contraction of the U(2) subnetwork along the a-and c-axis and that a translation of the chains along the c-axis causes an expansion along the b-axis.

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“…29 The motivation for studying uranyl difluoride is that the material is relevant to nuclear and safeguard applications (e.g., as an intermediate for UF UO 2 conversion). 32−34 Also, fluorinated U materials (UO 2 F 2 , UF 4 ) exhibit photoluminescent properties 35,36 that are studied to improve radiation detection technology, such as the detection of leaking UF 6 cylinders 37 and sensitive low-dose measurements. 38 Uranium fluoride mr and mp have not yet been reported (vide supra).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Recently, we reported one such approach and prepared uranyl difluoride microspheres from the reaction of UO 3 ms and HF (g) produced from the decomposition of silver bifluoride (SBF) . The motivation for studying uranyl difluoride is that the material is relevant to nuclear and safeguard applications (e.g., as an intermediate for UF 6 and UO 2 conversion). − Also, fluorinated U materials (UO 2 F 2 , UF 4 ) exhibit photoluminescent properties , that are studied to improve radiation detection technology, such as the detection of leaking UF 6 cylinders and sensitive low-dose measurements …”

Section: Introductionmentioning

confidence: 99%

Tailoring Triuranium Octoxide into Multidimensional Uranyl Fluoride Micromaterials

Jang,

Poineau

2024

ACS Omega

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Uranium microstructured materials with controlled size and shape are relevant to the nuclear industry and have found applications as targets for medical isotope production, fuels for nuclear reactors, standards for nuclear forensics, and energy sources for space exploration. Until now, most studies at the microscale have focused on uranium microspheres (oxides, nitrides, carbides, and fluorides), while micromaterials of uranium halides, carbides, and pnictides with other morphologies are largely unknown. A promising method to shape the morphology of uranium micromaterials is the replacement of O by F atoms in oxide materials using a solid−gas reaction. Here, with the aim to elaborate unexplored uranium fluoride micromaterials, the fluorination of uranium oxide (U 3 O 8 and UO 2 ) microspheres (ms), microrods (mr), and microplates (mp) in an autoclave at 250 °C with HF (g) (produced from the thermal decomposition of silver bifluoride (SBF)) and with ammonium bifluoride (ABF) was evaluated. We show that the reactions between U 3 O 8 mr and U 3 O 8 mp and SBF provided the most efficient way to elaborate mr and mp UO 2 F 2 micromaterials in a high yield (∼90%). The resulting UO 2 F 2 mr (length: 3−20 μm) and UO 2 F 2 mp (width: 1−7.5 μm) exhibited a well-defined geometry that was identical to that of the U 3 O 8 precursors. Agglomerated (NH 4 ) 3 UO 2 F 5 and UO 2 F 2 ms (2−3.5 μm) were prepared from the reaction of U 3 O 8 ms with ABF. It is noted that the reaction of UO 2 ms with SBF and ABF did not provide any uranium fluoride micromaterials. The successful preparation of uranium fluoride microstructures (ms, mr, and mp) developed here opens the way to novel actinide fluoride micromaterials.

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The Luminescence Spectra of UF₄ and UC₁₄

Cited by 8 publications

References 7 publications

Luminescence properties of tetravalent uranium in aqueous solution

Luminescence properties of tetravalent uranium in aqueous solution

Digging into the Intrinsic Negative Thermal Expansion of Uranium Tetrafluoride

Tailoring Triuranium Octoxide into Multidimensional Uranyl Fluoride Micromaterials

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The Luminescence Spectra of UF4 and UC14

Cited by 8 publications

References 7 publications

Luminescence properties of tetravalent uranium in aqueous solution

Luminescence properties of tetravalent uranium in aqueous solution

Digging into the Intrinsic Negative Thermal Expansion of Uranium Tetrafluoride

Tailoring Triuranium Octoxide into Multidimensional Uranyl Fluoride Micromaterials

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Product

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About

The Luminescence Spectra of UF₄ and UC₁₄