Spectroscopic Studies of Neodymium(III) and Praseodymium(III) Compounds in Molten Chlorides

Lambert, Hugues; Claux, Benoît; Sharrad, Clint A.; Souček, Pavel; Malmbeck, Rikard

doi:10.1016/j.proche.2016.10.057

Cited by 6 publications

(7 citation statements)

References 14 publications

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“…Likewise, the vibrational bands of the Raman spectra of minority metal ion complexes could be completely masked by the background spectrum of a multivalent host cation. Element-specific optical absorption − and extended X-ray absorption fine-structure (EXAFS , ) spectroscopy represent an excellent probe of the local structure, but the interpretation of the results for complex systems could be very ambiguous. For example, a solute Ni(II) ion in molten ZnCl 2 –alkali chloride mixtures exhibits a very complicated dependence of its coordination geometry on solvent composition and temperature. − Conventional EXAFS analysis assumes that the structural distribution (commonly represented by the pair distribution ( g ( r )) of ions/atoms) can be described by a Gaussian function.…”

Section: Introductionmentioning

confidence: 99%

A Holistic Approach for Elucidating Local Structure, Dynamics, and Speciation in Molten Salts with High Structural Disorder

et al. 2021

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To examine ion solvation, exchange, and speciation for minority components in molten salts (MS) typically found as corrosion products, we propose a multimodal approach combining extended X-ray absorption fine structure (EXAFS) spectroscopy, optical spectroscopy, ab initio molecular dynamics (AIMD) simulations, and rate theory of ion exchange. Going beyond conventional EXAFS analysis, our method can accurately quantify populations of different coordination states of ions with highly disordered coordination environments via linear combination fitting of the EXAFS spectra of these coordination states computed from AIMD to the experimental EXAFS spectrum. In a case study of dilute Ni(II) dissolved in the ZnCl 2 +KCl melts, our method reveals heterogeneous distributions of coordination states of Ni(II) that are sensitive to variations in temperature and melt composition. These results are fully explained by the difference in the chloride exchange dynamics at varied temperatures and melt compositions. This insight will enable a better understanding and control of ion solubility and transport in MS.

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Section: Introductionmentioning

confidence: 99%

A Holistic Approach for Elucidating Local Structure, Dynamics, and Speciation in Molten Salts with High Structural Disorder

et al. 2021

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“…The diffuse reflectance profiles of Nd-and Pr-containing MOFs contained several additional sharp signals that do not correlate with the photophysical response of embedded 4,4′-azopyridine (Figure 3) and appeared due to the presence of lanthanide ions. 61 For instance, in the case of Azo@Pr-MOF, there are four additional peaks in the diffuse reflectance profile at λ = 446, 470, 485, and 592 nm, while the diffuse reflectance profile of Azo@Nd-MOF contains four peaks at λ = 581, 745, 796, and 867 nm. These featured sharp absorption bands are characteristic of f-f transitions for the selected lanthanides and are in line with the previously reported ones for the lanthanide-based salts.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…These featured sharp absorption bands are characteristic of f-f transitions for the selected lanthanides and are in line with the previously reported ones for the lanthanide-based salts. 61 The Azo@Ce-MOF does not contain any additional sharp absorbance peaks beyond the broad absorption in the 350− 550 nm range (Figure S10).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Photochromic Ln-MOFs: A Platform for Metal-Photoswitch Cooperativity

Martin,

Thaggard,

Lehman-Andino

et al. 2024

Inorg. Chem.

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Optoelectronic devices based on lanthanide-containing materials are an emergent area of research due to imminent interest in a new generation of diode materials, optical and magnetic sensors, and ratiometric thermometers. Tailoring material properties through the employment of photo-or thermochromic moieties is a powerful approach that requires a deep fundamental understanding of possible cooperativity between lanthanide-based metal centers and integrated switchable units. In this work, we probe this concept through the synthesis, structural analysis, and spectroscopic characterization of novel photochromic lanthanide-based metal−organic materials containing noncoordinatively integrated photoresponsive 4,4′-azopyridine between lanthanide-based metal centers. As a result, a photophysical material response tailored on demand through the incorporation of photochromic compounds within a rigid matrix was investigated. The comprehensive analysis of photoresponsive metal−organic materials includes singlecrystal X-ray diffraction and diffuse reflectance spectroscopic studies that provide guiding principles necessary for understanding photochromic unit-lanthanide-based metal−organic framework (MOF) cooperativity. Furthermore, steady-state and time-resolved diffuse reflectance spectroscopic studies revealed a rapid rate of photoresponsive moiety attenuation upon its integration within the rigid matrix of lanthanide-based MOFs in comparison with that in solution, highlighting a unique role and synergy that occurred between stimuli-responsive moieties and the lanthanide-based MOF platform, allowing for tunability and control of material photoisomerization kinetics.

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“…In-situ electronic absorption spectra of the molten salt were acquired employing a spectroscopic system similar to those used previously to acquire absorption spectra of high temperature melts [ 9 , 26 , 27 ]. The incoming light beam was positioned ~ 1 cm above the uranium metal sample in order to attempt to identify any semi long-lived intermediate species in the melt during the reaction, but sufficiently far away from the metal sample to avoid light scattering from the Bi metal that formed.…”

Section: Resultsmentioning

confidence: 99%

Preparation of uranium(III) in a molten chloride salt: a redox mechanistic study

Lambert

Kerry

Sharrad

2018

J Radioanal Nucl Chem

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The most advanced methodology for the pyroprocessing of spent nuclear fuel is the electrorefining of uranium metal in LiCl–KCl eutectic, in which uranium is solubilized as U(III). The production of U(III) in LiCl–KCl eutectic by the chlorination of uranium metal using BiCl3 has been performed for research purposes. In this work, this reaction was studied in-situ by visual observation, electronic absorption spectroscopy and electrochemistry at 450 °C. The most likely mechanism has been determined to involve the initial direct oxidation of uranium metal by Bi(III) to U(IV). The dissolved U(IV) then reacts with unreacted uranium metal to form U(III).

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Spectroscopic Studies of Neodymium(III) and Praseodymium(III) Compounds in Molten Chlorides

Cited by 6 publications

References 14 publications

A Holistic Approach for Elucidating Local Structure, Dynamics, and Speciation in Molten Salts with High Structural Disorder

A Holistic Approach for Elucidating Local Structure, Dynamics, and Speciation in Molten Salts with High Structural Disorder

Photochromic Ln-MOFs: A Platform for Metal-Photoswitch Cooperativity

Preparation of uranium(III) in a molten chloride salt: a redox mechanistic study

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