Electrochemistry of thorium fluoride in LiCl-KCl eutectic melts and methodology for speciation studies with fluorides ions

Delpech, Sylvie; Jaskierowicz, Sébastien; Rodrigues, Davide

doi:10.1016/j.electacta.2014.07.096

Cited by 24 publications

(13 citation statements)

References 15 publications

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“…Additionally, it is worth noting that the cathodic peak current ( I pc ) of A decreases with the addition of F − (Figure 1d). Similar phenomenon was reported by Delpech et al., and was ascribed to the precipitation of metal oxides in the melt [11] . But it is not the case in this work since no precipitate was found during the whole measurement.…”

Section: Resultssupporting

confidence: 90%

“…The maximum number of F − anions coordinated with Ln 3+ was estimated by a mathematical analysis developed by Picard et al. and Delpech et al [11,13] . When the total concentration of F − ( C F‐, total ) is much higher than that of Ln 3+ ( C Ln3+ ), the complexation coefficient ( α Ln, F ) between Ln 3+ and F − ions will be expressed as…”

Section: Resultsmentioning

confidence: 99%

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Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La³⁺ and Nd³⁺) in Molten Salts

Jiang

Lan

Wang

et al. 2021

Chemistry A European J

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Molten salt electrolysis is a vital technique to produce high‐purity lanthanide metals and alloys. However, the coordination environments of lanthanides in molten salts, which heavily affect the related redox potential and electrochemical properties, have not been well elucidated. Here, the competitive coordination of chloride and fluoride anions towards lanthanide cations (La3+ and Nd3+) is explored in molten LiCl‐KCl‐LiF‐LnCl3 salts using electrochemical, spectroscopic, and computational approaches. Electrochemical analyses show that significant negative shifts in the reduction potential of Ln3+ occur when F− concentration increases, indicating that the F− anions interact with Ln3+ via substituting the coordinated Cl− anions, and confirm [LnClxFy]3−x−y (ymax=3) complexes are prevailing in molten salts. Spectroscopic and computational results on solution structures further reveal the competition between Cl− and F− anions, which leads to the formation of four distinct Ln(III) species: [LnCl6]3−, [LnCl5F]3−, [LnCl4F2]3− and [LnCl4F3]4−. Among them, the seven‐coordinated [LnCl4F3]4− complex possesses a low‐symmetry structure evidenced by the pattern change of Raman spectra. After comparing the polarizing power (Z/r) among different metal cations, it was concluded that Ln−F interaction is weaker than that between transition metal and F− ions.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La³⁺ and Nd³⁺) in Molten Salts

Jiang

Lan

Wang

et al. 2021

Chemistry A European J

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“…To confirm that the potential difference is due to ohmic drop, the electrolyte resistance has been determined by impedance spectroscopy (Fig. 4) using a same approach already described [27]. This kind of measurement does not require recording an impedance diagram in a large frequency range.…”

Section: Reference Dynamic Electrode Preparation For Redox Potential mentioning

confidence: 99%

Dynamic Reference Electrode development for redox potential measurements in fluoride molten salt at high temperature

Durán-Klie

Rodrigues

Delpech

2016

Electrochimica Acta

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International audienceMeasurement of redox potential in fluoride media is a major problem due to the difficulty to design a reference electrode with high stability, high mechanical resistance and high accuracy. In the frame of molten salt reactor studies, a dynamic reference electrode (DRE) is developed to measure redox potential in fluoride molten salt at high temperature. DRE is based on the in-situ generation of a transient redox system. The choice of the redox couple corresponds to the cathodic limit of the molten salt considered. As a preliminary step, the demonstration of feasibility of generating a DRE was done in LiF-NaF-KF (46.5–11.5–42 mol%) media at 500 °C. In this salt, the reference redox system generated by coulometry at applied current is KF/K, metallic potassium being electrodeposited on a tungsten wire electrode. The validation of the DRE response and the experimental optimization parameters for DRE generation were realized by following the NiF2/Ni redox potential evolution as a function of NiF2 concentration in the fused salt.The current value applied for DRE generation was optimized. It depends on the amount of metallic cations contained in the fused salt and which can be electrochemically reduced simultaneously during the DRE generation. The current corresponding to the DRE generation has to be 4 times greater than the current corresponding to the reduction of the other elements

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“…Different from Am(III), U(III) can interact with only one F − ion to form UCl 5 F 3− complex ions, as is shown in our recent study using XAS and MD simulation methods [40] . For tetravalent Ans, the Delpech and our groups explored the solution structures of Th(IV) and U(IV) in LiCl−KCl−LiF melts respectively and suggested that at most three F − ions can enter the first coordination sphere of An(IV) [40–41] …”

Section: Coordination Chemistry Of Actinide Elements In Molten Saltsmentioning

confidence: 99%

“…[40] For tetravalent Ans, the Delpech and our groups explored the solution structures of Th(IV) and U(IV) in LiClÀ KClÀ LiF melts respectively and suggested that at most three F À ions can enter the first coordination sphere of An(IV). [40][41] In addition, temperature also has a weak and irregular impact on the coordination behavior of Ans in molten salts. This impact will not be discussed here.…”

Section: Factors Affecting the Coordination Properties Of Actinide El...mentioning

confidence: 99%

The Coordination Chemistry of f‐Block Elements in Molten Salts

Jiang

Wang

Chai

et al. 2022

Chemistry A European J

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The coordination chemistry of f-block elements (lanthanide and actinide) in molten salts has become a resounding topic in view of its great importance to the research and development (R&D) of molten salt reactors and pyroprocessing. In this Review article, a general overview of the coordination chemistry of f-block elements in molten salts is provided including past achievements and recent advances.Particular emphases are placed on the oxidation state, speciation, and solution structure of f-block metal ions in molten salts, as well as their relationships with the salt composition. Furthermore, this review briefly discusses the spectroscopic and theoretical methods that complement each other in revealing the coordination properties.

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Electrochemistry of thorium fluoride in LiCl-KCl eutectic melts and methodology for speciation studies with fluorides ions

Cited by 24 publications

References 15 publications

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La³⁺ and Nd³⁺) in Molten Salts

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La³⁺ and Nd³⁺) in Molten Salts

Dynamic Reference Electrode development for redox potential measurements in fluoride molten salt at high temperature

The Coordination Chemistry of f‐Block Elements in Molten Salts

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Electrochemistry of thorium fluoride in LiCl-KCl eutectic melts and methodology for speciation studies with fluorides ions

Cited by 24 publications

References 15 publications

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La3+ and Nd3+) in Molten Salts

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La3+ and Nd3+) in Molten Salts

Dynamic Reference Electrode development for redox potential measurements in fluoride molten salt at high temperature

The Coordination Chemistry of f‐Block Elements in Molten Salts

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Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La³⁺ and Nd³⁺) in Molten Salts

Competitive Coordination of Chloride and Fluoride Anions Towards Trivalent Lanthanide Cations (La³⁺ and Nd³⁺) in Molten Salts