Investigation of the Electrochemical Behavior of Ytterbium Cations in LiCl-KCl Melt Using Spectro-Electrochemical Methods

Bae, Sang-Eun; Kim, Dae-Hyeon; Lee, Na-Ri; Park, Tae‐Hong; Kim, Jong-Yun

doi:10.1149/2.0751602jes

Cited by 10 publications

(11 citation statements)

References 23 publications

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“…Figure c shows the respective cathodic and anodic peak currents of Sm 3+ and Sm 2+ as a function of scan rates. The scan rate dependence for Sm 2+ was obtained after converting Sm 3+ to Sm 2+ in a LiCl-KCl melt by applying a cathodic potential of −1.2 V for an hour. , It is known that Sm 2+ tends to disproportionate into Sm 3+ and Sm 0 in solution phases including ionic liquids. , Similar results have also been observed for Nd 2+ in a LiCl-KCl molten salt . However, Sm 2+ generated in the LiCl-KCl melt at 450 °C was found to be stable during the whole electrochemical and spectroscopic measurements (vide infra).…”

Section: Resultsmentioning

confidence: 52%

“…Absorbance recorded during an electrochemical reaction provides information about the concentrations of the absorbing ions that undergo the redox reaction. , The absorbance observed in Figure is proportional to the concentrations of Sm 3+ and Sm 2+ according to Beer’s law. At the potentials applied, the electrochemical reaction involving the Sm cations on a W electrode is as shown below. …”

Section: Resultsmentioning

confidence: 99%

“…The scan rate dependence for Sm 2+ was obtained after converting Sm 3+ to Sm 2+ in a LiCl-KCl melt by applying a cathodic potential of −1.2 V for an hour. 9,19 It is known that Sm 2+ tends to disproportionate into Sm 3+ and Sm 0 in solution phases including ionic liquids. 19,22 Similar results have also been observed for Nd 2+ in a LiCl-KCl molten salt.…”

Section: Inorganic Chemistrymentioning

confidence: 99%

“…Samarium (Sm), , europium (Eu), and ytterbium (Yb) form stable and soluble divalent ions, as well as trivalent ones, in the molten salt unlike other lanthanides, which exist exclusively as trivalent ions in the melt. Moreover, these divalent ions can be electrochemically deposited as alloys in reactive solid electrodes and liquid electrodes, though their electrodeposition on a stable solid electrode is beyond the potential window offered by the molten salt.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Formation of Divalent Samarium Cation and Its Characteristics in LiCl–KCl Melt

et al. 2018

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The electrochemical reduction of trivalent samarium in a LiCl-KCl eutectic melt produced highly stable divalent samarium, whose electrochemical properties and electronic structure in the molten salt were investigated using cyclic voltammetry, UV-vis absorption spectroscopy, laser-induced emission spectroscopy, and density functional theory (DFT) calculations. Diffusion coefficients of Sm and Sm were electrochemically measured to be 0.92 × 10 and 1.10 × 10 cm/s, respectively, and the standard apparent potential of the Sm couple was estimated to be -0.82 V vs Ag|Ag at 450 °C. The spectroelectrochemical study demonstrated that the redox behavior of the samarium cations obeys the Nernst equation ( E°' = -0.83 V, n = 1) and the trivalent samarium cation was successfully converted to the divalent cation having characteristic absorption bands at 380 and 530 nm with molar absorptivity values of 1470 and 810 M cm, respectively. Density function theory calculations for the divalent samarium complex revealed that the absorption signals originated from the 4f to 4f5d transitions. Additionally, laser-induced emission measurements for the Sm cations in the LiCl-KCl matrix showed that the Sm ion in the LiCl-KCl melt at 450 °C emitted an orange color of fluorescence, whereas a red colored emission was observed from the Sm ion in the solidified LCl-KCl salt at room temperature.

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Section: Resultsmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Section: Inorganic Chemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrochemical Formation of Divalent Samarium Cation and Its Characteristics in LiCl–KCl Melt

et al. 2018

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“…19,22,26,27 Figure 3 shows the electronic absorption spectra of LiCl-KCl eutectic melts containing UCl 3 , NdCl 3 , and CeCl 3 . Prior to Li 2 O addition, U 3+ and Ce 3+ exhibit their characteristic f-d transitions at 400-700 nm and 250-350 nm, respectively.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical and Spectroscopic Monitoring of Interactions of Oxide Ion with U (III) and Ln (III) (Ln = Nd, Ce, and La) in LiCl-KCl Melts

Choi

Bae

Park

2017

J. Electrochem. Soc.

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Using cyclic voltammetry and UV-vis absorption spectroscopic methods, we studied the precipitation reactions of trivalent uranium and lanthanides (Nd, Ce, and La) with the oxide ion in LiCl-KCl molten salts, which are likely side reactions during the electrorefining process for nuclear fuel treatment. The in situ electrochemical and spectroscopic monitoring demonstrated that U 3+ consumed O 2− with the mole ratio of 2:1, whereas the lanthanide ions reacted with O 2− with the mole ratio of 1:1. Raman spectroscopy and X-ray diffraction were also employed to analyze the precipitates, confirming that U 3+ was precipitated and oxidized into UO 2 , while the trivalent lanthanide ions formed oxychlorides (LnOCl). As a preliminary study of actinide co-precipitation, we also electrochemically monitored the precipitation reactions in a mixed melt containing uranium and lanthanides, demonstrating a higher reactivity of the former with the oxide ion in LiCl-KCl. Understanding the chemical reactions in chloride-based molten salts at high temperatures is of fundamental importance for developing pyroprocessing technologies, which have been extensively examined over the last 30 years as a promising solution for accumulated spent nuclear fuel. [1][2][3][4] In particular, the electrochemical behaviors of actinides and lanthanides in LiCl-KCl melts have been widely studied to explain the fundamental electrochemical reactions in the electrorefining process, which partitions reusable metals and highly radioactive fission products.5-7 However, before the commercialization of this technology, it is necessary to obtain comprehensive insight of the molten salt chemistry of trace elements dissolved from the spent nuclear fuel, and the additives and/or impurities that enter during the process. 8,9 Li 2 O is a critical ingredient for the electrochemical reduction of spent oxide fuel. It affords O 2− ions that should diffuse to the anode at the beginning of the reduction process, and controls the O 2− concentration in the LiCl melt to prevent the Pt cathode from dissolving. 3 However, a trace amount of Li 2 O likely remains in the reduced fuel, even after distilling out the molten salt at the end of the oxide reduction process, and can enter the next process. During the electrorefining process, the oxide ion may react with trivalent actinide and lanthanide ions in the LiCl-KCl eutectic melt, affording insoluble oxides and oxychlorides 10,11 which contaminate the salt and reduce the purity and yields of recovered uranium. In addition, unreduced lanthanide oxides in the metal fuel feed play the role of oxo-donor in the LiClKCl melt.12 Therefore, knowledge of the reactions between the actinide/lanthanide ions and the oxide ion in the molten salt could lead to improvement in the electrorefining technology. Several research groups have studied such reactions by potentiometric titration of the oxide ion in the melt and product characterization, in order to estimate the thermodynamic properties for oxide reduction 10,12-15 and to partition lanthan...

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Study on the exchange current density of lanthanide chlorides in LiCl-KCl molten salt

Lim

Yun

2019

Electrochimica Acta

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Investigation of the Electrochemical Behavior of Ytterbium Cations in LiCl-KCl Melt Using Spectro-Electrochemical Methods

Cited by 10 publications

References 23 publications

Electrochemical Formation of Divalent Samarium Cation and Its Characteristics in LiCl–KCl Melt

Electrochemical Formation of Divalent Samarium Cation and Its Characteristics in LiCl–KCl Melt

Electrochemical and Spectroscopic Monitoring of Interactions of Oxide Ion with U (III) and Ln (III) (Ln = Nd, Ce, and La) in LiCl-KCl Melts

Study on the exchange current density of lanthanide chlorides in LiCl-KCl molten salt

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