Cathodic processes at electrolysis of chloride—fluoride and oxyfluoride melts of niobium

Electrochemical behavior of hexafluoroniobate, heptafluorotungstate, and oxotetrafluorovanadate anions in N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide room temperature ionic liquid

“…Although electrochemical data are available for some chloro-and bromo-metallate anions [17][18][19][20][21][22][23], there are not many reports on electrochemical data for fluorometallate and oxofluorometallate anions and, to our knowledge, no reports are available for the electrochemical behavior of Nb(V)F 6 À , W(VI)F 7 À , and V(V)OF 4 À at 298 K. In this paper, the electrochemical behavior of Nb(V)F 6 À , W(VI)F 7 À , and V(V)OF 4 À in BMPyrTFSA at 298 K is discussed in detail, where BMPyrTFSA was chosen as a medium because of its high electrochemical stability and easy handling. following relation holds [24]:…”

Investigation on the reaction progress of zirconium and cuprous chloride in the LiCl–KCl melt

“…The chosen of the liquid alloy anode can not only reduce the operating temperature, but also expect to provide a low cost and semi-continuous process for production nuclear grade zirconium. The electrorefining and electrochemical process of Zr has been studied in various molten salt systems, including all-chloride baths such as LiCl-KCl-ZrCl 4 [2,[5][6][7], KCl-ZrCl 4 [8,9], all-fluoride baths such as LiF-NaF-KF-ZrF 4 and K 2 ZrF 6 [10,11], LiF-KF-ZrF 4 [3], LiF-CaF 2 -ZrF 4 [12] and chloridefluoride-mixed baths such as KCl-NaCl-ZrF 4 [13], KCl-NaCl-K 2 ZrF 6 [8,13,14], and LiCl-KCl-K 2 ZrF 6 [15] at temperature ranges of 450 C to 750 C. However, the operating temperature of the all-fluoride baths is 100 C $ 200 C higher, and the corrosion issue is more severe compared to those of all-chloride baths. In consideration of the melting point of liquid alloy anode and a moderate experimental condition, the Zr electrorefining process is proposed in LiCl-KCl-ZrCl 4 molten salt at 500 C in the initial stage of research.…”

Electrochemical Studies of the Molten System K[sub 2]NbF[sub 7]-Na[sub 2]O-Nb-(LiF-NaF-KF)[sub eut] at 700°C

“…This mechanism is in agreement with previous work in alkali-fluoride melts 2,4,18 and mixed alkali-chloride-fluoride melts. 21,22,[26][27][28] Details concerning the simulation are previously described. 7 The diffusion coefficient of NbF 7 2Ϫ can be calculated using Eq.…”

“…Since there has been some debate as to the stability of Nb-oxofluoride ions with niobium in oxidation states different from five, this matter has also been studied more closely. Previous voltammetric investigations in alkali fluoride 2,4,22 or alkali-fluoride-chloride melts 5,23 have not shown a reduction step belonging to the reduction of NbOF 5 2Ϫ to a soluble product, e.g., a Nb(IV)-oxofluoride complex. On the other hand, adding Nb metal to a melt containing NbOF 5 2Ϫ , Christensen et al 2 observed dissolution of Nb metal, indicating reduction of Nb(V) in NbOF 5 2Ϫ to a Nb(IV) species.…”