The electrochemical behaviour of different graphite/cryolite alumina melt interfaces under potentiodynamic perturbations

Calandra, A.J.; Castellano, C.E.; Ferro, C.M.

doi:10.1016/0013-4686(79)87031-0

Cited by 50 publications

(18 citation statements)

References 26 publications

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“…Assuming that Eq. 14 is valid in this case 21' 25 E = E1/2 + 2.303 RT log I~ I ~n~F I [14] an ~ value of 0.58 was obtained for n~ equal to 5. Use of a molar ratio (Na~O/K2TaFT) close to two showed the absence of peaks associated with tantalum reduction from TaFt-and TaOF~-species (Fig.…”

Section: < Ementioning

confidence: 76%

Electrochemical Study of Tantalum in Fluoride and Oxofluoride Melts

Polyakova¹,

Polyakov²,

Matthiesen

et al. 1994

J. Electrochem. Soc.

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The electrochemical behavior of tantalum in the form of K2TaF7 in an LiF-NaF-KF eutectic melt has been studied by linear voltammetry in the temperature range of 560 to 815~ with and without additions of Na20. An amperometric titration has been performed by measuring the heights of the cathodic and the anodic peaks. It was shown that at a molar ratio Na20/K2TaF7 = 1 the predominating complex in the melt is TaOF~ , whereas with an Na20/K2TaF7 molar ratio of 2 it is TaO2F(= =-I)-, probably in the form of TaO2F~-. Increase in the Na20/K2TaF7 molar ratio in excess of two leads to a decrease of tantalum concentration in the melt, and precipitation of KTaQ occurs. Both the fluoro complex and the monooxefluoro complex were reduced to metal in a single five-electron step. The fluoro complexes, in the temperature range 625 to 815~ with potential scan rates <0.5 V 9 s i, discharge quasi-reversibly, but at potential scan rates >0.5 V 9 s -I they discharge irreversibly. Monooxofluore complexes discharge irreversibly at all temperatures and scan rates studied. The diffusion coefficient of the tantalum fluoro complex depends on the temperature as log D = -2.55 -2044/Twith an activation energy of 39.1 kJ 9 mol -~. For the tantalum monooxofluoro complex the dependence is log D = -2.35 -2293/T with an activation energy of 43.9 kJ 9 mol -I.

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Section: < Ementioning

confidence: 76%

Electrochemical Study of Tantalum in Fluoride and Oxofluoride Melts

Polyakova¹,

Polyakov²,

Matthiesen

et al. 1994

J. Electrochem. Soc.

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“…The next possible electrochemical reaction product has been shown to be COF 2 [4,5] according to the overall reaction, A120 3 + 3C + 2A1F 3 = 4A1 + 3COF 2 (g).…”

Section: The Anode Effectmentioning

confidence: 99%

“…and its electrochemical formation [5] has been established in carefully controlled laboratory research. It is clear that passivation of the electrode surface plays a role, but the cause and form that it takes is a subject of debate.…”

Section: The Anode Effectmentioning

confidence: 99%

Towards Eliminating Anode Effects

Zarouni

Welch²,

Al-Jallaf

et al. 2011

Light Metals 2011

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“…The sequence of complex electrochemical reactions on graphite and other carbon materials has received considerable attention [108,154,155] using fast sweep cyclic voltammetry. Amorphous carbon materials may also be electrodeposited from molten LiF-NaF medium.…”

Section: Carbonmentioning

confidence: 99%

Electrochemistry of metals and semiconductors in fluoride media

Noel

Suryanarayanan

2005

J Appl Electrochem

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The electrochemical surface transformations and diverse applications of a variety of metals and semiconductors in a wide range of fluoride media such as aqueous, non-aqueous media, liquid HF media, room temperature fluoride melts and molten fluoride media with a melting range covering 50-1000°C are reviewed. Nickel shows excellent corrosion resistance in the absence of water. The anodic performance of this metal in electrochemical perfluorination and NF 3 production is discussed. Compact carbon materials serve as anodes in fluorine generators. In high temperature melts, they perform as consumable anodes. Graphitic carbon undergoes intercalation/ de-intercalation process and related battery applications. Cu/CuF 2 couple is a good reference electrode. Pt and vitreous carbon materials are the inert electrodes of choice for electro analytical applications. Electrodeposition of Lithium as a non-dendritic uniform phase is important in Lithium metal based secondary batteries. High temperature fluoride melts are used in electro-deposition of valve metals such as Nb, Ta, and Ti. The stability and decomposition of fluoride complexes in these media are of interest.

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The electrochemical behaviour of different graphite/cryolite alumina melt interfaces under potentiodynamic perturbations

Cited by 50 publications

References 26 publications

Electrochemical Study of Tantalum in Fluoride and Oxofluoride Melts

Electrochemical Study of Tantalum in Fluoride and Oxofluoride Melts

Towards Eliminating Anode Effects

Electrochemistry of metals and semiconductors in fluoride media

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