Mechanism of the electrochemical reduction of tantalum(V) in molten fluorides

✍ Scribed by A. Espinola; A.J.B. Dutra; F.T. Silva

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 477 KB
• Volume: 251
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(91)87115-n

✦ Synopsis

The mechanism of the reduction of tantalum(\r) in molten fluorides (LiF-NaF-KF eutectic) was investigated in order to resolve the controversy in the literature.

The technique used was mainly chronopotentiometry. It was concluded that at a C-E-E mechanism applies, that is, a chemical reaction followed by two electrochemical steps, the first (reversible) giving a soluble product, with the transfer of two electrons, and the second a product with transfer of three electrons. The conclusion regarding the two-electron transfer was based on the determination of an average number of 1.94 + 0.40. The diffusion coefficient for the Ta(V) species, in accordance with the previously proposed dissociation of the TaF;-ion, was 3.14 x lo-' cm' s-l, estimated using the Stokes-Einstein equation; the estimated activation energy for diffusion was 10.34 kcal mol-' (4.33 x lo4 J mol-').