Abstract:The cathode process of tantalum ion in molten NaCI-KCI- K₂TaF₇ at 720℃ was investigated by three transient electrochemical techniques. The results show that the electroreduction reaction of Ta⁵⁺ involves a single reversible five electron step. The diffusion coefficients of the complexion containing Ta⁵⁺ measured by above mentioned techniques are alike such as 1.15×10^-5 by cyclic voltammetry, 1.10×10^-5 by chronopotentiometry and 1.15×10^-5' by chronoamperometry respectively. The effect of electroactive species containing oxygen on tantalum reduction process was also studied.

Key words: electrochemical reduction  tantalum  molten NaCI-KCI- K₂TaF₇