Electrochemical reduction mechanism of Zr⁴⁺ on tungsten electrode in LiF-CaF₂-BaF₂-ZrO₂ molten salt

The electrochemical process of Zr⁴⁺ on the tungsten electrode at the temperature of 1 373 K was studied through the methods of cyclic voltammetry, chronopotentiometry and chronoamperometry when LiF-CaF₂-BaF₂was taken as the molten salt system, and ZrO₂ as the raw material.This paper has carried out an electrochemical analysis for molten salt with different ZrO₂ contents of 0.5 %, 0.7 %, 0.9 %. The results show that the electrochemical reduction of Zr⁴⁺on the tungsten electrode is caused by two electrode reactions, namely Zr⁴⁺+2e→Zr²⁺ and Zr²⁺+2e→Zr. As a result, platinum reduction peak of the relative reference electrode is 0.9 V and 1.2 V respectively, which proves that this process is a quasi-reversible reaction controlled by diffusion. The diffusion coefficient of Zr⁴⁺ in the molten salt is 6.7×10^-6 cm²/s at 1 373 K.