Electrode process of La(III) in molten LiCl-KCl

The electrode process of La(III) at Mo electrode in the molten LiCl-KCl for temperatures ranging from 683 K to 773 K was studied by cyclic voltammetry and chronopotentiometry, respectively. The results showed that in the molten LiCl-KCl, reduction of La(III) occurred in a step with a global exchange of three electrons. Cyclic voltammetry studies indicated that at a sweep rate lower than 0.2 V/s, the electroreduction of La(III) to lanthanum metal was reversible and controlled by diffusion of La(III). However, the process became under a mixed control of both diffusion and electron transfer when sweep rate exceeded 0.2 V/s. And an empirical temperature dependence of the diffusion coefficient of La(III) was proposed: lnD_La(III)=7.742–1.441×10⁴/T. And the relation between the formal potential of La(III)/La versus Ag/AgCl reference electrode and temperature was described in the following equation: E^θ'=–1.402–4.689×10²/T.