Galvanostatic investigation of electrochemical processes at the LaF3/M (M: Ag, Bi) interface

Abstract

The electrochemical processes at the interface between solid fluorine-conducting electrolyte LaF3(Eu2+ 0.8 mol %) and silver or bismuth electrodes in the two-electrode cell with nonpolarizable reference electrode are studied using the galvanostatic method. The anodic galvanostatic transients of LaF3: Eu2+/Ag and LaF3: Eu2+/Bi interfaces are linearized on the log(η − ηmax), vs. t coordinates, i.e. the rate of LaF3|MF n |M electrode formation is limited by slow surface diffusion of metal adions. The initial portions of cathodic galvanostatic transients in the range of solid-electrolyte lanthanum reduction are approximated by the linear dependence of η on log(1 − √t/τ). The plots of logI vs. 1/η are linear both for the lanthanum reduction and for silver and bismuth oxidation involving mobile fluoride ion of solid electrolyte, which is typical for two-dimensional growth of new phase.