Dynamic voltammetry was used to determine the regions of electrochemic
al slability of LaF3/Me interfaces, which depend on the metal and are
confined by faradaic processes, viz, fluorination of the metals and re
duction of lanthanum ions in the solid electrolyte. Oxygen was found t
o influence the interfacial processes. The generation of oxygen compou
nds during anodic polarization is either coupled to fluoride formation
or constitutes an alternative to fluoride formation. The reduction of
lanthanum ions during cathodic polarization may be masked by oxygen r
eduction near -1 V.