The electrode reaction of the Pu3+/Pu couple at the surface of a liquid Cd
electrode was investigated by cyclic voltammetry at 723, 773 and 823 K in L
iCl-KCl eutectic melt. It was found that the diffusion of Pu3+ in the salt
phase was a rate-determining step in the cathodic reaction, but the dissolu
tion of Pu from the liquid Cd phase was so slow that the anodic wave broade
ned slightly. The redox potentials of the Pu3+/Pu couple at the liquid Cd e
lectrode at 723, 773 and 823 K were observed at more positive potentials, 0
.299, 0.269 and 0.239 V, respectively, than those at a solid Mo electrode.
This potential shift was thermodynamically analyzed by a lowering of activi
ty of Pu in the Cd phase due to the formation of the alloy PuCd6 at the int
erface. As well as the Gibbs energy of formation of PuCd6, the Gibbs energi
es of formation of the other intermetallic compounds PuCd2 and PuCd4 could
also be estimated by the analysis of the anodic peaks in cyclic voltammogra
ms of the Pu3+/Pu redox couple at a Cd-coated Mo electrode. (C) 2000 Elsevi
er Science S.A. All rights reserved.