The electrochemical behavior of europium fluoride complexes was studied, using various electrochemical methods, at glassy carbon electrodes at 973 to 1100K in NaCl-KCl melts. The diffusion coefficients of Eu(III) and Eu(II) were determined using linear sweep voltammetry, and were described by:

Eu(III):     D(cm2/s) = -2.22 – 2445/T

Eu(II):     D(cm2/s) = -2.20 – 2365/T

with activation energies of 46.8 and 45.3kJ/mol, respectively. The standard rate constants of charge transfer for the Eu(III)/Eu(II) redox couple were found using cyclic voltammetry, impedance spectroscopy and chronoamperometry. The electrochemical behaviors of europium fluoride and europium chloride complexes in NaCl-KCl melt were compared and considered in connection with the strength and stability of these complexes. It was shown that the formation of stronger fluoride complexes reduced the diffusion coefficients.

Redox Electrochemistry of Europium Fluoride Complexes in an Equimolar NaCl-KCl Melt. S.A.Kuznetsov, M.Gaune-Escard: Journal of Nuclear Materials, 2011, 414[2], 126-31