DIFFUSION AND PERMEATION OF HYDROGEN-DEUTERIUM IN PALLADIUM ELECTRODE

Electrochemical properties of palladium electrode in electrolytes of l ight/heavy waters, permeation efficiency and diffusion behaviors of hy drogen/deuterium through palladium were investigated. From potential c hange of Pd electrode during hydrogen/deuterium charging and polarizat ion curves after charging, growth rate of beta-phase is higher in heav y water than that in light water. The rate of hydrogen / deuterium abs orption into palladium in acidic solution is higher than in alkaline s olution. By using AC modulation technique diffusion coefficients of hy drogen D(H) and deuterium D(D) were evaluated as a function of tempera ture and charging time. At lower charging current, D(H) increases with charging time, probably due to filling trap states in Pd. On the othe r hand, at higher charging current, DH decreases with charging time. T his result can be explained by formation of a new phase with high H/Pd ratio at Pd surface in which D(H) is smaller than that in the known p hase (alpha or beta-phase).