The diffusion of H and D in this cubic (C15) Laves phase was investigated by using the magnetic after-effect method. The samples were charged electrolytically, and the resultant H concentration was deduced by means of thermal desorption measurements. It was shown to amount, at most, to only 0.01 H or D atoms per formula unit. The after-effect spectra exhibited peaks at 58 and 69K, after H-charging, and peaks at 70 and 85K after D-charging. Numerical analyses of the spectra yielded short-range diffusion activation enthalpies of 0.13 and 0.16eV for H and 0.15 and 0.18eV for D, with pre-exponential factors of 5 x 10-12s (H) and 3 x 10-11s (D). From these data, conclusions were drawn concerning the diffusion paths and occupation of interstitial sites by H and D atoms. Quantum-mechanical analysis yielded the lattice activation energy and the parameters of the potential well.

H.Reule, M.Hirscher, H.Kronmüller: Philosophical Magazine B, 1997, 76[6], 929-39