The macroscopic diffusivity of protons in the α-phase was investigated, at 140 to 910K, by using pulsed field gradient nuclear magnetic resonance. The data, at temperatures greater than 500K, could be described by:

D (m2/s) = 1.1 x 10-7 exp[-0.178(eV)/kT]

when H/Ta was equal to 0.04, and by:

D (m2/s) = 1.1 x 10-7 exp[-0.187(eV)/kT]

when H/Ta was equal to 0.14. The concentration dependence of the diffusivity at 670K was determined for H/Ta ratios of between 0.03 and 0.14. The results could be described by:

D (m2/s) = (5.45 x 109)[1 - 1.67(H/Ta)]

In the overlap region (140 to 570K), accord with Gorsky-effect data was good.

M.Hampele, R.Messer, A.Seeger: Zeitschrift für Physikalische Chemie, 1989, 164[1], 879-82