Data were obtained by making high-precision gravimetric measurements of the Ta lattice expansion due to H incorporation. Measurements were performed at temperatures of between 0 and 50C, for average H/Ta atomic ratios of up to 0.14. Values of 2.5 x 10-6 to 1.0 x 10-6cm2/s were obtained at 25C. These decreased with increasing H concentration. The activation energy was equal to 3.6kcal/mol. At higher H contents, the formerly straight Arrhenius plots exhibited sudden changes in slope; corresponding to higher activation energies (due to an effect of the β-phase).

E.Wicke, A.Obermann: Zeitschrift für Physikalische Chemie, 1972, 77[1-6], 163-75