Migration in foils was measured at 0 to 100C by using an electrochemical time-lag method (table 258). A modified strain model indicated that the tetrahedral sites in body-centered cubic lattices had to be assumed to be stable positions for dissolved H. Elementary jumps, from one tetrahedral site to the next, passed directly through a tetrahedral plane. This model described qualitatively the experimental results, with respect to the order of the activation energies for H diffusion.

N.Boes, H.Züchner: Zeitschrift für Naturforschung A, 1976, 31[7], 760-8

 

Table 259

Parameters for H and D Diffusion in Ta

 

Isotope

Temperature (K)

Do (cm2/s)

E (kJ/mol)

H

160-230

9.7 x 10-4

20.3

H

110-160

9.2 x 10-6

14.1

H

87-110

1.4 x 10-8

8.1

D

118-210

2.8 x 10-4

20.2

D

78-118

1.1 x 10-7

12.7