A pulsed field gradient nuclear magnetic resonance spin-echo technique was used to measure diffusivities. The activation energy increased with increasing H concentration, whereas the pre-exponential factor was not greatly concentration-dependent (table 262). The results were not consistent with the random occupation of tetrahedral sites, and it was suggested that repulsive interactions existed between H atoms on nearest-neighbour sites.

P.E.Mauger, W.D.Williams, R.M.Cotts: Journal of the Physics and Chemistry of Solids, 1981, 42[9], 821-6

 

Table 263

Diffusivity, Mobility and Effective Charge of H in Ta

 

Temperature (C)

m (cm2/Vs)

D (cm2/s)

Z*(e)

26

2.0 x 10-5

1.73 x 10-6

0.3

50

4.6 x 10-5

2.5 x 10-6

0.5

100

7.9 x 10-5

4.2 x 10-6

0.6

150

1.09 x 10-4

6.8 x 10-6

0.6

250

2.6 x 10-4

1.5 x 10-5

0.8

600

1.25 x 10-3

6.1 x 10-5

1.5