The migration of H was investigated, by means of quasi-elastic neutron scattering, at temperatures of 165 to 300K. A transition from a high-temperature activation energy of 0.106eV, to a low-temperature activation energy of 0.068eV, was observed in this region. The value of the low-temperature activation energy was confirmed by neutron scattering experiments. At temperatures below 250K, the results of scattering experiments yielded the relationship:

D (cm2/s) = 1.2 x 10-4 exp[-0.069(eV)/kT]

D.Richter, B.Alefeld, A.Heidemann, N.Wakabayashi: Journal of Physics F, 1977, 7[4], 569-74

 

Table 140

Parameters for D and H Diffusion in Nb

 

Isotope

Temperature (K)

Do (cm2/s)

E (eV)

D

120-600

5.4 x 10-4

0.129

H

120-300

9.0 x 10-5

0.068

H

300-600

5.0 x 10-4

0.106