Investigations were made of the diffusion and electromigration of H isotopes in an external electric field and in a Hall field. The diffusion parameters were determined at temperatures ranging from 293 to 573K, and the migration parameters were determined at 368K. The methods of electrolytic charging and resistometric transportation parameter determination were used. The values of the diffusion coefficient and electric charges were deduced by fitting an equation to experimentally measured temporal changes in the electrical resistivities. An analysis of the results implied that, in the case of H isotope diffusion, an anomalous isotope effect was caused mainly by an increase in the pre-exponential factor with increasing isotopic mass (table 101). The activation energies for D and T were lower than that for H. There also appeared to be a clear correlation between the effective valencies of both types of migration and diffusion coefficient. It was suggested that this implied that, during migration in an external field or migration in a Hall field, the thermodynamic forces that were caused by a concentration gradient played a lesser role than did the forces that were caused by the presence of an electric or Hall field.

Isotope Effect of Diffusion and Electromigration of Hydrogen in Nickel. R.Pietrzak: Journal of Materials Science Letters, 1996, 15[8], 731-3

Figure 18

Diffusivity of Fe in Ni

(circles: annealed [850C, 2h], open squares: annealed [500C, 1h],

filled squares: as cold-worked)