A relaxation method was used to investigate intrinsic H diffusivity in β-phase hydrides at temperatures of 15 to 45C and H pressures of 40 to 450bar (or to 23000bar at 25C). The diffusion parameters (table 230), as deduced from the temperature dependence of the intrinsic diffusion coefficient at various pressures exhibited, a maximum at between 300 and 400bar; thus indicating that the diffusion process could no longer be described by a single-jump mechanism between adjacent octahedral interstitials in the Pd lattice.

M.Kuballa, B.Baranowski: Berichte der Bunsengesellschaft für Physikalische Chemie, 1974, 78[4], 335-8

 

Table 232

Parameters for H Diffusion in Pd at 279 to 335K

 

Condition

Do (m2/s)

E (kJ/mol)

annealed

9.36 x 10-8

21.42

annealed

1.03 x 10-7

21.51

annealed

1.05 x 10-7

21.42

annealed

1.08 x 10-7

21.51

annealed

1.10 x 10-7

21.55

cold-worked

5.47 x 10-8

22.22

cold-worked

6.43 x 10-8

22.05

cold-worked

8.07 x 10-8

22.18

cold-worked

9.80 x 10-8

22.09

cold-worked

1.13 x 10-7

21.92