Pulsed gradient nuclear magnetic resonance methods were used to measure H diffusion in the β-phase material, Ni5LaHx, where x ranged from 6 to 7. The results, for 331 to 375K, could be described by the Arrhenius relationship:

D (cm2/s) = 1.4 x 10-1exp[-40(kJ/g-atom)/RT]

as compared with the result for the α-type material,

D (cm2/s) = 3 x 10-2exp[-40(kJ/g-atom)/RT]

It was suggested that the higher diffusivity in the β-type material was related to a 25% lattice expansion which occurred during the transition.

Hydrogen Diffusion in β-LaNi5 Hydride. R.F.Karlicek, I.J.Lowe: Solid State Communications, 1979, 31[3], 163-5

Figure 23

Diffusivity of H in Ni60Nb35Cr5

(open squares: 3at%H, filled squares: 1.6at%H)