Direct measurements of the self-diffusion coefficient of H in hydrided single crystals were performed at between 90 and 243C by using the nuclear magnetic resonance pulsed-field-gradient technique. In the case of α'-NbH0.6, the results could be described by:

D (cm2/s) = 6.6 x 10-4 exp[-0.165(eV)/kT]

By combining these measurements with spin-lattice relaxation rates for H, it was found that the root-mean-square jump distance was equal to between 50 and 80% of the body-centered cubic lattice constant.

Self-Diffusion Coefficient of Hydrogen in NbH0.6. O.J.Zogal, R.M.Cotts: Physical Review B, 1975, 11[7], 2443-6