The H self-diffusion coefficient was investigated by means of neutron spectroscopy at temperatures of between 450 and 950C, for x-values of between 1.80 and 1.97. When x was equal to 1.97, the diffusivity could be described by:

D (cm2/s) = 3.4 x 10-4exp[-0.35(eV)/kT]

The diffusivity did not exhibit the high-temperature anomaly (decreasing diffusivity with increasing temperature) which had been revealed by nuclear magnetic resonance data. At a given temperature, the diffusivity increased with increasing x-value. This effect was attributed to the partial H occupation of octahedral interstitial sites.

U.Stuhr, M.Schlereth, D.Steinbinder, H.Wipf, B.Frick, A.Magerl: Zeitschrift für Metallkunde, 1989, 164[1], 929-34