Ion-driven permeation was used to determine the diffusivity, rather than gaseous or electrochemical charging. The steady-state permeation rate and the diffusion coefficient tended to decrease with increasing fluence, because of changes in the surface or sub-surface regions. It was found that the results could be described by the expression:

D (m2/s) = 8.2 x 10-8 exp[-23.3(kJ/mol)/RT]

at between 500 and 1100K.

Determination of Deuterium Diffusion Coefficient by Ion Driven Permeation Technique. Y.Furuyama, T.Tanabe, S.Imoto: Journal of the Japan Institute of Metals, 1986, 50[8], 688-94