The nature of H diffusion in this material was investigated by using ionic conductivity, nuclear magnetic resonance, and infra-red optical methods. It was found that the diffusivities of OH- interstitial ions and of H during annealing in molten carbonic acid could both be described by the expression:

D (cm2/s) = 0.081 exp[-1.08(eV)/kT]

at temperatures of between 400 and 1000K.

W.Bollmann: Physica Status Solidi A, 1987, 104[2], 643-8