The migration of O through a layer of Sn-doped material was determined by means of admittance measurements. It was found that the results could be best fitted by a model which assumed that simultaneous O diffusion and generation occurred. The diffusion coefficient,

D (cm2/s) = 1.0 x 10-1 exp[-18000K/T]

did not depend significantly upon the O pressure.

J.Berger, I.Reiss, D.S.Tannhauser: Solid State Ionics, 1985, 15[3], 225-31