Diffusion into and out of bulk polycrystalline material in ambient O and He atmospheres was monitored by means of  in situ  resistivity measurements. The out-diffusion of O was found to be independent of the deviation from stoichiometry, and its rate was surface-reaction limited; with an activation energy of 1.7eV. The in-diffusion depended strongly upon the deviation from stoichiometry, and the activation energies for Cu3Ba2YO7 and Cu3Ba2YO6.62 were 1.1 and 0.48eV, respectively. The latter value was taken to be the activation energy for motion, while the former was the activation energy for diffusion. A defect mechanism in the CuO plane was proposed, for the anisotropic diffusion of O in this oxide, on the basis of kinetic and structural information.

K.N.Tu, C.C.Tsuei, S.I.Park, A.Levi: Physical Review B, 1988, 38[1], 772-5