The diffusion of O in and out of Cu3Ba2YO7-x was monitored by means of  in situ  resistivity measurements. The out-diffusion of O was studied by annealing the oxide in He at constant heating rates and various temperatures. The rate of O out-diffusion was found to be independent of x, while the resistivity changed linearly with time during isothermal annealing. By assuming that the rate of out-diffusion was surface-reaction limited, it was deduced that there was a surface barrier of 1.7eV. The in-diffusion of O was studied by annealing the O-deficient oxide (x = 0.38) in ambient O. The in-diffusion rate was found to depend strongly upon x. The activation energies for this process at x = 0.38 and x = 0 were estimated to be 0.5 and 1.3eV, respectively. The O diffusivity at x = 0 was found to be described by:

D (cm2/s) = 0.035 exp[-1.3(eV)/kT]

By combining kinetic and structural data, a vacancy mechanism and a twinning mechanism were deduced for anisotropic O diffusion in the CuO layer between BaO layers.

K.N.Tu, N.C.Yeh, S.I.Park, C.C.Tsuei: Physical Review B, 1989, 39[1], 304-14