An investigation was made of room-temperature O depletion in the near-surface region of samples which were held under high vacuum. The results of secondary ion mass spectroscopic and 4-probe-conductivity measurements were analyzed. It was found that the depletion process was limited by O out-diffusion from the samples, and involved diffusion coefficients which were of the order of 10-19 to 10-18cm2/s. The reverse O in-diffusion process occurred in an O atmosphere. The O out-diffusion process could be accelerated by direct ultra-violet irradiation of the samples in vacuum. The in-diffusion process was accelerated when ultra-violet light was used, in an O atmosphere, to produce ozone and atomic O.

Direct Measurements of Room-Temperature Oxygen Diffusion in YBa2Cu3Ox.  R.Mogilevsky, R.Levi-Setti, B.Pashmakov, L.Liu, K.Zhang, H.M.Jaeger, D.B.Buchholz, R.P.H.Chang, B.W.Veal: Physical Review B, 1994, 49[9], 6420-3

Table 64

Diffusivity of O in Cu4Ba2YO8