The permeation of O through material which contained 0.05Zr was studied, at 300 to 650C, under glow discharge conditions. A low-energy direct-current glow discharge in O2 was used to produce some 10% of O atoms. The permeation rate during glow discharge was found to be higher (by a factor of 10) than in the absence of glow discharge. The small fraction of O atoms which was generated appeared to dominate the permeation because of much higher solution probabilities. At temperatures below 500C, the activation energy for permeation in the presence of glow discharge was equal to 15.5kcal/mol, as compared with 22.0kcal/mol in the absence of glow discharge (molecular O). At temperatures above 500C, the enhanced permeation in the presence of glow discharge gradually decreased with increasing temperature and approached that which was observed in the absence of glow discharge. It was suggested that this was due mainly to the thermal instability of the supersaturated high-pressure interface at which atoms recombined and desorbed back into the gas phase.

D.Wu, R.A.Outlaw, R.L.Ash: Journal of Applied Physics, 1993, 74[8], 4990-4

Table 11

Grain-Boundary Diffusion (Type-B Regime) of 75Se in Ag