The tracer diffusivity of 18O was determined, at temperatures of between 300 and 850C, by using secondary ion mass spectrometry. It was found that the diffusion of O was markedly anisotropic (table 62). The faster-diffusing component, for migration in the ab-plane, was associated with an activation energy of 0.97eV. There was no break in the Arrhenius plot at the orthorhombic to tetragonal transformation temperature. The diffusion coefficient at 600C was not a sensitive function of O partial pressures ranging from 3kPa to 0.1MPa.

Tracer Diffusion of Oxygen in YBa2Cu3O7-δ. S.J.Rothman, J.L.Routbort, J.E.Baker: Physical Review B, 1989, 40[13], 8852-60