The kinetics of oxygen diffusion in tetragonally structured YBa2Cu3O7-x quenched from 910C was studied by means of dilatation measurements. The results showed that the tetragonal to orthorhombic transition associated with the oxygen content in the crystal was controlled by oxygen diffusion. If the diameter of a particle was assumed to be 20μm, the diffusivity could be expressed as:

D(cm2/s) = 3.47 x 10-6 cm2/s) exp[-17.69(kcal/mol)/RT]

J.Zhang, M.Yang, T.Chen: Materials Letters, 1988, 6[11-12], 379-84