Elastic after-effect due to oxygen relaxation in YBa2Cu3O7-δ above Tc

This paper reports on isothermal elastic after-effect measurements to obtain relaxation times for the stress-induced motion of oxygen in YBacCu3O7-δ made from 50 degrees C to 110 degrees C. These results extend the authors previous internal friction measurements of cover nine orders of magnitude in relaxation time, show a classical Arrhenius temperature dependence, activation energy Q = 1.13 ± 0.01 eV and attempt frequency τ0 = 1.6 x 10-13 s (log τ0 = 12.79 ± 0.13). The mechanism of the relaxation is considered to be stress-induced ordering of oxygen atoms on the CuO basal plane. Diffusivities obtained from these results are compared with those from tracer diffusion of oxygen