EXPERIMENTAL-STUDY OF COPPER DIFFUSION IN YBA2CU3O7-X POLYCRYSTALS

The self-diffusion of copper in YBa2Cu3O7-x ceramics has been studied using sputtered neutrals mass spectrometry with isotopic marking. Diffusion profiles were formed by the annealing of (CuO)-Cu-63 thin films deposited on YBa2Cu3O7-x polycrystal substrates. The effective diffusion coefficient was calculated by an error-function approach. The parameters of the temperature dependence were found to be D0 = (2 +/- 0.2) +/- 10(-1) cm2 s-1 and E(a) = 240 +/- 9 kJ mol-1 in the temperature range 730-880-degrees-C. The application of Fisher's grain-boundary diffusion model made it possible to separate contributions of volume and boundary diffusion. The dependence of the copper diffusion coefficient in YBa2Cu3O7-x on P(O2) was investigated.