Experimental study of copper diffusion in YBa2Cu3O7–x polycrystals

Abstract

The self-diffusion of copper in YBa₂Cu₃O_7–x ceramics has been studied using sputtered neutrals mass spectrometry with isotopic marking. Diffusion profiles were formed by the annealing of ⁶³CuO thin films deposited on YBa₂Cu₃O_7–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 °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 YBa₂Cu₃O_7–x on P(O₂) was investigated.