Oxygen diffusion in YBa2Cu3O6 +x ceramics

Abstract

On the basis of Fick's second law, a mathematical model to describe the oxygen diffusion process has been developed. To determine oxygen diffusion parameters direct coulometric titration (for low p_o2) and thermogravimetric (for high p_o2) techniques were used. The diffusion coefficients of oxygen were determined over wide temperature (350–900 °C) and (p_o2)(0.8 × 10^–5–1.3 × 10^–3 and 0.21–1 atm) ranges. The developed model satisfactorily describes oxygen diffusion processes in YBa₂Cu₃O_{6 +x} powders, low density pellets (in the approximation of spherical particles) and high-density ceramics (in the approximation of plates). Increasing the oxygen content in samples led to a decrease of the diffusion coefficient of oxygen.