Potentiostatic step technique to study ionic transport in mixed conductors

A potentionstatic step technique was used to measure oxygen transport in the mixed-conducting perovskite SrCo1−xFexO3-t σ where x=0.2, 0.5 and 0.8. A solid state sealed electrochemical cell configuration was employed for this purpose featuring a single crystal yttria-stabilized zirconia solid electrolyte. The chemical diffusion coefficient of oxygen was found to be fast but highly thermally activated. At 850°C, the chemical diffusion coefficient for oxygen was in the range 10−7–10−6 cm2/s with the SrCo0.5Fe0.5O3−σ composition exhibiting the higher value. Such rapid rate of oxygen transport makes this material attracti or oxygen selective membranes for high temperature gas separation applications.