Analysis of Oxygen Transport and Stoichiometry in Mixed‐Conducting SrFeCo0.5 O x by Conductivity and Thermogravimetric Analysis

Abstract

The conductivity and weight changes of in various different oxygen partial pressures were measured simultaneously by the four‐point dc method and a thermogravimetric analysis apparatus, respectively. The apparent oxygen diffusion coefficients were derived from the weight and conductivity relaxation experiments by abruptly changing the p _{O2 in the surrounding atmosphere and monitoring the change of weight and conductivity as functions of relaxation time. At 950°C in air, the obtained apparent oxygen diffusion coefficient of is . Conductivity increases while the weight decreases with increasing temperature within our experimental range , and the activation energy decreases while conductivity increases with increasing . The ‐dependent conducting behavior can be understood by considering the trivalent‐to‐divalent transition of transition metal ions in the sample. The oxygen stoichiometry of in air is x = 3 at 950°C.}