Powder samples of La0.4Sr0.6CoO3-δ were synthesized by using the glycine nitrate process. Selected area electron diffraction in a transmission electron microscope, and X-ray powder diffraction, were used to determine the basic crystal structure. Energy-filtering transmission electron microscopy was used to evaluate the homogeneity of the samples at the nm-level. The ionic conductivity of La0.4Sr0.6CoO3-δ was deduced, from galvanostatic polarization experiments, as a function of O non-stoichiometry for 3-δ values of between 2.70 and 2.81 (corresponding to pO2 values of between 10-4 and 10-1bar) at 775 and 825C. It was observed that the ionic conductivity exhibited a maximum which shifted towards larger values of O non-stoichiometry with increasing temperature. The maximum value was observed for 3-δ = 2.79 and 2.77, at 775 and 825C, respectively. This behavior was reported to be indicative of the formation of vacancy-ordered structures which were expected to lower the mobility of O vacancies.

Microstructure and Ionic Conductivity of Strontium-Substituted Lanthanum Cobaltites. E.Bucher, W.Sitte, I.Rom, I.Papst, W.Grogger, F.Hofer: Solid State Ionics, 2002, 152-153, 417-21