Oxygen stoichiometry and mixed ionic-electronic conductivity of Sr1-aCeaFe1-bCobO3-x perovskite-type oxides

The structure, oxygen stoichiometry, total and ionic electrical conductivit ies of Sr1-aCeaFe1-bCobO3-x (a = 0 divided by 0/2, b = 0 divided by 1.0) we re investigated. XRD patterns show the cubic perovskite structure of all ai r-treated samples. In reducing atmosphere the Co rich compositions were par tially decomposed. The change of the lattice parameter a with Ce content co uld be explained on the basis of the oxygen stoichiometry values, determine d by solid electrolyte investigations. The total conductivity (p-type: abov e 400-800 degrees C changing to metallic-like behaviour) was enhanced by th e Co content and reached 200 S cm(-1) at 600 degrees C. From permeation mea surements an ionic conductivity higher than YSZ and for the compositions of lower ceria content as high as gadolinia doped ceria was observed. The res ults are compared with those of La1-aSraFe1-bCObO3-x and of manganites. (C) 2000 Elsevier Science Ltd. All rights reserved.