Crystal structure, cobalt and iron speciation and oxygen non-stoichiometry of La0.6Sr0.4Co1-yFeyO3-δ nanorods for IT-SOFC cathodes

Single-phased La(0.6)Sr(0.4)Co(1-)yFe(y)O(3-delta) (y = 0.2, 0.5, 0.8) nanorods exhibiting the rhombohedral perovskite-type phase were synthesized by a pore-wetting technique. We studied their chemical composition, crystal and electronic structures, morphology and hyperfine properties as a function of the Co/Fe content of the samples. Our results demonstrate that Co cations exhibit a slightly lower oxidation state than Fe ones, resulting in a higher oxygen non-stoichiometry delta for Co-rich samples. In addition, the values of delta determined in this work for nanostructured samples are much higher than those reported in the literature for bulk materials. This can be attributed to the high number of defects in nanomaterials and is probably one important factor in the high electrochemical performance for the oxygen reduction reaction of nanostructured La(0.6)Sr(0.4)Co(1-)yFe(y)O(3-delta) IT-SOFC cathodes, which have been reported in a previous work. (C) 2019 Elsevier B.V. All rights reserved.