Mossbauer investigation of Fe-57 doped La4Ni3O10 +/- y phases

摘要

Fe-57 doped La4Ni2.97Fe0.03O9.95 Was synthesized by a citrate method and, afterwards, successfully oxidized and reduced by electrochemical methods. The compounds obtained were investigated by X-ray diffraction. electrical measurements and Mossbauer spectroscopy. The study allowed to follow the variation of the two nickel sites environment with the oxygen stoichiometry and a deeper understanding of the electrical behavior versus oxygen non-stoichiometry was achieved. The Mossbauer study revealed that after both oxidation and reduction treatments, the major modifications were observed on the octahedra adjacent to the La2O2 layers, while the middle octahedra of the triple perovskite block remained almost unchanged. The oxygen intercalation (oxidized treatment) takes place essentially in the La2O2 layers and the oxygen desintercalation (reduction treatment) occurs in the octahedral sites adjacent to those layers. (C) 2008 Elsevier Inc. All rights reserved.