resumo
Selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM) studies reveal that the crystal structure and microstructure of GdBaCo2O5+delta are highly influenced by the oxygen stoichiometry. In addition to layered-type ordering of the Ba and Gd atoms along the c-direction of the structure and location of anion vacancies within the (GdO)x planes giving a a(p) x a(p) x 2a(p) unit cell, two different perovskite related superstructures are observed. A superstructure with a(p) x 3a(p) x 2a(p) unit cell, probably due to extra ordering of the anion vacancies within the (GdO)(x) planes is formed for 6 values close to 033 and a superstructure with root 2a(p) x root 2b(p) x 2a(p) unit cell associated to tilting of the CoO6 octahedra appears for the compound with 6 values close to 1. Domain formation with perpendicular orientations of the unit cell occurs in crystals with orthorhombic symmetry of the structure. Physical properties of the aforementioned material, which is well known as a potential candidate of cathode for intermediate temperature solid oxide fuel cells, are likely to be strongly affected by its oxygen stoichiometry and therefore by its crystal structure and microstructure. (C) 2014 Elsevier B.V. All rights reserved.
palavras-chave
PHASE-TRANSITION; OXYGEN REDUCTION; IT-SOFCS; PEROVSKITE; CATHODE
categoria
Chemistry; Electrochemistry; Energy & Fuels; Materials Science
autores
Munoz-Gil, D; Perez-Coll, D; Pena-Martinez, J; Garcia-Martin, S
nossos autores
Daniel Muñoz Gil
Bolseiro de pós-Doutoramentoagradecimentos
S.G.-M., D. M-G. and J.P.-M. thank the Spanish MEC for funding Projects MAT2010-19837-C06-03 and PIB2010JP-00181 and CAM for Project MATERYENER-2 P2009/PPQ-1629 EC.