Redox behaviour of Sr4Fe6O13 +/-delta by Mossbauer spectroscopy and neutron diffraction
authors Waerenborgh, JC; Avdeev, M; Patrakeev, MV; Kharton, VV; Frade, JR
nationality International
journal MATERIALS LETTERS
author keywords strontium ferrite; Mossbauer spectroscopy; oxygen nonstoichiometry; neutron diffraction; crystal lattice
keywords OXYGEN PERMEATION PROPERTIES; POWDER DIFFRACTION; PHASE; PEROVSKITES; VACANCIES; TRANSPORT; SYSTEM; SR
abstract Mossbauer spectroscopy studies of the intergrowth Sr4Fe6O13 +/- delta phase, in combination with the structure refinement from X-ray and neutron powder diffraction data, showed that the point defects formed due to oxygen nonstoichiometry variations from approximately - 0.45 up to + 0.14 are accumulated in the nonperovskite layers, built of oxygen-iron polyhedra with pentacoordinated Fe cations. These defects include oxygen vacancies and Fe2+ cations, or oxygen interstitials and Fe4+ in the case of oxygen deficiency or hyperstoichiometry, respectively. The oxidation state of iron cations and the occupancy of oxygen sites in the perovskite-like layers, built of O2--Fe3+ octahedra in the Sr4Fe6O13 (+/-) (delta) lattice, are both essentially independent of the oxygen stoichiometry variations. The perovskite layers act thus as a frame of the lattice, which provides a substantial stability and a moderate chemically induced expansion on the oxygen content variations, but leads to relatively low ionic and electronic conductivities. (C) 2003 Elsevier Science B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0167-577X
year published 2003
volume 57
issue 21
beginning page 3245
ending page 3250
digital object identifier (doi) 10.1016/S0167-577X(03)00042-9
web of science category Materials Science, Multidisciplinary; Physics, Applied
subject category Materials Science; Physics
unique article identifier WOS:000183904300018
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