Oxygen vacancy ordering in SrFe0.25Co0.75O2.63 perovskite material
Résumé
SrFe0.25Co0.75O2.63 was synthesized by a solid-state reaction. Its structural study at room temperature using conventional X-ray as well as neutron powder diffraction, electron diffraction and high-resolution transmission electron microscopy is presented. An oxygen-vacancy ordering related to the “314” model known for the Sr3Y1Co4O10.5 oxide is proposed despite neither an A-site ordering nor an A-site mismatch. By means of Mössbauer spectroscopy, Mohr salt titration and the difference in the neutron cross sections of Fe and Co, a cation distribution within the crystallographic sites as the following Sr4(Fe0.143+Co0.363+)48h(Fe0.114+Co0.144+Co0.253+)48fO10.52 is suggested, highlighting a natural layered structure with Fe and Co in higher oxidation states in the oxygen replete layers than in the oxygen deficient ones.