Effect of the Oxygen Content on the Local Environment of Fe Atoms in Anion-Deficient SrFeO_3 – δ

The specific features of the structure in a polycrystalline anion-deficient strontium ferrite SrFeO_3 – δ have been studied at different oxygen contents by the Mössbauer spectroscopy, X-ray diffraction, and scanning electron microscopy. Three compounds with different compositions have been prepared in the dependence on the condition of heat treatment. Within each of the structures, there are several nonequivalent positions of Fe corresponding to different valence states of Fe and different local oxygen environments, the relation and the degree of distortion of which are changed in the dependence on the oxygen content. Based on the Mössbauer data, the oxygen content in each of the structures is estimated. Yet another ideal Sr₁₆Fe₁₆O₄₅ composition of the SrFeO_3 – δ compound is proposed for an intermediate composition in addition to those available in the literature.