Effect of oxygen content on a local atomic environment of fe atoms in anion-deficient SrFeO$_{3-\delta}$

The structure features of polycrystalline anion-deficient ferrite strontium SrFeO$_{3-\delta}$ have been investigated for different oxygen content by Mossbauer spectroscopy, X-ray diffraction analysis and scanning electron microscopy. Three structures with a different composition have been prepared depending on heat treatment conditions. Several non-equivalent Fe positions exist within each structure that correspond to different local oxygen environments the relation and distortion degree of which change depending on oxygen quantity. Based on the Mossbauer data obtained an oxygen content has been estimated for each structure. One more the model intermediate composition Sr$_{16}$Fe$_{16}$O$_{45}$ of the SrFeO$_{3-\delta}$ compound is proposed.