Solid state- and magneto-chemistry of the SrO-Fe2O3 system: III. The non-existence of single-phase “SrFe2O4”

A detailed Mössbauer investigation of 1 : 1 SrO : Fe₂O₃ has shown that a single phase with the SrFe₂O₄ composition does not exist in the SrO-Fe₂O₃ system when SrCo₃ and Fe₂O₃ are reacted in air. A multiphase assemblage of SrFe₁₂O₁₉, Sr₄Fe₆O₁₃, and SrFeO_3-x is observed in the material with an overall composition of “SrFe₂O₄”. By means of novel analyses of the complex Mössbauer spectra of the 1 : 1 SrO : Fe₂O₃ composition, all of the Fe containing phases have been identified and their respective mole percentages determined. The relative amounts of the phases present depend on the final firing temperature. The published X-ray powder data for “SrFe₂O₄” can be interpreted satisfactorilly in terms of the Mössbauer results, i.e., as a multiphase assemblage, and corresponds to a low temperature assemblage of SrFe₁₂O₁₉, Sr₄Fe₆O₁₃ and SrFeO_3-x for the overall composition of “SrFe₂O₄”.