Studies on the reaction between strontium carbonate and iron(III) oxide

Abstract

The reaction between strontium carbonate and iron(III) oxide has been studied in a system open to the atmosphere and in a vacuum. The extent of reaction was calculated from the analysis of the solid products by X-ray diffraction and, in the case of the experiments in vacuum, from the amount of carbon dioxide evolved from the system also.     In vacuum, the monoferrite SrFe₂O₄ results from the direct reaction of strontium carbonate and iron(III) oxide at comparatively low temperatures, while the hexaferrite SrFe₁₂O₁₉ is formed by the reaction of Sr₂Fe₂O₄ with iron(III) oxide at higher temperatures. The formation of the ferrite Sr₂Fe₂O₅ depends upon the prevailing atmosphere, since this compound was present only as an intermediate phase when the experiments were carried out in air and not in vacuum. Only three compounds of strontium, iron, and oxygen were found, namely the ferrites SrFe₂O₄, Sr₂Fe₂O₅, and SrFe₁₂O₁₉.     The observataions appear to be explicable in terms of Tammann temperatures.