Mössbauer spectroscopic analysis of Bi1−xSrxFeO3−δ perovskites

Bi1−xSrxFeO3−δ perovskites synthesised by solid-state reaction in ambient atmosphere or in a closed vessel were analysed by X-ray diffraction and Mössbauer spectroscopy. The evolution of the valence state of iron with both Bi/Sr ratio and oxygen content has been more particularly discussed. The samples are single phase and homogeneous for x ≤ 0.5 (Bi-rich) and x > 0.8 (Sr-rich). For intermediate Sr contents, the samples are less homogeneous and tend to contain both Bi-rich and Sr-rich phases. The appearance of Sr-rich phases for x > 0.5 corresponds to the appearance of Fe4+, to compensate for the lack of positive charges due to the replacement of Bi3+ by Sr2+.

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