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Much of the confusion regarding the ⁵⁷Fe Mössbauer spectroscopic hyperfine parameters of SrFe₁₂O₁₉ and BaFe₁₂O₁₉ at 300 K has been removed by means of an interlaboratory investigation of well-characterized samples prepared from high purity starting materials. In contrast to previous investigations, the contributions of each of the five Fe sublattices to the Mössbauer spectrum are discernible at 300 K and five components are necessary for an adequate fit of the data. The relative magnitudes of the hyperfine fields, H_n, and isomer shifts, δ, are as follows: for SrFe₁₂O₁₉ and BaFe₁₂O₁₉: H_n(2b)< H_n(12k)<H_n(4f₁) <H_n(2a)<H_n(4f₂), for SrFe₁₂O₁₉ δ(4f₁≤δ(2b)<δ(12k)δ(2a)<δ(4f₂), and for BaFe₁₂O₁₉ δ4f₂), and for BaFe₁₂O₁₉ δ(4f₁<δ(4f₁)<(12k) < δ(4f₂)<δ(2a). The above assignment is based on considerations of both magnetic and crystal/chemical structures.

The high purity starting materials seem to have …