Determination of the Antimony Valence State in Eu₁₀Mn ₆Sb₁₃

The antimony-121 Mössbauer spectra of Eu₁₀Mn ₆Sb₁₃ have been measured between 2 and 295 K. Although the Zintl formalism indicates that the nine crystallographically distinct antimony sites in Eu₁₀Mn₆Sb₁₃ should have formal valence states of -2, -1, 0, and +1, the Mössbauer spectral isomer shifts reveal that the valence states of the different sites are all quite similar and correspond to an average electronic configuration for antimony of 5S^1.75p^4.0. This configuration corresponds to an excess of negative charge on the antimony of 0.7 or an average valence of -0.7, a valence which is rather consistent with the average antimony valence of -0.61 obtained from the Zintl formalism for the nine antimony sites in Eu ₁₀Mn₆Sb₁₃. The spectra obtained between 90 and 295 K are more consistent with the absence rather than the presence of any transferred magnetic hyperfine field at the antimony. In contrast, the spectra obtained at 2 and 5 K reveal the presence of an average transferred magnetic hyperfine field of ca. 8 T, a field that arises from the ferromagnetic ordering of the near-neighbor manganese(II) ions.