Determination of the antimony valence state in Eu10Mn6Sb13

The antimony-121 Mossbauer spectra of Eu10Mn6Sb13 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 Mossbauer spectral isomer shifts reveal that the valence states of the 4.0 different sites are all quite similar and correspond to an average electronic configuration for antimony of 5s(1.7)5p(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 Eu10Mn6Sb13. 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