Antimony-121 Mössbauer spectral study of α-Zn₄Sb ₃

The Mössbauer spectra of α-Zn₄Sb₃, a compound that is best formulated as α-Zn₁₃Sb₁₀ or (Zn²⁺)₁₃(Sb^3-)₆(Sb₂ ^4-)₂, have been measured between 5 and 120 K. The resulting six spectra have been simultaneously fit with two components in the ratio of 3:2 corresponding to the Sb^3- and Sb^2- ions identified in this valence semiconductor. The fits yield temperature independent isomer shifts of -8.17(2) and -9.73(2) mm/s and quadrupole interactions of -4.9(2) and 0 mm/s for the Sb^3- and Sb^2- ions, respectively; the corresponding Mössbauer temperatures are 197(5) and 207(5) K, temperatures that are lower than the Debye temperature of β-Zn₄Sb₃. The isomer shifts correspond to electronic configurations between 5s²5p⁶ and 5s^1.755p ^4.01 for the Sb^3- ions and between 5s²5p ⁵ and 5s^1.805p^3.38 for the Sb^2- ions, configurations that are in good agreement with the expected configurations for this valence semiconductor and with the results of band structure calculations.