Antimony-121 Mössbauer Spectral Study of α-Zn₄Sb₃

The Mössbauer spectra of α-Zn ₄ Sb ₃ , a compound that is best formulated as α-Zn ₁₃ Sb ₁₀ or (Zn ²⁺ ) ₁₃ (Sb ^3- ) ₆ (Sb ₂ ^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 ß-Zn ₄ Sb ₃ . The isomer shifts correspond to electronic configurations between 5s ² 5p ⁶ and 5s ^1.75 5p ^4.01 for the Sb ^3- ions and between 5s ² 5p ⁵ and 5s ^1.80 5p ^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.