Antimony-121 Mössbauer spectral study of the Eu₁₄MnSb ₁₁ and Yb₁₄MnSb₁₁ zintl compounds

The antimony-121 Mössbauer spectra of the Yb₁₄MnSb ₁₁ and Eu₁₄MnSb₁₁ Zintl compounds have been measured between 2 or 5 and 300 K. The resulting three-dimensional arrays of the spectral counts, velocity, and temperature have been simultaneously fit with a minimum number of free parameters. These fits yield a 0 Kelvin transferred hyperfine field of 2.9(2) T, a Curie temperature of 57(3) K, and a Mössbauer temperature of 182(2) K for Yb₁₄MnSb₁₁; in this case the transferred field arises solely from the ordering of Mn ²⁺. Because Eu¹⁴MnSb₁₁ has both Eu²⁺ and Mn²⁺ ions that are magnetically ordered, its antimony-121 Mössbauer spectra are more complex and reveal two magnetic transitions, the first at 92(1) K resulting from the ordering of the Mn²⁺ ions and the second at 9.5(1.0) K resulting from the ordering of the Eu²⁺ ions; the corresponding 0 Kelvin transferred hyperfine fields are 1.3(1) and 3.7(1) T. The antimony-121 isomer shifts yield electronic configurations of 5s^1.745p^4.28 and 5s^1.745p^4.19 for the average antimony anion in Yb₁₄MnSb₁₁ and Eu ₁₄MnSb₁₁, respectively.