A 121 Sb and 151 Eu Mössbauer Spectroscopic Investigation of EuMn 2 Sb 2 , EuZn 2 Sb 2 , YbMn 2 Sb 2 , and YbZn 2 Sb 2

The antimonides Eu T 2 Sb 2 and Yb T 2 Sb 2 ( T = Mn, Zn) were synthesized from the elements in sealed tantalum tubes and their structures were refined on the basis of single‐crystal X‐ray diffractometer data: CaAl 2 Si 2 type, P $\bar{3}$ m 1, a = 458.1(1), c = 767.4(2) pm, wR 2 = 0.064, 188 F 2 values for EuMn 2 Sb 2 , a = 452.6(2), c = 744.5(3) pm, wR 2 = 0.026, 258 F 2 values for YbMn 2 Sb 2 , a = 449.38(7), c = 761.5(1) pm, wR 2 = 0.035, 355 F 2 values for EuZn 2 Sb 2 , and a = 444.51(9), c = 742.7(1) pm, wR 2 = 0.043, 336 F 2 values for YbZn 2 Sb 2 , with 10 variables per refinement. The structures consist of puckered two‐dimensional [ T 2 Sb 2 ] δ – networks, which are separated by the europium or ytterbium atoms. Each T and antimony atom has distorted tetrahedral coordination, while the europium and ytterbium atoms have six nearest antimony neighbors in distorted octahedral coordination. Temperature dependent 151 Eu Mössbauer spectra show purely divalent europium for EuMn 2 Sb 2 and EuZn 2 Sb 2 . At 4.2 K both antimonides show full magnetic hyperfine field splitting with hyperfine fields of 26.5 (EuMn 2 Sb 2 ) and 28.5 T (EuZn 2 Sb 2 ), respectively. The isomer shifts (–7 to –8 mm · s –1 ) of the 121 Sb Mössbauer spectra reflect the antimonide character. 121 Sb Mössbauer spectra of EuMn 2 Sb 2 and EuZn 2 Sb 2 at 4.2 K show transferred hyperfine field of ca. 9 T. EuMn 2 Sb 2 shows Curie–Weiss behavior above 630  K with an experimental magnetic moment of 10.6 μ B /fu, indicative of divalent europium and divalent manganese. Ferromagnetic ordering of the manganese magnetic moments sets in at about 600 K. At 128 K (specific heat data) one observes a spin reorientation of the manganese magnetic moments and at 10 K the europium atoms order antiferromagnetically.