A Sb-121 and Eu-151 Mossbauer Spectroscopic Investigation of EuMn2Sb2, EuZn2Sb2, YbMn2Sb2, and YbZn2Sb2

摘要

The antimonides EuT2Sb2 and YbT2Sb2 (T = Mn, Zn) were synthesized from the elements in scaled tantalum tubes and their structures were refined oil the basis of single-crystal X-ray diffractometer data: CaAl2Si2 type, P (3) over bar ml, a = 458.1(1), c = 767.4(2) pm, wR(2) = 0.064, 188 F-2 values for EuMn2Sb2, a = 452.6(2), c = 744.5(3) pm, wR(2), = 0.026, 258 F-2 values for YbMnSb2, a = 449.38(7), c = 761.5(1) pm, wR(2) = 0.035, 355 F-2 values for EuZn2Sb2, and a = 444.51(9), c = 742.7(1) pm, wR(2), = 0.043, 336 F-2 values for YbZn2Sb2, with 10 variables per refinement, The structures consist of puckered two-dimensional [T2Sb2](delta-) 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 Eu-151 Mossbauer spectra show purely divalent europium for EuMn2Sb2 and EuZn2Sb2. At 4.2 K both antinionides show full magnetic hyperfine Field splitting with hyperfine Fields of 26.5 (EuMn2Sb2,) and 28.5 T (EuZn2Sb2), respectively. The isomer shifts (-7 to 8 mm.s(-1)) of the Sb-121 Mossbauer spectra reflect the antimonide character. Sb-121 Mossbauer spectra of EuMn2Sb2 and EuZn2Sb2 at 4.2 K show transferred hyperfine field of ca. 9 T. EuMn2Sb2 shows Curie-Weiss behavior above 630 K with ail experimental magnetic moment of 10.6 mu(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.