Publication Date:
2013-09-21
Description:
. The ternary germanides RE Rh 6 Ge 4 ( RE = Y, La, Pr, Nd, Sm–Lu) were obtained by arc-melting of the elements and subsequent annealing. Single crystals were grown from bismuth fluxes. The samples were studied by X-ray diffraction on powders. The structures of five members were refined from single crystal diffraction data: LiCo 6 P 4 type, P m 2, a = 715.8(1), c = 387.33(8) pm, wR = 0.0238, 332 F 2 values for LaRh 6 Ge 4 , a = 715.0(1), c = 384.96(7) pm, wR = 0.0211, 329 F 2 values for PrRh 6 Ge 4 , a = 714.28(9), c = 382.57(6) pm, wR = 0.0136, 327 F 2 values for SmRh 6 Ge 4 , a = 714.2(1), c = 381.6(1), wR = 0.0270, 327 F 2 values for GdRh 6 Ge 4 , and a = 714.2(2), c = 379.0(1) pm, wR = 0.0273, 324 F 2 values for HoRh 6 Ge 4 with 19 variables per refinement. The RE Rh 6 Ge 4 structures have two crystallographically independent germanium sites in trigonal prismatic coordination, manifesting the close structural relationship with metal-rich phosphides. Together, the rhodium and germanium atoms build up three-dimensional [Rh 6 Ge 4 ] networks, which leave large channels for the rare earth atoms. Each rare earth atom has coordination number 20 with 12 Rh, 6 Ge, and 2 RE neighbors. Temperature dependent magnetic susceptibility measurements indicate Pauli paramagnetic behavior for YRh 6 Ge 4 , LaRh 6 Ge 4 , and LuRh 6 Ge 4 . The compounds RE Rh 6 Ge 4 ( RE = Gd–Yb) are Curie-Weiss paramagnets. Antiferromagnetic ordering was observed at 8.4(5) K (GdRh 6 Ge 4 ), 13.6(5) K (TbRh 6 Ge 4 ), 5.1(5) K (DyRh 6 Ge 4 ), and 8.9(5) K (YbRh 6 Ge 4 ). DyRh 6 Ge 4 and YbRh 6 Ge 4 show metamagnetic transitions at 2.5(5) and 45(2) kOe, respectively.
Print ISSN:
0044-2313
Electronic ISSN:
1521-3749
Topics:
Chemistry and Pharmacology
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