New Rhodium‐rich Germanides RERh6Ge4 (RE = Y, La, Pr, Nd, Sm–Lu)

Abstract

Abstract The ternary germanides RERh6Ge4 (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: LiCo6P4 type, P$\bar{6}$m2, a = 715.8(1), c = 387.33(8) pm, wR = 0.0238, 332 F2 values for LaRh6Ge4, a = 715.0(1), c = 384.96(7) pm, wR = 0.0211, 329 F2 values for PrRh6Ge4, a = 714.28(9), c = 382.57(6) pm, wR = 0.0136, 327 F2 values for SmRh6Ge4, a = 714.2(1), c = 381.6(1), wR = 0.0270, 327 F2 values for GdRh6Ge4, and a = 714.2(2), c = 379.0(1) pm, wR = 0.0273, 324 F2 values for HoRh6Ge4 with 19 variables per refinement. The RERh6Ge4 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 [Rh6Ge4] 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 YRh6Ge4, LaRh6Ge4, and LuRh6Ge4. The compounds RERh6Ge4 (RE = Gd–Yb) are Curie‐Weiss paramagnets. Antiferromagnetic ordering was observed at 8.4(5) K (GdRh6Ge4), 13.6(5) K (TbRh6Ge4), 5.1(5) K (DyRh6Ge4), and 8.9(5) K (YbRh6Ge4). DyRh6Ge4 and YbRh6Ge4 show metamagnetic transitions at 2.5(5) and 45(2) kOe, respectively.