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

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.

Was zählt?

“…The three prism types are condensed via common rhodium edges within the ab plane and via common triangular, square, and pentagonal rhodium faces along c . Three Sn@Rh 8 distorted square prisms condense around the origin of the cell, leaving an empty Rh 6 trigonal prism, similar to the RE Rh 6 Ge 4 germanides 10. At this point it is worthwhile to note, that the structures of UCoAl 4 38 and LaCuMg 4 39 can be described as filled variants of the Ho 3 Rh 9 Si 2 Sn 3 type with the 1 a sites occupied by a transition metal atom.…”

“…Temperature dependent magnetic susceptibility studies show stable trivalent rare earth elements for the whole RE Rh 6 Ge 4 series. Antiferromagnetic ordering has been 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 ) 10…”

Silicon‐Tin‐Ordering in RE3Rh9Si2Sn3 (RE = Y, Sm, Gd – Lu)

“…[10] At this point it is worthwhile to note, that the structures of UCoAl 4 [38] and LaCuMg 4 [39] can be described as filled variants of the Ho 3 Rh 9 Si 2 Sn 3 type with the 1a sites occupied by a transition metal atom.…”

“…The recently discovered silicide CeRh 6 Si 4 [8] and the germanides RERh 6 Ge 4 (RE = La -Nd, Sm -Lu) [9][10][11] with 1 rhodium (268-274 pm Sn-Rh in Ho 3 Rh 9 Si 2 Sn 3 ). Magnetic investigations were performed for RE 3 Rh 9 Si 2 Sn 3 (RE = Y, Gd -Yb).…”

“…Antiferromagnetic ordering has been 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 ). [10] When searching for isotypic LiCo 6 P 4 type compounds with tin as p element, an arc-melted button of the starting composition 1Ho:6Rh:4Sn was treated for crystal growth (similar to the germanides RERh 6 Ge 4 ) in a bismuth flux in an evacuated silica ampoule. This annealing experiment led to a severe attack of the silica tube and well-shaped needles of a new quaternary compound Ho 3 Rh 9 Si 2 Sn 3 had formed with full silicon-tin ordering.…”