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Ternary rare earth metal-rich intermetallic phases containing osmium and magnesium were obtained by induction melting of the elements in sealed niobium ampoules under argon followed by annealing in muffle furnaces. The large rare earth elements form the series of Gd4RhIn-type (F4̅3m) intermetallics RE4OsMg with RE = La–Nd and Sm, while the smaller rare earth metals gadolinium and terbium form the Y9CoMg4-type (P63/mmc) phases Gd9OsMg4 and Tb9OsMg4. All samples were characterized by X-ray powder diffraction (Guinier technique). The structures of Ce4Os0.973Mg1.027 (a = 1406.54(7) pm, wR2 = 0.0478), Nd4Os0.978Mg1.022 (a = 1402.00(7) pm, wR2 = 0.0463), Sm4Os0.920Mg1.080 (a = 1387.33(5) pm, wR2 = 0.0378) and Gd9OsMg4 (a = 971.01(5), c = 980.43(5) pm, wR2 = 0.0494) were refined from single-crystal X-ray diffractometer data. The three RE4OsMg phases show small degrees of Os/Mg mixing, as is frequently observed for Rh/In in Gd4RhIn-type intermetallics. The basic building units in both structures are osmium-centered RE6 trigonal prisms that are condensed with empty RE6 octahedra. The magnesium atoms in both types build Mg4 tetrahedra. The latter are isolated (312 pm Mg–Mg in Ce4OsMg) and incorporated within the three-dimensional network of prisms and octahedra in the RE4OsMg phases while one observes rows of corner- and face-sharing tetrahedra in Gd9OsMg4 (305 and 314 pm Mg–Mg). In both structure types direct Os–Mg bonding is not observed. [ABSTRACT FROM AUTHOR]

The equiatomic iron-silicides TFeSi as well as the corresponding germanides TFeGe with the electron-poor 4d and 5d transition metals (T=Zr, Nb, Hf, Ta) have been synthesized from the elements by arc-melting. All samples were characterized through their lattice parameters using powder X-ray diffraction (Guinier technique). Four structures were refined from single-crystal X-ray diffractometer data: a=640.16(3), b=393.45(5), c=718.42(6) pm, Pnma, 390 F2 values, 20 parameters, wR2=0.0294 for ZrFeSi (TiNiSi type), a=719.63(11), b=1119.27(7), c=649.29(7) pm, Ima2, 1103 F2 values, 54 parameters, wR2=0.0555 for NbFeGe (TiFeSi type), a=655.96(7), c=372.54(4) pm, P6̅2m, 251 F2 values, 15 parameters, wR2=0.0260 for HfFeGe (ZrNiAl type) and a=624.10(3), b=378.10(6), c=725.25(7) pm, Pnma, 369 F2 values, 20 parameters, wR2=0.0513 for TaFeGe (TiNiSi type). The common structural motif of the four different structures is the slightly distorted tetrahedral tetrel (tr) coordination of the iron atoms and a trigonal prismatic coordination of iron by T=Zr, Nb, Hf, Ta. Three compounds were characterized as Pauli-paramagnetic by measuring their susceptibility. The measurement of the electrical resistivity of NbFeSi characterises this compound as a good metal. Furthermore, 57Fe Mössbauer spectra of all compounds could be obtained at room temperature, revealing a clear correlation between the structural distortions and the quadrupole splitting parameters. [ABSTRACT FROM AUTHOR]

The rare earth-rich intermetallic phases RE 9 T Mg 4 ( RE  = Y, Dy-Tm, Lu; T  = Ru, Rh, Os, Ir) were synthesized by induction melting of the elements using sealed niobium ampoules as crucible material. The melted samples were additionally annealed in muffle furnaces and subsequently characterized by X-ray powder diffraction. The RE 9 T Mg 4 compounds adopt an ordered Co 2 Al 5 type structure, space group P 6 3 / mmc . Four structures were refined from single-crystal X-ray diffractometer data: a  = 953.71(5), c  = 968.41(5) pm, wR 2 = 0.00273, 603 F 2 values, 21 parameters for Tm 8.76 RuMg 4.24 ; a  = 958.37(5), c  = 975.66(5), wR 2 = 0.00384, 661 F 2 values, 20 parameters for Dy 9 OsMg 4 ; a  = 943.70(5), c  = 967.91(5) pm, wR 2 = 0.00430, 592 F 2 values, 21 parameters for Tm 8.74 OsMg 4.26 ; a  = 968.09(5), c  = 978.25(5) pm, wR 2 = 0.0439, 623 F 2 values, 21 parameters for Y 9.18 IrMg 3.82 . The compounds are prone to small homogeneity ranges ( RE /Mg mixing). The transition metal atoms have tricapped trigonal prismatic rare earth coordination. These T @ RE 9 units (TP) are condensed with empty RE 6 octahedra (O) via common triangular faces forming infinite strands with a sequence –TP–O–O–. These strands show the motif of hexagonal rod packing and they are separated by chains of edge- and corner-sharing tetrahedra. The magnesium substructures in the hexagonal Laves phase YMg 2 and the prototype Y 9 CoMg 4 are structurally closely related. Charge transfer trends, electronic band structures and bonding properties were studied within DFT. The resulting picture is that cobalt brings covalent character by reducing the overall charge transfer and modifies the Laves phase YMg 2 by providing larger localization in the density of states. The Y–Co bonding in Y 9 CoMg 4 prevails while weakening the Y–Mg bonds. The investigations of the magnetic properties of selected RE 9 T Mg 4 compounds revealed Pauli paramagnetic behavior for Y 9 CoMg 4 , Y 9 OsMg 4 and Y 9 IrMg 4 . A ferromagnetic ground state with Curie temperatures of 46.0 and 47.6 K was observed for Dy 9 RuMg 4 and Dy 9 OsMg 4 , respectively. Ho 9 RuMg 4 , Ho 9 OsMg 4 and Tm 9 OsMg 4 reveal antiferromagnetic ordering with Neél temperatures below 20 K. [ABSTRACT FROM AUTHOR]

The equiatomic rare earth iridium indides REIrIn (RE = La, Pr, Nd, Er-Yb) were synthesized by reaction of the elements in induction or muffle furnaces and were characterized through X-ray powder patterns. The structures of LaIr0.86In1.14, PrIr0.89In1.11, NdIr0.94In1.06, ErIrIn (all ZrNiAl type, P62m), and YbIrIn (TiNiSi type, Pnma) were refined from single crystal X-ray diffractometer data. Refinements of the occupancy parameters revealed small degrees of solid solutions with indium substitution on the iridium sites. Chemical bonding analyses and electronic structure calculations indicate the dominance of metallic bonding in addition to partial ionic interactions between the cations and polyanions, as well as covalent contributions between the indium and iridium atoms. [ABSTRACT FROM AUTHOR]

GdCuMg has been synthesized by inductionmelting of the elements in a sealed niobium ampoule followed by annealing in a muffle furnace. The sample was studied by powder and single crystal X-ray diffraction: ZrNiAl type, P62m (a = 749.2(4), c = 403.3(1) pm), wR2 = 0.0242, 315 F2 values and 15 variables. Temperature dependent magnetic susceptibility measurements have revealed an experimental magnetic moment of 8.54(1) μB per Gd atom. GdCuMg orders ferromagnetically below TC = 82.2(5) K and based on the magnetization isotherms it can be classified as a soft ferromagnet. [ABSTRACT FROM AUTHOR]

Eight new equiatomic RE PtMg intermetallics with RE = Y, Eu, Tb-Tm, Lu were synthesized from the elements in sealed niobium ampoules (induction melting followed by different annealing sequences). All samples were characterized through X-ray powder patterns and the structures of YPtMg, EuPtMg, DyPtMg, HoPtMg and TmPtMg were refined from single crystal X-ray diffractometer data. The RE PtMg phases crystallize with two different structure types. The representatives with RE = Y, Tb-Ho crystallize with the hexagonal ZrNiAl type, space group P 6 ¯ 2 m , while those with RE = Eu, Yb and Lu adopt the orthorhombic TiNiSi type, space group Pnma . ErPtMg and TmPtMg are dimorphic with a ZrNiAl type high and a TiNiSi type low-temperature modification. Temperature-dependent magnetic susceptibility measurements indicate Pauli paramagnetism for YPtMg and LuPtMg while EuPtMg, TbPtMg, DyPtMg and HoPtMg are Curie-Weiss paramagnets. Antiferromagnetic (T N = 12.6 K for EuPtMg) respectively ferromagnetic ordering (T C = 56.3 K for TbPtMg, 28.8 K for DyPtMg and 19.9 K for HoPtMg) occurs in the low-temperature regime. 151 Eu Mössbauer spectra confirm divalent europium (δ = −8.03 mm s −1 at 78 K) in EuPtMg and show strong magnetic hyperfine field splitting below the Néel temperature. [ABSTRACT FROM AUTHOR]