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  • Author: Rainer Pöttgen x
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The title compound was prepared by the reaction of the elemental components in a tantalum tube. EuAgGe (single crystal. X-ray, Imma, a = 467.0(1), b = 740.0(1), c = 798.1(1) pm, V = 0.2758(1) nm3, Z = 4, wR2 = 0.0371, 474 F2 values and 13 variables) crystallizes with the orthorhombic structure of CeCu2. The europium atoms occupy the cerium positions, while the silver and germanium atoms are randomly distributed on the copper positions. The crystal structure of EuAgGe is discussed together with the structures of EuAg2 and EuAuGe.

Ti2In5 was prepared from the elemental components in a tantalum tube at 970 K and investigated by X-ray diffraction of powders as well as of single crystals. The crystal structure was refined from four-circle diffractometer data: P4/mbm, a = 1000.35(5) pm, c = 299.77(2) pm, V = 0.29998(5) nm3, Z = 2, wR2 = 0.0367 for 369 F2 values and 15 variables. Ti2In5 crystallizes with the Mn2Hg5 type structure. The indium atoms form consecutive planar layers which may be considered as a tesselation of triangles, squares, and pentagons. The titanium atoms occupy the pentagonal prismatic voids between these layers. Ti2In5 is Pauli paramagnetic and a good metallic conductor with a specific resistivity of 50 μΩcm at room temperature. The compound was previously described with the composition “Ti3In4”.

Zr5CuSn3 was prepared from the elements in an arc-melting furnace and investigated by X-ray diffraction of powders as well as of single crystals. The crystal structure was refined from four-circle diffractometer data: P63/mcm, a = 860.04(7) pm, c = 586.80(5) pm, V = 0.3759(1) nm3, Z = 2, wR2 = 0.0402 for 371 F2 values and 15 variables. A refinement of the occupancy parameters re­vealed that the copper position is occupied to only 95.3(8)% in the crystal used for the X-ray investigation. Zr5CuSn3 crystallizes in the Hf5CuSn3 type structure, a filled variant of the Mn5Si3 type. The main features of the Zr5CuSn3 structure are condensed Zr6 octahedra that are centered by copper atoms

Abstract

The ternary stannides RE2Au2Sn (RE = Y, Dy, Ho, Er, Tm, Lu) were prepared by arcmelting of the elemental components and subsequent annealing at 800 °C. The structure of Er2Au2Sn (single crystal, X-ray, P42/mnm, Z = 4, a = 778.2(2) pm, c = 739.6(3) pm, V = 0.4479 nm3 and R = 0.026) is described as the ternary ordered version of the Zr3Al2-type structure, a superstructure of the U3Si2-type. It consists of two-dimensionally infinite layers (Au2Sn)n which are separated by the erbium atoms. The structure is built up from slightly distorted [SnEr8) square prisms and [AuEr6] trigonal prisms which are condensed in all three directions. These fragments are derived from the well known AlB2 and CsCl-type structures.

The new ternary stannides RE2Au2Sn (RE = Gd, Tb) and indides RE2Au2In (RE = Y, Gd-Tm, Lu) were synthesized by arc-melting of the elemental components and subsequent annealing at 800 °C. While Gd2Au2Sn, Tb2Au2Sn and the indides with RE = Y, Gd-Er crystallize in the ordered U3Si2 structure, Tm2Au2In and Lu2Au2In adopt the ordered Zr3Al2 structure, respectively. The crystal structure of Dy2Au2In was refined from single-crystal X- ray data: P4/mbm, Z = 2, a = 784.1(1) pm, c = 373.9(1) pm, V = 0.2299 nm3 and R = 0.028 for 342 F2 values and 12 variables. The tin (indium) atoms in these compounds occupy [RE8] square prisms and the gold atoms are surrounded by [RE6] trigonal prisms. These fragments are derived from the AlB2 and CsCl-type structures. The crystal chemistry of these com­pounds is briefly discussed.

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The title compound was prepared from the elemental components in a tantalum tube at 1070 K and investigated by X-ray diffraction of both powder as well as single crystals. The crystal structure was refined from four-circle diffractometer data: P21/n, a = 618.1(1), b = 613.6(1), c = 743.9(1) pm, β = 109.40(1)°, V = 0.2661(1) nm3, Z = 4, wR2 = 0.0536 for 1564 F2 values and 29 variables. EuPdGe crystallizes with the EuNiGe type structure. Both Pd and Ge atoms in EuPdGe have three germanium or palladium neighbors, respectively. They form two-dimensionally infinite [PdGe] polyanions which consist of corrugated 4.82 nets. These polyanions are separated by the europium atoms.

The title compound has been obtained by arc-melting of the elemental components and subsequent annealing at 800 °C. It crystallizes in the orthorhombic space group Immm, a = 430.3(1), b = 1235.0(2), c = 967.6(3) pm, V = 0.5142(2) nm3, Z = 2. The structure has been determined from single-crystal X-ray data and refined to R = 0.0181 for 747 F2 values and 28 variables. It is of a new type and can be described as a ternary ordered version of the binary La3Al11-type structure. Dy3Co6Sn5 is built up from DyCo2Sn2 and DyCo2Sn slabs with ThCr2Si2 and Cu3Au-like atomic arrangements, respectively. Its crystal chemistry is compared with that of structurally related rare earth transition metal gallides.

Abstract

EuPdSn and EuPtSn were prepared from the elements in tantalum tubes at 1070 K and investigated by X-ray diffraction on both powder as well as single crystals. They crystallize with the TiNiSi type structure of space group Pnma and with Z = 4 formula units per cell. Both structures were refined from single-crystal diffractometer data: a = 751.24(9), b = 469.15(6), c = 804.31(9) pm, V = 0.2835(1) nm3 for EuPdSn, and a = 753.38(7), b = 467.72(4), c = 793.08(7) pm, V = 0.2795(1) nnr for EuPtSn. The structures consist of three-dimensional [PdSn] and [PtSn] polyanionic networks in which the europium atoms are embedded. The crystal chemistry of these stannides is briefly discussed

Synthesis, Structure, Function