Structure refinements and some properties of the transition metal stannides Os sub 3 Sn sub 7 , Ir sub 5 Sn sub 7 , Ni sub 0.402(4) Pd sub 0.598 Sn sub 4 , alpha -PdSn sub 2 and PtSn sub 4

• Published in: Journal of alloys and compounds 2000-09, Vol.309 (1-2), p.1-9
• Main Authors: Jeitschko, W, Niepmann, D, Kunnen, B
• Format: Article
• Language: English
• ISSN: 0925-8388

The previously reported high-pressure compound Os sub 3 Sn sub 7 was prepared at normal pressure by long-time annealing of the elemental components at 300 deg C. Its Ir sub 3 Ge sub 7 -type crystal structure was refined from single-crystal X-ray data: Im3m, a = 937.8(2) pm, R = 0.037 for 220 F values and 11 variable parameters. The structure of Ir sub 5 Sn sub 7 and that of the low-temperature ( alpha ) modification of PdSn sub 2 are confirmed and refined from single-crystal data. Ir sub 5 Sn sub 7 has the tetragonal Co sub 5 Ge sub 7 type structure: I4mm, a = 853.6(1) pm, c = 646.5(1) pm, R = 0.026, 828 F values, 23 parameters; alpha -PdSn sub 2 (own type): I4 sub 1 /acd, a = 649.0(1) pm, c = 2432.7(5) pm, R = 0.026, 250 F values, 17 variables. The structure of PtSn sub 4 , previously described with the non-centrosymmetric space group Aba2, could be refined in the centrosymmetric group Ccca: a = 641.8(3) pm, b = 1136.6(6) pm, c = 638.4(2) pm, R = 0.025 for 436 F values and 14 variables. The isotypic palladium compound forms a solid solution with nickel, where the structure was refined for a single-crystal of the composition Ni sub 0.402(4) Pd sub 0.598 Sn sub 4 to R = 0.020. Ir sub 5 Sn sub 7 , alpha -PdSn sub 2 and PtSn sub 4 are diamagnetic at room temperature and show metallic conductivity. The structures of CoSn sub 2 . alpha -PdSn sub 2 , PtSn sub 2 and PtSn sub 4 are closely related and may be described as stacking variants of each other.