Secondary Au-Au and Sn-Sn Interactions in the Superstructure of YbAuSn-Missing Link in the Series of KHg2 Superstructures

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• 作者：Rolf-Dieter Hoffmann ; Rainer Pö ; ttgen ; Dirk Kussmann ; Ralf Mü ; llmann ; and Bernd D. Mosel
• 刊名：Chemistry of Materials
• 出版年：2001
• 出版时间：November 2001
• 年：2001
• 卷：13
• 期：11
• 页码：4019 - 4025
• 全文大小：152K
• 年卷期：v.13,no.11(November 2001)
• ISSN：1520-5002

文摘

The stannide YbAuSn has been synthesized in quantitative yield by reacting the elementsin sealed tantalum tubes in a high-frequency furnace. The structure was determined fromsingle-crystal X-ray data: Imm2, a = 469.7(1) pm, b = 2191.2(4) pm, c = 812.7(1) pm,wR2 = 0.111, 2061 F² values, and 58 variables. It crystallizes with a pronounced KHg₂ typesubcell (a, 1/3b, c, Imma). In the superstructure the tripled b axis allows an ordered stackingof Au₃Sn₃ hexagons with weak gold-tin, gold-gold, and tin-tin interlayer bondinginteractions. The determined stacking sequence - + - - + -, - + - - + - in YbAuSnrealizes a so far missing sequence within a general ordering scheme of KHg₂ typesuperstructures. The group-subgroup relation in going from the KHg₂ subcell and chemicalbonding in YbAuSn are discussed. Each ytterbium site has an ordered near-neighborenvironment of six gold and six tin atoms in the form of two tilted hexagons. Magneticsusceptibility measurements show a nonmagnetic ground state of the ytterbium atoms.YbAuSn is a metallic conductor with a specific resistivity of 50 cm at room temperature.¹¹⁹Sn Mössbauer spectroscopic data show one signal at an isomer shift of 1.922(5) mm/ssubjected to quadrupole splitting of 0.929(9) mm/s.