Indium Flux-Growth of Eu2AuGe3: A New Germanide with an AlB2 Superstructure

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• 作者：C. Peter Sebastian ; Christos D. Malliakas ; Maria Chondroudi ; Inga Schellenberg ; Sudhindra Rayaprol ; Rolf-Dieter Hoffmann ; Rainer Pttgen ; Mercouri G. Kanatzidis
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：October 18, 2010
• 年：2010
• 卷：49
• 期：20
• 页码：9574-9580
• 全文大小：931K
• 年卷期：v.49,no.20(October 18, 2010)
• ISSN：1520-510X

文摘

The germanide Eu₂AuGe₃ was obtained as large single crystals in high yield from a reaction of the elements in liquid indium. At room temperature Eu₂AuGe₃ crystallizes with the Ca₂AgSi₃ type, space group Fmmm, an ordered variant of the AlB₂ type: a = 857.7(4), b = 1485.5(10), c = 900.2(4) pm. The gold and germanium atoms build up slightly distorted graphite-like layers which consist of Ge₆ and Au₂Ge₄ hexagons, leading to two different hexagonal-prismatic coordination environments for the europium atoms. Magnetic susceptibility data showed Curie−Weiss law behavior above 50 K and antiferromagnetic ordering at 11 K. The experimentally measured magnetic moment indicates divalent europium. The compound exhibits a distinct magnetic anisotropy based on single crystal measurements and at 5 K it shows a metamagnetic transition at 10 kOe. Electrical conductivity measurements show metallic behavior. The structural transition at 130 K observed in the single crystal data was very well supported by the conductivity measurements. ¹⁵¹Eu Mssbauer spectroscopic data show an isomer shift of −11.24 mm/s at 77 K, supporting the divalent character of europium. In the magnetically ordered regime one observes superposition of two signals with hyperfine fields of 26.0 (89%) and 3.5 (11%) T, respectively, indicating differently ordered domains.