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Crystal Structure, Chemical Bonding, and Magnetic Hyperfine Interactions in GdRu2SiC

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posted on 2008-02-26, 00:00 authored by Thomas Fickenscher, Sudhindra Rayaprol, Jörg von Appen, Richard Dronskowski, Rainer Pöttgen, Kazimierz Łat̀ka, Jacek Gurgul
The silicide carbide GdRu2SiC was synthesized by arc-melting from the Laves phase GdRu2, silicon, and graphite. GdRu2SiC was characterized via X-ray powder and single-crystal data: DyFe2SiC type, Cmcm, a = 383.0(1) pm, b = 1106.9(2) pm, c = 715.7(1) pm, wR2 = 0.0363, 626 F2 values, and 20 variables. The silicon atoms have a distorted trigonal prismatic Gd2Ru4 coordination and the carbon atoms fill compressed [Gd4Ru2] octahedra. The shortest interatomic distances and strongest bondings occur for the Ru−C (187 pm) and Ru−Si (247 pm) contacts, the former ones even exhibiting double-bond strength. Together, these atoms build up a three-dimensional [Ru2SiC] network in which the gadolinium atoms fill channels. The magnetic and electronic properties of GdRu2SiC have been investigated by means of magnetometric and 155Gd Mössbauer spectroscopy measurements. Magnetic susceptibility measurements exhibit magnetic ordering with a broad feature around 10 K. Susceptibility increases below the broad peak, indicating complex magnetism in this compound. This fact is supported by Mössbauer spectroscopy, which exhibits a dramatic change of the Mössbauer spectrum below 4.2 K, indicating another magnetic phase transition. The results of Mössbauer spectroscopy are discussed here in detail to understand the nature of the magnetic ordering in GdRu2SiC below and above 4.2 K.