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

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.