Quaternary Silicide CarbidesAT2SiC (A=Rare Earth Elements and Actinoids,T=Mn, Re, Ru, Os) with DyFe2SiC-Type Structure

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

“…The indexing of the diffraction lines was facilitated by an intensity calculation using the positional parameters of the refined structure. Our powder (Table) and single-crystal lattice parameters ( a = 382.0(1) pm, b = 1104.0(1) pm, c = 714.0(1) pm) are in good agreement with the data reported previously ( a = 382.1(1) pm, b = 1105.5(1) pm, c = 714.5(1) pm) …”

“…The data set showed Laue symmetry mmm and the systematic extinctions were compatible with space group Cmcm . The atomic parameters of isotypic DyRu 2 SiC were taken as starting values and the structure was refined with anisotropic displacement parameters for all atoms using SHELXL-97 (full-matrix least-squares on F 2 ) . Because the single-crystal data of PrOs 2 SiC and ThOs 2 SiC revealed some Si/Os mixing and small defects on the carbon site, the occupancy parameters of all sites were refined in separate series of least-squares cycles.…”

“…Similar behavior was also observed for DyFe 2 SiC, were the dysprosium and iron atoms build up trigonal prisms [Dy 2 Fe 4 ] that are filled by silicon and the carbon atoms fully occupy the octahedral voids. Sometime later, a whole series of silicide carbide and phosphide carbides with filled Re 3 B structure has been reported. – So far, only some structural data on these intermetallics have been reported. Chemical bonding in ThFe 2 SiC has been investigated on the basis of extended Hückel tight binding calculations …”

“…The crystal structure, chemical bonding, magnetic and 155 Gd Mössbauer spectroscopic data of GdRu 2 SiC are reported herein. So far, GdRu 2 SiC was characterized only through a Guinier powder pattern …”

Unexpected Magnetic Ordering on the Cr Substructure in UCr2Si2C and Structural Relationships in Quaternary U-Cr-Si-C Compounds

“…An octahedral environment is usually encountered around carbon atoms in ternary or quaternary uranium carbides: for example, “CU 6 ” octahedra in U 20 Si 16 C 3 , U 6 Co 12 Ge 4 C . or U 6 Fe 16 Si 7 C, “CU 5 Si” in U 3 Si 2 C 2 , “CU 4 Mn 2 ” in UMn 2 SiC, and “CU 2 (Fe,Si) 4 ” in U 2 (Fe,Si) 17 C x . Carbon-centered “CU 4 Cr 2 ” and “CU 3 Cr 3 ” octahedra are also found in UCrC 2 .…”