Quaternary Silicide CarbidesAT2SiC (A=Rare Earth Elements and Actinoids,T=Mn, Re, Ru, Os) with DyFe2SiC-Type Structure
✍ Scribed by Thomas Hüfken; Anne M. Witte; Wolfgang Jeitschko
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 199 KB
- Volume
- 142
- Category
- Article
- ISSN
- 0022-4596
No coin nor oath required. For personal study only.
✦ Synopsis
The 49 compounds AMn 2 SiC (A ؍ Y, Sm, Gd-Tm, Lu, Th, U), ARe 2 SiC (A ؍ Y, Ce-Nd, Sm, Gd-Tm, Th), ARu 2 SiC (A ؍ Y, Ce-Nd, Sm, Gd-Tm, Th), and AOs 2 SiC (A ؍ Y, La-Nd, Sm, Gd-Tm, Th, U) have been prepared for the first time. They crystallize with DyFe 2 SiC-type structure, which was refined for PrOs 2 SiC from single-crystal X-ray data: Cmcm, a ؍ 396.02(5) pm, b ؍ 1105.8(1) pm, c ؍ 717.2(1) pm, Z ؍ 4, R ؍ 0.030 for 320 structure factors F and 18 variable parameters V. The refinement of the occupancy parameters revealed that the silicon site contains 2.0(3)% osmium. Mixed occupancy for this site resulted also from two structure refinements of the corresponding thorium compound, yielding the compositions ThOs 2.040(2) Si 0.960( 2) C (a ؍ 396.41(7) pm, b ؍ 1115.5(1) pm, c ؍ 717.0(1) pm, R ؍ 0.013, 245 F, 18 V) and ThOs 2.284(2) Si 0.716(2) C (a ؍ 397.1(1) pm, b ؍ 1113.9(2) pm, c ؍ 724.5(1) pm, R ؍ 0.025, 483 F, 18 V). No such deviations from the ideal compositions were detected by the (less accurate) Rietveld refinements of the structures of TbRe 2 SiC, DyRu 2 SiC, and HoRu 2 SiC. Magnetic susceptibility measurements with a SQUID magnetometer indicate Pauli paramagnetism for YRu 2 SiC and YOs 2 SiC. Chemical bonding in the DyFe 2 SiC-type compounds is discussed. It is shown that an electron count of 18 can be achieved for most of the transition metal atoms.