کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1330764 | 978977 | 2010 | 11 صفحه PDF | دانلود رایگان |
The lanthanide coinage-metal diarsenides LnTAs2 (Ln=La, Ce–Nd, Sm; T=Ag, Au) have been reinvestigated and their structures have been refined from single crystal X-ray data. Two different distortion variants of the HfCuSi2 type are found: PrAgAs2, NdAgAs2, SmAgAs2, GdAgAs2, TbAgAs2, NdAuAs2 and SmAuAs2 crystallize as twofold superstructures in space group Pmcn with the As atoms of their planar layers forming zigzag chains, whereas LaAgAs2, CeAgAs2 and PrAuAs2 adopt a fourfold superstructure (space group Pmca) with cis-trans chains of As atoms. The respective atomic positions can be derived from the HfCuSi2 type by group-subgroup relations. The compounds with zigzag chains of As atoms exhibit metallic behaviour while those with cis-trans chains are semiconducting as measured on powder pellets. The majority of the compounds including 4f elements show antiferromagnetic ordering at TN<20 K.
Text3Zigzig vs. cis-trans.Figure optionsDownload as PowerPoint slide
Journal: Journal of Solid State Chemistry - Volume 183, Issue 3, March 2010, Pages 510–520