New representatives of the linear structure series containing empty Ga/Ge cubes in the Sm–Ga–Ge system

✍ Scribed by Yaroslav O. Tokaychuk; Yaroslav E. Filinchuk; Anatoliy O. Fedorchuk; Artem Yu. Kozlov; Ivanna R. Mokra

• Book ID: 104029509
• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 502 KB
• Volume: 179
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2006.01.041

✦ Synopsis

New ternary intermetallic compounds Sm 2 Ga 7Àx Ge x (x ¼ 5:226:1) and Sm 4 Ga 11Àx Ge x (x ¼ 5:7628:75) were synthesized and their crystal structures were determined by X-ray powder diffraction at compositions Sm 2 Ga 1.8 Ge 5.2 and Sm 4 Ga 5.24 Ge 5.76 . Sm 2 Ga 1.8 Ge 5.2 crystallizes with the Ce 2 (Ga 0.1 Ge 0.9 ) 7 type of structure (space group Cmce, Pearson code oS80-8.00, a ¼ 8:46216ð13Þ, b ¼ 8:15343ð13Þ, c ¼ 21:1243ð3Þ Å, Z ¼ 8), while Sm 4 Ga 5.24 Ge 5.76 exhibits a new structure (space group Cmmm, Pearson code oS52-22.00, a ¼ 4:21038ð4Þ, b ¼ 35:8075ð3Þ, c ¼ 4:14023ð4Þ Å, Z ¼ 2). Both structures are the members of the linear intergrowth structure series built up from segments of BaAl 4 , AlB 2 and a-Po structure types. Their Ga/Ge networks contain characteristic empty cubes with one side capped by an atom subjected to an intrinsic displacive disorder. A model of Ga/Ge localization was suggested on the basis of crystal-chemical analysis.