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New representatives of the linear structure series containing empty Ga/Ge cubes in the Sm-Ga-Ge system |
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| Authors: | Yaroslav O Tokaychuk Yaroslav E Filinchuk Anatoliy O Fedorchuk Ivanna R Mokra |
| Institution: | a Laboratory of Crystallography, University of Geneva, 24 quai Ernest-Ansermet, CH-1211 Geneva, Switzerland b Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya str. 6, UA-79005 Lviv, Ukraine c Institute of Metallurgy, Clausthal University of Technology, Robert-Koch-Str. 42, D-38678 Clausthal-Zellerfeld, Germany |
| Abstract: | New ternary intermetallic compounds Sm2Ga7−xGex (x=5.2-6.1) and Sm4Ga11−xGex (x=5.76-8.75) were synthesized and their crystal structures were determined by X-ray powder diffraction at compositions Sm2Ga1.8Ge5.2 and Sm4Ga5.24Ge5.76. Sm2Ga1.8Ge5.2 crystallizes with the Ce2(Ga0.1Ge0.9)7 type of structure (space group Cmce, Pearson code oS80-8.00, a=8.46216(13), b=8.15343(13),  , Z=8), while Sm4Ga5.24Ge5.76 exhibits a new structure (space group Cmmm, Pearson code oS52-22.00, a=4.21038(4), b=35.8075(3),  , Z=2). Both structures are the members of the linear intergrowth structure series built up from segments of BaAl4, AlB2 and α-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. |
| Keywords: | Ternary gallides Crystal structure X-ray powder diffraction Linear structure series Disorder |
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