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

New ternary intermetallic compounds Sm2Ga7−xGex (image) and Sm4Ga11−xGex (image) 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, image, image, image, image), while Sm4Ga5.24Ge5.76 exhibits a new structure (space group Cmmm, Pearson code oS52–22.00, image, image, image, image). 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.