Crystal structures of Ba5Ru3−x−yAlxGayO11 with x = 1.24(2), y = 0; x = 0.67(1), y = 0.450(6) and x = 0, y = 1.26(2)

Members of the solid solution series Ba5Ru3−x−yAlxGayO11 with x = 1.24(2), y = 0; x = 0, y = 1.26(2) (quarternary border phases) and x = 0.67(1), y = 0.450(6) (quinquenary phase) were prepared by solid-state reactions of mixtures of BaCO3, RuO2, Al2O3 and Ga2O3. The quinquenary phase is the first oxide containing the metals Ba, Ru, Al and Ga. Furthermore, up to now a quarternary phase in the system Ba-Ru-Ga-O has not been reported either. The crystal structures of the Al containing phases were determined by X-ray single crystal diffraction technique, the structure of Ba5Ru1.74(2)Ga1.26(2)O11 by Rietveld refinements on an X-ray powder diffraction pattern. The compounds crystallize isostructurally to Ba5Ir2AlO11: orthorhombic, space group Pnma (No. 62), Z = 4 with the lattice parameters a = 18.665(1) Å, b = 5.7722(4) Å, c = 11.0724(6) Å for Ba5Ru1.76(2)Al1.24(2)O11 (I), a = 18.765(1) Å, b = 5.8009(4) Å, c = 11.0754(5) Å for Ba5Ru1.884(8)Al0.67(1)Ga0.450(6)O11 (II) and a = 18.8493(4) Å, b = 5.8212(1) Å, c = 11.1014(2) Å for Ba5Ru1.74(2)Ga1.26(2)O11 (III). The crystal structures contain octahedron pairs [M2O9] (M = I, II: Ru, Al; III: Ru, Ga) formed via face-sharing, additionally interconnected to one-dimensional chains extending along [0 1 0] via tetrahedra [MO4] (M = I: Ru, Al; II: Ga, Al; III: Ga).