Crystal Structure, Chemical Bonding and Magnetism Studies for Three Quinary Polar Intermetallic Compounds in the (Eu(1−x)Ca(x))(9)In(8)(Ge(1−y)Sn(y))(8) (x = 0.66, y = 0.03) and the (Eu(1−x)Ca(x))(3)In(Ge(3−y)Sn(1+y)) (x = 0.66, 0.68; y = 0.13, 0.27) Phases

Three quinary polar intermetallic compounds in the (Eu(1−x)Ca(x))(9)In(8)(Ge(1−y)Sn(y))(8) (x = 0.66, y = 0.03) and the (Eu(1−x)Ca(x))(3)In(Ge(3-y)Sn(1+y)) (x = 0.66, 0.68; y = 0.13, 0.27) phases have been synthesized using the molten In-metal flux method, and the crystal structures are characterized by powder and single-crystal X-ray diffractions. Two orthorhombic structural types can be viewed as an assembly of polyanionic frameworks consisting of the In(Ge/Sn)(4) tetrahedral chains, the bridging Ge(2) dimers, either the annulene-like “12-membered rings” for the (Eu(1−x)Ca(x))(9)In(8)(Ge(1−y)Sn(y))(8) series or the cis-trans Ge/Sn-chains for the (Eu(1−x)Ca(x))(3)In(Ge(3−y)Sn(1+y)) series, and several Eu/Ca-mixed cations. The most noticeable difference between two structural types is the amount and the location of the Sn-substitution for Ge: only a partial substitution (11%) occurs at the In(Ge/Sn)(4) tetrahedron in the (Eu(1−x)Ca(x))(9)In(8)(Ge(1−y)Sn(y))(8) series, whereas both a complete and a partial substitution (up to 27%) are observed, respectively, at the cis-trans Ge/Sn-chain and at the In(Ge/Sn)(4) tetrahedron in the (Eu(1−x)Ca(x))(3)In(Ge(3−y)Sn(1+y)) series. A series of tight-binding linear muffin-tin orbital calculations is conducted to understand overall electronic structures and chemical bonding among components. Magnetic susceptibility measurement indicates a ferromagnetic ordering of Eu atoms below 5 K for Eu(1.02(1))Ca(1.98)InGe(2.87(1))Sn(1.13).