Gallium‐Indium Ordering in the Complex [Ni 2 Ga 3 In] Network of GdNi 2 Ga 3 In

Polycrystalline samples of the isotypic quaternary compounds RE Ni 2 Ga 3 In ( RE = Y, Gd – Tm) were obtained by arc‐melting of the elements. Crystals of the gadolinium compound were found by slow cooling of an arc‐melted button of the initial composition “GdNiGa 3 In”. All samples were characterized by powder X‐ray diffraction. The structure of GdNi 2 Ga 2.89 In 1.11 was refined from single‐crystal X‐ray diffractometer data: new type, Pnma , a = 2426.38(7), b = 418.17(2), c = 927.27(3) pm, wR 2 = 0.0430, 1610 F 2 values and 88 variables. Two of the six crystallographically independent gallium sites show a small degree of Ga/In mixing. The nickel atoms show tricapped trigonal prismatic coordination by gadolinium, gallium, and indium. Together, the nickel, gallium, and indium atoms build up a complex three‐dimensional [Ni 2 Ga 3 In] δ – network, which leaves cages for the gadolinium atoms. The indium atoms form zigzag chains with In–In distances of 337 pm. The crystal chemical similarities of the polyhedral packing in the GdNi 2 Ga 3 In and La 4 Pd 10 In 21 structures are discussed.