Nd₃₉Ir_10.98In_36.02. A complex intergrowth structure with CsCl- and AlB₂-related slabs

The ternary indide Nd₃₉Ir_10.98In_36.02 was synthesized by arc-melting and characterized by single crystal X-ray diffraction. Nd₃₉Ir_10.98In_36.02 crystallizes with a new structure type: Pearson code oP172, Pbam, a = 3175.4(6), b = 3762.5(8), c = 378.02(8) pm, wR2 = 0.0828, 5544 F² values, and 262 variables. Although the structure contains 44 crystallographically independent sites, it can easily be explained as an intergrowth structure of CsCl and AlB₂ related slabs. The larger indium atoms fill all distorted CsCl slabs. The trigonal prismatic (AlB₂) slabs have no uniform size. The larger ones are filled by indium and the smaller ones by the iridium atoms. Additionally, one trigonal prism shows a mixed occupancy by indium and iridium. The crystal chemistry of Nd₃₉Ir_10.98In_36.02 is discussed in the context of other intergrowth structures with the same simple slabs.