Lead-flux Growth of Eu4Ir8As7 Crystals

Abstract

Single crystals of the new arsenide Eu4Ir8As7 were grown from a lead flux. The structure was refined on the basis of single-crystal X-ray diffractometer data: Ca4Ir8P7 type, P21=m, a=1311.3(1), b = 408:4(1), c = 1360:3(1) pm, β = 98:45(1)°, wR2=0.0640, 1985 F2 values, 95 variables. The iridium and arsenic atoms in the Eu4Ir8As7 structure build up a complex three-dimensional, covalently bonded [Ir8As7] network with Ir-As distances ranging from 239 to 260 pm. Each iridium atom has three or four arsenic neighbors in slightly distorted trigonal-planar or tetrahedral coordination. The four crystallographically independent europium atoms fill cavities of coordination numbers 12, 13, and 15 (2) within the [Ir8As7] network. Parts of the Eu4Ir8As7 structure resemble known simpler structure types, and one can describe the Eu4Ir8As7 structure as an intergrowth variant of CaBe2Ge2-, TiNiSi- and AlB2-related slabs.