THE CRYSTAL-STRUCTURE OF YBFE2AL10, A COMBINED SUBSTITUTION AND STACKING VARIANT OF THE THMN12 AND CEMN4AL8 TYPE STRUCTURES

YbFe2Al10 crystallizes with a new structure type, which was determined from single-crystal X-ray data: Cmcm, a = 896.6(1) pm, b = 1015.3(2) pm, c = 900.3(1) pm, Z = 4, R = 0.024 for 795 structure factors and 41 variable parameters. The structure is closely related to the tetragon al ThMn12 and CeMn4Al8 type structures, from which it can be derived b y substitution of some manganese by aluminum atoms, and in addition it has a different stacking of atomic layers. The ytterbium atoms have 2 0 neighbors (4 Fe + 16 Al), the iron atoms have distorted icosahedral coordination (2 Yb + 10 Al), and all of the five different aluminum si tes are coordinated by ytterbium, iron, and aluminum atoms with coordi nation numbers 12, 13, and 14.