Single crystal refinement of the first TbFeSi2-type structure germanide LaMnCu0.5Ge1.5

Synthesis and crystal chemistry of new pseudo-ternary compounds RMnCu(0.5)Ge(1.5) (R = La-Nd) are reported. These new compounds crystallize in the orthorhombic TbFeSi2-type structure (space group: Cmcm). The Cu substitution takes place in the AlB2 slab, yielding compounds which may be regarded as composed of an intergrowth of RMn(2)Ge(2) and RCuGe blocks. The stabilization of the TbFeSi2-type structure through partial substitution of Ge by Cu is discussed.