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 m ay be regarded as composed of an intergrowth of RMn(2)Ge(2) and RCuGe blocks. The stabilization of the TbFeSi2-type structure through partia l substitution of Ge by Cu is discussed.