Crystal structure of ternary germanides SrM2Ge2 (M = Ni and Ir)

Ternary intermetallics SrM2Ge2 (M = Ni and Ir) have been prepared by arc melting. The crystal structure of these intermetallics was determined by single-crystal X-ray diffraction. They are isostructural with the recently discovered superconductors (Ba,Sr)1−x(K,Cs)x Fe2As2 with ThCr2Si2-type structure with the space group I4/mmm (No. 139). The lattice parameters of SrNi2Ge2 and SrIr2Ge2 are a = 0.41801(1) and c = 1.02409(6) nm, and a = 0.41916(2) and c = 1.0674(1) nm, respectively. Neither of them shows superconductivity down to 1.8 K.