Ce 2Ir 5B 2, a new structure type of ternary borides

Abstract

The crystal structure of a new ternary boride Ce 2Ir 5B 2, space group R 3m , a=5.477(2) Å, c=31.518(5) Å, Z=6, V=818.79 Å, was refined down to R=0.0484, wR 2=0.1211 from single crystal X-ray diffraction data. This is the first representative of a new structure type of intermetallic compounds (an ordered variant of the binary Er 2Co 7 compound). The structure of Ce 2Ir 5B 2 is the stacking variant of the MgCu 2- and CeCo 3B 2-type slabs and belongs to the structural series with the general formula R 2+ n M 4+3 n X 2 n ( n=2).