Ternary Rare-Earth-Metal Nickel Indides RENiIn (RE = Gd, Tb, Dy) with YbCuMg-Type Structure.

The ternary rare-earth-metal nickel indides RENiIn (RE = Gd, Tb, Dy) were prepared by arc-melting mixtures of the elements followed by annealing at 870 K. They adopt the YbCuMg-type structure (space group 6/, Pearson symbol 68, = 2), as determined by laboratory and synchrotron powder diffraction methods for RE = Gd ( = 9.6435(10) Å, = 22.118(3) Å) and Tb ( = 9.5695(8) Å, = 21.983(3) Å), and single-crystal X-ray diffraction methods for RE = Dy ( = 9.533(5) Å, = 21.890(13) Å). The centrosymmetric YbCuMg-type structure is closely related to the noncentrosymmetric PrIrMg-type structure. Triangular In clusters within RENiIn represent a rare type of cluster found among metal-rich indides; the reasons for their formation were investigated by density functional theory methods.