Crystal structure of R₁₅Ni_96−xGa_x (R ≡ Sm, Y, Tb, Dy, Er, Tm, Yb, Lu)

The structure of the compound Sm15Ni52Ga44 was investigated by means of single-crystal methods (autodiffractometer "Syntex" P2(1), Mo K-alpha, graphite monochromator): space group P6m2BAR, a=8.771(1) angstrom; c=25.061(4) angstrom, Z=15, R(F)=0.079 for 391 reflections using the isotropic approximation for thermal parameters. The shortest interatomic distances are: Sm-Sm, 3.87; Sm-Ga, 2.76; Sm-Ni, 2.66; Ga-Ga, 2.20; Ni-Ni, 2.32; Ni-Ga, 2.30 angstrom. The coordination numbers for the atoms are: samarium, 18-20; nickel, 11, 12, 14; gallium, 11, 12, 14