New quaternary indides RE_7Ni_(5-x)Ge _(3+x)In_6 (RE = La, Nd, Sm)

摘要

The quaternary indides RE_7Ni_(5-x)Ge _(3+x)In_6 (RE = La, Nd, Sm) were synthesized from the elements by arc-melting. Single crystals were grown by slow cooling of the polycrystalline samples. The structures were characterized by powder and single-crystal X-ray diffraction: Ce_7Ni_(4.73)Ge _(3.27)In_6 type, P6/m, Z = 1, a = 1147.05(9), c = 426.82(4) pm, wR2 = 0.0652, 528 F~2 values for La_7Ni _(4.46)Ge_(3.54)In_6, a = 1134.5(7), c = 407.1(7) pm, wR2 = 0.0419, 441 F~2 values for Nd_7Ni _(4.91)Ge_(3.09)In_6, and a = 1133.5(2), c = 404.3(1) pm, wR2 = 0.0619, 498 F~2 values for Sm_7Ni _(4.31)Ge_(3.69)In_6, with 25 parameters per refinement. Characteristic features of the RE_7Ni_(5-x)Ge _(3+x)In_6 structures are hexagonal, AlB_2-related prisms around the RE1 atoms and a tricapped, trigonal-prismatic coordination of the nickel atoms.