A substitution of nickel by antimony:: Crystal and electronic structure of the new antimonide Hf6Ni1-xSb2+x

The ternary antimonides Hf6M1-xSb2+x (M=Fe, Co, Ni) were prepared by are-melting of stoichiometric mixtures of Hf, HfSb2 and M. According to the single crystal structure analyses, performed on Hf6NiSb2 and Hf6Ni0.76Sb2.24, Hf6M1-xSb2+x crystallizes in an ordered variant of the Fe2P structure type with the M and Sb atoms occupying the two P positions on Ib and 2c of space group P (6) over bar 2m, respectively (Zr6CoAl2 type). The 3d metal atoms M can partially be replaced by antimony, leading to significant, anisotropic changes in the lattice dimensions which are a=765.6(1) pm, c=362.10(7) pm, V=183.81(5)X10(6)pm(3) for Hf6NiSb2, and a=760.5(1) pm, c =372.40(7) pm, V= 186.53(5)x 10(6)pm(3) for Hf6Ni0.76Sb2.24 as determined by single crystal data. Calculations of the electronic structure of Hf6NiSb2 using the Extended Huckel approximation show strong bonding Hf-Hf, Hf-Ni, and Hf-Sb interactions. (C) 1998 Elsevier Science S.A.