Differences and Similarities between the Isotypic AntimonidesMFe1-xSb, ScCo1-xSb, andMNiSb (M=Zr, Hf)

The new antimonides MFe1-xSb can be synthesized by arc-melting of M, Fe, andMSb2(M=Zr, Hf). All title compounds crystallize in the TiNiSi structure type (space groupPnma,Z=4). The lattice parameters of the new phases MFe1-xSb, as obtained from the bulk samples of the nominal compositionsMFeSb, are (a=681.4(1) pm,b=417.87(7) pm,c=740.3(1) pm for ZrFe1-xSb anda=674.0(1) pm,b=412.0(2) pm,c=729.7(2) pm for HfFe1-xSb. Under the reaction conditions used, the occupancy factors of the iron position content of ZrFe1-xSb does not exceed 68(1)% (i.e.x=0.32(1)). Extended Hückel calculations, performed on the hypothetical model structures "ZrFeSb" and "ZrFe0.75Sb", point to the phase ZrFe1-xSb being metallic, independent of thexvalue. The band structure of "ZrFeSb", obtained withab initioLMTO calculations, reveals a threedimensional metallic conductivity and a nonmagnetic ground state.