Differences and similarities between the isotypic antimonides MFe1-xSb, ScCo1-xSb, and MNiSb (M = Zr, Hf)

The new antimonides MFe1-xSb can be synthesized by arc-melting of M, Fe, an d MSb2 (M = Zr, Hf), All title compounds crystallize in the TiNiSi structur e type (space group Pnma, Z = 4). The lattice parameters of the new phases MFe1-xSb, as obtained from the bulk samples of the nominal compositions MFe Sb, are (a = 681.4(1) pm, b = 417.87(7) pm, c = 740.3(1) pm for ZrFe1-xSb a nd a = 674.0(1) pm, b = 412.0(2) pm, c = 729.7(2) pm for HfFe1-xSb. Under t he reaction conditions used, the occupancy factors of the iron position con tent of ZrFe1-xSb does not exceed 68(1)% (i.e. x = 0.32(1)), Extended Hucke l calculations, performed on the hypothetical model structures "ZrFeSb" and "ZrFe0.75Sb", point to the phase ZrFe1-xSb being metallic, independent of the x value, The band structure of "ZrFeSb", obtained with ab initio LMTO c alculations, reveals a three-dimensional metallic conductivity and a nonmag netic ground state. (C) 1999 Academic Press.