Zr1-xTixSb: A novel antimonide on the quasibinary section ZrSb-TiSb with acomplex crystal structure exhibiting linear Sb chains and fragments of theTiSb structure

Zr1-xTixSb can be obtained in quantitative yields by are-melting suitable m ixtures of Zr, Ti, ZrSb2 and TiSb2, or alternatively via a solid-state reac tion at 1200 degrees C, This phase, although situated on the quasibinary se ction ZrSb-TiSb, crystallizes in an unprecedented structure type with 0.38( 3) less than or equal to x less than or equal to 0.549(6), which was determ ined by three single-crystal analyses using an IPDS diffracrometer: space g roup Cmcm, Z = 4, lattice dimensions ranging from a = 2455.8(2) pm, b = 852 .06(9) pm, c = 565.69(5) pm (x = 0.55) to a = 2479.7(6) pm, b = 859.4(2) pm , c = 568.91(9) pm (x = 0.38). The crystal structure consists in part of ch annels formed by the metal atoms (M = Zr, Ti), which include a planar Sb la dder exhibiting short Sb-Sb distances (284 pm c/2) parallel and longer ones (ca. 347 pm) perpendicular to the chain directions. The channels are furth er surrounded by Sb atoms, which belong in part to the embedding NiAs-type fragments. In contrast to TiSb (NiAs type) and ZrSb (ZrSb type), the new st ructure is stabilized by strong Sb-Sb bonding (in addition to M-Sb and M-M bonding). This is supported by the results of band structure calculations b ased on the ab initio LMTO method as well as on the semiempirical extended Huckel approach, which both also suggest three-dimensional metallic propert ies. The metallic character is confirmed by measurements of the thermopower and the electrical resistivity.