Zr 1- x Ti x Sb: A Novel Antimonide on the Quasibinary Section ZrSb−TiSb with a Complex Crystal Structure Exhibiting Linear Sb Chains and Fragments of the TiSb Structure
2000; American Chemical Society; Volume: 122; Issue: 5 Linguagem: Inglês
10.1021/ja993423d
ISSN1943-2984
Autores Tópico(s)Rare-earth and actinide compounds
ResumoZr1-xTixSb can be obtained in quantitative yields by arc-melting suitable mixtures of Zr, Ti, ZrSb2, and TiSb2, or alternatively via a solid-state reaction at 1200 °C. This phase, although situated on the quasibinary section ZrSb−TiSb, crystallizes in an unprecedented structure type with 0.38(3) ≤ x ≤ 0.549(6), which was determined by three single-crystal analyses using an IPDS diffractometer: space group Cmcm, Z = 4, lattice dimensions ranging from a = 2455.8(2) pm, b = 852.06(9) pm, c = 566.69(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 channels formed by the metal atoms (M = Zr, Ti), which include a planar Sb ladder exhibiting short Sb−Sb distances (284 pm = c/2) parallel and longer ones (ca. 347 pm) perpendicular to the chain directions. The channels are further 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 structure 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 based on the ab initio LMTO method as well as on the semiempirical extended Hückel approach, which both also suggest three-dimensional metallic properties. The metallic character is confirmed by measurements of the thermopower and the electrical resistivity.
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