A three-dimensional extended Sb network in the metallic antimonides (M ',Ti)(5)Sb-8 (M ' = Zr, Hf, Nb, Mo)

(M',Ti)(5)Sb-8 was prepared from the melt by are-melting suitable mixtures of Ti, TiSb2, and TiSb2, respectively. This phase exists at least with M' = Zr, Hf, Nb, and Mo. A significant phase range for ZrdeltaTi5-deltaSb8 was found to be within 1.10(8) less than or equal to 6 less than or equal to 3. 9(3). All (M',Ti)(5)Sb-8 representatives investigated occur in the same, ye t hitherto unknown structure type, as determined by single-crystal analyses . E.g., the lattice dimensions of ZrdeltaTi5-deltaSb8 range from a = 654.49 (3) pm, c = 2662.4(2) pm for delta = 1.10(8) to a = 671.06(6), c = 2679.7(4 ) pm for delta = 3.9(3) (space group I4(1)22, No. 98, Z = 4). The three che mically inequivalent metal sites are statistically occupied by different mi xtures of the M atoms M' and Ti, included in a three-dimensional network of Sb atoms on 6- to 8-fold Sb coordinated positions. Sb-Sb bonds of intermed iate lengths occur in addition to the predominating heteronuclear M-Sb bond s. Physical property measurements of (Zr,Ti)(5)Sb-8 reveal these phases bei ng metallic exhibiting specific resistances of several m Omega .cm and a sm all Seebeck coefficient at room temperature, in agreement with the results of the electronic structure calculations on the LMTO and extended Huckel le vels. The calculations indicate a possible change to semiconducting propert ies by heavy doping.