Main Group Element Size and Substitution Effects on the Structural Dimensionality of Zirconium Tellurides of the ZrSiS Type
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Chemical and structural variations in compounds related to the layered compound ZrSiTe have been examined. A study of ZrSi1-xGexTe solid solutions show that the Si:Ge ratio can be varied in any stoichiometric proportion with the result that increasing atomic size (increasing x) affects both the shrinkage of the c axis and the expansion of the a axis. Expansion of the a axis results in relief of steric crowding within and between Te layers that permits increased bonding between Zr and Te in adjacent layers. This steric-electronic synergy is discussed. A new member of this structural family, ZnSnTe, was synthesized (space group P4/nmm, No. 129, Z = 2, a = 4.0549(6) , c = 8.711(2) ). ZrSnTe has a fully three-dimensional structure; bond distances of Zr to the intralayer and interlayer Te, 3.038 and 3.084 , respectively, are almost equal. Four new pseudoternary tellurides are reported. Two of pseudoternary tellurides, ZrSi0.66As0.34Te and ZrSi0.5As0.7Te0.8, were refined in the same space group with lattice parameters a = 3.8116(1) , c = 8.398(3) for ZrSi0.5As0.7Te0.8 and t = 3.7110(3) , c = 9.723(2) for ZrSi0.66As0.34Te. ZrSi0.66As0.34Te., isostructural with ZrSiTe, has a c axis length 0.22 larger than that of ZrSiTe; arsenic in this material substitutes solely for silicon. The isotypic ZrSi0.5As0.7Te0.8 exhibits substitution for both Si and Te and can be formulated as Zr(Si0.5, As0.5)(As0.2Te0.8). Four-probe resistivity measurements (77300 K) show all ternary and pseudoternary tellurides to be metallic with resistivities of ~104 cm. 1995, American Chemical Society. All rights reserved.
