Crystal Structure and Physical Properties of the New One-Dimensional Metal Ba2Cu7–xTe6

The telluride Ba2Cu7–xTe6 was synthesized from the elements in stoichiometric ratios, heated to 1073 K, followed by slow cooling to 873 K over 120 h. Ba2Cu7–xTe6 crystallizes in space group P21/m with lattice dimensions of a = 6.8591(7) Å, b = 12.1439(12) Å, c = 9.0198(9) Å, β = 110.7509(14)°, V = 702.58(12) Å3, and Z = 2. The structure is comprised of Cu atoms forming a six-membered ring and triangles, interconnected to an infinite ribbon of Cu atoms. The ribbons are connected to each other via Cu–Te bonds to yield a three-dimensional structure, wherein each Cu atom is tetrahedrally coordinated by four Te atoms. A special feature of this telluride is the occurrence of a quasi-linear Te atom chain, which causes one-dimensional metallic properties, in accordance with electronic structure calculations and property measurements.