Crystal and electronic structure of the ternary monoclinic selenide Tl_2.59Sb_8.41Se₁₄ (TlSb₃Se₅)

Chem. Met. Alloys 9 (2016) 11-20

https://doi.org/10.30970/cma9.0316

Ihor BARCHIY, Anatoliy TATZKAR, Marian SABOV, Ewa ROŻYCKA-SOKOŁOWSKA, Bernard MARCINIAK, Volodymyr PAVLYUK

The ternary selenide Tl_2.59Sb_8.41Se₁₄ crystallizes with a monoclinic structure in space group P2₁/m where the atoms are located on 2e sites (site symmetry m). The structure of the title compound is closely related to the strongly disordered structure of K_2.5Sb_8.5Se₁₄. The coordination polyhedra of the thallium atoms are trigonal prisms with additional selenium atoms centering lateral faces. All the antimony atoms are coordinated by slightly deformed Se₆ octahedra. Three types of polyhedron: octahedron, trigonal bipyramid and tetrahedron, are observed for the selenium atoms. The crystal chemical analysis and electronic structure calculations by the TB-LMTO-ASA method show that the antimony and selenium atoms form a polyanionic network the negative charge of which is compensated by the thallium cations.

Polyanionic 3D-network of selenium and antimony atoms.

Keywords

Selenide / Crystal structure / Electronic structure