Multinary selenides with unusual coordination environment of bismuth

摘要: New multinary selenides Ae3SnPn2Se8 (Ae = Sr, Ba; Pn Sb, Bi), Sr8.01Ge2.04Bi7.95Se24, and Sr8YGe2Bi7Se24 were synthesized by solid-state reaction, their structures determined single-crystal X-ray diffraction. These compounds crystallize in orthorhombic space group Pnma (no. 62) for Bi) Pna21 33) Sr8.01Ge2.04Bi7.95Se24 Sr8YGe2Bi7Se24. The feature one-dimensional corner sharing tetrahedral ∞1[MSe3] units, edge octahedral ∞1[M4Se10], packed with the alkaline earth or rare cations. contain a triple cell superlattice structure derived from special arrangement of Bi Ge tetrahedrally coordinated chain. Diffuse reflectance spectra electronic resistivity measurements indicate semiconducting behaviors; Seebeck coefficient is −180 μV/K at 303 K. Electronic calculations confirm that electron count Sr8Y...