Synthesis and Characterization of New Multinary Selenides A₁₀B₁₈Se₃₇ (A=Sn/Pb; B=In/Sb/Bi)

Abstract

The crystal structure is related to Proudite-Felbertalite homologous series and is made up of layered units ∞ 2 M 16 Se 23 ½ � derived from the octahedrally coordinated MSe 6 with stepped layers of 16 octahedra overlapped by 8 octahedra units, and 1D ribbons ∞ 1 M 12 Se 14 ½ � with metal centers coordinated by 3 or 5 Se 2À anions. Structural anisotropy leads to their layered shape and strong preferred orientation. The quinary selenide Sn 3.84 Pb 6.16 Sb 5.68 Bi 12.32 Se 37 exhibits n-type semiconducting behavior and thermoelectric properties with an optimized thermoelectric figure of merit (zT) reaching ~0.09 at 440 K. Density functional theory (DFT) calculation on a chargebalanced model with a triple supercell indicates its indirect band gap.