Synthesis and Characterization of Multinary Selenides A4B10Se19 (A=Sn, Pb; B=Sb, Bi)

Multinary selenides A(4)B(10)Se(19) (A=Sn/Pb; B=Sb/Bi), including Sn4Bi10Se19, Pb4Sb6.71Bi3.29Se19, and Pb4Sb3.43Bi6.57Se19, were prepared by solid-state reactions. These compounds adopt the Felbertalite structure type that crystallizes in the monoclinic space group C2/m (No. 12). Single-crystal and powder X-ray diffraction measurements studied the crystal structure and site preference of metal sites. They exhibit stacking of stepped layers(infinity)(2) [M8Se13] (NaCl111-type) and ribbon-shape (1)(infinity) [M6Se6] (NaCl100-type) units that are connected via shared Se2- ions. Electronic structure calculations indicated semiconducting properties and were verified by temperature-dependent conductivity and Seebeck coefficient measurements. The thermoelectric properties show a maximum power factor of 1.06 mu W center dot m(-1) center dot K-2 at 550 K for Pb4Sb6Bi4Se19.