Several members of the new family A1-xM4-xBi11+xSe21 (A = K, Rb, Cs; M = Sn, Pb) were prepared by direct combination of A2Se, Bi2Se3, Sn (or Pb), and Se at 800°C. The single-crystal structures of K0.54Sn3.54Bi11.46Se21,K 1.46 Pb3.08Bi11.46Se21, Rb0.69Pb3.69Bi11.31Se21,, and Cs0.65Pb3.65Bi11.35Se21 were determined. The compounds A1-xM4-xBi11+x Se21 crystallize in a new structure type with the monoclinic space group C2/m, in which building units of the Bi2Te3 and NaCl structure type join to give rise to a novel kind of three-dimensional anionic framework with alkali-ion-filled tunnels. The building units are assembled from distorted, edge-sharing (Bi,Sn)Se6 octahedra. Bi and Sn/Pb atoms are disordered over the metal sites of the chalcogenide network, while the alkali site is not fully occupied. A grand homologous series Km(M6Se8)m(M5+nSe 9+n) has been identified of which the compounds A1-x M4-xBi11+xSe21 are members. We discuss here the crystal structure, charge-transport properties, and very low thermal conductivity of A1-xM4-xBi11+xSe21.
|Number of pages||12|
|Journal||Chemistry - A European Journal|
|Publication status||Published - May 4 2001|
- Structure elucidation
- Thermoelectric materials
ASJC Scopus subject areas
- Organic Chemistry