New members of the homologous series Am[M6Se8]m [M5+nSe9+n]: The quaternary phases A1-xM′3-xBi11+xSe20 and A1+xM′3-2xBi7+xSe14 (A = K, Rb, Cs; M′ = Sn, Pb)

A. Mrotzek, L. Iordanidis, M. G. Kanatzidis

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17 Citations (Scopus)


The compounds A1+xM′3-2xBi7+xSe14 and A1-xM′3-xBi11+xSe20 (A = K, Rb, Cs; M′ = Sn, Pb) were discovered from reactions involving A2Se, Bi2Se3, M′, and Se at 760 °C. The single-crystal structures reveal that A1+xM′3-2xBi7+xSe14 are isostructural to K2.5Bi8.5Se14 whereas A1-xM′3-xBi11+xSe20 adopt a new structure type. Both compound types belong to the homologous series Am[M6Se8]m [M5+nSe9+n] (M = di- and trivalent metal), whose characteristics are three-dimensional anionic frameworks with tunnels filled with alkali ions. The building units are derived from different sections of the NACI lattice, perpendicular to the [111] (NaCl111-type) and [100] (NaCl100-type) directions, respectively, with dimensions and shapes defined by m and n. The structures of A1+xM′3-2xBi7+xSe14 (m = 2, n = 3) and A1-xM′3-xBi11+xSe20 (m = 1, n = 3) exhibit the same type of stepshaped NACl111-type layer but differ in the size of the NaCl100-type unit. In both structures, the Bi and Sn (Pb) atoms are extensively disordered over the metal sites of the chalcogenide network. The physicochemical and charge transport properties of A1+xM′3-2xBi7+xSe14 and A1-xM′3-xBi11+xSe20 (A = K, Rb, Cs; M′ = Sn, Pb) are reported.

Original languageEnglish
Pages (from-to)6204-6211
Number of pages8
JournalInorganic Chemistry
Issue number24
Publication statusPublished - Nov 19 2001

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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