Sb and Se substitution in CsBi 4Te 6: The semiconductors CsM 4Q 6 (M = Bi, Sb; Q = Te, Se), Cs 2Bi 10Q 15, and CsBi 5Q 8

Duck Young Chung, Ctirad Uher, Mercouri Kanatzidis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


The solid solutions of CsBi 4Te 6, a high ZT material at a low temperature region, with Sb and Se were synthesized with general formulas CsBi 4-xSb xTe 6 and CsBi 4Te 6-ySe y. The introduction of Sb and Se in the lattice of CsBi 4Te 6 is possible but only to a limited extent. The Sb and Se atoms substituted are not uniformly distributed over all crystallographic sites but display particular site preferences. The structure of new Sb/Bi solid solutions retains the original framework of CsBi 4Te 6 composed of NaCl-type Bi/Te slabs interconnected by characteristic Bi-Bi bonds and Cs atoms located in the interlayer space. A structurally modified phase in Se/Te solid solutions was found from the reactions targeted for 0.2 < y < 2.4 with the formula of CsBi 5Te 7.5-ySe y (or Cs 2Bi 10Q 15, (Q = Se, Te)). The new structure is constructed by the same structural motif with an extended Bi/Te slab (29 Å) compared to that in CsBi 4Te 6 (23 Å). The CsBi 5Te 7.5-ySe y possesses Bi/Te slabs that extend by an additional "Bi 2Te 3" unit compared to the structure of CsBi 4Te 6, which implies the existence of a phase homology of compounds with the adjustable parameter being the width of the Bi/Q slab. In the reactions targeted for the compounds with higher y, a new phase CsBi 5Te 3.6Se 4.4 with a different type of framework was found. The electrical conductivity and thermopower for the selected samples show p-type conduction with metallic behavior. The room temperature values measured are in the range of 300-1100 S/cm and 100-150 μV/K for Sb-substituted samples and 20-500 S/cm and 70-140 μV/K for Se-substituted samples, respectively. Thermal conductivities of these samples are in the range of 0.9-1.2 W/m•K at room temperature. Tailoring the transport behavior of these materials for thermoelectric applications may be achieved by doping, as is possible for the parent compound CsBi 4Te 6.

Original languageEnglish (US)
Pages (from-to)1854-1863
Number of pages10
JournalChemistry of Materials
Issue number10
StatePublished - May 22 2012


  • chalcogenide
  • crystal growth
  • electronic materials
  • homologous series
  • narrow bandgap semiconductors

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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