Synthesis and Thermoelectric Properties of the New Ternary Bismuth Sulfides KBi6.33S10 and K2Bi8S13

Mercouri G. Kanatzidis, Timothy J. McCarthy, Troy A. Tanzer, Li Heng Chen, Lykourgos Iordanidis, Tim Hogan, Carl R. Kannewurf, Ctirad Uher, Baoxing Chen

Research output: Contribution to journalArticlepeer-review

105 Citations (Scopus)


KBi6.33S10 and K2Bi8S13 were synthesized by the direct combination Of K2S/Bi2S3 at high temperature (>700 °C). The reaction of K2S/3.3Bi2S3 at 800 °C revealed the presence of a new ternary sulfide KBi6.33S10 (I, 92% yield). The shiny, silver polycrystalline material crystallizes in the orthorhombic space group Pnma (No. 62) with a = 24.05(1) Å, b = 4.100-(2) Å, c = 19.44(1) Å, V = 1917(3) Å, Z = 4, and dc = 5.828 g/cm3. Data with F02 > 3σ(Fo2), 862; no. of variables 108, 2θmax 50°. The final R/RW = 4.3/4.7%. The structure consists of blocks of Bi2Te3- and CdI2-type units that are connected to form a three-dimensional network with K+ ions located in the channels that run along the b axis. The same reaction but with a different reactant ratio at 750 °C gave the new ternary sulfide K2Bi8S13 (II, 94% yield). This compound crystallizes in the monoclinic space group P21/m (No. 11) with a = 16.818(2) Å, b = 4.074(5) Å, c = 17.801(3) Å, β = 90.48(1)°, V = 1220(2) Å3, Z = 2, and dc = 5.900 g/cm3. Data with F02 > 3σ(F02), 1924; no. of variables 131, 2θmax 50°. The final R/RW = 7.3/8.2%. The structure of the shiny rodlike crystals is closely related to that of I. As in I, it also consists of Bi2Te3- and CdI2-type fragments that connect to form K+-filled channels. The two potassium atoms and one bismuth atom are disordered over three sites. Electrical conductivity on I show semiconducting behavior with 102 S/cm at 300 K. Compound II possesses an electrical conductivity of 102 S/cm at 300 K. The optical bandgaps of I and II (0.06-0.24 eV) were estimated by infrared diffuse reflectance measurements. Thermal analysis and thermal conductivity data for I and II are reported. The thermal conductivity of KBi6.33S10 is found to be substantially lower than that of Bi2Te3.

Original languageEnglish
Pages (from-to)1465-1474
Number of pages10
JournalChemistry of Materials
Issue number7
Publication statusPublished - Jul 1996

ASJC Scopus subject areas

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

Fingerprint Dive into the research topics of 'Synthesis and Thermoelectric Properties of the New Ternary Bismuth Sulfides KBi<sub>6.33</sub>S<sub>10</sub> and K<sub>2</sub>Bi<sub>8</sub>S<sub>13</sub>'. Together they form a unique fingerprint.

Cite this