Abstract
New quaternary chalcogenide Cs4Cu3Bi9S17 has been synthesized by solid state reaction in a vacuum-sealed silica tube. Cs4Cu3Bi9S17 adopts monoclinic space group P21/m, with the following dimensions: a = 20.006(4) Å, b = 4.0556(8) Å, c = 22.279(5) Å, and β = 96.921°. The crystal structure of Cs4Cu3Bi9S17 features a unique three-dimensional framework consisting of interconnected Bi2Te3- and CdI2-type fragments forming three different-sized tunnels running parallel to the b-axis. The tunnels are filled with different numbers (1, 2, or 4) of Cs atoms. Cs4Cu3Bi9S17 is stable in air at room temperature, and differential thermal analysis showed that it decomposes at elevated temperatures. Cs4Cu3Bi9S17 is a semiconductor with a direct optical band gap of 0.9 eV, which is in agreement with density functional theory calculations. Electrical conductivity and Seebeck coefficient measurements show n-type semiconductor behavior. The electrical conductivity is 10-4 S/cm at 300 K and increases to 0.9 S/cm at 773 K. Cs4Cu3Bi9S17 possesses a very low thermal conductivity of 0.71 W m-1 K-1 at room temperature that decreases linearly with an increase in temperature to 0.46 W m-1 K-1 at 773 K. The low thermal conductivity shows the promise of Cs4Cu3Bi9S17 as a new thermoelectric material with appropriate doping.
Original language | English (US) |
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Pages (from-to) | 1744-1751 |
Number of pages | 8 |
Journal | Chemistry of Materials |
Volume | 29 |
Issue number | 4 |
DOIs | |
State | Published - Feb 28 2017 |
Funding
This work was supported by National Science Foundation (NSF) Grant DMR-1410169 (synthesis) and the U.S. Department of Energy, Office of Science, Basic Energy Sciences, via Grant DE-SC0014520 (thermal transport, electronic structure calculations). S.M.I. is supported by the MRSEC program (NSF DMR-1121262). This work made use of the EPIC facility (NUANCE Center, Northwestern University), which has received support from the State of Illinois, Northwestern University, and the National Science Foundation via Grant DMR-1121262 through the MRSEC program at the Materials Research Center, and EEC-0118025/003 through The Nanoscale Science and Engineering Center
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry