Crystal structure, characterization and thermoelectric properties of the type-I clathrate Ba8-ySryAl14Si32 (0.6≤y≤1.3) prepared by aluminum flux

John H. Roudebush, Eric S. Toberer, Håkon Hope, G. Jeffrey Snyder, Susan M. Kauzlarich

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The title compound was prepared as single crystals using an aluminum flux technique. Single crystal and powder X-ray diffraction indicate that this composition crystallizes in the clathrate type-I structure, space group Pm3n. Electron microprobe characterization indicates the composition to be Ba 8-ySryAl14.2(2)Si31.8(2) (0.77<y<1.3). Single-crystal X-ray diffraction data (90 and 12 K) were refined with the Al content fixed at the microprobe value (12 K data: R 1=0.0233, wR2=0.0441) on a crystal of compositions Ba. The Sr atom preferentially occupies the 2a position; mixed Al/Si occupancy was found on all framework sites. These refinements are consistent with a fully occupied framework and nearly fully occupied cation guest sites as found by microprobe analysis. Temperature dependent electrical resistivity and thermal conductivity have been measured from room temperature to 1200 K on a hot-pressed pellet. Electrical resistivity reveals metallic behavior. The negative Seebeck coefficient indicates transport processes dominated by electrons as carriers. Thermal conductivity is between 22 and 25 mW/cm K. The sample shows n-type conductivity with a maximum figure of merit, zT of 0.3 at 1200 K. A single parabolic band model predicts a five-fold increase in zT at 800 K if carrier concentration is lowered.

Original languageEnglish (US)
Pages (from-to)1176-1185
Number of pages10
JournalJournal of Solid State Chemistry
Volume184
Issue number5
DOIs
StatePublished - May 2011

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clathrates
Aluminum
Crystal structure
Single crystals
Fluxes
aluminum
crystal structure
Thermal conductivity
single crystals
thermal conductivity
Chemical analysis
conductivity
electrical resistivity
Seebeck coefficient
Electrons
Seebeck effect
diffraction
pellets
figure of merit
X ray powder diffraction

Keywords

  • 12 K structure
  • BaAlSi
  • Clathrate type-I
  • Inorganic clathrate
  • Low temperature X-ray diffraction
  • Thermoelectric properties
  • Zintl phase

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry

Cite this

Crystal structure, characterization and thermoelectric properties of the type-I clathrate Ba8-ySryAl14Si32 (0.6≤y≤1.3) prepared by aluminum flux. / Roudebush, John H.; Toberer, Eric S.; Hope, Håkon; Jeffrey Snyder, G.; Kauzlarich, Susan M.

In: Journal of Solid State Chemistry, Vol. 184, No. 5, 05.2011, p. 1176-1185.

Research output: Contribution to journalArticle

Roudebush, John H. ; Toberer, Eric S. ; Hope, Håkon ; Jeffrey Snyder, G. ; Kauzlarich, Susan M. / Crystal structure, characterization and thermoelectric properties of the type-I clathrate Ba8-ySryAl14Si32 (0.6≤y≤1.3) prepared by aluminum flux. In: Journal of Solid State Chemistry. 2011 ; Vol. 184, No. 5. pp. 1176-1185.
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