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Title: Band structure engineering and thermoelectric properties of charge-compensated filled skutterudites

Thermoelectric properties of semiconductors are intimately related to their electronic band structure, which can be engineered via chemical doping. Dopant Ga in the cage-structured skutterudite Co4Sb12 substitutes Sb sites while occupying the void sites. Combining quantitative scanning transmission electron microscopy and first-principles calculations, we show that Ga dual-site occupancy breaks the symmetry of the Sb-Sb network, splits the deep triply-degenerate conduction bands, and drives them downward to the band edge. The charge-compensating nature of the dual occupancy Ga increases overall filling fraction limit. By imparting this unique band structure feature, and judiciously doping the materials by increasing the Yb content, we promote the Fermi level to a point where carriers are in energetic proximity to these features. Increased participation of these heavier bands in electronic transport leads to increased thermopower and effective mass. Further, the localized distortion from Ga/Sb substitution enhances the phonon scattering to reduce the thermal conductivity effectively.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4] ;  [3] ;  [2] ;  [1] ;  [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Univ. of Washington, Seattle, WA (United States)
  3. General Motors R&D Center, Warren, MI (United States)
  4. General Motor Global Design, Engineering and Product Programs, Warren, MI (United States)
Publication Date:
OSTI Identifier:
1235857
Report Number(s):
BNL--111606-2015-JA
Journal ID: ISSN 2045-2322; R&D Project: MA015MACA; KC0201010
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal Issue: 48; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY electronic properties and materials; thermoelectrics