title: Band Structure Engineering and Thermoelectric Properties of Charge-Compensated Filled Skutterudites.
abstract: 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.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Xiaoya
authors.initials: X
authors.lastname: Shi
authors.affiliation: Materials Science &Engineering Department, University of Washington, Seattle, WA 98195, USA.
authors.forename: Jiong
authors.initials: J
authors.lastname: Yang
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
authors.affiliation: Chemical and Materials Systems Lab, General Motors R&D Center, Warren, MI 48090, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Salvador
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Fuel Systems Engineering, General Motor Global Design, Engineering and Product Programs, Warren, MI 48090-9020.
authors.forename: William L
authors.initials: WL
authors.lastname: Villaire
authors.affiliation: Chemical and Materials Systems Lab, General Motors R&D Center, Warren, MI 48090, USA.
authors.forename: Daad
authors.initials: D
authors.lastname: Haddad
authors.affiliation: Materials Science &Engineering Department, University of Washington, Seattle, WA 98195, USA.
authors.forename: Jihui
authors.initials: J
authors.lastname: Yang
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Yimei
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li