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Direct and Indirect Effects of Filling on Electronic Structure of Skutterudites

Published online by Cambridge University Press:  31 January 2011

Daehyun Wee
Affiliation:
Daehyun.Wee@us.bosch.com, Robert Bosch LLC, Research and Technology Center, 4009 Miranda Ave, Suite 200, Palo Alto, California, 94304, United States
Boris Kozinsky
Affiliation:
Boris.Kozinsky@us.bosch.com, Robert Bosch LLC, Research and Technology Center, Cambridge, Massachusetts, United States
Fornari Marco
Affiliation:
fornari@phy.cmich.edu, Central Michigan University, Department of Physics, Mt. Pleasant, Michigan, United States
Nicola Marzari
Affiliation:
marzari@mit.edu, Massachusetts Institute of Technlogy, Department of Materials Science and Engineering, Cambridge, Massachusetts, United States
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Abstract

We perform ab-initio computations to investigate the family of CoSb3 skutterudites in an attempt to develop deeper understanding of the effect of fillers. Primary focus is on Ba-filled CoSb3 systems, while Ca and Sr-filled systems are also compared for checking consistency. We analyze both global and local structural effects of filling. We show the specific deformation of Sb network introduced by the filler. Such a deformation is localized around the filler site since soft Sb rings accommodate the distortion. Rearrangement of Sb atoms affects the band structures, and we perform additional analysis to clarify the effect of volume on the band gap. Phonon dispersions are briefly discussed, and filler-dominated vibrations are identified. These modes form the first optical modes at Γ. They manifest themselves in phonon dispersion curves as flat lines, showing that they are localized, while filler vibration is strongly coupled with nearby Sb atoms.

Type
Research Article
Copyright
Copyright © Materials Research Society 2009

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