Configuring pnicogen rings in skutterudites for low phonon conductivity

Title
Configuring pnicogen rings in skutterudites for low phonon conductivity
Authors
Hang Chi김형철John C. ThomasXianli SuStephen StackhouseMassoud KavianyAnton Van der VenXinfeng TangCtirad Uher
Keywords
Thermoelectrics; Skutterudites; Thermal conductivity; Lattice dynamics; Phase diagram
Issue Date
2012-11
Publisher
Physical review B, Condensed matter and materials physics
Citation
VOL 86, NO 19, 195209-1-195209-7
Abstract
Dominant heat-carrying modes in skutterudites are associated with vibrations of the pnicogen rings. Apart from filling the structural cages with foreign species, disrupting the pnicogen ring structure by substitutional alloying should be an effective approach to reduce thermal conductivity. In this paper we explore alloying configurations of pnicogen rings (Sb rings in the case of CoSb3) that yield particularly low values of the thermal conductivity. We find that IV-VI double substitution (replacing two Sb atoms with one atom each from the column IV and column VI elements to achieve an average charge of two Sb atoms) is a very effective approach. Our ab initio calculations, in combination with a cluster expansion, have allowed us to identify stable alloy configurations on the Sb rings. Subsequent molecular and lattice dynamics simulations on low energy configurations establish the range of atomic displacement parameters and values of the thermal conductivity. Theoretical results are in good agreement with our experimental thermal conductivity values. Combining both approaches of compensated double substitution and filling of structural cages should be an effective way of improving the thermoelectric figure of merit of skutterudites.
URI
http://pubs.kist.re.kr/handle/201004/44324
ISSN
10980121
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KIST Publication > Article
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