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Effect of nanocrystallinity on lattice dynamics in Bi2Te3 based thermoelectrics

 
: Klobes, B.; Bessas, D.; Juranyi, F.; Görlitz, H.; Pacheco, V.; Hermann, R.P.

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Physica status solidi. Rapid research letters 9 (2015), Nr.1, S.57-61
ISSN: 1862-6254
ISSN: 1862-6270
Deutsche Forschungsgemeinschaft DFG
SPP 1386;
Englisch
Zeitschriftenaufsatz
Fraunhofer IFAM, Institutsteil Pulvermetallurgie und Verbundwerkstoffe Dresden ()

Abstract
The lattice dynamics in as-cast and nanocrystalline thermoelectric Bi2Te3 based p-type and n-type material were investigated using inelastic neutron scattering. Generalized densities of phonon states show substantial agreement between the lattice dynamics in as-cast samples and previous studies. The lattice dynamics in the nanocrystalline materials differ significantly from its as-cast counterparts in the acoustic phonon regime. In nanocrystalline p-type and n-type compounds, the average acoustic phonon group velocity was found to be reduced to 80(5)% and 95(2)% of the value in as-cast material. It is argued that point-defect and strain contrast scattering may play an important role for the understanding of lattice thermal conductivity in (nanocrystalline) Bi2Te3 based thermoelectrics beside the observed decrease of sound velocity.

: http://publica.fraunhofer.de/dokumente/N-332072.html