Dresden 2006 – scientific programme
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DY: Dynamik und Statistische Physik
DY 50: Lattice Dynamics and Non-Linear Excitations
DY 50.3: Talk
Friday, March 31, 2006, 10:45–11:00, H\"UL 186
Soft local phonon modes in thermoelectric materials — •Werner Schweika1 and Raphael Hermann2 — 1Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich — 2Department of Physics, B5, University of Liege, Belgium
We have studied powders of three different thermoelectric materials, Tl-filled skutterudites[1], Ba- and Sr-filled germanium clathrates[2], and Zn4 Sb3 alloys, by inelastic neutron scattering. For all materials, a common feature of a prominent soft local phonon mode with an energy of about 5 meV has been observed consistently with Einstein modes of rattling atoms in these relatively open cage-like structures. While approaches to thermoelectric properties often focus on the electronic structure our results indicate that local phonon modes play a key role in providing an effective scattering mechanism for the heat transporting acoustic phonons.
[1] Phys. Rev. Lett. 90, 135505-1 (2003).
[2] Phys. Rev. B 72, 174301 (2005).