Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Nat Mater. 2008 Oct;7(10):811-5. doi: 10.1038/nmat2273. Epub 2008 Aug 31.

Avoided crossing of rattler modes in thermoelectric materials.

Author information

  • 1Center for Energy Materials, Department of Chemistry and Interdisciplinary Nanoscience Center iNANO, University of Aarhus, DK-8000 Aarhus C, Denmark. moc@ansto.gov.au

Abstract

Engineering of materials with specific physical properties has recently focused on the effect of nano-sized 'guest domains' in a 'host matrix' that enable tuning of electrical, mechanical, photo-optical or thermal properties. A low thermal conductivity is a prerequisite for obtaining effective thermoelectric materials, and the challenge is to limit the conduction of heat by phonons, without simultaneously reducing the charge transport. This is named the 'phonon glass-electron crystal' concept and may be realized in host-guest systems. The guest entities are believed to have independent oscillations, so-called rattler modes, which scatter the acoustic phonons and reduce the thermal conductivity. We have investigated the phonon dispersion relation in the phonon glass-electron crystal material Ba(8)Ga(16)Ge(30) using neutron triple-axis spectroscopy. The results disclose unambiguously the theoretically predicted avoided crossing of the rattler modes and the acoustic-phonon branches. The observed phonon lifetimes are longer than expected, and a new explanation for the low kappa(L) is provided.

Comment in

PMID:
18758454
[PubMed]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Nature Publishing Group
    Loading ...
    Write to the Help Desk