Inelastic neutron scattering study of phonon density of states in nanostructured Si1xGex thermoelectrics

Chetan Dhital, D. L. Abernathy, Gaohua Zhu, Zhifeng Ren, D. Broido, and Stephen D. Wilson
Phys. Rev. B 86, 214303 – Published 17 December 2012

Abstract

Inelastic neutron scattering measurements are utilized to explore relative changes in the generalized phonon density of states of nanocrystalline Si1xGex thermoelectric materials prepared via ball-milling and hot-pressing techniques. Dynamic signatures of Ge clustering can be inferred from the data by referencing the resulting spectra to a density functional theoretical model assuming homogeneous alloying via the virtual-crystal approximation. Comparisons are also presented between as-milled Si nanopowder and bulk, polycrystalline Si where a preferential low-energy enhancement and lifetime broadening of the phonon density of states appear in the nanopowder. Negligible differences are however observed between the phonon spectra of bulk Si and hot-pressed, nanostructured Si samples suggesting that changes to the single-phonon dynamics above 4 meV play only a secondary role in the modified heat conduction of this compound.

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  • Received 9 August 2012

DOI:https://doi.org/10.1103/PhysRevB.86.214303

©2012 American Physical Society

Authors & Affiliations

Chetan Dhital1, D. L. Abernathy2, Gaohua Zhu1, Zhifeng Ren1, D. Broido1, and Stephen D. Wilson1,*

  • 1Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
  • 2Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA

  • *stephen.wilson@bc.edu

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Vol. 86, Iss. 21 — 1 December 2012

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