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Title: Nanocrystalline silicon: Lattice dynamics and enhanced thermoelectric properties

In this study, silicon has several advantages when compared to other thermoelectric materials, but until recently it was not used for thermoelectric applications due to its high thermal conductivity, 156 W K-1 m-1 at room temperature. Nanostructuration as means to decrease thermal transport through enhanced phonon scattering has been a subject of many studies. In this work we have evaluated the effects of nanostructuration on the lattice dynamics of bulk nanocrystalline doped silicon. The samples were prepared by gas phase synthesis, followed by current and pressure assisted sintering. The heat capacity, density of phonons states, and elastic constants were measured, which all reveal a significant, ≈25%, reduction in the speed of sound. The samples present a significantly decreased lattice thermal conductivity, ≈25 W K-1 m-1, which, combined with a very high carrier mobility, results in a dimensionless figure of merit with a competitive value that peaks at ZT ≈ 0.57 at 973 °C. Due to its easily scalable and extremely low-cost production process, nanocrystalline Si prepared by gas phase synthesis followed by sintering could become the material of choice for high temperature thermoelectric generators.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Julich Centre for Neutron Science JCNS and Peter Grunberg Institut PGI, Julich (Germany); Univ. de Liege, Liege (Belgium)
  2. Univ. of Duisburg-Essen, Duisburg (Germany)
  3. Peter Grunberg Institut PGI-5, Julich (Germany)
  4. Julich Centre for Neutron Science JCNS and Peter Grunberg Institut PGI, Julich (Germany)
  5. Institut Laue Langevin, Grenoble (France)
  6. Technische Univ. Munchen, Garching (Germany)
Publication Date:
OSTI Identifier:
1164945
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 16; Journal Issue: 47; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
ENGLISH
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY NESDPS Office of Nuclear Energy Space and Defense Power Systems