Nanocrystalline silicon: Lattice dynamics and enhanced thermoelectric properties
- Julich Centre for Neutron Science JCNS and Peter Grunberg Institut PGI, Julich (Germany); Univ. de Liege, Liege (Belgium)
- Univ. of Duisburg-Essen, Duisburg (Germany)
- Peter Grunberg Institut PGI-5, Julich (Germany)
- Julich Centre for Neutron Science JCNS and Peter Grunberg Institut PGI, Julich (Germany)
- Institut Laue Langevin, Grenoble (France)
- Technische Univ. Munchen, Garching (Germany)
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.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1164945
- Journal Information:
- Physical Chemistry Chemical Physics. PCCP, Vol. 16, Issue 47; ISSN 1463-9076
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
Web of Science
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