Phonon scattering effects from point and extended defects on thermal conductivity studied via ion irradiation of crystals with self-impurities
- Univ. of Virginia, Charlottesville, VA (United States). Dept. of Mechanical and Aerospace Engineering
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of Virginia, Charlottesville, VA (United States). Dept. of Material Science and Engineering
- Univ. of California, Los Angeles, CA (United States). Materials Science and Engineering
- Univ. of Virginia, Charlottesville, VA (United States). Dept. of Mechanical and Aerospace Engineering. Dept. of Material Science and Engineering. Dept. of Physics
Fundamental theories predict that reductions in thermal conductivity from point and extended defects can arise due to phonon scattering with localized strain fields. In this paper, to experimentally determine how these strain fields impact phonon scattering mechanisms, we employ ion irradiation as a controlled means of introducing strain and assorted defects into the lattice. In particular, we observe the reduction in thermal conductivity of intrinsic natural silicon after self-irradiation with two different silicon isotopes, $$^{28}\mathrm{Si}^{+}$$ and $$^{29}\mathrm{Si}^{+}$$. Irradiating with an isotope with a nearly identical atomic mass as the majority of the host lattice produces a damage profile lacking mass impurities and allows us to assess the role of phonon scattering with local strain fields on the thermal conductivity. Our results demonstrate that point defects will decrease the thermal conductivity more so than spatially extended defect structures assuming the same volumetric defect concentrations due to the larger strain per defect that arises in spatially separated point defects. Finally, with thermal conductivity models using density functional theory, we show that for a given defect concentration, the type of defect (i.e., point vs extended) plays a negligible role in reducing the thermal conductivity compared to the strain per defect in a given volume.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Virginia, Charlottesville, VA (United States); Univ. of California, Los Angeles, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC); Air Force Office of Scientific Research (AFOSR) (United States); Nuclear Regulatory Commission (NRC) (United States); Office of Naval Research (ONR) (United States)
- Grant/Contract Number:
- NA0003525
- OSTI ID:
- 1472264
- Alternate ID(s):
- OSTI ID: 1667394
OSTI ID: 1471156
- Report Number(s):
- SAND--2018-9495J; 667447
- Journal Information:
- Physical Review Materials, Journal Name: Physical Review Materials Journal Issue: 9 Vol. 2; ISSN 2475-9953
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Spatially resolved thermoreflectance techniques for thermal conductivity measurements from the nanoscale to the mesoscale
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journal | October 2019 |
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