Journal
MATERIALS TODAY PHYSICS
Volume 21, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.mtphys.2021.100566
Keywords
Silicon allotrope; Lattice thermal conductivity; Inelastic neutron scattering measurements; First-principles calculations
Funding
- National Science Foundation of China [1217021241]
- Beijing Natural Science Foundation, China [Z190011]
- National Science Foundation [1750786]
- NSF-DMR [1809756]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [1809756] Funding Source: National Science Foundation
- Directorate For Engineering
- Div Of Chem, Bioeng, Env, & Transp Sys [1750786] Funding Source: National Science Foundation
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The study shows that flat phonon bands in BC8-Si play a critical role in reducing lattice thermal conductivity by enlarging the phonon-phonon scattering phase space. This provides insights into the significant reduction of lattice thermal conductivity in this novel silicon allotrope.
The BC8 silicon allotrope has a lattice thermal conductivity 1-2 orders of magnitude lower than that of diamond-cubic silicon. In the current work, the phonon density of states, phonon dispersion, and lattice thermal conductivity are investigated by inelastic neutron scattering measurements and first-principles calculations. Flat phonon bands are found to play a critical role in the reduction of lattice thermal conductivity in BC8-Si. Such bands in the low-energy range enhance the phonon scattering between acoustic and low-energy optical phonons, while bands in the intermediate-energy range act as a scattering bridge between the high- and low-energy optical phonons. They significantly enlarge the phonon-phonon scattering phase space and reduces the lattice thermal conductivity in this novel silicon allotrope. This work provides insights into the significant reduction of the lattice thermal conductivity in BC8 -Si, thus expanding the understanding of novel silicon allotropes and their development for electronic devices. (C) 2021 Elsevier Ltd. All rights reserved.
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