About this Abstract |
Meeting |
2021 TMS Annual Meeting & Exhibition
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Symposium
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Functional Nanomaterials: Functional Low-dimensional Materials (0D, 1D, 2D) Driving Innovations in Electronics, Energy, Sensors, and Environmental Engineering and Science 2021
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Presentation Title |
Giant Low-temperature Anharmonicity in Silicon Nanocrystals |
Author(s) |
Shuonan Chen, Devin Coleman, Douglas L. Abernathy, Arnab Banerjee, Luke L. Daemen, Lorenzo Mangolini, Chen W. Li |
On-Site Speaker (Planned) |
Shuonan Chen |
Abstract Scope |
The phonon density of states of silicon nanocrystals with size between 4 and 7.5 nm was measured by inelastic neutron scattering in the 5~600 K temperature range. The narrow particle size distributions enable the study of size effects on phonon dynamics. Giant softening of phonon features below 30 meV, universal broadening of phonon features, and the disappearance of intermediate-energy phonons were observed with decreasing nanocrystals size. Such size effects are mostly attributed to the structure variations within the nanocrystals. The phonons below 30 meV in silicon nanocrystals show temperature dependence opposite to the bulk silicon, explained by the large anharmonicity of the under-constrained near-surface phonons. This is supported by the abnormal atomic mean-square-displacement, and low energy phonon population in small silicon nanocrystals. This work provides crucial information on the phonon dynamics in spatially confined materials. |
Proceedings Inclusion? |
Planned: |