Wei, B.; Sun, Q.; Li, C.; Hong, J.
Phonon anharmonicity: a pertinent review of recent progress and perspective Journal Article
In: SCIENCE CHINA Physics, Mechanics & Astronomy, vol. 64, no. 117001, 2021.
Links | BibTeX | Tags: anharmonicity, lifetime, metal-insulator transition, neutron scattering, thermal transport, vibrational entropy
@article{Hong2021,
title = {Phonon anharmonicity: a pertinent review of recent progress and perspective},
author = {B. Wei and Q. Sun and C. Li and J. Hong},
url = {https://link.springer.com/article/10.1007/s11433-021-1748-7},
doi = {10.1007/s11433-021-1748-7},
year = {2021},
date = {2021-09-28},
urldate = {2021-07-01},
journal = {SCIENCE CHINA Physics, Mechanics \& Astronomy},
volume = {64},
number = {117001},
keywords = {anharmonicity, lifetime, metal-insulator transition, neutron scattering, thermal transport, vibrational entropy},
pubstate = {published},
tppubtype = {article}
}
Kim, D. S.; Hellman, O.; Shulumba, N.; Saunders, C. N.; Lin, J. Y. Y.; Smith, H. L.; Herriman, J. E.; Niedziela, J. L.; Abernathy, D. L.; Li, C. W.; Fultz, B.
Temperature-dependent phonon lifetimes and thermal conductivity of silicon by inelastic neutron scattering and ab initio calculations Journal Article
In: Phys. Rev. B, vol. 102, pp. 174311, 2020.
Abstract | Links | BibTeX | Tags: lattice, lifetime, phonon
@article{Fultz2020,
title = {Temperature-dependent phonon lifetimes and thermal conductivity of silicon by inelastic neutron scattering and ab initio calculations},
author = {D. S. Kim and O. Hellman and N. Shulumba and C. N. Saunders and J. Y. Y. Lin and H. L. Smith and J. E. Herriman and J. L. Niedziela and D. L. Abernathy and C. W. Li and B. Fultz},
url = {https://doi.org/10.1103/PhysRevB.102.174311},
doi = {10.1103/PhysRevB.102.174311},
year = {2020},
date = {2020-11-16},
journal = {Phys. Rev. B},
volume = {102},
pages = {174311},
abstract = {Inelastic neutron scattering on a single crystal of silicon was performed at temperatures from 100 to 1500 K. These experimental data were reduced to obtain phonon spectral intensity at all wave vectors Q and frequencies ω in the first Brillouin zone. Thermal broadenings of the phonon peaks were obtained by fitting and by calculating with an iterative ab initio method that uses thermal atom displacements on an ensemble of superlattices. Agreement between the calculated and experimental broadenings was good, with possible discrepancies at the highest temperatures. Distributions of phonon widths versus phonon energy had similar shapes for computation and experiment. These distributions grew with temperature but maintained similar shapes. Parameters from the ab initio calculations were used to obtain the thermal conductivity from the Boltzmann transport equation, which was in good agreement with experimental data. Despite the high group velocities of longitudinal acoustic phonons, their shorter lifetimes reduced their contribution to the thermal conductivity, which was dominated by transverse acoustic modes.},
keywords = {lattice, lifetime, phonon},
pubstate = {published},
tppubtype = {article}
}
Inelastic neutron scattering on a single crystal of silicon was performed at temperatures from 100 to 1500 K. These experimental data were reduced to obtain phonon spectral intensity at all wave vectors Q and frequencies ω in the first Brillouin zone. Thermal broadenings of the phonon peaks were obtained by fitting and by calculating with an iterative ab initio method that uses thermal atom displacements on an ensemble of superlattices. Agreement between the calculated and experimental broadenings was good, with possible discrepancies at the highest temperatures. Distributions of phonon widths versus phonon energy had similar shapes for computation and experiment. These distributions grew with temperature but maintained similar shapes. Parameters from the ab initio calculations were used to obtain the thermal conductivity from the Boltzmann transport equation, which was in good agreement with experimental data. Despite the high group velocities of longitudinal acoustic phonons, their shorter lifetimes reduced their contribution to the thermal conductivity, which was dominated by transverse acoustic modes.
Chen, Shuonan; Coleman, Devin; Abernathy, Douglas L.; Banerjee, Arnab; Daemen, Luke L.; Mangolini, Lorenzo; Li, Chen W.
Giant low-temperature anharmonicity in silicon nanocrystals Journal Article
In: Phys. Rev. Materials, vol. 4, pp. 056001, 2020.
Abstract | Links | BibTeX | Tags: anharmonicity, high temperature, lifetime, neutron
@article{Li2020,
title = {Giant low-temperature anharmonicity in silicon nanocrystals},
author = {Shuonan Chen and Devin Coleman and Douglas L. Abernathy and Arnab Banerjee and Luke L. Daemen and Lorenzo Mangolini and Chen W. Li},
url = {https://journals.aps.org/prmaterials/pdf/10.1103/PhysRevMaterials.4.056001},
doi = {10.1103/PhysRevMaterials.4.056001},
year = {2020},
date = {2020-05-04},
journal = {Phys. Rev. Materials},
volume = {4},
pages = {056001},
abstract = {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.},
keywords = {anharmonicity, high temperature, lifetime, neutron},
pubstate = {published},
tppubtype = {article}
}
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.
Tang, X; Li, Chen W; Fultz, B
Anharmonicity-induced phonon broadening in aluminum at high temperatures Journal Article
In: Physical Review B, vol. 82, no. 18, pp. 184301, 2010.
Abstract | Links | BibTeX | Tags: Al, anharmonicity, high temperature, lifetime, phonon
@article{tang_anharmonicity-induced_2010,
title = {Anharmonicity-induced phonon broadening in aluminum at high temperatures},
author = {X Tang and Chen W Li and B Fultz},
url = {https://link.aps.org/doi/10.1103/PhysRevB.82.184301},
doi = {10.1103/PhysRevB.82.184301},
year = {2010},
date = {2010-11-01},
journal = {Physical Review B},
volume = {82},
number = {18},
pages = {184301},
abstract = {Thermal phonon broadening in aluminum was studied by theoretical and experimental methods. Using second-order perturbation theory, phonon linewidths from the third-order anharmonicity were calculated from first-principles density-functional theory (DFT) with the supercell finite-displacement method. The importance of all three-phonon processes were assessed and individual phonon broadenings are presented. The good agreement between calculations and prior measurements of phonon linewidths at 300 K and new measurements of the phonon density of states to 750 K indicates that the third-order phonon-phonon interactions calculated from DFT can account for the lifetime broadenings of phonons in aluminum to at least 80% of its melting temperature.},
keywords = {Al, anharmonicity, high temperature, lifetime, phonon},
pubstate = {published},
tppubtype = {article}
}
Thermal phonon broadening in aluminum was studied by theoretical and experimental methods. Using second-order perturbation theory, phonon linewidths from the third-order anharmonicity were calculated from first-principles density-functional theory (DFT) with the supercell finite-displacement method. The importance of all three-phonon processes were assessed and individual phonon broadenings are presented. The good agreement between calculations and prior measurements of phonon linewidths at 300 K and new measurements of the phonon density of states to 750 K indicates that the third-order phonon-phonon interactions calculated from DFT can account for the lifetime broadenings of phonons in aluminum to at least 80% of its melting temperature.