Predicting Phonon Properties and Thermal Conductivity of Rigid Molecular Crystals Using Rotational Lattice Dynamics

2021 ◽  
Author(s):  
Hyun-Young Kim ◽  
Alan Mcgaughey
Keyword(s):  
Thermal Conductivity ◽  
Lattice Dynamics ◽  
Molecular Crystals ◽  
Phonon Properties

Phonon Transport in Thin Films: A Lattice Dynamics/Boltzmann Transport Equation Study

2010 ◽  
Author(s):  
Daniel P. Sellan ◽  
Joseph E. Turney ◽  
Eric S. Landry ◽  
Alan J. H. McGaughey ◽  
Cristina H. Amon
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Lattice Dynamics ◽  
Boltzmann Transport Equation ◽  
Boltzmann Transport ◽  
Phonon Modes ◽  
Bulk Phonon ◽  
Plane Direction ◽  
The Cross ◽  
Phonon Properties

The cross-plane and in-plane phonon thermal conductivities of Stillinger-Weber (SW) silicon thin films are predicted using the Boltzmann transport equation under the relaxation time approximation. We model the thin films using bulk phonon properties obtained from harmonic and anharmonic lattice dynamics calculations. The cross-plane and in-plane thermal conductivities are reduced from the corresponding bulk value. This reduction is more severe for the cross-plane direction than for the in-plane direction. For the in-plane direction, we find that the predicted reduction in thermal conductivity gives a good lower bound to available experimental results. Including the effects of boundary scattering using the Matthiessen rule, which assumes that scattering mechanisms are independent, yields thermal conductivity predictions that are at most 12% lower than our more accurate results. Neglecting optical phonon modes, while valid for bulk systems, introduces 22.5% error when modeling thin films. Using phonon properties along the [001] direction (i.e., the isotropic approximation) yields bulk predictions that are 15% lower than that when all of the phonon modes are considered. For thin films, this deviation increases to 25%. Our results show that a single bulk phonon mean free path is an inadequate metric for predicting the thermal conductivity reduction in thin films.

THEORY OF THERMAL CONDUCTIVITY IN MOLECULAR CRYSTALS, APPLICATION TO ALCALI CYANIDES

1981 ◽  
Vol 42 (C6) ◽  
pp. C6-247-C6-249 ◽  
Author(s):  
W. Bauernfeind ◽  
J. Keller ◽  
U. Schröder
Keyword(s):  
Thermal Conductivity ◽  
Molecular Crystals

Improvement of the Thermal Conductivity in 4H-SiC Epitaxial Layer by Introducing Gettering Sites

2008 ◽  
Vol 600-603 ◽  
pp. 525-528
Author(s):  
Laurent Ottaviani ◽  
Michel Kazan ◽  
Pierre M. Masri ◽  
Thierry Sauvage
Keyword(s):  
Thermal Conductivity ◽  
Epitaxial Layer ◽  
Active Area ◽  
Specific Process ◽  
Metal Impurities ◽  
Silicon Based ◽  
Phonon Properties

Metal impurities are known to degrade dramatically the performances of silicon-based devices, even at concentrations as low as 1012 cm-3. A specific process, named proximity gettering, has been optimised by some authors in order to reduce the influence of these impurities [1]. This process consists in the building of a favourable impurity trapping zone in a non-active area of the device, by introducing implantation defects. This paper reports on the application of introducing such gettering sites as an approach to control phonon properties in 4H-SiC epilayer, and increase the thermal conductivity.

Lattice dynamics of molecular crystals using atom—atom and multipole—multipole potentials

1978 ◽  
Vol 29 (1-2) ◽  
pp. 167-179 ◽  
Author(s):  
N. Neto ◽  
R. Righini ◽  
S. Califano ◽  
S.H. Walmsley
Keyword(s):  
Lattice Dynamics ◽  
Molecular Crystals

Effect of bromine deficiency on the lattice dynamics and dielectric properties of alpha-phase diisopropylammonium bromide molecular crystals

2018 ◽  
Vol 113 ◽  
pp. 82-85 ◽  
Author(s):  
Ahmad Alsaad ◽  
Chris M. Marin ◽  
Nabil Alaqtash ◽  
Hsien-Wen Chao ◽  
Tsun-Hsu Chang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Lattice Dynamics ◽  
Molecular Crystals ◽  
Alpha Phase

scholarly journals Anomalous behavior of thermal conductivity at high temperatures for molecular crystals composed of flexible molecules

2019 ◽  
Vol 127 ◽  
pp. 151-157 ◽  
Author(s):  
Yuliia V. Horbatеnko ◽  
Olesia O. Romantsova ◽  
Oksana A. Korolyuk ◽  
Andrzej Jeżowski ◽  
Daria Szewczyk ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperatures ◽  
Molecular Crystals ◽  
Anomalous Behavior ◽  
Flexible Molecules
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