Theory and molecular simulation of lattice vibrational heat transport in carbon nanotubes
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Bruns, Daniel K.W.
issued: 2022-07-12T20:33:52Z
issued: 2022
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Heat conduction phenomena of carbon nanotubes (CNTs) have attracted great interest both from the viewpoint of engineering applications and fundamental science, but the thermal conductivity of individual single-walled CNTs remains a rather controversial topic. Starting from an empirical, realistic atomic interaction potential, we study the lattice thermal conductivity (LTC) of single-walled CNTs by employing two approaches: quantum mechanical calculations of three-phonon scattering rates in the framework of the Peierls-Boltzmann transport theory (PBTT) and classical molecular dynamics (MD) simulations. First, we compare the system-size and temperature dependence of the LTC determined from an iterative solution of the linearized phonon transport equation in the framework of the PBTT and from a nonequilibrium MD (NEMD) approach. At room temperature, qualitatively similar trends for the tube-length dependence are found in the limit of short tubes, where an extensive regime of ballistic heat transport prevailing in CNTs of lengths L ≲ 1 µm is independently confirmed. In the limit of long tubes, the PBTT-derived LTC diverges. Using PBTT and equilibrium MD approaches, we perform numerical calculations of acoustic phonon lifetimes to clarify the source of divergence. NEMD-derived temperature dependencies obtained for micrometer-long CNTs and temperatures T ≤ 800 K confirm the 1/T behavior of the LTC at moderately high temperatures. Next, we revisit the tube-length dependence of the LTC by use of the relaxation time approximation in the PBTT. Through a combination of numerics and analytical considerations, we derive exact asymptotic scaling laws of the LTC. In particular, we demonstrate the importance of tensile lattice strain, previously overlooked in the long-standing dispute over tube-length convergence vs divergence of the LTC. Namely, it is proved that, in the long-tube limit, the relaxation time approximation yields a finite value for stress-free but an infinite value …
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/82115
note: Theory and molecular simulation of lattice vibrational heattransport in carbon nanotubesbyDaniel K.W. BrunsB.Sc., University of Rostock, 2014M.Sc., University of Rostock, 2016a thesis submitted in partial fulfillmentof the requirements for the degree ofDoctor of Philosophyinthe faculty of graduate and postdoctoral studies(Physics)The University of British Columbia(Vancouver)July 2022© Daniel K.W. Bruns, 2022The following individuals certify that they have read, and recommend to the Faculty ofGraduate and Postdoctoral Studies for acceptance, the thesis entitled:Theory and molecular simulation of lattice vibrational heat transport incarbon nanotubessubmitted by Daniel K.W. Bruns in partial fulfillment of the requirements for the degreeof Doctor of Philosophy in Physics.Examining Committee:Jo¨rg Rottler, Professor, Department of Physics & Astronomy, UBCCo-supervisorAlireza Nojeh, Professor, Department of Electrical & Computer Engineering, UBCCo-supervisorGeorge Sawatzky, Professor Emeritus, Department of Physics & Astronomy, UBCSupervisory Committee MemberMona Berciu, Professor, Department of Physics & Astronomy, UBCUniversity ExaminerChristoph Ortner, Professor, Department of Mathematics, UBCUniversity ExaminerPhilip B. Allen, Professor Emeritus, Department of Physics and Astronomy, Stony BrookUniversityExternal ExaminerAdditional Supervisory Committee Members:A. Srikantha Phani, Professor, Department of Mechanical Engineering, UBCSupervisory Committee MemberiiAbstractHeat conduction phenomena of carbon nanotubes (CNTs) have attracted great interest bothfrom the viewpoint of engineering applications and fundamental science, but the thermalconductivity of individual single-walled CNTs remains a rather controversial topic. Startingfrom an empirical, realistic atomic interaction potential, we study the lattice thermal con-ductivity (LTC) of single-walled CNTs by employing two approaches: quantum mechanicalcalculations of three-phonon scattering rates in the framework of …
has type: Thesis/Dissertation
date issued: 2022-11
is shown at: 10.14288/1.0416244
language: eng
degree discipline: Physics
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
contributor: Rottler, Joerg
contributor: Nojeh, Alireza
type: Text
identifier URI: http://hdl.handle.net/2429/82115