MEASURING AND UNDERSTANDING ANISOTROPIC HEAT CONDUCTION IN LAYERED MATERIALS AND NANOSTRUCTURES

Abstract

This dissertation presents experimental and theoretical studies of anisotropic heat conduction in distinctive nanostructures with an emphasis on advancing understanding of the correlation between anisotropic thermal conductivity and specific microscopic mechanisms. I studied the anisotropic heat transport mechanisms in three materials or nanostructures, i.e., layered materials, GaN with oriented dislocations and ligand layers in GNRs. The main contributions of this thesis contain three parts. First, I proposed two empirical formulas to predict the thermal conductivity anisotropy. Importantly, I have identified that the main contributor to intrinsically anisotropic heat transport in layered materials is heat capacity. Second, I have demonstrated that previous studies overestimated the phonon-dislocation resistance. Finally, my analysis suggests new possible energy flow routes across Au-ligand junctions in GNRs. This work provides significant insights into the anisotropic heat transport in layered materials, semiconductors with dislocations and functionalized GNRs. It will greatly benefit the design of electronics in various applications.