Multiscale modeling of thermal conductivity of polycrystalline graphene sheets

Abstract

We developed a multiscale approach to explore the effective thermal conductivity of polycrystalline graphene sheets. By performing equilibrium molecular dynamics (EMD) simulations, the grain size effect on the thermal conductivity of ultra-fine grained polycrystalline graphene sheets is investigated. Our results reveal that the ultra-fine grained graphene structures have thermal conductivity one order of magnitude smaller than that of pristine graphene. Based on the information provided by the EMD simulations, we constructed finite element models of polycrystalline graphene sheets to probe the thermal conductivity of samples with larger grain sizes. Using the developed multiscale approach, we also investigated the effects of grain size distribution and thermal conductivity of grains on the effective thermal conductivity of polycrystalline graphene. The proposed multiscale approach on the basis of molecular dynamics and finite element methods could be used to evaluate the effective thermal conductivity of polycrystalline graphene and other 2D structures.

Anisotropic thermal conductivity and mechanical properties of phagraphene: a molecular dynamics study

“…All simulations employed periodic boundary conditions along both in-plane directions and free boundary conditions in the perpendicular directions, such that our simulations would correspond to suspended phagraphene samples. It is important to notice that the presence of 5-and 7-membered rings in the structure of phagraphene is similar to some topological defects found in graphene and may result in technical difficulties such as instabilities during simulations at finite temperature 19,21 . To avoid this problem, in all molecular dynamics simulations the equations of motion were integrated with a relatively small time increment of 0.25 fs.…”

“…Interaction between carbon atoms are modeled by the Tersoff empirical potential with parameters optimized for graphene and carbon nanotubes 15,16 . This optimized Tersoff potential had been shown to appropriately reproduce phonon dispersions of graphene, and has been employed in several studies involving thermal transport 12,[17][18][19][20][21][22][23] and mechanical properties [23][24][25] of graphene and graphene-like materials. In order to verify the accuracy of the optimized Tersoff potential in describing the atomic bonding structure of phagraphene we calculated its phonon dispersions via the lattice dynamics software GULP 26,27 .…”

“…A similar decrease in thermal conductivity relative to graphene has also been predicted for penta-graphene via molecular dynamics simulations 33 and lattice dynamics 34 . The thermal conductivity of ultra-fine grained graphene was also predicted to be one order of magnitude smaller than pristine single-crystal graphene because of increased phonon scattering along grain boundaries 19 . Figure 3 Inverse thermal conductivity versus inverse length.…”

Scaling properties of polycrystalline graphene: a review

“…Their multigrain structure, with dimensions down to the microand nanoscale, is likely an important pre-existing cause for the wide range of κ values reported above. However, the systematic investigation of the effect of size, shape, and distribution of grains on thermal transport properties is still ongoing [9,[67][68][69][139][140][141].…”

First‐Principle‐Based Phonon Transport Properties of Nanoscale Graphene Grain Boundaries

“…among misoriented, but crystallographically perfect, graphene lattices. Moreover, it has been widely proved that the transport properties can be reduced one to two orders of magnitude below those of graphene films 2, 3, 10, 11, 12, 13. Hence, the presence of grain boundaries can have a dramatic impact on the performance of various graphene‐based nanodevices.…”