Bimodal grain-size scaling of thermal transport in polycrystalline graphene from large-scale molecular dynamics simulations
journal contributionposted on 08.11.2017, 10:41 authored by Zheyong Fan, Petri Hirvonen, Luiz F. Pereira, Mikko M. Ervasti, Ken R. Elder, Davide Donadio, Ari Harju, Tapio Ala-NissilaTapio Ala-Nissila
© 2017 American Chemical Society. Grain boundaries in graphene are inherent in wafer-scale samples prepared by chemical vapor deposition. They can strongly influence the mechanical properties and electronic and heat transport in graphene. In this work, we employ extensive molecular dynamics simulations to study thermal transport in large suspended polycrystalline graphene samples. Samples of different controlled grain sizes are prepared by a recently developed efficient multiscale approach based on the phase field crystal model. In contrast to previous works, our results show that the scaling of the thermal conductivity with the grain size implies bimodal behavior with two effective Kapitza lengths. The scaling is dominated by the out-of-plane (flexural) phonons with a Kapitza length that is an order of magnitude larger than that of the in-plane phonons. We also show that, to get quantitative agreement with the most recent experiments, quantum corrections need to be applied to both the Kapitza conductance of grain boundaries and the thermal conductivity of pristine graphene, and the corresponding Kapitza lengths must be renormalized accordingly.
This research has been supported by the Academy of Finland through its Centres of Excel- lence Program (Project No. 251748). Z.F. acknowledges the support of the National Natural Science Foundation of China (Grant No. 11404033). P.H. acknowledges financial support from the Foundation for Aalto University Science and Technology, and from the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters. L.F.C.P. acknowledges financial support from the Brazilian govern- ment agency CAPES for project “Physical properties of nanostructured materials” (Grant No. 3195/2014) via its Science Without Borders program. K.R.E. acknowledges financial support from the National Science Foundation under Grant No. DMR-1506634.
- Mathematical Sciences