At present,there have been few direct molecular dynamics simulations on the thermal conductivity of polycrystalline nanofilms.In this paper,we generate polycrystalline argon nanofilms with random grain shape using the...At present,there have been few direct molecular dynamics simulations on the thermal conductivity of polycrystalline nanofilms.In this paper,we generate polycrystalline argon nanofilms with random grain shape using the three-dimensional Voronoi tessellation method.We calculate the out-of-plane thermal conductivity of a polycrystalline argon nanofilm at different temperatures and film thicknesses by the Muller-Plathe method.The results indicate that the polycrystalline thermal conductivity is lower than that of the bulk single crystal and the single-crystal nanofilm of argon.This can be attributed to the phonon mean-free-path limit imposed by the average grain size as well as the grain boundary thermal resistance due to the existence many grain boundaries in polycrystalline materials.Also,the out-of-plane thermal conductivity of the polycrystalline argon nanofilm is insensitive to temperature and film thickness,and is mainly dominated by the grain size,which is quite different from the case of single-crystal nanofilms.展开更多
基金supported by the National Natural Science Foundation of China (50776053 and 50730006)
文摘At present,there have been few direct molecular dynamics simulations on the thermal conductivity of polycrystalline nanofilms.In this paper,we generate polycrystalline argon nanofilms with random grain shape using the three-dimensional Voronoi tessellation method.We calculate the out-of-plane thermal conductivity of a polycrystalline argon nanofilm at different temperatures and film thicknesses by the Muller-Plathe method.The results indicate that the polycrystalline thermal conductivity is lower than that of the bulk single crystal and the single-crystal nanofilm of argon.This can be attributed to the phonon mean-free-path limit imposed by the average grain size as well as the grain boundary thermal resistance due to the existence many grain boundaries in polycrystalline materials.Also,the out-of-plane thermal conductivity of the polycrystalline argon nanofilm is insensitive to temperature and film thickness,and is mainly dominated by the grain size,which is quite different from the case of single-crystal nanofilms.
