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Mechanical and thermal properties of grain boundary in planar heterostructure of graphene and hexagonal boron nitride

Abstract

In this paper, the mechanical properties of grain boundaries (GBs) in planar heterostructures of graphene and hexagonal Boron Nitride (h-BN) are studied with molecular dynamics method in combination with density functional theory and classical disclination theory. The hybrid interface between graphene and h-BN grains is optimally matched by non-bisector GB composed of pentagon-heptagon defects arranged in a periodic manner. GB is found a vulnerable spot where failure initiates under uniaxial tension, and the tensile strength is found to anomalously increase with the mismatch angle between graphene and h-BN grains, i.e., the density of pentagon-heptagon defects along GBs. The disclination theory is successfully adopted to predict the stress field caused by the lattice mismatch at GB. Comparison between stress contours of GBs with different mismatch angle demonstrates that the arrangement of 5-7 disclinations along GB is crucial to the strength, and the stress concentration at GB decreases with the increase of disclination density, resulting in the anomalous increase of strength with mismatch angle of grains. What’s more, the thermal transfer efficiency of hybrid GB is also revealed to depend not only on the mismatch angle of grains but also the direction of thermal flux. Thermal transfer efficiency from graphene to h-BN is higher than that from h-BN to graphene. Detailed analyses for the phonon density of states (PDOS) of GB atoms are carried out for the mismatch angle-dependence of interfacial conductance. Our results provide useful insights into the application of two dimensional polycrystalline heterostructures for next-generation electronic nanodevices.

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Publication details

The article was received on 30 Sep 2017, accepted on 26 Dec 2017 and first published on 26 Dec 2017


Article type: Paper
DOI: 10.1039/C7NR07306B
Citation: Nanoscale, 2017, Accepted Manuscript
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    Mechanical and thermal properties of grain boundary in planar heterostructure of graphene and hexagonal boron nitride

    Y. Li, A. Wei, H. Ye and H. Yao, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR07306B

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