Grain-size dependence of mechanical properties in polycrystalline boron-nitride: a computational study

Abstract

The field of research in polycrystalline hexagonal boron nitride (PBN) has been enjoying extraordinary growth recently, in no small part due to the rise of graphene and the technical advancement of mass production in polycrystalline 2D materials. However, as the grain size in 2D materials can strongly affect their materials properties and the performance of their relevant devices, it is highly desirable to investigate this effect in PBN and leverage the service capability of PBN-based devices. Here we employ molecular dynamics simulations to explore the effects of grain size in PBN on its mechanical properties such as Young's modulus, yield strength, toughness, and energy release rate as well as its failure mechanism. By visualizing and comparing the tensile failure of PBN with and without a predefined crack we have shown that the grain size of PBN is positively correlated with its elastic modulus, yield strength and toughness. Through inclusion of a crack with varying length in the PBN samples, the energy release rate is determined for each grain size of PBN and it is concluded that the energy release rate increases with an increase in the average grain size of PBN. These findings offer useful insights into utilizing PBN for mechanical design in composite materials, abrasion resistance, and electronic devices etc.

A review on mechanics and mechanical properties of 2D materials—Graphene and beyond

“…This means that, for an accurate prediction of strength, it might be necessary to map out all the topological defects in the material, which is not always possible or desirable. The findings for graphene are expected to be applicable also for other 2D materials, as demonstrated by a recent study on fracture in polycrystalline boron-nitride (BN) sheet [133]. Net charge can exist in some defects (such as five-seven rings) in BN sheet [134], whose effect on the material fracture has not yet been fully explored in the literature.…”

“…Most large-scale 2D materials contain various topological defects [120][121][122] that make the prediction of their failure strength extremely challenging [13,14,31,101,102,104,105,[123][124][125][126][127][128][129][130][131][132][133]. For example, the strength of a bi-crystal graphene is highly dependent on the grain boundary [101,102,123], which was recently explained with a disclination dipole theory [102].…”

Boron Nitride‐supported Sub‐nanometer Pd6 Clusters for Formic Acid Decomposition: A DFT Study

“…Although computational approaches are well suited for this analysis, it has been demonstrated that these catalytic systems cannot be realistically modeled without taking into account support effects . In this spirit, it is appropriate to focus on emerging catalyst supports such as boron nitride based materials, which besides possessing high thermal, mechanical, and chemical resistance, have also been recently investigated as hydrogen storage platforms and in nanocatalysis …”

Probing the Atomic Structures of Synthetic Monolayer and Bilayer Hexagonal Boron Nitride Using Electron Microscopy

“…Furthermore, unlike graphene, h-BN has a binary configuration and its lack of inversion symmetry results in more complex bonding structures with unfavorable homonuclear bonds (Gibb et al, 2013;Li et al, 2015;Liu et al, 2012). The presence of such defects is known to alter the properties of h-BN films (Becton & Wang, 2015;Li et al, 2015;Mortazavi et al, 2015). Hence, to fully exploit these scalable films and achieve better growth procedures, deep insights into their structural configuration, defects, and growth behaviors are critical.…”