Elastic properties of edges in BN and SiC nanoribbons and of boundaries in C-BN superlattices: A density functional theory study

Abstract

Using density functional theory calculations, we compute the edge energies and stresses for edges of SiC and BN nanoribbons, and the boundary energies and stresses for domain boundaries of graphene-BN superlattices. SiC and BN armchair nanoribbons show pronounced edge relaxations, which obliterate the threefold oscillatory behavior of the edge stress reported for graphene. Our calculations show small boundary stresses in graphene-BN superlattices, suggesting that such domain boundaries will not experience severe deformation. We have also found that the C-terminated and Si-terminated zigzag edges in SiC nanoribbons have different compressive stresses which results in different rippling behavior of these edges.

Edge stability of boron nitride nanoribbons and its application in designing hybrid BNC structures

“…For example, the average armchair edge stress of ABNNRs (ZBNNRs) is 0.26 (0.64) eV/Å in our calculations while this value is 0.55 (+0.32) eV/Å in Ref. [23], but the general conclusion remains the same, i.e., ABNNRs are under compressive stress while ZBNNRs are under tensile stress. The average edge energy of ABNNRs (ZBNNRs) is 0.76 (1.24) eV/Å in our calculations while this value is 0.93 (1.45) eV/Å in the work by Jun et al [23].…”

“…[23], but the general conclusion remains the same, i.e., ABNNRs are under compressive stress while ZBNNRs are under tensile stress. The average edge energy of ABNNRs (ZBNNRs) is 0.76 (1.24) eV/Å in our calculations while this value is 0.93 (1.45) eV/Å in the work by Jun et al [23]. This edge energy difference is mainly due to the different choice of the DFT method [20,21].…”

“…Very recently, Jun et al [23] calculated the edge stresses of BNNRs as a function of ribbon width by using a classical method based on first-principles energy calculations. It is known that the value of edge stress is quite sensitive to the choice of calculation method [18][19][20][21].…”

“…Edge reconstruction or edge saturation can effectively lower the edge energies as well as relieve the edge compression and hence stabilize the edge structures of GNRs [19][20][21]. BNNRs have similar geometry to GNRs but quite different electronic properties, and thus some essential differences in edge stability exist between BNNRs and GNRs [22][23][24]. Such a difference may eventually determine the structural characteristics and electronic properties of hybrid BNC materials.…”

The mechanical and electronic properties of two-dimensional superlattices

“…With the recent advances in controllable growth of large-area, high-quality, twodimensional (2D) layered materials (e.g., graphene (Bae et al, 2010;Li et al, 2009;Reina et al, 2009;Sun et al, 2010) and hexagonal boron nitride (hBN) (Lee et al, 2012;Song et al, 2010)) on metallic substrates, the field has naturally progressed toward the design and/or investigation of heterostructures based on out-of-plane (Liu et al, 2011;Wang et al, 2013;Xue et al, 2011;Yang et al, 2013) or in-plane Jun et al, 2011;Sutter et al, 2012) stacking of these nanomaterials. Layered heterostructures of graphene on boron nitride offer the best avenue of preserving the exotic properties of graphene and using them in nanoscale devices because of the near-perfect epitaxial lattice match, small van der Waals interactions between graphene and hBN, and most importantly because of the insulating nature of the underlying hBN layer(s).…”