Elastic constants of two-dimensional BN nanostructures

The study of mechanical properties is of key importance for electronics, composite fabrication, and fundamental understanding of the mechanical behavior of two-dimensional structures that will bring these materials closer to commercial use. BN nanostructures (bornitrane and graphyne-like BN) can be considered as competitors of two-dimensional carbon nanostructures due to their unusual properties: high thermal and chemical stability, good mechanical strength, superior resistance to oxidation, good thermal conductivity, and electrical insulation. Bornitrane is a two-dimensional structure consisting of two hexagonal monolayers of boron nitride with interlayer covalent bonds. Due to their unique properties, bornitranes are considered as the candidates for application as elements of resonant nonlinear optics and optoelectronic devices. Graphyne-like BN is a monolayer of sp- and sp2 hybridized nitrogen and boron atoms arranged in a crystal lattice. The combination of sp2 and sp hybridization in these material leads to unique chemical and physical properties, and has promising prospects and potential applications in nanoelectronics. Molecular dynamics was used to obtain the stiffness and compliance constants, Young’s and shear modulus, Poisson’s ratio for bornitrane and graphyne-like BN. The elastic properties of new configuration of graphyne-like BN are calculated for the first time. It is found, that the morphology of bornitrane has an insignificant effect on the stiffness constants. Young’s modulus of bornitrane E = 416.7 N / m is close to that of for hexagonal and wurtzite boron nitride. Both bornitrane and graphyne-like BN are isotropic in linear regime. The obtained results open new opportunities for the development of new nanomechanical devices based on such 2D materials.

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