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Over the last two decades, interest in the applications of graphene and carbon nanotubes has continuously grown in a variety of fields, including microelectronics, sensoring and actuation systems, energy generation and storage, biotechnologies and composite materials. In parallel, many researchers have also investigated nanomaterials consisting of elements other than carbon (C), including boron (B), nitrogen (N) and silicon (Si). Some examples are boron nitride (BN) and silicon carbide (SiC) nanosheets and the relative nanotubes. Similarly to their C analogues, these nanomaterials exhibit exceptional thermal and mechanical properties (e.g., low density, high thermal conductivity, high tensile stiffness and strength). Moreover, the different atomic composition leads to some specific properties, such as stronger resistance to oxidation and chemical stability at high temperatures, giving them advantages over C nanomaterials in harsh environments. As of now, these nanomaterials have drawn attention in different technological fields, including the composites, the manufacture of semiconductors and hydrogen storage. In addition, BN compounds can also be cleaned and reused by means of heating and burning in air, are biocompatible, have low friction coefficient, have excellent sorption performance and are hydrorepellent. For these reasons, they are studied also for applications in medicine (e.g. drug delivery), as lubricants and for water purification from oil, solvents and dyes. The effective exploitation of these nanomaterials goes hand in hand with in-depth knowledge of their physical behavior. Electronic, optical and mechanics properties are crucial and, moreover, also mutually interacting, even with the possibility of tuning the former trough control of deformation [7]. Knowledge of the mechanical behavior of these nanostructures is also related to the availability of predictive models, e.g., provided by ab-initio methods, by molecular dynamics (or statics) mechanics, but also by continuum mechanics and structural mechanics. In the context of linearized models, aimed at determining just elastic moduli, the cost of computationally onerous methods is not prohibitive; on the contrary, when the mechanical behaviour is highly non-linear, e.g., in post-buckling behaviour, in case of mode interaction or in fracture problems, the recourse to models as simple as possible becomes preferable. In the present paper a molecular mechanics model diatomic nanomaterial with hexagonal nanostructure is presented. The model is equipped by simple potentials, incorporating binary, ternary and quaternary atomic interactions. The parameters for BN sheets and tubes are derived. Numerical examples regarding linear and nonlinear behaviours of BN sheets and tubes are presented. |
