Predicting elastic properties of single-walled boron nitride nanotubes and nanocones using an atomistic-continuum approach

An atomistic-continuum approach is used to investigate structural parameters and elastic properties of boron nitride nanotubes and nanocones. A representative cell that each atom is connected to three neighboring atoms by B-N covalent bonds is selected and a higher-order gradient theory is adopted to derive the constitutive relationship. It is found that the chirality has an effect on structural parameters and elastic properties of tubes and cones but the effect decreases as the radius increases. The apex angle has an apparently decreasing effect on side edge's Young's moduli of cones but an increasing effect on circumferential Young's moduli, and the effect becomes smaller and smaller as the chiral angle increases. As the radius increases, the effect of both chirality and apex angle decreases, and elastic properties and structural parameters of tubes and cones tend toward those of planar boron nitride sheet.