Size effects in mechanical properties of boron nitride nanoribbons

Size effects in mechanical properties are investigated through molecular dynamics simulations with Tersoff-like potential for boron nitride nanoribbons (BNNRs) in the armchair and zigzag directions under uniaxial tension. It is found that tensile properties of rectangular BNNRs of fixed lengths are significantly affected by the length-width ratios, while these aspect ratios are less sensitive to tensile properties of rectangular BNNRs of fixed widths. Size effects are minor in square boron nitride nanosheets. For zigzag BNNRs of fixed length, Young's modulus, fracture stress and fracture strain increase when decreasing the width. For armchair BNNRs of fixed length, Young's modulus and fracture strain increase, while fracture stress varies slightly when decreasing the width. Young's modulus of zigzag BNNRs decreases from 299 N/m for a very narrow sheet to 258 N/m for square sheets, while this mechanical property increases from 231 N/m to 250 N/m for armchair BNNRs. Fracture stress of zigzag BNNRs decreases from 44.4 N/m for a very narrow sheet to 35.6 N/m for square sheet.