  One-dimensional nanostructures such as nanowires and nanotubes are
stimulating tremendous interest due to their structural, electronic and
magnetic properties. In this study, the first principle calculation was
performed to investigate on the size effect on the electronic, mechanic and
piezoelectric properties of hexagonal-BN nanotube (BNNT). It demonstrates that
the nanotube diameter can modulate the direct bandgap significantly of the
zigzag-BNNT, increasing from 3.96eV to 4.44eV with the larger diameter from 10
to 16 unit cells in circular direction. Both armchair and zigzag BNNT exhibit
large elastic modulus, implying promising applications in nanoscale surface
engineering, tribology and nanomanufacturing/nanofabrication. Outstanding
piezoelectricity is also observed with large piezoelectric coefficient of
0.084C/m2 for 10-zigazag-BNNT and 0.13 C/m2 for 16-zigzag-BNNT, exhibiting
excellent potential in producing mechao-electric power generators.
