Coalescence of BnNn fullerenes: A new pathway to produce boron nitride nanotubes with small diameter

Using density functional theory calculations, we predict that single-walled hemispherical-caped boron nitride (BN) nanotubes with small diameters can be produced via the coalescence of stable nanoclusters. Specifically, the assembly of B_nN_n (n=12,24$n=12,24$) clusters exhibiting particularly high stability and leading to armchair (3,3)$(3,3)$ and (4,4)$(4,4)$ BN nanotubes, respectively, are considered. The formed finite-length BN nanotubes have semiconducting properties with wide band gaps attractive to nano-device applications.