FRUSTRATION EFFECTS AND MICROSCOPIC GROWTH MECHANISMS FOR BN NANOTUBES

Using ab initio molecular dynamics simulations, we have studied the gr owth mechanisms of boron-nitride (BN) nanotubes. In this experimental conditions of temperature, the behavior of single-wall BN nanotubes st rongly depends on their helicity. Open-ended ''zigzag'' tubes close in to an amorphouslike tip, preventing further growth. In the ''armchair' ' case, the formation of squares traps the tip into a flat cap able to revert to a growing hexagonal network by incorporating incoming atoms . These findings are related to the greater stability of B-N bonds as compared to B-B or N-N bonds.