Theoretical study of the site-dependent stabilities of intrinsic defects in a polar bn nanotube with finite length

Intrinsic defects, including single vacancy and Stone-Wales defects in a finite-length (8, 0) BN tube are investigated using density functional theory calculations. It is found that the stabilities of all defects are enhanced as they get close to the tube ends. We propose the possible physical origins for the defect energetic preference toward the tube ends and prove that the spontaneous electric polarization field of the BN tube can affect the stability of the defect by making the different electrostatic potential to the defect at different site. We also discuss the potential experimental consequences and provide the theoretical support for one experimental method for the synthesis of BN tubes.