Influence of Stone–Wales defects on the structural and electronic properties of double-walled boron nitride nanotubes: density functional theory

We investigated the influence of different orientations of Stone–Wales defects on the structural and electronic properties of DWBNNT. Upon introducing Stone–Wales defects to the nanotube surface, homo-nuclear B–B and N–N bonds were generated. These bonds are unfavorably in withdrawer–withdrawer and donor–donor contacts. Our result indicates that the formation energy difference for all cases of Stone–Wales defects lies generally in the different rolling-up strain of these three defects. This energy difference originated for the two concentric tubes in the DWBNNT. The calculated B–B and N–N bond lengths for type I Stone–Wales defects (inner and outer walls) longer than those for Stone–Wales defect-type II and Stone–Wales defects-type III. Upon introducing different orientations of Stone–Wales defects, protrude was observed when Stone–Wales defects created in the outer tube. However, intrude was observed when Stone–Wales were generated in the inner tube of DWBNNT. In either case, the pyramidalization angle was least for type I Stone–Wales defects. While calculating the band gap for all cases, a slight reduction in the band gap were observed compared to pristine double-walled boron nitride nanotubes.