Formation energy of native defects in BN nanotubes: anab initiostudy

Abstract

Electronic and structural properties of several charge states of vacancies, antisites and carbon substitutional impurities in a (10, 0) BN nanotube are investigated through density functional theory calculations. The formation energies indicate that neutral and simply charged states occur in the range of allowable electronic chemical potential. For carbon substitutional impurities, the most probable states are, besides the neutrals, the positively charged state for carbon at a boron site (CB+), and the negatively charged state for carbon at a nitrogen site (CN−). The charge compensation between neighbouring pairs of CB+ and CN− defects is suggested to explain the successful experimentally obtained boron carbonitride nanotubes. Vacancies always present high formation energies. The neutral and positively charged states of the nitrogen antisite show low formation energies. The calculated formation energies for all defects studied here can be interpreted as due to two main effects: a tendency to recover the number of electrons of the defect-free BN nanotube and the screening effects due to the perturbative potential of the defects.

Native defects in hybrid C/BN nanostructures by density functional theory calculations

“…26 The labels N and B will be used to denote the edge at which the defect is placed, where N designates the interface with C-N bonds, whereas B is the edge with C-B bonds. Accordingly defects are published in the literature, [27][28][29] considering that the formation energy depends on the chirality and increases with tube's diameter. 27,30 The cost of removing atoms (vacancy formation) is generally larger than the energy of atom substitution (disorder), which is indicative of the high stability of the honeycomb structure.…”

Symmetry and Models of Single-Wall BN and TiO2 Nanotubes with Hexagonal Morphology

“…Numerous simulations were performed so far on 1D single-wall (SW) and multi-wall (MW) models of BN nanotubes possessing hexagonal honeycomb morphology and the two equilibrium structures with either armchair (ac) or zigzag (zz) type chirality and a wide range of uniform diameters (0.5-2 nm). [13][14][15][16][17] In most theoretical simulations on titania nanotubes, a model 3D f 2D f 1D of structural transformations described in ref 18 was applied, i.e., the bulk (3D) phase first formed a lamellar product (3D f 2D) and then was bent and rolled to a nanotubular form (2D f 1D). The lamellar product was mainly formed by an anatase (101) surface, identified as prevailing in TiO 2 NTs.…”

A first principles study on organic molecule encapsulated boron nitride nanotubes

“…The energy gap can be adjusted by changing the chemical composition, for example, by substituting the B or N atoms with C atoms. 6,7,8,9 However, it is difficult to control precisely the atom concentration of carbon within BCN nanotube at the stage of tube growth. BNNT band structure can also be tuned by organic molecules covalent functionalization, 10,11,12,13 or by applying transverse electric field through the Stark effect.…”