Size-dependent electronic structures of boron carbonitride (BC 2N) nanotubes. A DFT approach

Abstract

The electronic structures and physical properties of zigzag BC 2N ( n,0; n = 4–10) and armchair BC 2N ( n, m; n = m = 4–10) nanotubes (type III) are studied by using density functional theory with the generalized gradient approximation. From a comparison of the binding energies, it is inferred that in the large diameter BC 2N nanotubes, the zigzag form is thermally more stable than the armchair form. BC 2N nanotubes (with the exception of (4,0) which is conductor) are gapless semiconductors. Depend on the chirality index, the zigzag forms of BC 2N nanotubes have narrower band gap than the armchair form. Semiconductor character in the studied BC 2N nanotubes is due to contribution of p electrons in the Fermi level. Mulliken population analyses show that significant amounts of electron charge are transferred between atoms; which suggests the existence of polar covalent bonds in the BC 2N nanotubes.