Size-dependent electronic structures of boron carbonitride (BC_2N) nanotubes. A DFT approach

摘要

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.