Estudo teórico das propriedades mecânicas e eletrônicas de nanoestruturas de BN

Abstract

Boron Nitride (BN) is a stable compound where boron and nitrogen are united by covalent bonds. It is also a material with hardness similar to diamond but more stable, retaining their hardness up to 2.000 °C while diamond discards on graphite at about 900 °C. Furthermore, it is a chemically inert, has high melting point, is a semiconductor with a band gap, etc. In summary, it is a material with potential to be used in various applications in the electronic industry. Using first principles calculations within the formalism of the density functional theory (DFT) we investigate the stability, mechanical and electronic properties of BN nanosctructures: nanotubes (NTs) and nanowires (NWs). The calculations were performed using the SIESTA computer-code that solve the Kohn-Sham (KS) equations in a self-consistent way. In order to represent the KS orbitals we use a linear combination of atomic orbitals with two zeta functions for each Gaussian and for a better rearrangement of the charge density we add a polarization function through the inclusion of d orbital, forming the DZP basis set. To modulate the strong electron-core interactions we use standard norm conserving pseudopotentials. Our initial results for the BN NTs show that these nanostructures have mechanical properties similar to carbon nanotubes (similar Young Modulus), are always semiconductor with a band gap energy almost independent of the tube diameter and chirality. For the BN NWs we observe that their properties (mechanical and electronic) are dependent of the structural symmetry (wurtzite or zinc blende).