Estudo da deformação espontânea em nanotubos de BCN e suas propriedades eletrônicas

Abstract

The amazing properties of carbon nanotubes (such as good flexibility while high mechanical strength) technologies and their applications motivate research in this area. Following the successful synthesis of carbon nanotubes, we sought to find new chemical elements capable of forming nanotubes, as was the case of boron nitride (BN). Nanotubes of mixed C and BN were predicted theoretically and then synthesized. The object of this work is the study of nanotubes mixed BN and C, known in the literature by BxCyNz. For this, it was initially taken a literature review in order to understand the most important existing theories to solve the problem of many bodies in quantum chemistry and solid state as the Density Functional Theory and approaches necessary for solving equations Kohn-Sham. The determination of molecular systems and / or crystal is very complex task and is accomplished through the use of computer codes. In this study, we used the SIESTA code to obtain the relaxed structures of the nanotubes as well as to obtain the electronic properties. The nanotubes in this paper are formed by the junction of bands C and BN arranged interchangeably, and the straight cutting section of these takes the form of an ellipse. There was, then, the study undertaken by the eccentricity of nanotubes according to the width of the strips that compose it. It also made a study of electronic properties of nanotubes, since they expect the electronic properties of the intermediate C and BN nanotubes. The present study was to examine how the gap varies with increasing width of the strips of BN. In addition, we calculated the formation energy of nanotubes based on the formation energies of the hexagonal phase of C and BN. Both the formation energy as the band structures were determined in order to find such a relationship with the eccentricity of the nanotubes. Nanotubes were analyzed in this research ziz-zag type ((6.0) (8.0) (10.0) (12.0) and (14.0)) and armchair ((6.6), (8.8), (10.10) (12.12) and (14.14)) with different widths of the BN tracks, totaling 70 nanotubes. The nanotubes studied present a variation of the eccentricity with the width of the bands of BN and C quite varied, it is not possible to describe them with a single mathematical equation. It was observed that zig-zag nanotubes are quite distinct from armchair eccentricity on the relationship width of the strips of BN and C. The results showed that these nanotubes assume the intermediate electronic properties of BN nanotubes and C. It is observed an increase in the value of the gap with increasing width of the strips of BN, but for the type zig-zag nanotubes, there is a discontinuity in this trend for some bandwidths.