Of Rh Filling Carbon Nanotubes / Boron Nitride Nanotube Geometric Structure And Electronic Properties Of Theoretical Research

Since carbon nanotubes were discovered by Japanese scholar lijima in 1991, nanomaterial has become a hot spot of material science field for their unique properties and potential application. They exhibit many effects such as better thermal and electric conductive and other physical or chemical properties. Many experimental and theoretical studies have shown that the nanotubes will have widely potential applications in constructing nano-scale electronic devices, monitor, hydrogen storage, high strength fibers and so on in the future. In addition, nanotubular materials have also been widely studied as supports for nanoscopic metal catalysts. Recent, Bao et al. found a striking enhancement of the catalytic activity of Rh particles confined inside CNTs for the conversion of CO and H2 to ethanol. So carbon nanotubes also have potential application in promoting catalytic reaction.The BN nanotube is another nanotubular material synthesized in laboratory after the discovery of carbon nanotubes. Though they are alike in their structures, but the electronic property of BN nanotubes is different from that of carbon nanotubes. The electronic properties of CNTs may range from metallic to semiconducting with the strong dependence on chirality and diameter while BNNTs exhibit relatively uniform semiconducting behavior with a wide band gap weakly dependent on geometrical configuration. Beside, BN nanotubes together with other two characters of high temperature endurance and anti-oxidant ability make BN nanotubes a wider application prospects.With the explositve of high perfomance computer, computational simulation plays a very important role in science and technology. It becomes the third extremely powerful tool to study physical world following experiments and theories. It is a bridge between theory and experiments and theories and helps us to study regions which are not accessible experimentally. There exist two kinds of computational methods to study nanoscale materials. One is empirical or semi-empirical method; the other is ab initio or first-principle calculation.In this thesis, the density functional calculations were performed to investigate the atomic and electronic structures of Rh-filled carbon/boron nitride nanotubes. The first part introduces the theoretical fundamentals that we used in our research work. The second part introduces the main work done during my master's study. The follows gives a introduction.Ⅰ.The Theoretical Fundamentals Used in Our Research WorkIn charter 2, we give a briefly described of the first principle calculation and Dmol3 package.Ⅱ.The Theoretical Study of Rh-filled carbon/ boron nitride nanotubesIn charter 3, we study the structure, the mechanical, electronical, thermal and magnetic property of CNTs and BNNTs. In charter 4 and charter 5, we investigate the atomic and electronic structures of Rh-filled carbon/ boron nitride nanotubes, respectively. Our results indicate that Rh atoms encapsulated in nanotubes self-aggregate to form ultrathin nanowires, of which the atomic arrangement depends on the diameter of the nanotubes as well as the Rh content. The electronic structures of the Rh-filled carbon/ boron nitride nanotubes can be tuned from semiconducting to matellic by controlling the Rh content. This may therefore be useful in a much-miniaturized scale that serves as building blocks for the next generation of electronic devices.