carbon and boron nitride nanotubes physical and mechanical properties and device schematic

Title: carbon and boron nitride nanotubes physical and mechanical properties and device schematic Author: Tao Dai Italy Degree awarded: Nanjing University of Aeronautics and Astronautics Keywords: carbon nanotubes;; boron nitride nanotubes;; high-frequency oscillator;; terahertz;; energy conversion;; electroluminescent deformation;; satisfied drive;; quantum mechanics;; molecular dynamics Summary: Carbon nanotubes and boron nitride nanotubes have unique geometric structure and excellent physical, mechanical and chemical properties, is an important material for building nanodevices. In this paper, ab initio quantum molecular dynamics, molecular dynamics, density functional theory and quantum mechanics and classical mechanics of the hybrid model, combining the methods of classical mechanics analysis of high-frequency axial vibration of carbon nanotubes, boron Rare earth magnets nitride nanotubes deformation caused by electricity and electromagnetic neutral theory of molecular electric drive on a large scale parallel computing simulations and theoretical analysis, try to explore the carbon and boron nitride nanotubes in the presence of physical and mechanical coupling behavior, and behavior of this coupling device in the Nagorno-scale development the potential applications. Based on the above studies, made the following progress: 1) high-frequency axial vibration of carbon nanotubes: high-frequency vibrations of carbon nanotubes that people conduct a lot of research, but the lack of testing quantum molecular dynamics, and electromechanical coupling effects of vibration by understanding the influence of very less. In this paper, the axial vibration of carbon nanotubes, for example, the use of ab initio quantum molecular dynamics simulation of its vibration process was. The results show that the axial vibration of carbon nanotubes under axial electric field has little effect, while influenced by the charge injection. Classical molecular dynamics method can be used to describe the main features of the vibration, however, the intrinsic frequency of the vibration prediction and compared the results of quantum molecular dynamics are still differences. In addition, the vibration by the electromechanical coupling effect, especially with the case of charge injection, the classical molecular dynamics can not give a reasonable description. http://www.chinamagnets.biz/faq.php Select the appropriate parameter, spring - mass model and the model of the hollow rod axial vibration of the fundamental frequency can give more accurate predictions, but for the higher modes, the above two models of error was relatively large. In addition, the use of high-frequency axial vibration behavior of carbon nanotubes, we propose a terahertz radiation source works and apply for a national patent. 2) boron nitride nanotubes electrostrictive deformation density functional study: looking for a large strain energy density of smart materials has been the people working for. We use first-principles density functional method of boron nitride nanotubes electrostrictive deformation behavior has been studied. The results show that, in the axial direction under the effect of external electric field, and the experiment can be achieved in the electric field strength, the zigzag boron nitride nanotubes axial electrostrictive deformation of up to 4%, the corresponding volume power density than has been reported polymer intelligent materials of the highest value of more than 100 times higher than conventional piezoelectric ceramic materials to three orders of magnitude higher. Electroluminescence of Boron Nitride Nanotubes deformation due to the inverse piezoelectric effect and electrostrictive effect, and the latter is caused by the deformation of up to twice the former. Taking into account the boron nitride nanotubes good thermodynamic and chemical stability and insulation, it is expected to be a highly intelligent potential of nano-materials. 3) magnetic neutral theory of molecular electric-driven exploration of research: nanotechnology and molecular machinery of the drive, especially for the electromagnetic drive system of the neutral molecule, is a challenging scientific and technical problems. They contain no net charge or magnetic moment, magnetic domain or electric domains, so can not use a uniform electric or magnetic field to drive and operate. In this paper, the semi-empirical quantum molecular dynamics simulation to prove: by controlling the end of the closed end of the opening of single-walled carbon nanotubes on the charge distribution, you can change it with the internal interaction between neutral molecules, and thus the drive to achieve the neutral molecule and operation. When carbon nanotubes uniformly distributed positive charge to bring, you can play inside the neutral molecule; and when it is uniformly distributed negative charge to bring when you can not play within the neutral molecule, but was able to located its open end near the neutral molecule inhalation. These findings are expected for nano-devices and systems to provide a new drive and control mechanism. Degree Year: 2009