First Principle Calculations Of The SrTiO₃ Oxygen Sensed Materials And Carbon Nanotubes

The research in this dissertation is mainly based on the Density Functional Theory (DFT for short) in First Principle Calculations. The calculation software are CASTEP Module in Materials Studio and VASP.The response time of SrTiO3 oxygen sensors is mainly determined by the O2 adsorbing and escaping energy in the surface of SrTiO3. This dissertation mostly researched on the O2 adsorbing reaction procedures in pure and doped with Fe, Cr and Mg SrTiO3 (100) surface. As the results show, the escaping energy of O2 on SrTiO3 surface can be reduced by doping Fe, both of the adsorbing energy and escaping energy of O2 on SrTiO3 surface by doping Cr and Mg, O2 can firstly adsorb on Pd on the SrTiO3 surface and then transfer to the surface atoms, which all makes a contribution to shorten the response time.Filling with the ferromagnetic nano particles or dispersing in the polymer substrate, the Carbon Nanotubes can be used to prepare light-in-weight and high-in-intensity microwave shielding and absorbing materials. This dissertation researches on the structure of single-wall nanotubes (5,5) filling with Fe, Co and Ni. As the results show, the nanotubes filling with ferromagnetic particles present definite magnetic moment while the magnetic moment of the ferromagnetic particle is larger inside the nanotubes. It is considered that the variation of magnetic moment is an important factor to impact the magnetism dissipating in the wave absorbing properties of Carbon Nanotubes.