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First-Pinciples Study of the Nanostructures of Zinc Oxides

Author: LiLei
Tutor: ZhouZuoWan
School: Southwest Jiaotong University
Course: Materials Science and Engineering
Keywords: Zinc oxide Clusters First-principles Nonlinear Optical Properties Oxygen adsorption Iron-doped
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 328
Quote: 0
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Abstract


Band gap semiconductor zinc oxide (ZnO) as typical of Ⅱ - Ⅵ wide direct band gap material, because of its much by self-assembly to form a variety of nanostructures and unique optical, electrical, biological and piezoelectric functions attention. In recent years, it has been successfully synthesized a series of ZnO nanostructures, experimental and theoretical studies on the structure, morphology and functional characteristics is becoming a hot research field of chemical, materials, microelectronics, MEMS, solid state physics. In the field of nanotechnology, ZnO has gradually become one of the nanomaterials attractive after following carbon nanotubes in future electronic devices. Clusters and other physical properties of nanomaterials are difficult to be measured directly from the experimental, theoretical calculations have important academic significance for the understanding of ZnO nanostructures. Computational chemistry as an important theoretical research methods, provides an important theoretical basis for revealing the physical properties of nanomaterials. In this thesis, using the calculation method based on first-principles density functional theory, the study of the zinc oxide clusters ground state configuration, the optical properties of adsorbed oxygen characteristics, characteristics of the iron ion-doped crystals. Preliminary theoretical calculation method for ZnO system and its characteristics, carry ZnO antibacterial mechanism related theoretical studies laid the foundation for the further system. The theories and methods of using DFT (density functional theory), NRLMOL, and GAUSS03 software systems, ZnO cluster structure, configuration, stability and electronic structure simulation based on first-principles calculation results show that the ZnO cluster structures With the increase of the number of atoms, stable cluster structure consists of a single ring to a multi-ring and the cage. Take advantage of the ZnO cluster structures established under the limited field theory to simulate the nonlinear optical properties of ZnO clusters. The results showed that the difference in energy between the the ZnO clusters ring structure, the stability of clusters, electronic lowest unoccupied molecular orbital and the highest occupied molecular orbital (HOMO-LUMO Gap), a covalent bond and an ionic bond for the dipole distance, polarizability The first-order and second-order hyperpolarizability significant impact. Application of the DFT theoretical and calculated method for the first time 2 adsorption of atomic structure, structural stability and electronic structure of ZnO clusters with O simulation. The results show that the the ZnO cluster surface O 2 adsorption mainly by physical adsorption, The ZnO clusters surface adsorption O 2 easier to capture the photo-generated electron. ZnO crystal structure using the plane wave expansion and pseudopotential method the the ZnO crystal doped Fe 2 , the electronic density of states and band structure of the simulation. The calculation results show that the the Fe 2 doped ZnO band narrowing lead absorption spectral redshift, and it has a ferromagnetic.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
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