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Synthesis of Novel Nanostructures by Using Millisecond Pulsed Laser

Author: LvKuiMing
Tutor: SunJing；DuXiWen
School: Tianjin University
Course: Materials Science
Keywords: Millisecond pulse laser Metal -based nanostructures Silicon - carbon nanostructure Diamond nanoparticles
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 22
Quote: 0
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Abstract


Laser can provide local high-temperature and high-pressure environment , and heating , cooling speed , the laser method has become a green , a simple method of preparation of nanomaterials . Laser prepared nanomaterials using nanosecond pulsed laser , the short duration of action , low efficiency of synthetic materials . This paper millisecond pulse laser action the vapor and liquid phase in the solid target prepared different compositions and different structure of nanomaterials research millisecond pulse laser to form a mechanism of nanomaterials and its advantages . Millisecond pulse laser irradiation in the gas phase metal targets , different metal -based nanostructures at room temperature and atmospheric pressure , and to study the physical processes of laser with gas metal targets and the formation mechanism of these nanostructures . Laser irradiation after the metal target , the metal nano-particles is formed first , and then surface reaction occurs due to the different capacities of the diffusion coefficient of the metal atom and the solid solution carbon , resulting in the formation of the different structures of the nano - material , including magnesium oxide hollow tetradecahedral structure of carbon-coated cobalt (Ni , Fe) nanoparticles of cobalt oxide ( zinc, lead ) package cobalt ( zinc, lead ) core-shell structure and alumina ( Cu) nanocrystals . Millisecond pulse laser irradiation argon / n-heptane vapor of a silicon wafer , is prepared by changing the laser parameters such as frequency, pulse width , etc., to a different silicon - carbon nanostructure , such as fine silicon carbide nanocrystalline, carbon coated The tubular structure of a core-shell structure of silicon carbide , carbon-coated silicon and carbon-coated silicon carbide nanorods formation process follow the same model of surface reactions . Using silicon millisecond pulse laser action in the aqueous solution of glucose , for the first time using an organic liquid carbon source, a good diamond nanoparticles dispersed in solution was prepared . Nano- diamond formation mechanism and chemical vapor deposition prepared diamond films similar mechanism , Laser role of silicon , the silicon wafer is heated to provide heat to the glucose molecule decomposition and ionization generated C as a carbon source , the formation of a variety of structure carbon clusters , while generating OH groups and F etching the ability of the non-diamond carbon is stronger than the capacity of the etching of diamond , the clusters can be formed of only a diamond structure nucleation and growth . The experiments show that this mechanism can also be extended to other carbon sources , is preparing diamond nanoparticles a promising method .

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