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

Fabrication and Characterization of Nano-ZnO by PLA in Liquid Solution

Author FangHe
Tutor TangWeiHua
School Zhejiang University of Technology
Keywords pulsed laser ablation surfactant nano-ZnO Zn/ZnO core/shell structure defect photoluminescence
CLC TB383.1
Type Master's thesis
Year 2011
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We applied a novel method called pulsed laser ablation in liquid (PLA) to synthesize nano-ZnO. We mainly studied the effects of different solution, ablation time and solution concentration on structure, morphololy, size, optical and photoluminescence properties of nano-ZnO, and also investigated formation mechanism and defect photoluminescence. The results can be summarized as follows:1. ZnO nanoparticles were synthesized by ablating zinc target in deionized water. The mean diameters of ZnO nanoparticles are 43 nm and 19 nm, respectively, after ablating the zinc target for 2 and 4 hours in deionized water. The longer-time ablation may lead to the interaction of the ablating laser beam with the ZnO nanoparticles, resulting in the decrease of the mean diameter of ZnO nanoparticles.2. Zn/ZnO core/shell structured nanoparticles were synthesized by ablating zinc target in 0.005mol/L sodium dodecyl sulfate (SDS) solution. The formation of this core/shell structured nanoparticles was due to the enwrapping of SDS to part of the Zn clusters. The bilayer of SDS molecules which could inhibit reaction between Zn clusters and liquid solution were formed on Zn clusters surface.3. The uneven Flake-like nano-ZnO was synthesized by ablating zinc target in different concentration cetyltrimethylammonium bromide (CTAB) solution. The uneven Flake-like nano-ZnO was formed by self-assembly,which is attributed to electrostatic repulsion between CTAB molecules and nano-ZnO. In the process of self-assembly, the small nano-ZnO self-attach to build a bigger nanostructured assembly by self-adjusting and by lattice fusion.4. The photoluminescence property of the uneven Flake-like nano-ZnO was investigated. A violet photoluminescence peak at about 411 nm was due to zinc interstitials in lattice. Blue photoluminescence peaks from 450 nm to 436 nm was due to derivative zinc interstitials in lattice. And a green photoluminescence peak at about 558 nm was due to oxygen vacancies. We also investigated the different concentration of CTAB that affect on the defects of uneven Flake-like nano-ZnO, and thouht the best concentration of CTAB that could passivate the defects of zinc interstitials was critical micell concentration. But CTAB could not passivate the defects of oxygen vacancies. A blue shift of blue photoluminescence peak from 450 nm to 436 nm was due to the increasing of Zni(?)、Zni(?)(?) with the increasing of Zni.

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