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Liquid-phase Synthesis，characterization and Photoluminescence Properties of Novel Nanostructures

Author: FengKeBao
Tutor: JiaChong
School: Hefei University of Technology
Course: Materials Science
Keywords: liquid-phase synthesis CdS nanostuctures Ni/AAM composite thin films ZnO nanosheets photoluminescence
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 49
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Abstract


The research focuses of the current nanomaterials are to precisely control their morphologies, microstrctures and properties. The aim of essay is focused on synthetic methods of inorganic functional materials. We have synthesized some novel nanostructures using low/high temperature mixed solvothermal or electrochemical deposition methods. The effect of the parameter changes on morphologies, structures and photoluminescence properties of the nanostructures are studied as the emphasis. The main results and conclusions are summarized as follows:1. Highly uniform porous AAO membranes were prepared in 0.3 M H2C2O4 electrolyte using two-step anodic oxidation process. The morphologies of AAO membranes were characterized by the field emission scanning electron microscope (FESEM). The techniques, mechanics and influencing factors of AAO membranes were also analysed in detail. Especially, we invented a method that can simply and fast remove the Au film sputtered on AAO membranes and easily recover the aluminum oxide powder. The process laid a good foundation for next electrodeposition.2. Two kinds of dendritic CdS nanorods with different sizes were prepared in the mixed solvothermal system at the temperature of 180℃using thiourea and thioacetamide. The testing results showed that the as-synthesized CdS nanorods had dendritic structure. The typical sizes and PL properties of the CdS nanorods were easily affected by sulfur sources. Thus, we can control the sizes and PL properties of the CdS nanorods by adjusting the sulfur sources. Moreover, the growth mechanics of the CdS nanorods in thiourea and thioacetamide were also studied.3. Ni/AAM composite thin fims were obtained by electrochemical depositing Ni into the uniform porous AAO membranes. We studied the PL properities of the Ni/AAM composite thin fims and also analysed the effect of the diameters of Ni nanowires on the PL properities of the Ni/AAM composite thin fims. The PL result displayed that a strong emission peak band locating at 350～500 nm can be found, and the emission intensities were influenced by the diameters of the Ni nanowires. The emission intensities would decrease when the diameters of the Ni nanowires reduced. The machanics are not clear and nead to be further studied. We guessed that it should be attributed to the interactions between the AAM and Ni nanowires, and nonradiative energies might also lead to the decrease of the emission intensities.4. The current-dependent morphology evolution and photoluminescence properties of ZnO films grown on polycrystalline Zn foils by cathodic electrodeposition method at 70℃were studied. It had been shown that the morphologies of ZnO films varied from nanosheets to nanoparticles with the increase of deposition currents. The room-temperature PL spectra of ZnO films showed that all the ZnO films prepared over a wide current range exhibit two peaks which are respectively located at 407 nm (intrinsic luminescence) and 550 nm (extrinsic luminescence), which also show deposition current dependence in intensity. Finally, the machanics of the ZnO films were studied, and the impact factors on the morphologies and properties were also analysed.

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