Arc Discharge Synthesis And Growth Mechanism Of AlN, ZnO Nanostructures

AlN and ZnO low-dimensional nanomaterials and nanostructures have become a research focus in nanomaterial fabrication, for their potential application in future nanodevices. The arc discharge method has shown great potential in nanomaterial synthesis, especially in complex nanostructures. This dissertation have carried out a systematic study on AlN nanomaterial fabrication by arc discharge, and the growth mechanism of the as-prepared nanostructures has been analyzed and discussed.Cobalt-doped AlN nanorods and flower-shaped nanorod arrays have been synthesized by a direct reaction of Al-Co ingot with nitrogen during arc discharge, which supplies a new approach to prepare diluted magnetic semiconductor nanomaterials. The growth of the as-prepared nanometerials was analyzed using a VLS model. Co-doped AlN flower-shaped nanorod arrays exhibited ferromagnetic behavior at temperatures of 300 K and 500 K.By employing a large discharge current, complex feather-like and coral-like AlN self-assembled nanostructures were synthesized by a direct reaction of high-purity Al with nitrogen. A alternating growth mechanism based on VS model had been used to explain the formation of the feather-like nanostructure. Furthermore, the unique nanostructure was considered as a dendrite growth in VS phase transition. The photoluminescence spectra of the feather-like products showed strong visible light emission.ZnO nanoparticles, the classic tetrapod ZnO nanostructure and a novel buttress-root shaped ZnO tetrapod-like nanostructure were also synthesized by a direct reaction of high-purity Zn granules with oxygen using the arc discharge method. The morphology of the products could be controlled by adjusting the oxygen partial pressure. A nanorod-centered growth model has been proposed to explain the novel buttress-root shaped ZnO tetrapod-like nanostructure.AlN nanomaterials have also been prepared by a CVD method for comparative study. Necklace-like AlN nanowires, classic AlN nanowires and flower-shaped AlN nanowire arrays were synthesized by a direct reaction of commercial Al powders with nitrogen using a simple catalyst-aided CVD method. The morphology of the products could be controlled by adjusting heating temperature, holding time and dispersion method of the catalyst. The morphology analysis and crystal geometry computation indicated that the surface of the necklace-like nanowire was assembled with {10 1 1} of the h-AlN. A VLS and VS cooperative growth model has been proposed to explain the formation of the novel necklace-like AlN nanowire. By comparing with CVD method, the features of arc discharge method were discussed.