| Porous anodic alumina (PAA) films have diverse applications in the fabrication of nanostructured materials and photonic devices due to their hexagonally ordered pore arrangement, anti-erosion, fine transparency and mechanical properties. The fabrication of PAA films is quite simple and of low cost, and ordered PAA films with inter-pore distances from tens to hundreds of nanometers can be obtained by controlling the anodizing conditions, which make them quite popular among scientific and business world. This dissertation focused on the fabrication and mechanism of highly ordered PAA films by high-field anodization, as well as the fabrication, growth mechanism, and properties of ZnO nanostructures based on PAA films.Firstly, we gave a brief introduction on the concept, history and two basic approaches of nanotechnology. The main apparatus used for characterizing nanostructured materials were also introduced, such as transmission electron microscope, scanning electron microscope, scanning tunneling microscope, atomic force microscope, and photoluminescence (PL) spectra. Then, the major research developments of PAA films were discussed in details to present a full and accurate knowledge about PAA, including the structure models, formation mechanisms, fabrication techniques, and main applications.Based on our knowledge learned from the normal two-step anodization, we firstly realized stable high-field anodization in phosphoric acid electrolyte, and highly ordered PAA films were achieved with high efficiency. The key factor to maintain stable electrolysis under high-filed conditions is to solve the serious heat dispersion problem in order to eliminate'burning'of the PAA films. By adding adequate ethanol to the phosphoric acid electrolyte, the temperature of the electrolyte could be lowered to -10 oC without freezing. It was found that the ethanol not only lowered the freezing point of the electrolyte, but also served as coolant during anodization. By the aid of a powerful low-constant-temperature system, a vigorous stirrer, and a large electrolysis bath, stable high-field anodization (195 V, 1500-4000 A/m2) has been realized in H3PO4-H2O -C2H5OH electrolyte. Highly ordered PAA films with the inter-pore distances of 320-380 nm, pore sizes of 80-140 nm, and ordered regions of 4-6μm were obtained. The growth rates of the PAA films were as high as 4-10μm/min under high-field conditions, which were much higher than that of normal anodization (50-100 nm/min). Using the same strategy, we have realized high-field anodization in H2SO4-H2O-C2H5OH (30-80 V) and C2H2O4-H2O-C2H5OH (100-180 V) electrolytes, respectively. Highly ordered PAA films with arbitrary inter-pore distances in the range of 70-450 nm could be obtained by this simple method. Using PAA films formed by high-field anodization as starting materials, alumina nanowire arrays, alumina nanowire pyramids, and Y-branched PAA films were also achieved.Using PAA films with different surface configuration as substrates, different ZnO nanostructures were synthesized by non-catalytic thermal evaporation. Novel lotus-leaf-like ZnO micro-nanostructures were formed on the top of alumina nanowire pyramids by thermal evaporation. The structural characters and growth mechanism were studied, and the hydrophobicity of this surface was also measured. The results show that the surface not only is superhydrophobic, but also has ultra-strong adhesive force toward water droplets. This superhydrophobic surface with ultra-strong adhesive force may have applications in micro-fluidic devices. Using the top side of PAA films with tip-like structures as substrates, high-density ZnO nanorod networks were synthesized by the same thermal evaporation process. The structural characters and growth mechanism were studied, and the PL spectrum of the ZnO nanorod networks was also measured. By studying the ZnO nuclei on the PAA films with different surface morphology during the initial stage of the thermal evaporation, we found that the morphology of PAA films had an inducing effect on the formation of different ZnO nanostructures.
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