Fabrication And Formation Mechanism Of One-dimension Functional Nanomaterials Based On AAO Template Method

Due to their surprising size effect, surface effect and quantum effect, Nano-materials which were studied as completely new structural materials started in the early 1980's, have special mechanical, optical, electrical, magnetic, thematic and chemical properties, thereby having great potential applications in many industry and high-technology fields, as well as promoting the development of the foundational researches.One-dimensional nanostructures have at least two-dimensional size in the range of nanometer scale,such as nanowires and naonotubes. Anodic alumina oxide (AAO) membrane prepared by anodizing of Al not only has a simple process, but also contains uniform parallel pores and high pore density. The pore diameter is controllable in accordance with practical needs,so one-dimensional nano-arrays synthesized by AAO template has many studied deeply in these years.This paper prepared the AAO film by electrochemical anodic oxide method, synthesized the Al₂O₃ nanowires by chemical corrosion method, obtained Li₄Ti₅O₁₂ ordered nanoarrays by Sol-Gol template method. The results can be summarized as follows:1. Synthesis and characterization of AAO template.The porous anodic alumina template with diameter of 30nm to 120nm, was successfully produced in H2SO4,H2C2O4 and H3PO4 by two-step anodization process, as well as we considered the effect of cell voltage(40⁶0V), electrolyte temperature(0²5℃), concentration of electrolyte(0.2⁰.4mol/L) and corrosion time(0²h) on template morphology, which was charactered by SEM. The results showed that pores diameter increases with the raising of cell voltage, concentration of electrolyte and the prolonging of corrosion time. The distribution density is inversely proportional to the cell voltage and concentration of electrolyte. But the e electrolyte temperature has minimal impact on the diameter and density.2. Electrochemical synthesis and formation mechanism of Al₂O₃ nanowires.Al₂O₃ nanowires, whose morphology and structure were characterized by SEM, EDS and IR, were prepared with the method of electrochemical oxidation followed by acid corrosion. The experimental results showed that Al₂O₃ nanowires with a hexagonal arrangement were formed from Al₂O₃ porous film by electro-oxidation of aluminum substrate, as well as had a large aspect ratio. The diameter of the pure Al₂O₃ nanowires is from 16nm to 60nm, and decreases with the raising of electrolyte temperature, cell voltage and the increasing of corrosion time. On the basis of characterization for nanowires on Al₂O₃ porous film, a possible formation mechanism was supposed.3. Preparation Li₄Ti₅O₁₂ ordered nanoarrays by Sol-Gol template method.Li₄Ti₅O₁₂ nanoarrays of spinel structure were prepared with the method of Sol-Gol template method. The morphology and structure of Li₄Ti₅O₁₂ nanoarrays were characterized by SEM, EDS and XRD. The experimental results show that spinel Li₄Ti₅O₁₂ nanoarrays with mean diameter of 70nm and large aspect ratio were synthesized by roasting at 900℃for 20h after immersing the porous AAO in sol of 0.8mol/L under negative pressure for four times. The formation of Li₄Ti₅O₁₂ nanoarrays, whose crystal structure depends on calcination temperature(600⁹00℃) and time(10²0h), are determined by sol concentration(0.7⁰.9mol/L) and deposition times(1⁴times).