Abstract:With larger surface areas and nanochannels for mass delivery and gas diffusion, three-dimensional tubular anodic aluminum oxide (AAO) films have practical advantages over two-dimensional AAO films for medical and energy applications. In this research, we have developed a process for batch production of tubular AAO films using a 6061 Al tube. The tubular AAO films have open nano-channels on both sides, with average pore dimensions of about 60 nm and pore densities of about 10 8 to 10 9 pore/cm 2 . It was found that the porous AAO material with nano-channel structure exhibited dialysis behavior, allowing for liquid/gas exudation through diffusion between the inner and outer surfaces of the tubular AAO films. Ar gas bearing test and aeration test were conducted to find the pressure bearing capacity of tubular AAO films. It was demonstrated that the AAO film with a thickness of 100 µm can resist an argon pressure up to 8 atm; however, 30 µm AAO film can only withstand 3 atm of Ar gas. The tubular AAO films with exudation characteristics have the potential for applications in advanced technologies, such as liquid or gas filters, drug delivery, and energy applications.

The CsI-based scintillators have been widely used for X-or gamma-ray detections. It has been known that columnar scintillators favor the detections with higher efficiency and spatial resolution. In this paper, we report a facile and low-cost method to fabricate submicron nanoscale CsI columns. We integrated the thermodynamic calculations, positive chamber design, mold design, electrochemical bath design, anodization process, and solidification techniques to fabricate such submicron CsI columns. When the CsI melt is confined to AAO channels with a high aspect ratio, stable CsI columns solidified with smooth surfaces, and free of dendrites or grain boundaries. Different solidification approaches have been attempted, including mechanical injection in vacuum under a negative pressure, injection at 1 atm, 3 atm and 25 atm using Ar gas only, and mechanical injection with 1.6 atm Ar pressure. The mechanical injection or high-pressure Ar injection at 25 atm produced good filling of CsI melt into AAO channels. Such CsI columns inside the smooth AAO walls enable the highenergy radiation detection with high light emission for pixelated scintillator applications.

A simple method to indium tin alloy and oxide nanowires were achieved by using the extrusion molding process in the air. Eutectic indium tin bulk were firstly injected into AAO templates. After dissolving AAO, the indium tin nanowires were collected in ethanol. Furthermore, in order to have oxide nanowires, alloy nanowires were directly oxidized by heat treatment in the air below its melting point for 24 hours. Finally, crystalline indium-tin oxide and indium oxide nanowires with diameters 90-110 nm and lengths 2-20 μm were obtained.

Anodic aluminum oxide (AAO) is well known for its unique controllable structure and functional contributions in research and developments. However, before AAO can be widely used in the industry, some engineering problems should be overcome. In this study, we designed a novel electrochemical mold, which can resolve the exothermal problem for large-size aluminum sheets during high-voltage anodization process. AAO film with a large sample size of 11 x 11 cm2 in area, 148 μm in thickness and 450 nm in average pore diameter, decorated with ordered-pattern structure, was successfully obtained through a 200 V anodization process. It was noticed that the local heat was generated with increasing the anodizing voltage, resulting in undesired pits and burr defects on the AAO surface. In order to retain AAO’s quality and reduce the producing cost of the anodization process, a mass producing system combining with an overhead conveyor was proposed. The convenient anodization system, novel electrochemical mold and bath may help to fabricate high-quality AAO films efficiently.

The cesium iodide (CsI) scintillator can converts incident X-ray into visible light with very high conversion efficiency of optical photons. The incident energy, response time, film thickness, sample size, and spatial resolution require in engineering and medical applications are difference. A smooth and flat surface and single crystal structure of CsI enhance the X-ray to visible light conversion. However, the regular CsI is soft and extremely hygroscopic; it is very difficult to polish to obtain a smooth and optical flat plane. In order to obtain a good quality of CsI scintillator for X-ray application we used an ordering channel as template and formed sub-micron CsI wire in the template. The fabrication process including: (1) Ordering structure of nano or sub-micron channels were made by an anodization method; (2) fill CsI scintillated film on the channel by CsI solution, (3) fill CsI melt into the channel formation single crystal of sub-micron crystalline scintillator after solidification. The non-vacuum processes of anodization and solidication methods were used for the sub-micron CsI scintillator column formation that is cost down the scintillator fabrication. In addition, through the fabrication method, the ordering structure scintillator of scintillator can be made by anodic treatment and die casting technology with low cost and rapid production; moreover, the film oxidized metal tubes of the tubular template can be further manufactured to nano tubes by adjusting electrolyte composition, electrolysis voltage, and processing time of anodic treatment, and the aperture size, the thickness and the vessel density of the nano tube can be controlled and ranged from 10 nm to 500 nm, 0.1 μm to 1000 μm, and hundred million to thousand billion tube/cm 2 , respectively.