Papers by Keyword: Anodization

Abstract: In recent study, vertically aligned TiO₂ nanotubes have become the primary candidates that can provide direct control of many type cell behaviors and its functionality. TiO₂ nanotubes were successfully developed within 10 V to 40 V of applied potential. The intensity of peaks (101) increases with increasing voltage up to 40 V, indicating an improvement in degree of crystalinity. The average crystallite size of the samples anodized at 10 V is about 19.65 nm and increase to 30.88 nm at 40 V. PA6 cell interaction were high on 40 V sample (110 nm-diameter) TiO₂ nanotubes . It was found that anatase phase with appropriate diameter are believed to affect the growth of cells.

Abstract: We report the synthesis of Al-doped TiO₂ nanotubes (Al-TNT) by DC anodization method at 50 volts. The method is simple, cost effective, environmentally safe and the samples produced are of good quality. The electrolytesolution was composed of ethylene glycol (EG), ammonium fluoride (0.3% wt NH₄F), deionized water (2% vol H₂O) and varying molar masses of aluminum nitrate - Al (NO₃)₃. The samples were analyzed XRD before and after annealing at 450 °C for 2 hours. The surface morphology and the elemental analysis of the annealed samples were characterized by SEM and ED-XRF respectively. The results show that phase transformation only occur after annealing. And that the surface organization, uniformity and structure are influenced by the concentration of the dopant element.

Abstract: A dense TiO₂ film was fabricated on the titanium surface using the anodization technique. Surface morphology and phase structure of anodic TiO₂ film were investigated before and after the hydrothermal exposure at 160 °C for 24 h. The hydrothermal solution was 3.5 wt% NaCl solution and the films were either immersed in NaCl solution or exposed to water vapor during the exposure. It was found that the as-prepared anodic TiO₂ film consisted primarily of amorphous oxides and exhibited a relatively smooth surface. After the hydrothermal exposure, lots of rod-like crystals were formed on the solution-immersed film, while aggregated fine nanoparticles emerged on the vapor-exposed one. Thin film X-ray diffraction analysis indicated that the hydrothermal exposure transformed amorphous oxides into crystalline anatase. The corrosion behavior investigation showed that the structural transition of anodic TiO₂ film during the exposure reduced the corrosion resistance of anodized titanium greatly.

Abstract: Nanotubes of TiO₂ have been synthesized on titanium metal by DC anodization at 50 V in an EG/NH₄F/D.I. H₂O electrolyte. The anodization apparatus which uses a platinum cathode is unique and designed to allow only for a single-face anodization. The influence of deionized water (D.I. H₂O) on the surface morphology of the nanotubes was investigated using the scanning electron microscope (SEM), while the microstructure before and after calcination was studied using X-ray diffraction technique (XRD). Results show that the surface density and uniformity of the TiO₂ nanotube arrays varies with the percentage of D.I. H₂O in the electrolyte. The best result was obtained at 6% vol D.I. H₂O after calcination. This result is useful since, the surface morphology and microstructure play a vital role in the performance of TiO₂ nanotubes in various applications.

Abstract: Anodic aluminum oxide (AAO) is well known for its nanoscopic structures and its applications in microfluidics, sensors and nanoelectronics. The pore density, the pore diameter, and the interpore distance of an AAO substrate can be controlled by varying anodization process conditions. In this research, the self-organized two-step anodization is carried out with a low-grade (Al6061) aluminium substrate using a 40V voltage at the temperature of 2 to 5 °C. Three experiments are done with the anodization time of 24 hours, 48 hours and 72 hours. The structural features of AAO are characterized by a field emission electron microscope (FE-SEM). The data from FE-SEM show that the average pore diameter increases with the anodization time, and that the Al6061 aluminium substrate can be used to fabricate a nanoporous AAO film with an average pore diameter smaller than 17 nanometers.

Abstract: We reported on the influence of applied voltage on the surface morphology of anodic titanium dioxide (ATO) thin films. At first, titanium (Ti) thin films were prepared by DC-magnetron sputtering for use as a base material in the anodization process. The titanium dioxide (TiO₂) nanoporous ATO was fabricated by the anodization process from the Ti thin film, with different applied voltages from 20 V to 60 V in an electrolyte based on an ethylene glycol containing NH₄F. Pore size distribution of ATO thin films can be varied from 20-50 nm by increasing the applied voltage, while the thickness of the film also increases. In addition, to observe the effect of time, the optimal condition of anodizing voltage was studied by increasing the anodizing time. The results clearly showed the nanoporous ATO over the films and the thickness of the nanoporous ATO is approximately 260 nm.

Abstract: The purpose of this study was to evaluate the TiO₂ nanotubes growth and the variation in its diameter to improve the surface properties of Ti-7.5Mo to use for biomedical applications. For the nanotubes TiO₂ growth, the samples were anodized in glycerol and ammonium fluoride and divided according to the anodizing potential at 5V to 10V and 24 hour time. The surfaces were examined by scanning electron microscope (SEM), X-ray analysis (XRD) and contact angle measurements. The average tube diameter, ranging in size from 13 to 23 nm, was found to increase with increasing anodizing voltage. It was also observed a decrease in contact angle in accordance with the increase in the anodizing potential. The X-ray analysis showed the presence of anatase phase in samples whose potential was 10V and this condition represents a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications.

Abstract: The present study employs NaOH as an oxygen source in fluorinated ethylene glycol (EG) electrolyte for the formation of titanium dioxide nanotube arrays (TiO₂ NTs) by anodic process. The nanotube formed were 125 nm in diameter with length of ~ 7 µm after 30 min of anodization. They were then annealed to study the effect of annealing temperature on the photocurrent generated by the TiO₂ NTs. It is found that TiO₂ NTs annealed at 400 °C has the highest photocurrent (0.716 mA cm^-2 at 0.5 V vs Ag/AgCl). This is attributed to the crystallinity (mostly anatase) of the TiO₂ NTs as well as the nanotubular structure which retains at this temperature but not at higher temperature.

Abstract: In this work, we present the effect of preparation temperature of electrolytes for fabricating undoped and silver (Ag) doped titanium dioxide (TiO₂) nanotubes by the electrochemical anodic oxidation of pure titanium sheets in electrolytes, mixtures of ethylene glycol (EG), ammonium fluoride (NH₄F) and deionized water, that contain with different of silver ions. Heat treatment of electrolytes was carried out at 100 °C during preparation process. The morphology and structure of prepared nanotubes were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The structures of TiO₂ nanotubes obtained from heat treatment and non-heat treatment of electrolyte solutions and adding silver ions in electrolyte solution are similar. The nanotubes appear in arrays and the diameters of nanotubes were about 92 nm for non-heat treatment electrolyte solution and undoped TiO₂ and about 102 nm for heat treatment electrolyte solution and all Ag-doped TiO₂ nanotube arrays. When the concentration of silver nitrate (AgNO₃) increases, the TiO₂ nanotube arrays cracked and are not well arranged.

Abstract: Hybrid TiO₂ nanowire–nanotube structure was synthesized by a facile anodization on Ti substrate. To study the origin and evolution of TiO₂ nanotubes, the morphology of TiO₂ nanotubes was investigated. It was found that nanotubes corrode gradually into nanowires, and the critical time was about 8.5 h after the beginning of anodization. Uniform nanotubes were obtained by ultrasonic cleaning. It was demonstrated experimentally that the inner diameter of TiO₂ nanotube increased with the extension of anodization time, but the outer diameter of TiO₂ nanotubes, which were fabricated under different anodization time, was almost the same.