No abstract

No abstract

In the present work, well ordered arrays of TiO 2 nanotubes were obtained by anodization at different voltages of Ti foil in a solution containing anhydrous ethylene glycol + 0.27 M NH 4 F and 0.2 wt% water. A detailed study has been performed to evaluate the morphology and electrochemical characteristics of the anodized Ti foil synthesized in different anodization potentials. Correlation between the physical properties and the dimensional aspect of TiO 2 nanotubes was examined. In this paper, we report the electrochemical characteristics of the Ti/TiO 2 nanotube surfaces from Tafel plots. The electronic properties of TiO 2 nanotubular layers were also determined by electrochemical impedance spectroscopy analysis (EIS). EIS is considered to be a valuable tool that allows determining barrier oxide parameters. A linear dependence of barrier thickness on the anodizing voltage was verified from 20 to 50 V, the proportionality constant of the barrier layer thickness in relation to the applied anodizing voltage was estimated from the proposed equivalent circuit.

CoPt and FePt nanowire arrays were successfully prepared by electrodeposition into nanochannels of porous alumina membranes. The as-deposited CoPt alloy has a face centred cubic structure and displays soft magnetic properties. Heat treatment at 700 °C for different durations, under vacuum condition was carried out in order to obtain the ordered face centred tetragonal phase L10, exhibiting hard magnetic properties. After annealing, arrays of nanowires actually show hard magnetic properties with coercive fields up to 1.1 T at room temperature. Phase transformation, structural and magnetic properties were analysed and necessary conditions to obtain optimum magnetic properties are concluded.The first results obtained with FePt nanowires denote a more complicated system since the as-deposited material shows no magnetization. Magnetism appears only after annealing at 700 °C minimum. Coercivity up to 1.1 T has been obtained at room temperature but with inhomogeneous phase composition.

No abstract