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We report on the synthesis and characterization of nanofibrous structures of vanadium oxide V 2 O 5 by anodic electrodeposition. The electrodeposits are thick layers of several micrometers consisting of fibers with length in the micrometer range and a width of about 10 nm. At variance with available reports, the vanadium oxide nanofibers were obtained without the use of templates or additives. Electrochemical synthesis was performed in aqueous solutions containing VOSO 4 and Na 2 SO 4 . The observed sponge-like structure, and consequent large surface area, with strong entanglement of the nanofibers are potentially important material ' features for applications such as gas sensors, lithium batteries, and catalysis.

We investigate the influence of chloride Cl - ions in a broad range of chloride concentrations on the kinetics and mechanism of copper electrodeposition from sulfate-based acidic electrolytes. Chloride ions influence copper deposition through two competitive effects: at low Cl - concentration (few mM), chloride ions depolarize the Cu reduction process, while higher Cl - concentrations induce complexation of copper species and cause a cathodic polarization of the deposition process. Cu reduction proceeds through two parallel mechanisms, a direct two-step reduction and a chloride-mediated route, whose relative importance depends on the amount of chloride present. A transition between these two mechanisms can be identified both by steady-state and impedance methods; however, the chloride concentration at which it occurs depends on the time scale probed by the two techniques. Impedance measurements further demonstrate that the presence of chlorides changes the double-layer structure.

We present a study of the effect of chloride anion additions on the electrochemical nucleation and growth of copper on n-Si(100) from acidic sulfate solutions. Chloride additions in the millimolar range depolarize copper reduction, while additions in the 100 mM range and above have the opposite effect. Chlorides have no effect on the nucleation and growth mode. Deposition at constant potential in the presence of small amounts of chloride leads to an increased deposition overpotential, but contrary to the predictions of nucleation theory, this results in a lower density of nuclei with larger size. We hypothesize that adsorption of chlorides on the copper islands enhances surface diffusion processes which lead to island coarsening through Ostwald ripening. Morphological changes during deposition are possible at room temperature due to the high values of diffusivities at the electrolyte/ solid interface.

CoNiP alloy films have been grown by electrodeposition from a chloride bath under galvanostatic control. Film growth, structure, composition, magnetic properties, and morphology have been found to depend significantly on deposition current density. Hard magnetic films were successfully grown at the current density of 7 mA/cm 2 with thickness up to 10 μm, at which a perpendicular coercivity of 188 kA/m was achieved. The magnetic hardness and perpendicular anisotropy of these films are the combined result of a microstructure composed of columnar grains and of a hexagonal phase oriented with the c axis perpendicular to the film plane. Preliminary investigations of magnetization reversal processes suggest the presence of pinning sites located probably at grain boundaries.

Co-Pt (Pt ∼ 20 atom %) alloy films were electrochemically grown at constant current density on Cr seed layers in order to study the influence of the Cr surface on their morphology and magnetic properties. The Cr seed layer favors the growth of a hexagonal close-packed phase, as revealed by X-ray diffraction. Morphological investigation using a scanning electron microscope revealed the electrocrystallization of Co-Pt on Cr to be proceeding through the nucleation and growth of three-dimensional (3D) clusters with columns growing outward in all directions from isolated nucleation centers. The 3D growth is likely due to the presence of a thin oxide layer on the Cr seed. At lower current density, individual micrometer-sized clusters were formed with distinct hexagonally shaped faces. Increasing current density results in a finer grain microstructure. At early stages of growth and low current density, the clusters exhibit a faceted morphology similar to that of the substrate. Samples prepared at higher current density or with larger thickness show larger coercivities, reaching values as high as 3490 Oe (278 kA/m) and 2275 Oe (181 kA/m) in the perpendicular and parallel directions, respectively, for a 500-nm-thick film deposited at 50 mA/cm 2 .