Jeremy Mallet

Fabrication and magnetic properties of fcc CoXPt1−X nanowires

CoXPt1−X alloy nanowires were fabricated by electrochemical template synthesis from a solution containing both Co(II) and Pt(II) ions. Over a wide range of deposition conditions, single-phase, fcc CoXPt1−X alloy nanowires were obtained. The nanowires exhibit both shape and magnetocrystalline anisotropy leading to large coercivity and high remanence along the wire axis. The magnetocrystalline anisotropy constant Ku was determined for 〈111〉 textured nanowires.

Aging effect on the copper sorption on a vineyard soil: column studies and SEM-EDS analysis.

The uptake of copper by a vineyard soil in fixed bed column systems was investigated in order to study the influence of the aging time on the soil retention capacity. The application of copper by means of several additions, as in field conditions, increases the retention capacity of the soil relative to a single one application of the metal. The aging effect is responsible for this phenomenon, since its increase enhances the amount of adsorbed copper. Moreover, aging the soil reduces the amount of available copper during a Ca(NO(3))(2) leaching of the soil columns which suggests a redistribution of a weakly-bound copper fraction to a more strongly-bound fraction. Scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS) indicates that copper is heterogeneously distributed within the soil sample. Nevertheless, copper is preferentially associated with fractions containing Fe and Al atoms.

Low electric field strength self-organization of anodic TiO2 nanotubes in diethylene glycol electrolyte

Self-organization of TiO2 nanotubes with large interconnecting space in-between the tubes has been demonstrated by the anodization of titanium in diethylene glycol/HF electrolyte containing a desired amount of water. The unique morphological features are a consequence of low electric field strength conditions, leading to the growth of tubes on a low population of nucleation sites. The proposed growth model assumes the presence of a metallic titanium in-between the tube cells that are oxidized/etched, resulting in the generation of an inhomogeneous oxide at the bottom of the nanostructure. The presented work contributes to the research field by the following aspects: (i) the low field strength conditions have been demonstrated to have an impact on the tube spacing, (ii) the water content in the electrolyte allows the precise control of the interconnecting space in-between the tubes, (iii) the tubes separation is controlled by the presence of Ti in-between the tube cells.

Temperature and pH influences on the structural and the emission properties of electrodeposited CdSe nanowires

Cadmium selenite (CdSe) nanowires have been electrodeposited by potentiostatic method using polycarbonate membranes as template. For the same potential value, the pH modification of the solution or the temperature variation of the substrate leads to drastic differences of the CdSe composition. A meticulous study of the influence of both temperature and pH value on the stoichiometry of electrodeposited CdSe nanowires has been done and several combinations of temperature/pH leading to the 50–50 CdSe composition have been found. The as-electrodeposited CdSe nanowires under these specific conditions reveal a good crystallinity with a <111> preferred growth orientation exhibiting a luminescence band in the visible range corresponding to the CdSe gap.

Single step electrodeposition process using ionic liquid to grow highly luminescent silicon/rare earth (Er, Tb) thin films with tunable composition

A one-step method for the electrodeposition of silicon–erbium (Si/Er) and silicon–terbium (Si/Tb) thin films using room temperature ionic liquid (RTIL) has been successfully developed. By playing with the electrochemical parameters, the concentration of incorporated rare earth (RE) ions (Er3+ and Tb3+) in the thin films can be tuned. The obtained thin films have been characterized by electron microscopy and composition analysis techniques. The structural quality of the obtained thin films is characterized by a uniform distribution of Si atoms and RE ions throughout the thickness. The study of the optical properties, carried out by photoluminescence (PL) spectroscopy, demonstrates the efficient optical activity of the films with typical Er and Tb luminescence at room temperature depending on the RE content. The deposition method described is a promising strategy for incorporating RE ions in semiconducting thin films to achieve materials for opto-electronic applications.