We present an overview of template synthesis as it applies to our nanomaterials research. This bottom-up approach is motivated by our desire to find an alternative to the big, top-down approaches to nanoscience, such as clean-rooms and X-ray lithography. Using universally available templates and materials, and very modest synthesis techniques, we have created a variety of interesting and useful structures. Starting with homogeneous ferromagnetic nanowires, we were able to study and manipulate spin-dependent transport. Next, we branched into multi-layer GMR and spin-valve structures for spintronics. As a side trip, we put carbon-encapsulated fullerene nanoparticles into nanopores for ballistic magnetoresistance studies. Carbon nanotube molecules were grown in templates by CVD self assembly. The carbon nanotubes grown using a cobalt catalyzer show spin-valve, ballistic transport, and Coulomb blockade effects. Very recently, we have started to study templated semiconductor nanorods with the amazing result that their behaviour is very similar to that of the carbon nanotubes and can be reduced to a scaling law. Essentially, the template acts as a skeleton for the nanoscale synthesis and macroscale contact of an infinite variety of materials and structures. It is our hope that by the following examples we demonstrate that high quality nanoscience research is available to everybody.

The galvanomagnetic effects in new diluted magnetic semiconductors Pb$_{1-x}$SnxTe:Yb were studied to build the energy level diagram under variation of the alloy composition and establish the connection between the parameters of electronic structure and magnetic properties. It was found that the Hall coefficient increases almost by order of magnitude with increasing the temperature. As tin content decreases, while the ytterbium concentration grows, the hole concentration decreases by several times. The results are explained by assuming a formation of an ytterbium-induced deep defect level in the energy spectrum of the alloys, which moves up to the top of the valence band with increasing the ytterbium concentration and pins the Fermi level within the valence band at sufficiently high impurity content. The hole concentration vs. ytterbium content dependence was used to calculate the energy position of the Fermi level in the frame of two-band dispersion law and to determine the position of Yb level in the alloys. The diagram of the charge carrier energy spectrum under varying the alloy composition was built.

We have calculated the subband structure and confinement potential of modulation-doped Ga$_{1-x}$AlxAs-GaAs symmetric double quantum wells a function of the doping concentration. Electronic properties of this structure are determined by solving the Schrödinger and Poisson equations self-consistently. To understand the exchange correlation potential effects on the band bending and subband populations, this potential has been included in the calculation at 0 K and, at room temperature. We find that at low doping concentrations the effect of the exchange correlation potential is more pronounced on the subband populations.

We discuss the fabrication and characterization of undoped hydrogenated and crystallized silicon thin films grown by reactive magnetron sputtering at growth rate of about 2 Å/s and at a temperature as low as 100 °C for various ratios of hydrogen dilution in the gas phase mixture (argon + x% hydrogen). Combined infrared absorption and Raman scattering spectroscopy techniques as well as conventional and high resolution transmission electron microscopy and stress measurements are used to fully characterize the films. In this temperature range, a minimum hydrogen dilution of 30% with respect to the plasma mixture (argon + hydrogen) is necessary to produce nanocrystalline films with crystalline volume fraction of about 65%. Moreover, these films are found to promote much lower stress intensity than those reported in previous works. The nature and strength of the stresses are dependent on the film microstructure.


The paper presents a reliable model for the susceptibility analysis of a Rectenna (Rectifying Antenna) in the context of microwave energy transfer. The approach allows to take into account both distributed electromagnetic portions of the antenna and the rectifier circuit including lumped elements. From the 3D electromagnetic modelling of the structure the input impedance is obtained as a function of frequency. Then a rational approximation of the Laplace variable is chosen to describe the port behaviour. The technique provides a straightforward way for a time domain simulation using Pspice or Saber. The proposed approach can be efficiently used to provide a non-linear time-domain study in the framework of EMC (Electromagnetic Compatibility) for various electronic equipments involving printed circuit-boards, internal structures of electronic components or Micro-Electro-Mechanical Systems (MEMS).

A synthetic route is presented for the preparation of a gold film in the presence of UV-radiation. Methoxypolyethylene glycol, a water-soluble polymer, was used as the reducing agent of gold ions in the presence of an ultra-violet source, and gold nanoparticles resulted. During stirring, a centrifugal force is generated at the center of the solution (at the point where the meniscus is at its lowest level with respect to the vertical orthogonal). At this point, the nanoparticles coalesce and form a self-assembly of smaller subunits that ultimately forms a film like network.

The phase diagram of nanoparticles is known to be a function of their size. Since this dependence is also a function of the surface to volume ratio and of the surface tensions, it is expected that it varies with the shape of the nanoparticles. The variation of the melting temperature of polyhedral elemental nanosolids is studied theoretically. It turns out that, in most cases, the size variation of the melting temperature of a sphere is less than for the other shapes. However, there is no general rule regarding the order of the shape parameters of the polyhedra.

Optical spectroscopy studies of Nd3+-doped scheelite calcium molybdate (CaMoO4) single crystal grown by a floating zone-like technique was performed using Judd-Ofelt analysis, besides luminescence data and lifetime measurements in the visible and near infrared domains. The excited state absorption in cross section units of this material was measured by two different methods for all expected infrared emission. By using calculated intensity parameters $\Omega _{t}$ (t=2, 4, 6), it were determined branching ratios, emission cross-sections, and lifetimes for all related transitions. The observed single excited state absorption calibrated in absorption cross-section units was found too small to disturb the laser efficiency in the 1030–1100 nm spectral range. A comparison of main spectroscopic parameters of this material with those of other Nd3+-doped crystals is presented.

This paper presents several techniques for determining the complex conductivity of highly electrically conducting polymer films at microwave frequencies. The advantages and disadvantages of these techniques are discussed. Microwave measurements were investigated using resonant cavity, reflection/transmission and impedance surface techniques. The dc conductivity was measured using the four wires technique. Polyaniline (Pani/DEHEPSA) films of 120 $\mu $m thickness, have conductivity of (5000-6000 S/m) and permittivity of $6000 \pm 1000$ over X and S bands. The high values of the measured conductivity and its weak dependence on frequency at least up to 12 GHz, confirm the metallic character of Pani-films and their efficient use in micro-electronic technology such as microwave integrated circuits (MMIC) and microwave devices.

The analysis by means of X-ray $\mu $CT offers a versatile tool for the non destructive characterisation of metallic foams. The most important methods for the quantitative feature determination will be presented and applied to an Al-foam produced by a powder-metallurgical processing route. The special properties of monochromatic synchrotron radiation have been used to study not only the pore- and cell-wall space quantitatively at a high resolution, but also the distribution and geometric parameters of the blowing agent TiH2. The analysis steps can be used as a standard procedure to characterise the structure of metallic foams.

Internal oxidized copper was tested by isothermal mechanical spectroscopy in a medium temperature range (300–600 K). Experimental results show the existence of a non-thermally activated effect at low temperature and of a relaxation peak at higher temperatures. The material microstructure was studied by combination of Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectrometry (EELS). The TEM study allowed us to investigate the distribution of fine spherical particles and the presence of particular network dislocations inside the grains. The EELS method was used to identify the nature of these fine particles as Cu2O. The internal friction has revealed a non thermally activated maximum occurring at 0.1 Hz for temperatures ranging from 290 K to 394 K, and a relaxation peak obtained after annealing at 573 K. This peak is stable after successive annealings at 723 K and 873 K. Comparison of the microstructure observations, their evolution with annealing and the evolution of the relaxation effect with annealing temperature enables us to interpret the phenomena described in this work: on the one hand, the microstructural characterisation using TEM and EELS allows us to assign the first effect to the result of a transformation of metastable Cu2O particles to CuO under the cyclic stress; on the other hand, the relaxation peak that does not change after high temperature annealing is linked with a particular stable dislocation network observed in many grains. 


X-ray emission from a compact diode consisting of a sharp edged cathode and flat anode of copper and lead, energized by simple capacitor discharge is reported. With a sewing machine needle cathode, and lead target, the generation efficiency upto 0.4% is obtained. The efficiency is expected to enhance further with the increase in discharge energy, charging voltage and reducing the parasitic inductance.

Gas mixtures containing humid air, various proportions of CO2 and traces of NO2 are submitted to a short gap point-to-plane DC corona discharge in a reactor at atmospheric pressure. These mixtures can be considered as the basic component of most industrial effluents. Coming after an electrical study previously published, this work is centered on the physico-chemical effects of the discharge. Concentric circular alterations appearing on a copper cathode have been analyzed by XPS, showing an oxidation and acidification spread over a great part of the surface by the electric wind. The NO2 removal and corresponding by-products have been studied by UV absorption spectroscopy on gas samples after treatment, in the 200–400 nm wavelength range where NO2 abatement and O3 concentrations can be evaluated. Being partly produced in liquid phase, HNO3 which is responsible of the acidification of cathode surface, can be studied only qualitatively. A few chemical mechanisms are propounded for both bulk and surface actions of the discharge.

YO molecules in the vapor phase above Y2O3 melted in a solar furnace exhibit a fluorescence phenomenon induced by absorption of the incident radiation. The simulation of these spectra by a two temperature model and comparison with measured spectra allowed to estimate the temperature field in the gas phase above the melted sample. The results are compared to the results of a simulation by a commercial fluid dynamics software.

The dynamics of shock waves and cavitation bubbles generated by short laser pulses in water and elastic-plastic media were investigated theoretically in order to get a better understanding of their role in short-pulsed laser surgery. Numerical simulations were performed using a spherical model of bubble dynamics which include the elastic-plastic behaviour of the medium surrounding the bubble, compressibility, viscosity, density and surface tension. Breakdown in water produces a monopolar acoustic signal characterized by a compressive wave. Breakdown in an elastic-plastic medium produces a bipolar acoustic signal, with a leading positive compression wave and a trailing negative tensile wave. The calculations revealed that consideration of the tissue elasticity is essential to describe the bipolar shape of the shock wave emitted during optical breakdown. The elastic-plastic response of the medium surrounding the bubble leads to a significant decrease of the maximum size of the cavitation bubble and pressure amplitude of the shock wave emitted during bubble collapse, and shortening of the oscillation period of the bubble. The results are discussed with respect to collateral damage in short-pulsed laser surgery.