ZnO thin films have been deposited on Si(111) substrates at different positions of the focusing lens by pulsed laser deposition (PLD) of a ZnO target in an oxygen atmosphere. The strong influence of the position of the focusing lens on the deposition rate, crystallinity, surface morphology and optical properties of the deposited ZnO thin films are studied. The results show that the ZnO thin films deposited at lens-target distance $(D_{l-t}) =59.5$ cm (the focal length is 70 cm) have the highest deposition rate and crystalline quality. The photoluminescence (PL) spectrum with the strongest ultraviolet (UV) peak and blue peak is observed in this condition. Moreover, the results of scanning electron microscopy (SEM) and selected area electron diffraction (SEAD) indicate that the films deposited at this lens position show the transition from monocrystalline to polycrystalline. Perfect monocrystalline ZnO films are obtained only when Dl-t is changed in the range from 63 cm to the focus position.

We produced gallium oxide (Ga2O3) nanomaterials with various widths on chromium (Cr) substrates by the thermal evaporation of GaN powders. We characterized the samples using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and photoluminescence spectroscopy. The results showed that the products consisted of belt-like Ga2O3 nanomaterials, which had monoclinic structures. The photoluminescence spectrum showed a blue light emission.

We report on the integration of erbium doped silicon-rich oxide into toroidal microcavities. Coupling of erbium ions to microtorus whispering gallery modes is evidenced at room temperature under excitation of silicon clusters. The fabrication process is controlled so that no luminescence quenching occurs during the silica melting step. The spatial and spectral distributions of outgoing light are investigated thanks to independent excitation and collection optics.

In this paper, the linear perturbation theory is used to study material instability in a classical elasto-plastic model. In this framework, the well known Rice criterion of bifurcation into localized modes is found to be a limiting case corresponding to unbounded growth of perturbation. In the first part, derived expression of the critical plastic modulus is numerically plotted versus the spherical coordinates of the potential normal to the localization band in order to describe the whole space. In the second part, conditions of occurrence of the other types of instability are established, namely divergence and flutter types of instability, and modelling details influencing them checked. These conditions are also relative to the parameter of growth of perturbations which can be plotted versus the plastic modulus considered as the loading parameter. When several modes of instability are possible, an hierarchy is established.

PbO-P2O5-As2O3 glasses containing different concentrations of Al2O3 ranging from 0 to 5 mol% were prepared. Dielectric properties (viz., dielectric constant $\varepsilon{'}$, loss tan $\delta $ and a.c. conductivity $\sigma_{ac}$ over a moderately wide range of frequency and temperature and dielectric breakdown strength in air medium), optical properties (optical absorption, IR spectra and thermoluminescence) and differential thermal analysis have been studied. The interesting changes observed in these studies have been explained in the light of different structural groups of aluminium ions.

The local electric behaviour of IMPATT diodes was studied by scanning transmission electron beam induced current in cross-section method (X-STEBIC). This technique of induced current measurement makes it possible to probe the depletion zone of a junction with the beam of a transmission electron microscope. Two series of experiments were carried out. The X-STEBIC signal was analyzed according to the sample thickness and under different electrical polarizations. Moreover, these measurements were done and compared at room and low temperature (≅110 K). From these data, simulations of X-STEBIC profile allowed us to determine the main physical parameters brought into play in the signal formation. We have shown that, in the vicinity of the junction, the intensity of the induced current partly depends on the avalanche effect. The kinetic energy of the minority carriers generated by the electron beam is sufficient to induce collisions in cascade, even when the junction is not polarized. At low temperature, surface recombination has an essential role on the lateral resolution of the X-STEBIC method. By choosing carefully the range of sample thickness and by positioning the probe in the field of the diode, it is possible to optimize the resolution. Surface recombination annihilates the diffusion of the carriers so that the STEBIC image becomes a true image of the electric field. Consequently, semi-quantitative physical data can be obtained on the junction field.

We model the ejection of tungsten atoms from a hot filament by a binomial distribution. A normal approximation is made and the lamp is supposed to fail if the undecayed atomic fraction drops below a critical value. The resulting formula for the lamp survival probability has no free parameter and is shown to be in excellent agreement with the experimental mortality curve.

The surface modifications produced by treatment of a synthetic sulfur vulcanized styrene-butadiene rubber with oxidizing (oxygen, air, carbon dioxide) and non oxidizing (nitrogen, argon) RF low pressure plasmas, and by treatment with atmospheric plasma torch have been assessed by ATR-IR and XPS spectroscopy, SEM, and contact angle measurements. The effectiveness of the low pressure plasma treatment depended on the gas atmosphere used to generate the plasma. A lack of relationship between surface polarity and wettability, and peel strength values was obtained, likely due to the cohesive failure in the rubber obtained in the adhesive joints. In general, acceptable adhesion values of plasma treated rubber were obtained for all plasmas, except for nitrogen plasma treatment during 15 minutes due to the creation of low molecular weight moieties on the outermost rubber layer. A toluene wiping of the N2 plasma treated rubber surface for 15 min removed those moieties and increased adhesion was obtained. On the other hand, the treatment of the rubber with atmospheric pressure by means of a plasma torch was proposed. The wettability of the rubber was improved by decreasing the rubber-plasma torch distance and by increasing the duration because a partial removal of paraffin wax from the rubber surface was produced. The rubber surface was oxidized by the plasma torch treatment, and the longer the duration of the plasma torch treatment, the higher the degree of surface oxidation (mainly creation of C–O moieties). However, although the rubber surface was effectively modified by the plasma torch treatment, the adhesion was not greatly improved, due to the migration of paraffin wax to the treated rubber-polyurethane adhesive interface once the adhesive joint was produced. On the other hand, the extended treatment with plasma torch facilitated the migration of zinc stearate to the rubber-adhesive interface, also contributing to deteriorate the adhesion in greater extent. Finally, it has been found that cleaning of SBS rubber in an ultrasonic bath prior to plasma torch treatment produced a partial removal of paraffin waxes from the surface, and thus improved adhesion was obtained.

The aim of this work is to identify the main process responsible for sterilization of Geobacillus Stearothermophilus spores in O2:N2 RF inductively coupled plasma. In order to meet this objective the sterilization efficiencies of discharges in mixtures differing in the initial O2/N2 ratios are compared with plasma properties and with scanning electron microscopy images of treated spores. According to the obtained results it can be concluded that under our experimental conditions the time needed to reach complete sterilization is more related to O atom density than UV radiation intensity, i.e. complete sterilization is not related only to DNA damage as in UV sterilization but more likely to the etching of the spore.

We present the optimization of a sterilization process with a N2 flowing afterglow post-discharge. First we study the inactivation of bacteria (E. coli) submitted to the post-discharge, and discuss the mechanisms of bacteria inactivation. Then we evaluate the volume repartition of the active species (N atoms produced by plasma discharge) in the chamber of treatment.

In this work is presented a detailed physicochemical, structural and optical characterization of SiOxNy thin films. The films deposited using PECVD in SiH4-N2O-He discharges were thermally annealed at 1273 K for 1 hour in ambient nitrogen. The film stochiometry was measured by Rutherford Backscattering Spectroscopy. The chemical composition was dominated by silicon suboxide containing some Si-N and Si-H bonds. Raman scattering measurements suggest the formation of nanocrystallite silicon in the annealed films. The Raman observation is strongly supported by Transmission Electron Microscopy analysis which shows a high density of silicon nanocrystals, having a mean radius ranging between 3 and 6 nm. Using Spectroscopic Ellipsometry, we discussed the dielectric function evolution as a function of the deposition parameters.

In this review, we report on the use of low pressure plasmas for elaborating materials at the heart of solid polymer fuel cells (SPFC), especially electrodes and the membrane electrolyte. Electrodes are formed using plasma sputtering techniques while the ion conducting membranes are built up using plasma polymerization. Fuel cell performance will be improved by these approaches. The electrode catalyst profile is optimized while membrane working temperature is increased and methanol crossover is lowered compared to conventional PEM fuel cells.

This paper presents a novel dual plasma enhanced chemical vapor deposition (PECVD) process developed to grow carbon nitride nanofibres (CN-NFs) at room temperature (RT) and its basic version used to grow multi-walled carbon nanotubes (MWCNTs) at temperatures as low as 550 °C. The dual process alternates two low pressure-high density plasmas, one inductively coupled (ICP) and the other one excited by distributed electron cyclotron resonance (DECR). MWCNTs can be synthesized using only the DECR plasma source. The paper focuses on the comparison between CN-NFs and MWCNTs detailing their structure as revealed by transmission electron microscopy (TEM), X-ray photo electron spectroscopy (XPS) and Raman spectroscopy.