we report the growth of BaTiO3 thin films by standard Radio Frequency sputtering. Without any in situ or post annealing, these polycristalline films are oriented relative to the substrate even when it is amorphous. We show that this preferential orientation may be monitored using a DC Bias during the film growth. At room temperature, cubic films of (100) and (110) orientations have been achieved, on fused silica substrate. Some optical waveguiding properties of these films have been studied. The resulting film index is 2.26 and the optical step index at the substrate interface is sharp. This allows the use of standard RF sputtering techniques to monitor oriented BaTiO3 films for linear optical applications.

Tin disulfide β-SnS2 thin films have been prepared on pyrex substrates by the spray pyrolysis technique using tin tetrachloride and thiourea as starting materials. The depositions were carried out in the range of substrate temperatures from 240 to 400 °C. Highly c-axis oriented β-SnS2 films, having a strong (001) X-ray diffraction line are obtained at temperature 280 °C and using concentration ratio in solution $\Re = [{\rm S}]/[{\rm Sn}] = 2.5$. Films surfaces were analyzed by contact Atomic Force Microscopy (AFM) and by Scanning Electron Microscopy (SEM) in order to understand the effect of the deposited temperature on the surface structure. On the other hand, from transmission and reflection spectra, the band gap energy determined is about 2.71 eV. Finally using the photodeflection spectroscopy technique, the thermal conductivity Kc and diffusivity Dc were obtained. Their values are 10 Wm−1K−1 and 10−5 m2s−1 respectively.

The electromagnetic properties of thin dielectric or composite layers are considered. We study the case when the thickness d of a slab is so small that only a few particles forming the effective medium are located on the interval d. A novel approach to the quasistatic modelling of the local field acting on a particle is suggested. In this case the local "permittivity" near the upper and lower surfaces of the slab differs from the bulk permittivity of the same material. This can influence the reflection and transmission properties of the slab. Even if the particles are isotropically polarizable or are randomly oriented in the slab volume, this thin structure has anisotropic (uniaxial) electromagnetic properties.

Mm(OH)3 (Mm = mischmetal) single crystalline needles with [001] growth axis form upon exposure of MmNi5-substituted alloys to aqueous KOH. Crystal structure, chemical composition and morphology of the needles are studied by means of scanning electron microscopy and quantitative transmission electron microscopy. The needles can be either solid (whiskers) or hollow (nanotubes). Their morphology and growth kinetics are studied as a function of immersion temperature, stirring rate of the aqueous KOH electrolyte and presence of tracer. Based on the observations, a model mechanism is developed for their growth.

The aim of this work is to study the kerosene explosibility in closed or vented vessels and to develop an application to safety systems. The basic characteristics of the model have been developed for the ignition and the combustion of propulsive powders and adapted to liquid fuels with appropriate parameters linked to simplified kinetics. A simple representation of the combustion phenomena based on energy transfers and the action of specific molecular species is presented. The pressure venting, due to the vent breaking is calculated taking into account the mass rate of discharge of the different products in the assumption of the standard orifice equations. The model allows the study of various parameters such as the nature of the kerosene, the fuel ratio of the mixture, the ignition energy, the thermal exchanges and the influence of the pressure venting or the vent area. The theoretical results have been compared with data obtained in the course of experiments performed in small vessel volumes (V0 = 13 and 33 l) and indicate correct preliminary tendencies.

Diffractive multifocal lenses are usually discussed in terms of geometric zone profiles imparted a surface of a refractive lens. Consequently, the zeroth order diffractive power is usually called the "refractive power" of the diffractive lens. By contrast, we focuss on the refractive power or refractive power profile of the zones of a diffractive lens and calculate the path length error of any of the zones in a given defocus position on the lens axis. From this the phase angle of the resulting amplitudes can be calculated. Analytical expressions for the positions of the diffractive powers as a function of (average) zone powers are derived as well as analytical expressions for the intensities in such positions. Also, general restrictions on usable zone power profiles are derived.

A large-core multi mode optical fiber is used to deliver 100 mJ, 5 ns laser pulses produced by a frequency-doubled Nd:YAG laser over a distance of several meters. No damage is observed neither inside the fiber nor at its surface. The transmitted pulses are focused to a diameter of 700 μm onto a water-immersed type 304 stainless steel sample for laser shock processing. With a pulse density of 10000 pulses/cm2, a compressive residual surface stress is achieved. The affected depth is almost 900 μm, the maximum compressive stress −700 MPa.

In this paper we present the results of modeling concerning current-voltage (V < 0) characteristics of metal/ultra-thin oxide/semiconductor structures, where the oxide thickness varies from 45 Åto 80 Å. We analyze the theoretical influence of the temperature and Schottky effect, on the Fowler-Nordheim (FN) conduction. The results obtained show that these influences depend on the electric field in the oxide and the potential barrier at the metal/oxide interface. At the ambient temperature, the influence on this potential barrier is lower than 1.5% . However, it can reach 45% on the pre-exponential coefficient (K1). It is therefore necessary to consider in the FN classical conduction expression a correction term that takes account of the temperature and Schottky effects. These results are validated experimentally by modeling at high field, the current-voltage characteristics of the realized structures. At low field, we have determined the excess current [3], which is due to defects localized in the oxide layer, according to the structure area and the oxide thickness. By modeling this excess current, we show that it is of FN type, and deduct that the effective defect barrier depends little on the structure area and the oxide thickness. By taking into account the effective barrier value and the corrective factors due to the temperature and Schottky effect, we determine the defect effective area and show that it is related to the breakdown field of the structures: when the defect effective area increases, the breakdown field decreases.

An experimental investigation of hysteretic switching in antiferroelectric liquid crystals has been carried out. It is shown that in switching from the antiferroelectric state to the ferroelectric state there exists both a heterogeneous process involving the growth of finger-like domains and a homogeneous process in which the whole cell uniformly switches. At high field slew rates the homogeneous process dominates. However, ferroelectric to antiferroelectric switching involves only a heterogeneous process. A simple analytic model is then used to describe the experimental results and thus understand the competition between homogeneous and heterogeneous switching.

The linear stability analysis of a Newtonian fluid between two coaxial vertical cylinders with a radial temperature gradient shows the existence of thermal and hydrodynamic axisymmetric oscillatory modes. The critical parameters depend on the nature of the fluid and on the radius ratio of the cylinders. The two modes have the same threshold on a line of the codimension 2 points in a plane spanned by the radius ratio and Prandtl number.