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

Tin disulfide β-SnS2 thin films have been prepared on pyrex substrates bythe spray pyrolysis technique using tin tetrachloride and thiourea as starting materials. Thedepositions were carried out in the range of substrate temperatures from 240 to400 °C. Highly c-axis oriented β-SnS2 films, having a strong (001) X-raydiffraction line are obtained at temperature 280 °C and using concentration ratioin solution $\Re = [{\rm S}]/[{\rm Sn}] = 2.5$ . Films surfaces were analyzed by contactAtomic Force Microscopy (AFM) and by Scanning Electron Microscopy (SEM) in order tounderstand the effect of the deposited temperature on the surface structure. On the otherhand, from transmission and reflection spectra, the band gap energy determined is about2.71 eV. Finally using the photodeflection spectroscopy technique, the thermal conductivityK c and diffusivity D c were obtained. Their values are 10 Wm−1K−1 and 10−5 m2s−1 respectively.

The electromagnetic properties of thin dielectric or composite layersare considered. We study the case when the thickness dof 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 casethe 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 particlesare 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 formupon 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 (V 0 = 13 and 33 l) and indicate correct preliminary tendencies.

Diffractive multifocal lenses are usually discussed in terms of geometric zoneprofiles imparted a surface of a refractive lens. Consequently, the zeroth order diffractivepower is usually called the "refractive power" of the diffractive lens. By contrast, wefocuss on the refractive power or refractive power profile of the zones of a diffractivelens and calculate the path length error of any of the zones in a given defocus position onthe 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 suchpositions. 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 shockprocessing. With a pulse density of 10000 pulses/cm2, a compressive residual surface stressis achieved. The affected depth is almost 900 μm, the maximum compressive stress −700 MPa.

In this paper we present the results of modeling concerningcurrent-voltage (V < 0) characteristics of metal/ultra-thin oxide/semiconductorstructures, where the oxide thickness varies from 45 Åto 80 Å. We analyzethe theoretical influence of the temperature and Schottky effect, on the Fowler-Nordheim (FN) conduction. The results obtained show that these influencesdepend on the electric field in the oxide and the potential barrier at themetal/oxide interface. At the ambient temperature, the influence on thispotential barrier is lower than 1.5% . However, it can reach 45% on thepre-exponential coefficient (K 1). It is therefore necessary to consider in the FNclassical conduction expression a correction term that takes account of thetemperature and Schottky effects. These results are validated experimentally bymodeling at high field, the current-voltage characteristics of the realizedstructures. At low field, we have determined the excess current [3],which is due to defects localized in the oxide layer, according to the structurearea and the oxide thickness. By modeling this excess current, we show that itis of FN type, and deduct that the effective defect barrier depends little onthe structure area and the oxide thickness. By taking into account the effectivebarrier value and the corrective factors due to the temperature and Schottkyeffect, we determine the defect effective area and show that it is related tothe breakdown field of the structures: when the defect effective area increases, the breakdown field decreases.

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