Most of NdBaCuO synthesis were realized under oxygen controlled melt growth (OCMG) which allows to avoid the solid solution formation. However, for industrial applications air synthesis is preferable due to its simplicity and its cost. In this work, different seeds and thermal cycles have been investigated in order to optimize the nucleation conditions for the obtention of a single domain. Several criteria have been defined for the choice of the seed. The solid solution Nd1+xBa2−xCu3Oy formed in these air synthesised samples appears in the range of x = 0.10 to 0.15, corresponding to $T_{\rm c_{onset}}$ between 60 K and 80 K. The nominal composition and the synthesis conditions (substrate, thermal treatments.) have to be accurately defined in order to avoid neodymium-rich solid solution formation.

The floating zone method is currently used to obtain Y123 melt textured bars, however the final sample length is always limited by the sample lower part weight which is sustained only by the liquid phase tension surface energy. Indeed, the basic scheme is to attach the bar only by the upper part and the lower part is totally free. A vertical furnace permits then to heat locally the bar and to create the floating zone. The sample translation at low speed (about 1 mm/h) allows the formation of a re-crystallization zone, according to the well known reaction Y211+Liquid (Ba and Cu rich) $\to$Y123, permitting the fabrication of a well textured bar. This work is devoted to present a modification of this process in order to have no limitation in the sample length. The idea which is developed here is to include inside the bar and co-axially a platinum wire. We have chosen a platinum wire due to its high melting temperature and its relatively low reactivity with Y123. We present here results obtained in term of reactivity, texture formation and superconducting properties when Y123 is textured in the presence of platinum wire versus different doped element introduced in the initial mixture.

Chiral sculptured thin films (STFs) have unidirectionally periodic electromagnetic constitutive properties and therefore exhibit the circular Bragg phenomenon. The time-domain Maxwell equations are solved using finite difference calculus in order to establish the spatiotemporal anatomy of the action of axially excited, chiral STF slabs on optical narrow-extent pulses (NEPs) modulating circularly polarized carrier waves. A Lorentzian model was adopted for the permittivity dyadics of the chiral STFs. The time-domain manifestation of the circular Bragg phenomenon is focussed on. First, on examining the refraction of NEPs by a chiral STF half-space, a light pipe and the pulse bleeding phenomenon are shown to occur -when the handednesses of the carrier wave and the chiral STF coincide and the carrier wavelength is in the vicinity of the center-wavelength of the Bragg regime. Next, pulse bleeding inside a chiral STF slab is shown to be responsible for the long wakes of reflected pulses and low energy contents of transmitted pulses, when the incident wave spectrums significantly overlap with the Bragg regime and the carrier waves have the same handedness as the chiral STF slab. Thus, a chiral STF slab can drastically affect the shapes, amplitudes, and spectral components of femtosecond pulses.

The redistribution of Ni in InP is studied by annealing samples of InP implanted with 0.9 MeV Ni at 60o angle of ion incidence with respect to target surface normal as a function of dose (8.5×1012−4.5×1015 cm−2). Ni profiles are measured by secondary ion mass spectrometry (SIMS) and implantation induced damage by Rutherford backscattering spectrometry in channeling (RBS/C) condition. The highest dose sample is characterised by remarkable Ni accumulation near the surface (at ∼$0.3R_{\rm np}$) that has not been observed earlier along with two other distinct accumulation zones at Rnp+$\Delta R_{\rm np}$ and $2.2R_{\rm np}$ after annealing at 650 °C for 30 min. Here, Rnp is the normal component of the projected range for oblique angle bombardment.

Differential scanning calorimetry measurements under non-isothermal conditions were performed on the chalcogenide glasses Se98−x Sx Sn2 (x = 8, 18) and Se77 S20 X3 (X = Sn, Pb). The values of the glass transition temperature and crystallization temperature were found to depend on the heating rate. The activation energy for the glass transition and the activation energy for crystallization were calculated from the heating rate-dependence. The thermal stability and the glass forming tendency were calculated and they were found to have the same trend.

N-type lightly doped germanium has been irradiated at room temperature with different particles: swift heavy ions, protons and electrons. Hall effect measurements have been carried out versus either the temperature (at a given fluence) or the fluence (at room temperature). Using the level positions determined by DLTS results previously reported, we extract from the Hall coefficient simulation at low doses the creation kinetics of the irradiation-induced defects. These defects are typically at room temperature the A-centre, the E-centre and the divacancy complexes. At higher doses, in the case of electron irradiation, these simulations are still feasible using only the previous defects mentioned above since the material leads towards a quasi-intrinsic state. But we point out that it is necessary in the case of proton and swift heavy ion irradiations to add an acceptor level in the forbidden band probably associated with a multivacancy defect. Indeed, in these cases, the material becomes p-type. Finally, the experimental introduction rates are compared to the theoretical ones. It appears that the relative damage creation efficiency is not very different from a projectile to another, proving that there is no strong dependence on the electronic energy loss.

The transmissivity of heterogeneous films is computed with the help of Green functions, solutions of discretized Maxwell's equations. These functions, developed in continued fractions, are determined using the spectral moments method (SMM). This spectral method, which allows us to obtain the response for all frequency with two series of iterations. We report computation of the transmissivity of a 2d photonic lattice and a 3d granular layer.

This work is concerned with the study of thermal expansion coefficient of Al-0.59 wt.% Mg-0.88 wt.% Si-0.30 wt.% Fe-0.44 wt.% Mn alloy. The presence of the anisotropy was concluded on the basis of the thermal expansion coefficient $\alpha(T)$ which depends up on the two directions: radial (1) and axial (2). However $\alpha(T)$ measured along the axial direction (2) appeared to be inferior to the measured one along the radial direction (1) in both as-cast and homogenised alloy.

Carbon nitride films synthesised by magnetron sputtering at different substrate temperatures have been studied using electron energy loss spectroscopy (EELS) during annealing performed in situ in a transmission electron microscope (TEM). The proportion of sp2 hybridised carbon slightly decreases initially during heating, presumably because of the removal of defects in the structure, whilst it increases at higher temperatures when graphitisation tends to take place, as confirmed by high resolution electron microscopy (HREM). Substantial amounts of nitrogen (up to ~ 80% ) are removed following annealing at 1000 °C. A corresponding decrease in the pre-peak of the nitrogen spectra suggests that pyridine-like N is released by annealing. As this peak component decreases, a second peak, of weaker intensity, is becoming apparent in the EELS spectra when the films are heated at temperatures above approximately 700 °C. The possibility has been suggested that this corresponds to N substituted for C in a graphitic structure, with possibly also some N2 contributing to the peak.

We have performed atomic scale simulations of heteroepitaxial growth of thin films using the valence force field approximation and Monte Carlo techniques. The case of CdTe/(001)GaAs is considered. Our simulations indicate valley formation presenting (111) facets with unstable bottoms in the early stages of the growth. This roughening is a source of dislocation, as it appears to relax the elastic energy of the deposited layers by formation of V-grooves. We have used a calculated RHEED as an in situ control of deposited layers. Finally, we present the influence of an imperfect surface in the morphology of the deposited films.

Performing both ex situ transmission electron microscopy (TEM) and in situ scanning tunnelling microscopy (STM) experiments on the same samples, we have characterized in detail a model catalyst (Pd/graphite). The Pd clusters were epitaxially grown at high temperature on clean natural graphite substrates under ultra high vacuum (UHV) conditions. For the chosen growth conditions the density of clusters is rather low (109 cm−2), and their size is typically few tens of nanometers. TEM diffraction studies reveal that most of the clusters (92% ) are in a same epitaxial orientation which is defined by: (1 1 1)Pd$\parallel$ (0 0 . 1)Gr and $[1 1\bar{2}]_{\rm Pd}$$\parallel$$[1 \bar{1} . 0]_{\rm Gr}$. Moreover, both STM imaging and TEM observations show that the clusters have truncated tetrahedron shapes. The combination of TEM and STM characterizations of the same samples appears to be a very efficient way to get a detailed knowledge of the global properties of a collection of supported clusters (spatial and size distributions) as well as of their individual properties (structure, morphology).

The objective of the present study is to improve the modelling of heat transfer by elementary cells, aiming to increase the quality of their representation in the Laplace space. From the twoport representation and its connections with the classical nodal method, we show that the systematic increase of the order leads to improve the simulation results in transients. But, we would like to find a better reduced topology of the equivalent elementary network of heat conduction, closer to the analytical solution and verifying its terms for higher orders. The wall representation can be performed by an impedance network with “Π” or “T” shaped cells. The approximation of these impedances leads to define a new cell topology, which introduces capacitances with a negative value called "compensation capacitors". The value of these new elements only depends on the model nodal thermal capacitances in a wall. We study the transfer functions of these various equivalent networks as twoports that we will then compare to the analytical solution of the heat transfer equation. Some interesting values of the negative compensation capacitors are then obtained from transfer function; however, the optimal value would only be given from simulation results. All the established results will be confirmed by transient response simulations, which show the high performances of these new structures. These results are also validated by a modal analysis of these systems. The study of the model's accuracy show that the importance of the reduction for equivalent maximum errors corresponds to the square of the number of elementary cells.

An original method enabling the in-situ and real time monitoring of a polymer structure evolution using an inserted piezoelectric sensor is presented. The validation of this technique is done at constant temperature by comparison to the results obtained on several polymers by classical ultrasonic methods in practically the same conditions. The complete validation is achieved by monitoring the complex cure of a polymer matrix fibre reinforced composite PMR-15 under sever conditions of temperature.

The fabrication of refractive microlenses with self-developing photopolymers is reported. A spatially controlled illumination of the photosensitive layer induced an inhomogeneous photopolymerization involving formation of 3-D polymer network, mass-transport process of reactive species and bending of the surface. The process exhibited a completely self-processing character without any chemical post-treatment to reveal the relief. The lens arrays displayed diameters ranging from less than 100 μm to 1 mm and focal lengths from 100 μm to a few millimeters, depending on photonic, optical and physico-chemical parameters. The paper focuses on the importance of photonic parameters in the generation of microlens arrays and discusses the flexibility of this technique in the visible range.

This article presents the numerical simulation with finite element method of the transient regime of an asynchronous generator with iron-free cylindrical solid rotor. During this operation kinetic energy of the rotor is transferred through the ideal rectifier bridge to a load-inductance in order to create a high magnetic field pulse. The interest of this device is the less value of capacitors battery for self-oscillations of the asynchronous generator compared to this one necessary for direct transfer of its energy to the load-inductance.

The magnetic material's deformation caused by magnetostriction is represented by an equivalent set of mechanical forces, giving the same deformation to the material as magnetostriction does. This is done in a way similar to how thermal stresses are usually incorporated into stress analysis. The resulting magnetostriction force distribution can be superposed onto other force distributions, like the magnetic force distribution. These two force distributions are the key ingredients of a numerically strong coupling of the magnetic and the mechanical finite element systems.

An adaptive meshing technique is proposed. For a given number of nodes, the method allows a better precision, with a better repartition of the position of the nodes. It is based on the analysis of the influence of the node position and edge connection on the functional of the problem.

This paper presents two original types of SMES structures for energy storage. These two groups of SMES structures proceeded from an ideal structure: the full toroid, are modeled by the use of purely surface current densities. Their main advantage is to present no flux leakage, they give then satisfactory solution to the problem of energy storage.

This paper presents two structures of superconducting coils able to give satisfactory solutions to the problem of generation of uniform field of high magnetic forces. The first structure is modeled by the use of purely surface current densities, whereas the second one can be described with volume current densities. Both of these structures proceed from the study of a particular expression of the complex magnetic potential introduced for structures with two-dimensional geometry. This work is carried out in a research collaboration between the GREEN and the DSM-DAPNIA department of the CEA Saclay.