In this paper, we discuss a general method for symmetry synthesis of electromagnetic multiports. Two approaches are possible in this problem: (1) solution for all the possible symmetry groups describing the multiports, and (2) determination of the symmetry group of a given ideal scattering matrix and calculation of the real matrix. A three-way nonreciprocal divider synthesis illustrates the second approach. Also, for four-ports defined is the group tree allowing one to calculate all the possible scattering matrices.

The mixed sulphate acid Rb0.7(NH4)0.3HSO4 presents at room temperature a phase with a structure similar to the one of the parent compounds RbHSO4 and NH4HSO4. Different techniques of the study of phase transitions show that this compound exhibits five phases with varying temperature and in particular the appearance of a new phase (noted IV) in comparison of the phase diagram of parent compounds, this phase takes place in the range of temperature T between 330 and 435 K. The symmetry of the mixed compound at room temperature (phase III) has been performed again by X-ray diffraction on single crystals. The crystallographic characterization of the phase IV is made by X-ray diffraction on powder sample. Crystallographic parameters in this phase are then obtained whereas group theory considerations gives the most probable space group of this phase. In this work, the phase transitions are studied by dielectric measurements. Theoretical study of the behaviour of dielectric susceptibility based on LANDAU theory of phase transitions shows an improper ferroic character of the transition occurring at 330 K with a faintness index f equal to 2.

We study the optical behavior of Au-TiO2 thin cermet films, the gold volume fraction of which is varied over the range 10−3 to 8 × 10−2. In this low concentration range, it is mainly governed by the metallic particles size, which very much depends on the deposition substrate temperature and the annealing time and temperature. The samples structure and morphology are characterized by several complementary techniques. Spectrophotometric measurements at quasi-normal incidence have been performed in visible and near infrared regions. Using a short pulse Nd:YAG laser, we also look for nonlinear optical behavior due to the enhancement of the electromagnetic field close to the surface plasmon resonance of the metallic grains.

We report on the annealing effect on the structural and magnetic properties of Ta5nm/Cu5nm/FeMn8nm/Co8nm/FeMn8nm/Ta5nm samples prepared by sputtering, on silicon substrate, at room temperature. For the as-deposited samples the interfacial exchange anisotropy field (He) between the Co and FeMn layers is about 95 Oe. It increases sensitively with annealing to reach a maximum value of 135 Oe at 240 °C annealing temperature. Above this temperature, we observe a strong decrease of He, down to 90 Oe after annealing at 280 °C, and an increase of 50% of the saturation magnetization. In order to understand the effect of the annealing on the magnetic properties, we performed a detailed structural analysis by means of Rutherford back scattering spectroscopy (RBS), nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM). All these techniques attribute the large changes in the magnetic properties to the formation of a new ferromagnetic FeMnCo phase at the FeMn/Co interfaces.

Pb(Zr,Ti)O3 (PZT) and Pb(Zr,Ti,Nb)O3 (PNZT) thin films have been grown on platinized silicon substrates by RF magnetron sputtering followed by a post-annealing treatment. The niobium, Nb, concentration varied from 1 to 7 at.% by increment of 1 at.% The effects of the Nb introduction on the PZT electrical properties, i.e., dielectric and ferroelectric ones have been investigated. We have found that the relative dielectric constant $(\varepsilon_{\rm r})$ is very sensitive to the Nb introduction; $(\varepsilon_{\rm r})$ reaches 1100 for a PNZT film doped at 2 at.% in comparison to 820 for a PZT film. The ferroelectric properties are also dependent of the doping level; in particular the remnant polarization reaches its maximum value ($17 \mu$C/cm2) for a 2 at.% Nb doped PZT film.

Chromium-doped silica-based optical fibres emit infrared fluorescence at 77 K near 1250 nm (500 nm band-width) under 860−980 nm excitation. Visible and near-infrared absorption spectra of fibres were analysed using the Tanabe-Sugano formalism. It is shown that although the fibre core is codoped with only 1 mol% of aluminium, chromium is preferentially stabilized as Cr4+ in Al-rich regions of the glassy matrix in distorted tetrahedrally coordinated sites. The infrared fluorescence is assigned to Cr4+ along a transition from the 3T2 state down to the 3A2 ground state.

In this paper we present an experimental study concerning electrode erosion under the sole action of an electric arc. An experimental device allowing to generate electric arc current pulses of constant intensity has been realized. It allows also to ignite the arc for a given electrode gap up to 10 mm by means of a HV discharge. The influence of several parameters on the electrode erosion has then been studied. These parameters are: the nature of the contact material (Ag, AgSnO2, AgCdO, Cu, CuSnO2), the value of the electrode gap, the nature of the cover gas... Films realized with the help of a high speed framing camera have brought interesting elements of interpretation concerning the test erosion results.

An analytical model for ozone concentration calculation, previously described in [1,2], is applied to an oxygen-fed DBD cylindrical ozonizer. It is shown that this model can be applied to DC or DBD discharges, using an appropriate temperature law in the reaction zone. The ozone concentration, the overall parameters for ozone formation and destruction, the specific energy and the economical criterion are presented as functions of the ozonizer geometry, the electric power, the fluid flow, the temperature and the pressure. These results are compared to industrial data and a good agreement is observed.

This paper describes a numerical method applied to speckle photography to measure the in- plane displacement field on a thin film and specially adapted to microtensile test. Speckle photography is chosen to avoid touching and stressing the specimen. A Spectral Phase Algorithm particularly useful in the case of small displacement or/and strain is compared with the Intercorrelation and Double FFT methods. A final algorithm using first the Intercorrelation method without interpolation and secondly the Spectral Phase Algorithm is then adopted to estimate with good accuracy the in-plane displacement field in quasi-real time during the microtensile tests.

A first application of the method to the tensile tests performed on thin films of electroplated copper of 18, 35 and 70 μm of thickness is then presented.

We describe the realization of an ultrahigh vacuum scanning ion beam apparatus. The ion gun is based on the principle of field emission from a liquid gallium film wetting a sharp needle. The beam can be focused to a probe spot with a diameter less than 40 nm. The gun is fixed to an ultrahigh vacuum chamber, and is driven by a digital scanning device that works at variable frequency. The video image is built from the outgoing electrons resulting from the ion beam impacts. We describe the setup and discuss the relation between the ion probe current and the scanning speed. Specific applications to surface imaging are presented.