Etude des complexes sulfosalicylate de cuivre(III), nickel(II), cobalt(II) et uranyle(II) a l'aide d'une resine echangeuse de cations: Study of the sulphosalicylate complexes ofcopper(II), nickel(II), cobalt(II) and uranyl(II) by means of cation-exchange resins.

Study of the sulphosalicylate complexes of copper(II), nickel(II), cobalt(II) and uranyl(II) by means of cation-exchange resins.The conditional stability constants of the 1:1 complexes of the sulphosalicylate ions (L^3-) with copper(II), nickel(II), cobalt(II) and uranyl ions have been determined in a sodium perchlorate solution (0.1 M) and at various pH values by a cation-exchange method based on Schubert's procedure. The limits of application of the method are discussed. The variation with pH of the conditional stability constants can be explained by the existence of the complexes: CuH₂L, CuHL, CuL^-; NiH₂L⁺, NiHL, NiL^-; CoHL, CoL^-; UO₂H₂L⁺, UO₂HL, UO₂L^-, UO₂LOH^2-. The stability constants of these complexes are reported. Distribution diagrams of the various complexes of each element with pH and total concentration of sulphosalicylate parameters are given.     

Dual-cure processes: towards deformable crosslinked coatings

Two dual-cure processes consisting of a UV-initiated radical polymerization followed by either a UV-induced cationic polymerisation, or a thermal addition reaction, were investigated. The feasibility of the processes was studied using an acrylate-oxetane monomer for the UV/UV combination, and an acrylated oligoester for the UV/Heat combination. It was shown by FTIR and Tg measurements, that both steps of each process could be performed efficiently and separately. This allowed the production of a deformable partially cured coating, whose cure can then be completed, leading to the required final properties. Furthermore, it was demonstrated that the increase of the functionality of the reactive diluent led to a decrease of the thermal crosslinking extent. This is probably due to the reduced mobility of the reactive species that is caused by an enhanced UV crosslinking taking place during the first step.     

Photoreflectance study at the micrometer scale

Photoreflectance (PR) spectroscopy has proven to be a very efficient non-destructive tool to get information on various semiconducting epitaxial structures as it is very sensitive to every direct optical transitions in semiconducting quantum structures and allows as well to optically measure internal electric fields in space charge layers, through Franz-Keldysh oscillation (FKO) analysis. We have developed an experimental setup to get micro-PR spectra on epitaxial structures or devices on a few micrometer size spots. Due to very low signal intensity, experimental conditions have to be very carefully controlled: the signal/noise ratio strongly depends on the pump-probe power ratio.We give experimental micro-PR results recorded on antimonide-based heterojunction bipolar transistors (HBTs), which give the local electric field at the emitter-base junction under different biasing conditions. A second part of the paper is devoted to micro-PR analysis performed on tuneable vertical cavity surface emitting layers (VCSELs) with InP/air Bragg mirrors. In such VCSELs, both the cavity Fabry-Perot peak and the active region quantum well ground state are giving transitions in the micro-PR spectrum. This is very useful in the case of a tuneable structure. Feasibility of micro-PR analysis at the device scale is demonstrated.     

Structural,electrochemical, electronic,and magnetic properties of monoclinic LixV2(PO4)3 for x = 3, 2, 1 using first-principles calculations

Journal of Solid State Electrochemistry - Monoclinic lithium vanadium phosphate Li3V2(PO4)3 is a very promising cathode candidate for applications in Li-ion batteries, with a high operational...     

AC conductivity analysis and dielectric relaxation behavior of (C6H20N3)BiBr6.H2O

The N‐(3‐ammoniumpropyl)‐1,3 diammoniumpropane hexabromobismuthate (III) monohydrate exhibits a structural phase transition at T = 330 °K, which has been characterized by differential scanning calorimetric. The alternating current electrical conductivity and the dielectric relaxation properties of the (C₆H₂₀N₃)BiBr₆.H₂O compound have been investigated by means of impedance spectroscopy measurements over a wide range of frequencies and temperatures, 100 Hz–1 MHz and 290–355 °K, respectively. The Z′ and Z″ versus frequency plots are well fitted to an equivalent circuit consisting of series of combination of grains and grain boundary elements. The frequency dependent alternating current conductivity is well described by Jonscher's universal power law: σ(ω,T) = σ_DC(T) + A(T)ω^s(T). The nature of direct current conductivity variation suggests the Arrhenius type of electrical conductivity. Furthermore, the modulus plots can be characterized by full width at half height or in terms of a non‐experiential decay function φ(t) = exp(?t/τ)^β. The variation of the value of these elements with temperatures confirmed the result detected by differential scanning calorimetry measurements. Thus, the near values of activation energies obtained from the impedance and modulus spectra confirm that the transport is through an ion hopping mechanism. Copyright © 2015 John Wiley & Sons, Ltd.     

Reactivite Des N 1 -Tosylamidrazones Vis-À-Vis du Chlorure de Thionyle et du Reactif de Lawesson: Obtention Des Thiatriazoles et Des Triazaphospholines

Thionyl chloride 2 and Lawesson Reagent (L.R.) 4 react with N 1 -tosylamidrazones 1 to give respectively 1-oxyde-1,2,3,5-thiatriazole 3 and triazaphospholines 5 derivatives. The structure of products 3 and 5 is confirmed by IR and NMR spectroscopy.     

REACTIVITE DES N 1-TOSYLAMIDRAZONES VIS-À-VIS DU TRICHLORURE DE THIOPHOSPHORYLE ET DU DISULFURE DE CARBONE: OBTENTION DES TRIAZAPHOSPHOLINES ET DES TRIAZOLETHIONES

The condensation of N ¹ -tosylamidrazones with thiophosphorus trichloride and carbone disulfide forms a new synthetic method for access to new phosphorus or sulfur heterocycles such as triazaphospholines and triazolethiones.     

Photoreflectance spectroscopy of self-organized InAs/InP(0 0 1) quantum sticks emitting at 1.55 μm

Photoreflectance (PR) measurements are performed as a function of temperature on self-organized InAs/InP(0 0 1) quantum sticks (QSs) grown by solid-source molecular beam epitaxy. With a very weak excitation power, three PR transition energies are arising and associated with the ground state and two excited states, respectively, in good agreement with both photoluminescence (PL) and PL excitation measurements. The temperature dependence of the PR transition energies is in good agreement with the Bose-Einstein behavior.From PL analysis of these InAs/InP QSs, the ground state was assumed to be partially filled because of the residual n-type doping of the InP barrier layers. The PR spectra analysis allows us to further confirm this assumption, considering mainly the relative PR intensity of the different transitions, as well as the Franz Keldysh oscillations (FKO) above the InP bandgap.     

Ultraviolet–ultraviolet dual‐cure process based on acrylate oxetane monomers

A dual‐cure process consisting of two subsequent ultraviolet‐initiated radical and cationic polymerizations was investigated. The process was studied with two acrylate oxetane monomers, one of them having a spacer between the two polymerizable moieties. It was shown by Fourier transform infrared (FTIR) that the first (radical) step was performed successfully for both systems. As for the second (cationic) step, only the monomer with the spacer was able to polymerize, allowing the crosslinking of the polyacrylic chains generated by the first step. The efficiency of the process was confirmed by differential scanning calorimetry because the glass‐transition temperatures of the cured films were ?16 and + 34 °C after the first and second steps, respectively. The dual cure of this system was further analyzed by real‐time FTIR, which showed that 86% of the acrylate and 80% of the oxetane moieties were converted after 20 and 50 s of light exposure, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 469–475, 2003