Obtention par PVD de condensateurs à base d'oxyde de germanium amorphe

This paper describes the elaboration of thin amorphous films of germanium dioxide and mixed germanium and lead oxides by RF cathodic sputtering in order to develop low loss capacitors with the highest possible capacity. The composition and the structure of the films are respectively determined by RBS and EXAFS. The best dielectric characteristics in low frequencies are obtained for the GePb$_{1.40}$O$_{3.40}$ material.Cet article décrit l'élaboration par pulvérisation cathodique RF de films minces amorphes de dioxyde de germanium et d'oxydes mixtes de germanium et de plomb dans le but de réaliser des condensateurs à faibles pertes et de plus grande capacité possible. La composition et la structure des films sont déterminées respectivement par RBS et par EXAFS. Les meilleures caractéristiques diélectriques en basses fréquences sont obtenues pour le matériau GePb$_{1,40}$O$_{3,40}$

Synthesis and investigation of TiO2/g-C3N4 performance for photocatalytic degradation of Bromophenol Blue and Eriochrome Black T: Experimental design optimization and reactive oxygen species contribution.

International audienceGraphitic carbon nitride (g-C3N4) based photocatalyst was synthesized and the photocatalytic performance was investigated for the removal of Eriochrome Black T (EBT) and Bromophenol Blue (BPB) under UV irradiation. The prepared materials were characterized by SEM-EDX, XRD, Raman, FTIR and DRS. Higher degradation efficiency for the same initial concentrations of EBT and BPB in presence of TiO2/g-C3N4 have been achieved within 160 min of irradiation. The kinetic study showed that the photodegradation of BPB by TiO2/g-C3N4 follows pseudo-first-order kinetics with an R2 value of 0.98. The addition of persulfate (PS) in BPB solution improved the degradation yield from 8.81% to 80.14% within 20 min of UV light irradiation. A Box-Behnken model was developed from three factors and Response surface methodology (RSM) was employed to identify the optimum conditions for the treatment of BPB solution by TiO2/g-C3N4. The experimental values of degradation of BPB agreed with predicted values obtained from central composite design (CCD) analysis with an R2 value of 0.9999. The scavenger study revealed that superoxide radical anion (O2•−) plays a key role (68.89% of contribution) followed by OH• and h+ with 22.40% and 15.55% of contribution, respectively. This study has obviously exhibited the potential of TiO2/g-C3N4 composite as a promising catalyst for photocatalytic purposes

Synthesis and investigation of TiO2/g-C3N4 performance for photocatalytic degradation of Bromophenol Blue and Eriochrome Black T: Experimental design optimization and reactive oxygen species contribution.

International audienceGraphitic carbon nitride (g-C3N4) based photocatalyst was synthesized and the photocatalytic performance was investigated for the removal of Eriochrome Black T (EBT) and Bromophenol Blue (BPB) under UV irradiation. The prepared materials were characterized by SEM-EDX, XRD, Raman, FTIR and DRS. Higher degradation efficiency for the same initial concentrations of EBT and BPB in presence of TiO2/g-C3N4 have been achieved within 160 min of irradiation. The kinetic study showed that the photodegradation of BPB by TiO2/g-C3N4 follows pseudo-first-order kinetics with an R2 value of 0.98. The addition of persulfate (PS) in BPB solution improved the degradation yield from 8.81% to 80.14% within 20 min of UV light irradiation. A Box-Behnken model was developed from three factors and Response surface methodology (RSM) was employed to identify the optimum conditions for the treatment of BPB solution by TiO2/g-C3N4. The experimental values of degradation of BPB agreed with predicted values obtained from central composite design (CCD) analysis with an R2 value of 0.9999. The scavenger study revealed that superoxide radical anion (O2•−) plays a key role (68.89% of contribution) followed by OH• and h+ with 22.40% and 15.55% of contribution, respectively. This study has obviously exhibited the potential of TiO2/g-C3N4 composite as a promising catalyst for photocatalytic purposes

A methodology for large scale finite element models, including multi-physic, multi-domain and multi-timestep aspects

This works concerns the development of a virtual prototyping tool dedicated to electro-thermo-mechanical simulation of power converters. The FEM code, written using an object-oriented language, includes a dual Schur Domain Decomposition Method. The solving of problems including floating subdomains can be performed in steady-state cases, whereas one can couple multi-timestep implicit and explicit integration schemes in transient analysis. The last part of this work is about the study of an industrial benchmark concerning the power converters used in railway transport: the electro-thermal simulation of a switch in transient analysis. This example allows to compare different strategies of tearing into subdomains and the use of different timesteps on the same structure