Search results for "Réactivité"
showing 8 items of 8 documents
Reactivity of arsenic compounds on trapping masses and role of the active phase
2019
The aim of the thesis is to study the reactivity of organic arsenic compounds on various recovery masses and to identify the role of the nature of the active phase and the reaction mechanisms involved. The active phase is composed of metals (Ni, Co, Mo, Cu, Zn, Fe, etc.), pure or in a mixture, in the reduced state or in the sulphide state. The selection of the metallic phases will be carried out by molecular modeling "ab initio", and the synthesis by impregnation of metallic salts on mesoporous aluminas). The reactivity of the solids will be studied in a static reactor on simplified model loads, with kinetic monitoring. The advanced characterization of the solids after synthesis and after r…
Microstructure-process relationship and reactivity at the nanoscale : a molecular dynamics study of Ni, Ni-Al, and Ti-Al metallic systems
2023
The process-microstructure relationship is central in materials science because the microstructure will determine the properties of the materials developed by the processes. In our work, we focused on different metallurgical processes by adopting a description at the atomic scale. This approach allows us to detect the elementary mechanisms that are at the origin of the observed microstructures without having to postulate macroscopic mechanisms or estimate the associated parameters. In this respect, molecular dynamics simulations provide a tool for "in-situ" observation of metallic systems as long as an atomic interaction potential is available. The originality of our approach consists in mo…
Study of the fuel/clad bonding of pressurized water reactors fuel rods
2017
Durability and integrity of materials used in nuclear power plants is a continuous concern of the nuclear power plant owners and developers. During the fuel irradiation in pressurised water reactors (PWR), the whole fuel-clad assembly is subjected to several irradiation-induced modifications. In particular, the fuel element expansion concomitant to the cladding creeping, leads to the contacting of both materials, allowing the oxidation of the inner side of the clad, locally at first, then tending to affect the overall cladding inner surface. At high burnup, a bonding of the fuel periphery with the metallic cladding can be observed, forming the fuel-clad bonding phenomenon, which conditions …
Initial stages of metal oxides thin films growth by MOCVD: physicochemical characterisation of the film/substrate interface
2006
The initial stages of Metalorganic Chemical Vapour Deposition (MOCVD) of TiO2 thin films on Si(100) were studied in situ by surface analyses (XPS, ARXPS, AES). An original experimental set-up was built for this purpose and developed. Information obtained from these in situ experiments was completed by ex situ characterisations (HRTEM, SIMS, GIXRD...).The formation of an interfacial SiOy<2 layer resulting of the interaction of the precursor Ti(OCH(CH3)2)4 with the substrate takes place before the formation of stoichiometric TiO2 and leads to the presence of carbon at the interface. At the deposition temperature, 675 °C, silicon diffusion within the TiO2 external layer was also revealed. Conc…
Elaboration and interfacial reactivity of Lanthanum Strontium Chromium Ruthenium (LSCrRu) perovskite oxides as intermediate temperature fuel cell (IT…
2005
New data on the interest of ruthenium doped lanthanum strontium chromite La1-xSrxCr1-yRuyO3δ (LSCrRu) as anode in ITSOFC are presented. Microwave synthesis of mixed oxides allowed shaping of half-cells and complete cells using sputtering and screen printing methods. LSCrRu methane reforming property had been studied in a mono-chamber system coupled with a mass spectrometer in collaboration with Institut de REcherche Hydro-Québec. Anode/electrolyte interfacial reactivity had been analysed using SIMS and XRD on half cells models after ageing under H2 at 800°C. This experiment gave the chemical composition of the film after treatment. Complete cells, tested under working conditions, highlight…
Fabrication and characterization of barium silicate ultrathin films as an alternative gate oxide
2008
Down-scaling of elementary CMOS elements requires the replacement of SiO2 as a gate oxide. By the identification of the formation conditions of barium silicate in direct contact of a silicon substrate, this study revealed a potential candidate. First of all, a reaction between Ba and SiO2 leading to the formation of barium silicate as been evidenced by in-situ XPS and SR-PES analyses. Then, barium silicate films have been elaborated by oxygen and barium co-deposition at 580 °C. Thermal treatments under vacuum showed that barium silicate was thermally stable up to 900 °C. TEM and SIMS ex-situ analyses revealed a sharp interface with the substrate. Finally, an experimental setup dedicated to …
Couches minces d'oxynitrure de titane : la réactivité comme moyen original de caractérisation physico - chimique
2002
Titanium oxinitride thin films, TiNxOy, were elaborated on Si(100) by the MOCVD (Metal Organic Chemical Vapor Deposition) method, using titanium isopropoxide Ti(OCH(CH3)2)4 and ammonia NH3 as precursors. By varying the growth temperature, it is possible to modify the N/O ratio and change the conductivity of the films.The target of this work was to determine the composition and the structure of these TiNxOy thin films in order to understand the electrical properties. However, this study was difficult because classical characterization techniques (SEM, XRD, Raman, XPS...) were unable to describe the whole TiNxOy system. Indeed, only a structure which is isomorphic to TiN (NaCl structure) was …
Parental Competence in Infant and Primary Education: design and validation of an instrument
2021
Actualmente, la familia se encuentra ante retos que requieren de su eficiencia y eficacia en la crianza, protección y orientación de los hijos, es decir, la parentalidad y la capacidad de los padres de ejercerla de forma competente. Desde este punto de vista, destaca la necesidad de un modelo educativo centrado en el desarrollo de las competencias parentales que proporcione conocimientos, habilidades y actitudes que optimicen el rol parental respecto al desarrollo pleno y sistémico del ser humano. Ante la necesidad de conocer si los padres asumen de forma óptima su papel en la educación de sus hijos, se plantea como objetivo principal de este artículo el diseño de un instrumento para el aná…