The European Physical Journal Applied Physics, 1998
... Nous avons déterminé par analyse `a la microsonde élec-tronique, diffraction de rayons X et a... more ... Nous avons déterminé par analyse `a la microsonde élec-tronique, diffraction de rayons X et analyse ESCA (XPS), que seuls les dépôts de cuivre et de bismuth sont effec-tivement métalliques, le premier restant stable `a la sor-tie du bain et le second s'oxydant ... u e (K elvin ) ...
ABSTRACT Nanoporous molybdenum oxynitride has been synthesized and studied for the first time as ... more ABSTRACT Nanoporous molybdenum oxynitride has been synthesized and studied for the first time as an oxygen reduction catalyst in a 0.1 M KCl aqueous solution (pH 5.6). Modified electrodes containing the oxynitride catalyst, TIMCAL Super P™ Li carbon as a conducting carbon additive and polyvinylidene fluoride as a binder were prepared, and the ratios of the different components were studied in detail to yield the optimum composition. The oxygen reduction reaction mechanism has been analyzed by the Koutecky–Levich equation using a rotating disk electrode and is in concordance with a four-electron pathway for the molybdenum oxynitride catalyst. Rotating ring-disk electrode experiments have further confirmed the electrocatalytic performance of such oxynitrides toward oxygen reduction, determining an average production of H2O2 of just 2.35%. Finally, we have also compared the performance of vanadium and tungsten oxynitrides under the same conditions as the optimal molybdenum oxynitride.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any fo... more All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.3-02/09/11,19:06:48) ... Diffusion in Materials DIMAT2000 doi:10.4028/www. ...
Micron thick silver films, vapour deposited onto high purity polycrystalline nickel substrates, d... more Micron thick silver films, vapour deposited onto high purity polycrystalline nickel substrates, dewet the substrate after high temperature annealing in oxygen rich atmospheres, while the films remain stable after annealing at the same temperature in a nitrogen atmosphere. Dewetting occurs when a nickel oxide layer is formed at the silver-nickel interface as a consequence of oxygen diffusion through the silver film.
Tin dioxide (SnO2) is an important material in the field of solid-state gas sensors and the perfo... more Tin dioxide (SnO2) is an important material in the field of solid-state gas sensors and the performances are strongly linked to the microstructure. Particularly, a decrease in the crystallite grain size leads to an increase in the sensing properties. Many chemical and physical techniques have been used to prepare nanosized SnO2 particles, but few papers report the use of a
Thick silver films vapour deposited under ultra high vacuum onto high purity nickel foils, dewet ... more Thick silver films vapour deposited under ultra high vacuum onto high purity nickel foils, dewet the substrate when annealed at high temperature in air. No hole is observed in the silver film after an annealing at the same temperature in a pure argon atmosphere. SEM observations of the film surface and of cross-sections reveal that dewetting occurs when a nickel
The characteristics of strengthening nanoclusters (NCs) have a major influence on the mechanical ... more The characteristics of strengthening nanoclusters (NCs) have a major influence on the mechanical properties of oxide dispersion strengthened (ODS) steels. To determine how to control NC formation, ODS powders are synthesized in different ball-milling and annealing conditions, then characterized by electron probe micro-analysis and small angle neutron scattering. During ball-milling, reactants are dissolved into the metallic matrix until a Ti, Y and O solid solution is formed and then NC nucleation begins. Nucleation is greatly enhanced during the first minutes of annealing at 800 °C without any coarsening afterwards. The intensity and temperature of ball-milling influence this mechanism and thus the characteristics of the formed NC, whereas the nature of reactants, for a given composition, has no impact on NC size and volume fraction. Consequently, to promote the formation of fine and dense dispersion of NC, two main modifications to the usual process are proposed: (i) perform a lon...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008
ABSTRACT Simple alkali alumino-borosilicate glasses were doped with iron and/or molybdenum oxides... more ABSTRACT Simple alkali alumino-borosilicate glasses were doped with iron and/or molybdenum oxides. The chemical composition was then fully characterized before irradiation at room temperature with 255keV Xe ions to fluence ranging from 1015 up to 1017ions/cm2. After irradiation, glass samples were leached in deionised water at 90°C for 7 days. Scanning electron microscopy, electron microprobe analysis and ion beam analysis have been used to characterize the investigated samples.Irradiation induces a strong anti-correlated migration of boron and sodium. Alternatively enriched/impoverished zones are formed in the centre (irradiated) as well as at the rim (unirradiated) of the glass samples. Silicon, calcium, iron and molybdenum do not exhibit any perturbations in both surface and volume distributions. Boron and sodium mobility is mainly due to the coupling of thermal, electrical and stress gradients during ion irradiation.Glasses pre-irradiated before leaching exhibit stronger Na and B release than unirradiated glasses. A higher aluminium and iron surface enrichment is observed; it is probably due to the highest reactivity of the irradiated glasses having lost part of B and Na from the damaged network.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2006
... S. Gavarini, F. Carrot, P. Trocellier and G. Matzen, . J. Non Cryst. Sol., 332 (2003), p. 141... more ... S. Gavarini, F. Carrot, P. Trocellier and G. Matzen, . J. Non Cryst. Sol., 332 (2003), p. 141 See also. [9] JF Ziegler. Available from: <http://www.srim.org/SRIM/SRIM2003.htm>.. [10] P. Hsiung, Ph.D. Thesis, University of Paris Sud Orsay, 1983.. [11] S. Gin et al.. Mat. Res. Soc. ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2005
ABSTRACT Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at ro... more ABSTRACT Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at room temperature, 60 and 90 °C in solutions with pH ranging between 0 and 12. Analytical scanning electron microscopy (SEM), ion beam analysis (IBA) techniques, isotopic tracing and secondary ion mass-depth profiling (SIMS) have been used to investigate the variations of the surface composition of glass. In acidic medium, the glass surface is generally covered by a thick hydrated silica layer, mobile elements like Li, Na and B and transition elements (Fe, Zr, Mo, etc.) are strongly depleted. Near pH 7, relative enrichments of aluminium, iron and rare earths are shown together with strong Li, Na and B depletions. In basic medium, the glass surface exhibits relative enrichments of the major part of transition metals (from Cr to U) whereas mobile elements seem to be kept close to their nominal concentration level at the glass surface and Si is severely impoverished. Hydrogen incorporated at the glass surface after leaching is much more immobile in neutral and basic media than in acid medium.
ABSTRACT Reactive-inspired ball-milling is proposed as a new production route for oxide dispersio... more ABSTRACT Reactive-inspired ball-milling is proposed as a new production route for oxide dispersion strengthened (ODS) steels. So a Fe–14Cr–2W–1Ti–0.8Y–0.2O (wt.%) ODS steel is elaborated by ball-milling of FeCrWTi and YFe3 plus Fe2O3 powders instead of Y2O3 and then by annealing at 800 °C for 5 min. Characterizations by Electron Probe MicroAnalysis and Atom Probe Tomography (APT) are performed after milling and after annealing. For the very first time, nanoclusters are observed after ball-milling by APT. Those nanoclusters are enriched in titanium, yttrium and oxygen and their mean radius is 0.8 nm. With annealing, the mean radius rises up to 1.4 nm and the number density as well as the enrichment factor in O, Ti and Y increase. So a new formation mechanism of nanoclusters is observed in those conditions of synthesis: ball-milling initiates the nanoclusters nucleation and during annealing, nucleation continues, accompanied by a slight growth of nanoclusters. Thus reactive-inspired ball-milling appears as a promising route for synthesizing ODS steels with a fine and dense dispersion of oxides.
The European Physical Journal Applied Physics, 1998
... Nous avons déterminé par analyse `a la microsonde élec-tronique, diffraction de rayons X et a... more ... Nous avons déterminé par analyse `a la microsonde élec-tronique, diffraction de rayons X et analyse ESCA (XPS), que seuls les dépôts de cuivre et de bismuth sont effec-tivement métalliques, le premier restant stable `a la sor-tie du bain et le second s&#x27;oxydant ... u e (K elvin ) ...
ABSTRACT Nanoporous molybdenum oxynitride has been synthesized and studied for the first time as ... more ABSTRACT Nanoporous molybdenum oxynitride has been synthesized and studied for the first time as an oxygen reduction catalyst in a 0.1 M KCl aqueous solution (pH 5.6). Modified electrodes containing the oxynitride catalyst, TIMCAL Super P™ Li carbon as a conducting carbon additive and polyvinylidene fluoride as a binder were prepared, and the ratios of the different components were studied in detail to yield the optimum composition. The oxygen reduction reaction mechanism has been analyzed by the Koutecky–Levich equation using a rotating disk electrode and is in concordance with a four-electron pathway for the molybdenum oxynitride catalyst. Rotating ring-disk electrode experiments have further confirmed the electrocatalytic performance of such oxynitrides toward oxygen reduction, determining an average production of H2O2 of just 2.35%. Finally, we have also compared the performance of vanadium and tungsten oxynitrides under the same conditions as the optimal molybdenum oxynitride.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any fo... more All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 66.249.66.3-02/09/11,19:06:48) ... Diffusion in Materials DIMAT2000 doi:10.4028/www. ...
Micron thick silver films, vapour deposited onto high purity polycrystalline nickel substrates, d... more Micron thick silver films, vapour deposited onto high purity polycrystalline nickel substrates, dewet the substrate after high temperature annealing in oxygen rich atmospheres, while the films remain stable after annealing at the same temperature in a nitrogen atmosphere. Dewetting occurs when a nickel oxide layer is formed at the silver-nickel interface as a consequence of oxygen diffusion through the silver film.
Tin dioxide (SnO2) is an important material in the field of solid-state gas sensors and the perfo... more Tin dioxide (SnO2) is an important material in the field of solid-state gas sensors and the performances are strongly linked to the microstructure. Particularly, a decrease in the crystallite grain size leads to an increase in the sensing properties. Many chemical and physical techniques have been used to prepare nanosized SnO2 particles, but few papers report the use of a
Thick silver films vapour deposited under ultra high vacuum onto high purity nickel foils, dewet ... more Thick silver films vapour deposited under ultra high vacuum onto high purity nickel foils, dewet the substrate when annealed at high temperature in air. No hole is observed in the silver film after an annealing at the same temperature in a pure argon atmosphere. SEM observations of the film surface and of cross-sections reveal that dewetting occurs when a nickel
The characteristics of strengthening nanoclusters (NCs) have a major influence on the mechanical ... more The characteristics of strengthening nanoclusters (NCs) have a major influence on the mechanical properties of oxide dispersion strengthened (ODS) steels. To determine how to control NC formation, ODS powders are synthesized in different ball-milling and annealing conditions, then characterized by electron probe micro-analysis and small angle neutron scattering. During ball-milling, reactants are dissolved into the metallic matrix until a Ti, Y and O solid solution is formed and then NC nucleation begins. Nucleation is greatly enhanced during the first minutes of annealing at 800 °C without any coarsening afterwards. The intensity and temperature of ball-milling influence this mechanism and thus the characteristics of the formed NC, whereas the nature of reactants, for a given composition, has no impact on NC size and volume fraction. Consequently, to promote the formation of fine and dense dispersion of NC, two main modifications to the usual process are proposed: (i) perform a lon...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008
ABSTRACT Simple alkali alumino-borosilicate glasses were doped with iron and/or molybdenum oxides... more ABSTRACT Simple alkali alumino-borosilicate glasses were doped with iron and/or molybdenum oxides. The chemical composition was then fully characterized before irradiation at room temperature with 255keV Xe ions to fluence ranging from 1015 up to 1017ions/cm2. After irradiation, glass samples were leached in deionised water at 90°C for 7 days. Scanning electron microscopy, electron microprobe analysis and ion beam analysis have been used to characterize the investigated samples.Irradiation induces a strong anti-correlated migration of boron and sodium. Alternatively enriched/impoverished zones are formed in the centre (irradiated) as well as at the rim (unirradiated) of the glass samples. Silicon, calcium, iron and molybdenum do not exhibit any perturbations in both surface and volume distributions. Boron and sodium mobility is mainly due to the coupling of thermal, electrical and stress gradients during ion irradiation.Glasses pre-irradiated before leaching exhibit stronger Na and B release than unirradiated glasses. A higher aluminium and iron surface enrichment is observed; it is probably due to the highest reactivity of the irradiated glasses having lost part of B and Na from the damaged network.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2006
... S. Gavarini, F. Carrot, P. Trocellier and G. Matzen, . J. Non Cryst. Sol., 332 (2003), p. 141... more ... S. Gavarini, F. Carrot, P. Trocellier and G. Matzen, . J. Non Cryst. Sol., 332 (2003), p. 141 See also. [9] JF Ziegler. Available from: <http://www.srim.org/SRIM/SRIM2003.htm>.. [10] P. Hsiung, Ph.D. Thesis, University of Paris Sud Orsay, 1983.. [11] S. Gin et al.. Mat. Res. Soc. ...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2005
ABSTRACT Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at ro... more ABSTRACT Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at room temperature, 60 and 90 °C in solutions with pH ranging between 0 and 12. Analytical scanning electron microscopy (SEM), ion beam analysis (IBA) techniques, isotopic tracing and secondary ion mass-depth profiling (SIMS) have been used to investigate the variations of the surface composition of glass. In acidic medium, the glass surface is generally covered by a thick hydrated silica layer, mobile elements like Li, Na and B and transition elements (Fe, Zr, Mo, etc.) are strongly depleted. Near pH 7, relative enrichments of aluminium, iron and rare earths are shown together with strong Li, Na and B depletions. In basic medium, the glass surface exhibits relative enrichments of the major part of transition metals (from Cr to U) whereas mobile elements seem to be kept close to their nominal concentration level at the glass surface and Si is severely impoverished. Hydrogen incorporated at the glass surface after leaching is much more immobile in neutral and basic media than in acid medium.
ABSTRACT Reactive-inspired ball-milling is proposed as a new production route for oxide dispersio... more ABSTRACT Reactive-inspired ball-milling is proposed as a new production route for oxide dispersion strengthened (ODS) steels. So a Fe–14Cr–2W–1Ti–0.8Y–0.2O (wt.%) ODS steel is elaborated by ball-milling of FeCrWTi and YFe3 plus Fe2O3 powders instead of Y2O3 and then by annealing at 800 °C for 5 min. Characterizations by Electron Probe MicroAnalysis and Atom Probe Tomography (APT) are performed after milling and after annealing. For the very first time, nanoclusters are observed after ball-milling by APT. Those nanoclusters are enriched in titanium, yttrium and oxygen and their mean radius is 0.8 nm. With annealing, the mean radius rises up to 1.4 nm and the number density as well as the enrichment factor in O, Ti and Y increase. So a new formation mechanism of nanoclusters is observed in those conditions of synthesis: ball-milling initiates the nanoclusters nucleation and during annealing, nucleation continues, accompanied by a slight growth of nanoclusters. Thus reactive-inspired ball-milling appears as a promising route for synthesizing ODS steels with a fine and dense dispersion of oxides.
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