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Featured researches published by J. Tousset.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1990

Boron analysis of thin layers using prompt nuclear techniques

N. Moncoffre; N. Millard; H. Jaffrezic; J. Tousset

We present the use of boron nuclear analysis in order to determine the boron depth distribution in implanted layers and the stoichiometry of thin NiBx, FeNIBx and TiBx films. For this purpose several nuclear reactions that have already given analytical results could be considered (11B(p, α)2α, 11B(p, γ)12C, 10B(d,p)11B, 10B(d, n)11 etc.). The 11B(α, α) reaction has been chosen and we have studied its excitation function between 3.50 and 7.50 MeV. It displays in particular an interesting plateau between 5.92 and 6.04 MeV. In this 120 keV region the reaction cross section is nearly constant and rather high (σcm = 310 mb/sr). It allows us to take advantage of the nuclear contribution of the elastic scattering and to make a quantitative analysis with a good sensitivity and a depth resolution of about 20 nm. We have compared these reaction performances with those of the resonant nuclear reaction 11B(p, γ) at 163 keV and of the 11B(p, α1) reaction at 660 and 163 keV. Advantages and disadvantages of these reactions for boron profiling are discussed.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1990

Iron-implanted sintered alumina studied by RBS, CEMS AND SEM techniques

C. Donnet; H. Jaffrezic; G. Marest; N. Moncoffre; J. Tousset

Abstract Sintered plates of alumina have been implanted at room temperature with 1.2 × 10 17 57 Fe + /cm 2 at 110 keV. Rutherford backscattering spectrometry and conversion electron Mossbauer spectrometry have been used to characterize respectively the depth distribution and charge states of iron. A theoretical approach of the as-implanted iron profile has been carried out by using a modified TRIM code which takes into account the fluence, the sputtering effects and the modification of the surface composition during ion bombardment. The iron profile and charge-state evolutions after isochronal air annealings from 200° C to 1600° C have been investigated. Correlations with the surface topography evolution investigated by SEM are proposed.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1992

Nitrogen profiling in nitride films and nitrogen-implanted samples using the 14N(α, α) and14N(α, p) reactions at 6 MeV incident energy

H. Artigalas; A. Chevarier; N. Chevarier; M. El Bouanani; E. Gerlic; N. Moncoffre; B. Roux; M. Stern; J. Tousset

We investigate the nitrogen profiling potentially using incident alpha particles from 5 to 7 MeV. In this energy range the alpha scattering cross sections on light elements are substantially larger than the Rutherford cross sections and therefore lead to competitive sensitivity. Moreover, another advantage is the high mass resolution which allows to profile simultaneously carbon, nitrogen and oxygen. The analysis of TiN, NbTiN films and nitrogen implanted steel are presented. The inclusion, in the simulation program, of the 14N(α, α) and14N(α, p) cross sections allows to get a complete reproduction of the spectra and authorizes to determine accurately the nitrogen profile. Such a dual nitrogen analysis improves profile determination in case of thick analyzed layers. The sensitivity limits connected to the alpha scattered yield on steel substrate are 1016 and 5 × 1016 N atoms/cm2 for the 14N(α, α) and14N(α, p) reactions, respectively.Abstract We investigate the nitrogen profiling potentially using incident alpha particles from 5 to 7 MeV. In this energy range the alpha scattering cross sections on light elements are substantially larger than the Rutherford cross sections and therefore lead to competitive sensitivity. Moreover, another advantage is the high mass resolution which allows to profile simultaneously carbon, nitrogen and oxygen. The analysis of TiN, NbTiN films and nitrogen implanted steel are presented. The inclusion, in the simulation program, of the 14 N (α, α) and 14 N (α, p ) cross sections allows to get a complete reproduction of the spectra and authorizes to determine accurately the nitrogen profile. Such a dual nitrogen analysis improves profile determination in case of thick analyzed layers. The sensitivity limits connected to the alpha scattered yield on steel substrate are 1016 and 5 × 1016 N atoms/cm2 for the 14 N (α, α) and 14 N (α, p ) reactions, respectively.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1991

Copper, iron and zirconium implantation into polycrystalline α-Al2O3

C. Donnet; G. Marest; N. Moncoffre; J. Tousset; A. Rahioui; C. Esnouf; M. Brunel

Abstract Polycrystalline α-Al2O3 samples have been implanted by 1017 Zr, Fe or Cu ions/cm 2 at 110 keV in order to form oxide precipitates in the near-surface region after annealing in air. A chemical and microstructural characterization has been performed on the as-implanted surface and on the samples annealed in the temperature range from 600 to 1600°C. The nature of the chemical phases and the precipitate evolution have been characterized by combining RBS, XPS, GXRD, CEMS, TEM and SEM techniques. XPX, CEMS and TEM experiments on as-implanted specimens detect copper, iron and zirconium as Cu° (small metallic precipitates), Fe° (small α-iron precipitates), FeII (associated with FeAl2O4), and FeIV (metastable state), Zr° and ZrIV (ZrO2) in the as-implanted region. Analyses carried out after heat treatments between 600 and 1000 °C indicate a complete surface oxidation in this temperature range. Additionally, some precipitates appear along grain boundaries. Annealing at temperatures ranging from 1000 to 1600°C leads to drastic surface composition changes. The stability and size of the different observed precipitates (ZrO2, AlFeO3, Fe2O3, Fe3O4, CuO, CuAl2O4) strongly depend on the annealing temperature.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1990

Sputtering yield and residual vacuum influence during titanium implantation into iron

M.A. El Khakani; H. Jaffrezic; G. Marest; N. Moncoffre; J. Tousset

Abstract Ti implantation into iron-based alloys is known to improve tribological properties (low friction and wear) by formation of an amorphous Fe-Ti-C surface layer due to the interaction of the carbonaceous molecules in the residual vacuum with the surface during implantation. To state precisely the conditions of this amorphous-layer formation, thin evaporated iron targets were implanted with 110 keV Ti ions at room temperature with fluences ranging from 6 × 1016 to 3 × 1017 Ti/cm2 and at different residual pressures. Samples were analysed using backscattering spectrometry with 5.7 MeV 4He ions to obtain titanium profiles and to follow the evolution of sputtering yield versus fluence and residual vacuum pressure, and also for determining the amount of carbon and oxygen incorporated on the Ti-implanted surface as a function of fluence and pressure. Theoretical calculations of sputtering and high-fluence Ti distributions were performed and compared to experimental data. The importance of the reactions that occur between the implanted surface and the residual gases in the vacuum during implantation (C and O competition) is discussed.


Surface & Coatings Technology | 1992

Physicochemical and tribological characterization of titanium or titanium plus carbon implanted AISI M2 steel

M.A. El Khakani; G. Marest; N. Moncoffre; J. Tousset

Abstract AISI M2 steel samples were implanted with 110 keV titanium ions at fluences ranging from 5 × 1016 to 4 × 1017 Ti cm-2. Titanium plus carbon dual implantation was also studied. Titanium distribution profiles were determined using the 48Ti(p,γ)49V resonant nuclear reaction. The incorporation of carbon and oxygen from residual gases was studied as a function of titanium fluence and residual pressure using nuclear backscattering spectrometry at 5.7 and 7.5 MeV He+ ion energies respectively. A competition phenomenon between carbon and oxygen incorporation is pointed out. Analysis of the phases formed was performed using conversion electron Mossbauer spectroscopy. Fe(Ti) solid solution, a-FexTi100−x and superficial a-Fe-Ti-C amorphous phases were identified. Tribological tests involving a ball (Al2O3 or 52100) and disc contact were performed to characterize the friction behaviour of the implanted surface. It is shown that titanium or titanium plus carbon implantation leads to a reduction in the friction coefficient. The wear tracks and debris were examined using scanning electron microscopy and electron microprobe cartography. For the two types of balls a reduction in the wear track width was observed together with oxidation of the wear debris. The tribological improvement observed depends not only on the presence of the superficial a-Fe-Ti-C amorphous layer but also on the surface chemical reaction during the wear process.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1991

Effects of annealing environment on surface chemical phases of iron-implanted sintered alumina

C. Donnet; G. Marest; N. Moncoffre; J. Tousset

Abstract Annealing in various environments was performed on high-dose (10 17 ions/cm 2 , 110 keV) iron-implanted polycrystalline alumina samples in order to study the nature of the chemical phases formed during the recovery of the implanted layer. The influence of oxygen partial pressure was studied by comparing samples annealed in air and in argon environments. Anneals in a reducing environment (pure H 2 ) were also performed. Conversion electron Mossbauer spectroscopy and Rutherford backscattering spectrometry clearly reveal the importance of the annealing atmosphere on the nature of the surface phases in the temperature range 600–1600 °C.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1990

Characterization of polycrystalline α-Al2O3, zirconium implanted and annealed at various temperatures

C. Donnet; H. Jaffrezic; N. Moncoffre; J. Tousset; G. Fuchs

Abstract Polycrystalline α-Al2O3 samples implanted with 50–190 keV Zr ions from 5 × 1016 to 2.5 × 1017 ions/cm2 have been investigated. A physico-chemical characterization of the as-implanted specimen has been carried out. By using XPS. it is shown that the four chemical states ZrO2, Al2O3, Al and Zr are present in the implanted layer. Moreover, TEM indicates no precipitate formation. Thermal annealings have been performed between 700 and 1600°C for one hour in an oxidizing atmosphere. RBS and SEM techniques, used to follow the evolution of the zirconium versus the annealing temperature, show that under air, from 700°C, zirconium is entirely oxidized. Up to 1000°C small oxide precipitates are formed. The ZrO2 grain size increases with temperature between 1200 and 1600°C. At 1600°C a heterogeneous distribution of ZrO2 nodules (∼ 0.7 ω) is observed in conjunction with Zr release from the surface (~ 60% of Zr loss). Moreover, this study is completed by in situ annealing TEM observations.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1990

Depth profiling of nickel using the nuclear resonant 58Ni(p,γ)59Cu reaction: Application to NiFe mixed bilayers and Ni-implanted iron

M.A. El Khakani; G. Marest; N. Moncoffre; J. Tousset

Abstract The nuclear resonant 58 Ni(p,γ) 59 Cu reaction at E p = 1424 keV was used to determine nickel depth distributions in iron-nickel based alloys. γ radiations were detected by using a high efficiency Ge detector. For quantifying the reaction yield, the γ transitions of E γ = 4.82 MeV, 4.33 MeV and 0.491 MeV energies were considered. This technique allows nickel to be profiled with a depth resolution of about 10 nm at the surface of iron matrix. Applications of the method to NiFe ion beam mixed bilayers and Ni-implanted iron are presented.


Radiation Effects and Defects in Solids | 1994

Nitrogen implantation in iron : influence of the beam current density and of the chamber residual pressure

N. Millard‐Pinard; H. Jaffrezic; G. Marest; N. Moncoffre; J. Tousset; B. Rauschenbach

Abstract Iron samples were implanted at a fluence of 1017 N+ ions.cm−2 with an energy of 50 keV. The beam current density was varied in the range 6–60 μA.cm−2 as well as the quality of the vacuum in the implantation chamber. Implantations were performed at 150°C to favour the carburization process. Carbon and oxygen contaminations were controlled using nuclear backscattering spectrometry (NBS) with α particles of 5.7 MeV and 7.5 MeV respectively or by using Auger electron spectroscopy (AES). The depth profiles of implanted nitrogen were determined by the 15N(p,αγ) nuclear reaction or by AES when 15N or 14N ions were implanted respectively. Implantation induced chemical phases were characterized using Mossbauer spectroscopy and electron diffraction. It is shown that at 150°C the beam current density which has an influence on the implantation time as well as the contamination carbon content at the surface play an important role in the migration process of nitrogen. Consequently, the nitrogen depth distribut...

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N. Moncoffre

Centre national de la recherche scientifique

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G. Marest

Centre national de la recherche scientifique

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C. Donnet

Centre national de la recherche scientifique

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H. Jaffrezic

Centre national de la recherche scientifique

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M.A. El Khakani

Centre national de la recherche scientifique

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A. Chevarier

Centre national de la recherche scientifique

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B. Roux

Centre national de la recherche scientifique

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E. Gerlic

Centre national de la recherche scientifique

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H. Artigalas

Centre national de la recherche scientifique

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M. Stern

Centre national de la recherche scientifique

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