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This work focuses on the evolution of the morphology and structure of La2NiO4 (namely, LNO) coatings deposited by reactive magnetron sputtering (RMS) with subsequent annealing processes. The LNO coatings start to crystallize at 600 °C, and the LNO with K2NiF4 structure was formed at 700 °C. A small amount of La3Ni2O7 appeared in the La2NiO4 coatings at 1100 °C. Interestingly, the LNO coatings realize the transformation from dense to different porous morphologies due to the annealing process. The LNO coating with abundant pores was formed after annealing treatment at 1000 °C for 2 h. This porous morphology can be stably maintained after short-term thermal stability experiments at 750 °C for 120 h. The electrochemical impedance spectroscopy (EIS) measurement of the LNO/YSZ/LNO symmetrical half-cells shows that the LNO cathode coating after annealing at 1000 °C for 2 h exhibits lower polarization resistance (Rpol) and activation energy.

Nanoporous BiVO4 thin films were deposited using reactive magnetronsputtering in Ar and O2 atmosphere, on various substrates,employing pulsed direct-current (DC) power supplies applied tometallic Bi and V targets for rapid deposition. The procedure wasfollowed by a post-annealing treatment in air to crystallize thephotoactive monoclinic scheelite structure. The influence of totalpressure and substrate on the crystal structure, morphology,microstructure, optical and photocatalytic properties of the filmswas investigated. The crystallization of monoclinic scheelitestructure deposited on fused silica substrate starts at 250 °C andthe films are stable up to 600 °C. The morphology of the films israther dense, despite at the high sputtering pressure (>2 Pa),with embedded nanopores. Among the thin films deposited on fusedsilica, the one deposited at 4.5 Pa exhibits the highest porosity(52%), with the lowest bandgap (2.44 eV) and it shows the highestphotocatalytic activity in the degradation of Rhodamine-B (26%after 7 h) under visible light irradiation. The film deposited onthe silicon substrate exhibits the highest photoactivity (53% after7 h). Lack of hypsochromic shift in the UV−Vis temporal absorptionspectra shows the dominance of the chromophore cleavage pathway inthe photodecomposition.

International audience; The p-type Ge-doped (0, 1, 4 and 7 at.%) Mg

Herein, intrinsic p-type conductivity of NiO films were enhanced by high power impulse magnetron sputtering (HiPIMS) technology, where more charged Ni3+ ions are created during the deposition process. The formation of Ni3+ ions are advantageous for strengthening the p-type conductivity of NiO films. As the pulse off-time increases from 0 μs to 3000 μs, Ni3+ concentration improves greatly, indicating the amount of Ni vacancies as well as the hole concentration significantly enhances. It confirms that HiPIMS is a preferential technology for preparing NiO films with high p-type conductivity. Especially, when pulse off-time reaches 3000 μs, a high carrier concentration of 2.86 × 1021 cm−3 and a relatively low electrical resistivity about 0.07 Ω·cm are achieved.

International audience; Exsolution is a promising technique to design metal nanoparticles for electrocatalysis and renewable energy. In this work, Ni-doped perovskites, (Pr(0.5)Ba(0.5))(1-x/2)Mn(1-x/2)Ni(x/2)O(3-δ) with x = 0, 0.05, 0.1, and 0.2 (S-PBMNx), were prepared to design exsolution systems as solid oxide fuel cell anodes and for catalysis applications. X-ray diffraction and transmission electron microscopy (TEM) analyses demonstrated that correlating A-site deficiency with Ni content can effectively induce exsolution of all Ni under H(2) atmosphere at T ∼ 875 °C, yielding the reduced (exsolved) R-PBMNx materials. On heating the exsolution systems in air, metal incorporation in the oxide lattice did not occur; instead, the Ni nanoparticles oxidized to NiO on the layered perovskite surface. The lowest area-specific resistance (ASR) under wet 5% H(2)/N(2) in symmetrical cells was observed for R-PBMN0.2 anode (ASR ∼ 0.64 Ω cm(2) at 850 °C) due to the highest Ni particle density in the R-PBMNx series. The best performance for dry reforming of methane (DRM) was also obtained for R-PBMN0.2, with CH(4) and CO(2) conversion rates at 11 and 32%, respectively, and the highest production of H(2) (37%). The DRM activity of R-PBMN0.2 starts at 800 °C and is sustained for up to at least 5 h operation with little carbon deposition (0.017 g·gcat(-1)·h(-1)). These results clearly demonstrate that varying Ni-doping in layered double perovskite oxides is an effective strategy to manipulate the electrochemical performance and catalytic activity for energy conversion purposes.

International audience; Gadolinia doped ceria coatings were elaborated by cathodic arc evaporation from a metallic Ce–Gd (90–10 at.%) target inserted into a conventional multiarc Ti evaporation target in the presence of a reactive argon–oxygen gas mixture. The structural and chemical features of these films were determined by x-ray diffraction and scanning electron microscopy. Their electrical properties were characterized using impedance spectroscopy measurements. It was shown that the as-deposited coatings crystallize in the fluorite type fcc structure of ceria and that their composition is the same as that of the target. The morphology of the coatings is influenced by the evaporation parameter (stress and droplet). The electrical measurements showed two contributions in Nyquist representation and the activation energy was slightly higher than that given in the literature data for the bulk material.

International audience; Delafossite CuFeO2 films have been synthesized by reactive magnetron sputtering at different substrate temperatures from 380 up to 550 °C. The films adopt the rhombohedral structure from 380 to 550 °C. At the highest temperature, the delafossite phase partially dissociates in FCC Cu and Fe3O4 magnetite phases. In addition to the average crystallite size increase, a change of the preferential orientation in the out-of-plane direction from the [012] to [006] directions occurs between 460 and 510 °C. Modelling of the optical properties shows the presence of 2 interband transitions in the visible range. The 1st main transition at 1.5 eV is ascribed to the absorption component parallel to the c-axis whereas the 2nd transition (2.10 – 2.26 eV) is related to the absorption component in the (a, b) plane. Both evolutions with temperature of the refractive index (~ 2.5) and absorption coefficient (~ 10-3 cm-1) in the infrared suggest the formation of secondary phases. The electronic conductivity, dominated by positive charge carrier, varied from 0.01 to 10 S m-1 according to the preferential orientation and to the presence of secondary phases. A very small amount of a short-range ferromagnetic component (magnetization ~ 10 kA m-1 at 1.5 T) is clearly observed at room temperature thanks to magnetometry confirming the formation of secondary phases undetected by X-ray diffraction. In addition to depend on the film orientation, the presence of secondary phases in weak proportion alters the optical and electrical behaviours such as the transmittance in the visible range..

TaC/a-C:H films with varying carbon content within a narrow window were deposited employing HiPIMS in the Ar/C2H2 atmosphere. The DC deposited TaC/a-C:H reference films were prepared under the same deposition parameters for comparison. Analysis and comparison of the chemical bonding state, structure, mechanical and tribological properties, and oxidation resistance of the films were conducted, with the aim of emphasizing the differences in the nanocomposite structure and properties of the films correlated to deposition conditions. It reveals that the HiPIMS deposited TaC/a-C:H films outperform the DC deposited ones, exhibiting higher hardness and toughness, lower friction coefficient and wear rate, and stronger oxidation resistance. The improved performances in HiPIMS are attributed to HiPIMS plasma, which enables (i) the volume fraction of crystalline TaC phase and amorphous carbon phase, (ii) the stoichiometric ratio and grain size of the crystalline phase, (iii) the sp2/sp3 –C ratio, and (iv) the residual stress to develop in the manner that is conducive to film properties. It is demonstrated that HiPIMS plasma can be used as an effective means to modulate the chemical bonding state and nanocomposite structure of TaC/a-C:H film for achieving higher performance in terms of hard yet tough, wear and oxidation resistance.

In PVD technology, it has been demonstrated that the conformal coverage on the microtrench can be improved by substrate biasing, but to a limited extent. Inspired by this, applying an auxiliary magnetic field in HiPIMS was proposed to reinforce the effect of substrate bias on conformal coverage capability. Zr films were deposited on the two microtrenches (aspect ratio of 4.75:1 and 1:1) by the HiPIMS with the auxiliary magnetic field and the conventional HiPIMS, operated at different substrate bias. The coverage ratio and film morphology of Zr films on the two microtrenches were systematically investigated by SEM. It showed that the introduction of the auxiliary magnetic field achieved an improved conformal coverage on two differently sized microtrenches, exhibiting a denser morphology, higher coverage ratio and higher uniformity. Moreover, the composition of the plasma impinging into the microtrenches and the electric field of substrate bias surrounding the microtrenches were analyzed by OES and finite element method. The plasma behavior and the deposition mechanism on the microtrenches were discussed. It revealed that the auxiliary magnetic field greatly increases the collision events, plasma density and thus the proportion of low energy ions in front of the substrate. These altered plasma characteristics make three contributions to the coverage of the microtrenches: (i) enhanced plasma density provided more film-forming species for microtrenches (ii) and appropriately increased the degree of resputtering on the bottom of the microtrenches under the substrate bias, and (iii) a higher proportion of low energy ions reinforced the deflection of the substrate bias on the motion path of incident plasma. They fundamentally enhance the effectiveness of substrate bias on plasma behavior control and weaken the shadowing effect. The results demonstrated that HiPIMS operating with auxiliary magnetic field and substrate bias is a reliable solution to improve the coverage ratio and dense morphology of the microtrenches.

Metallic platinum&ndash, titanium coatings were deposited by co-sputtering of two metallic Pt and Ti targets in pure argon atmosphere. The titanium concentrations varied from 0 to 47 atomic percent and were adjusted as a function of the current applied to the titanium target. The structural and chemical features of these films were assessed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). All as-deposited coatings exhibit a perfect covering of the alumina pellets&rsquo, substrate surface. The coatings containing more than 4 at.% Ti are amorphous, whereas the others crystallize in the face-centered cubic (fcc) structure of platinum. After an annealing treatment under air for 2 h, all of the coatings adopt the fcc structure with a crystallization temperature depending on the titanium content. For titanium concentrations higher than 32 at.%, the TiO2 phase appears during the annealing treatment. For the smaller film thickness of Pt&ndash, Ti alloys (15 nm), the Ostwald ripening mechanism is observed by SEM increasing the annealing temperature regardless of the content of Ti. The film resistivity measured at room temperature is lower than 7 10&minus, 4 &Omega, &middot, cm and increases with the temperature to achieve an insulating behavior (in air and reducing atmosphere Ar-H2 (90-10) at 1123 K the resistivity is &rho, 10+36 &Omega, cm). When the thickness of intermetallic Pt3Ti layer is higher than 50 nm, the coating is continuous and the resistivity is below 5 10&minus, cm in air and in reducing atmosphere (Ar with 10% of H2) up to 1273 K.

Ta, Hf, TaCx, HfCx, and TaxHf1-xCy coatings were deposited by reactive pulsed Direct Current (DC) magnetron sputtering of Ta or Hf pure metallic targets in Ar plus CH4 gas mixtures. The properties have been investigated as a function of the carbon content, which is tuned via the CH4 flow rate. The discharge was characterized by means of Optical Emission Spectroscopy and, in our conditions, both Ta-C and Hf-C systems seem to be weakly reactive. The structure of the as-deposited pure tantalum film is metastable tetragonal &beta, Ta. The fcc-MeCx carbide phases (Me = Ta or Hf) are {111} textured at low carbon concentrations and then lose their preferred orientation for higher carbon concentrations. Transmission Electron Microscopy (TEM) analysis has highlighted the presence of an amorphous phase at higher carbon concentrations. When the carbon content increases, the coating&rsquo, s morphology is first compact-columnar and becomes glassy because of the nano-sized grains and then returns to an open columnar morphology for the higher carbon concentrations. The hardness and Young&rsquo, s modulus of TaCx coatings reach 36 and 405 GPa, respectively. For HfCx coatings, these values are 29 and 318 GPa. The MeCx coating residual stresses increase with the addition of carbon (from one-hundredth of 1 MPa to 1.5 GPa approximately). Nevertheless, the columnar morphology at a high carbon content allows the residual stresses to decrease. Concerning TaxHf1-xCy coatings, the structure and the microstructure analyses have revealed the creation of a nanostructured coating, with the formation of an fcc superlattice. The hardness is relatively constant independently of the chemical composition (22 GPa). The residual stress was strongly reduced compared to that of binary carbides coatings, due to the rotation of substrates.

International audience; Nanocrystalline Ni–W coatings with a range of compositions from pure nickel to pure W were obtained by magnetron sputtering. A multiscale analysis was conducted to characterize the microstructure of the deposits. Their electrochemical behavior in acidic medium was studied using polarization curves and Electrochemical Impedance Spectroscopy. The Ni–W coatings were of similar grain size, roughness and crystallographic texture over a broad range of compositions, which enabled us to examine the role of W on the electrochemical behaviour. The results showed that W incorporation reduced corrosion at the open circuit potential, while for both the cathodic and the anodic domains, the electrochemical reactivity was amplified and reached a maximum value at a W content range of around 15–19 at.%. Although pure nickel and pure tungsten tend to passivate at anodic potential, Ni–W alloys form a mixture of non-protective corrosion products for this composition range. © 2018 Elsevier B.V.

Tungsten oxide thin films are grown by DC reactive magnetron sputtering combining glancing angle deposition (GLAD) and reactive gas pulsing process (RGPP). Inclined, zigzag and spiral columnar architectures are produced with various oxygen injections during the growth. The dodecane and ozone sensing properties of these tungsten oxide nanostructured active layers are comparatively studied with that of films deposited by conventional sputtering process. Microstructure, morphologies and electrical behaviors are characterized as a function of the growing conditions. As-deposited films systematically exhibit an amorphous crystal structure with a porous microstructure, which depends on the GLAD architecture. Annealing at 300 °C in air for 12 h leads to a polycrystalline structure keeping voided networks. Dodecane and ozone sensing performances are the most significant for inclined columnar architectures but they also depend on the RGPP sputtering conditions. As a result, the GLAD + RGPP combination proves to be a relevant strategy for the fabricating tungsten oxide nanostructured films as active layers with an attractive potential for gas sensors.

International audience; This work focuses on the comparison of Ln-Ni-O coatings (Ln = La, Nd, Pr) deposited by reactive magnetron sputtering using Plasma Emission Monitoring (PEM) which allows high deposition rate. Each layer is deposited by different steps. The optimal regulation setpoint for oxide rare-earth deposition is determined and then the current dissipated on the nickel target is adjusted to obtain the convenient Ln/Ni ratio and to achieve the K2NiF4 structure. After an appropriate annealing treatment, all coatings exhibit crystalline structures, which depend on the Ln/Ni ratio. Due to the instability of Pr2NiO4 structure at intermediate temperatures, the crystallization step of praseodymium nickelate is performed at higher temperature than the other materials. This further thermal treatment implies a more porous structure. Each coating exhibits interesting properties. Electrical and electrochemical characterizations performed on these deposits prove better properties of the praseodymium nickelate coating.

International audience; Tungsten oxide thin films were prepared by DC magnetron sputtering. The reactive gas pulsing processwas implemented to modify tungsten and oxygen concentrations in the films. A rectangular pulsingsignal was used with a pulsing period fixed at P ¼ 16 s, whereas the duty cycle a was systematicallychanged from a ¼ 0e100% of P. The chemical composition of the films showed a gradual increase ofoxygen-to-tungsten concentrations ratio from 0 to more than 3.0 as a function of the duty cycle. Filmsbecame poorly crystallized and even amorphous with an increase of the oxygen content. Similarly, atypical columnar structure was observed for pure or oxygen-rich tungsten films, which vanished whenthe duty cycle was higher than a few % of P. The optical transmittance in the visible range of WOx filmsdeposited on glass also showed a progressive change from absorbent to transparent as the duty cycle wasincreased. Electronic transport properties including conductivity, carrier mobility and concentration alsodemonstrated the controlled and regular evolution of the electrical properties from metallic to insulatorwhen the duty cycle and thus oxygen concentration in the films changed from pure tungsten to overstoichiometricWO3 compound.

The functional properties of both electrodeposited and sputtered nickel and NiW nanostructured alloys are discussed as a function of their main microstructural features. As W is incorporated into the Ni matrix, several metallurgical parameters that can influence the functional properties were also modified, namely grain size, crystallographic texture, morphology and element contamination. The hardness measurements for the different coatings were analysed in terms of both grain size and W incorporation effects. In addition, the high level of Argon, particularly for the NiW-PVD coating, was shown to be responsible for the highest hardness value obtained. Comparing the behavior of NiW coatings with that of pure nickel in both elaboration processes shows that tungsten incorporation greatly enhances abrasion resistance.

International audience; The LFPECVD (Low-Frequency Plasma-Enhanced Chemical Vapor Deposition) technique is now used on an industrial scale for the deposition of carbon-based coatings for several applications. This short review recalled the main principles of LFPECVD and provided examples of DLC-based films. The main differences between low-frequency (LF) and radio-frequency (RF) discharges were also recalled here and examples of deposition and characterization of carbon-based films were proposed. The influence of the bias voltage or the temperature of the active electrode on the deposition rate and the structure of a-C: H films obtained in cyclohexane/hydrogen mixtures was first discussed. Next, the properties of carbon-based films doped with silicon were described and, finally, it was shown that multilayer architectures make it possible to reduce the stresses without altering their tribological properties.

In this study, nanoporous BiVO4 thin films were deposited using reactive direct-current (DC) magnetron sputtering. The effects of thickness on the film morphology, crystal structure, microstructure, composition, optical and photocatalytic properties under visible light were investigated. The film porosity and refractive index were also determined via the UV-Vis spectrophotometric technique using transmittance and reflectance spectra and Cauchy dispersion law as the fitting model. The nanoporous morphology was observed using field-emission scanning electron microscopy (FESEM) with average pore sizes in the 20–40 nm range. The X-ray diffraction (XRD) results showed different texture grades corresponding to the (040) crystallographic plane, establishing the film thickness influence on the preferential orientation. The X-ray photoelectron spectroscopy (XPS) was also implemented to investigate the chemical state of the film surface, as well as to determine the valence band position. The film 715 nm in thickness showed the highest porosity (52%), narrowest bandgap (2.44 eV), highest exposed (040) crystallographic plane and highest visible-light-driven photodegradation towards Rhodamine-B (RhB) solution. The pH of the solution also impacted the RhB photodegradation which was optimum at pH 3 with chromophore cleavage pathway dominance, whereas at neutral pH it had distinctively slow kinetics probably due to poor electrostatic interactions and the N-deethylation kinetics bottleneck. The photocatalytic cycle experiments exhibited high stability and recyclability of BiVO4 thin-film photocatalysts after four cycles (4 × 7 h) of exploitation. The photocatalytic mechanism was determined using scavengers and the significance of hydroxyl radicals and photogenerated holes were established. The photocatalytic activity reached 97% after 7 h of illumination with a 400 W light source.

As machine tool coating specifications become increasingly stringent, the fabrication of protective titanium aluminum nitride (Ti-Al-N) films by physical vapor deposition (PVD) is progressively more demanding. Nanostructural modification through the incorporation of metal dopants can enhance coating mechanical properties. However, dopant selection and their near-atomic-scale role in performance optimization is limited. Here, yttrium was alloyed in multilayered Ti-Al-N films to tune microstructures, microchemistries, and properties, including mechanical characteristics, adhesion, wear resistance, and resilience to oxidation. By regulating processing parameters, the multilayer period (Λ) and Y content could be adjusted, which, in turn, permitted tailoring of grain nucleation and secondary phase formation. With the composition fixed at x = 0.024 in (Ti0.6Al0.4)1–x Y x N and Λ increased from 5.5 to 24 nm, the microstructure transformed from acicular grains with 〈111〉 preferred orientation to equiaxed grains with 〈200〉 texture, while the hardness (40.8 ± 2.8 GPa to 29.7 ± 4.9 GPa) and Young’s modulus (490 ± 47 GPa to 424 ± 50 GPa) concomitantly deteriorated. Alternately, when Λ = 5.5 nm and x in (Ti0.6Al0.4)1–x Y x N was raised from 0 to 0.024, the hardness was enhanced (28.7 ± 7.3 GPa to 40.8 ± 2.8 GPa) while adhesion and wear resistance were not compromised. The Ti-Al-N adopted a rock-salt type structure with Y displacing either Ti or Al and stabilizing a secondary wurtzite phase. Moreover, Y effectively retarded coating oxidation at 1073 K (800 °C) in air by inhibiting grain boundary oxygen diffusion.

In this study, we investigated the structural and elastic properties of Zr-TL (late transition metal TL = Cu, Co, Ni) thin films metallic glasses (TFMG) deposited by dc magnetron co-sputtering from pure TL targets in Ar plasma discharge. The influence of the deposition parameters on the microstructure, chemical composition and elastic properties of the thin films has been explored. Advanced non-destructive techniques such as the picosecond ultrasonics and the Brillouin light scattering were employed to selectively measure the longitudinal V L and the transversal V T sound velocities, leading to the determination of the elastic constants C 11 , C 44 , respectively. From these data sets, the elastic constants of metastable amorphous single elements a -Zr, a -Cu, a -Co and a -Ni have been extrapolated. Some relationships between elastic moduli (Young's modulus E and shear modulus G = C 44 ) and the structural state either crystalline or amorphous are established. Predicted ductility/brittleness character was emphasized based on the Blackman's diagram, Pugh's ratio and the Pettifor criteria. Equivalently, the newly introduced δ parameter termed as ‘the cooperation parameter’ and related uniquely to the Poisson's ratio ν , confirmed the improvement of ductility with TL alloying.

Reactive magnetron sputtering deposition technique was used for formation of gadolinium doped ceria oxide (GDC) thin films 5- 10µm. Material characteristics and chemical compositions of GDC films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and 3D profilometry. In order to optimize the deposition of GDC to obtain high electrochemical performance of the cells, the influence of film thickness is studied. The GDC thin films were deposited on porous NiO–GDC (nickel oxide–Gadolinium stabilized ceria), the pre-sintered anode green tape were coated with a GDC electrolyte film by reactive magnetron sputtering using PEM (Plasma Emission Monitoring). An Alcatel SCM650 sputtering chamber was used for synthesizing the dense GDC layers. A Ce-Gd metallic target (90-10% at) was powered by a pinnacle + pulsed current generator from Advanced Energy. The structural, microstructural and morphological features of the half-cells were determined by XRD, SEM and 3D profilometry as deposited and after different annealing treatments. The obtained half-cell, 28 mm of diameter, anode supported solid oxide fuel cell, the porous and density of Ni-GDC10 composite anodes have been elaborated by tape casting method. The chosen ceramic powders in suspension were prepared with the mass ratio of 65:35 for NiO to GDC10. The microstructural morphological /porosity/surface features of the half-cell were analyzed by Scanning Electron Microscopy (SEM), XRD and 3D profilometry before and after different annealing treatment. Pycnometry and porosimetry techniques were primarily used to determine pore size and pore volume by equation Washburn and Ideal gas law-method. Finally, the EIS (Electrochemical Impedance Spectroscopy) measurements were done on Ni-GDC10/GDC10 half-cells under 60 sccm nitrogen by the means of a Solartron SI 1260 impedance / gain analyser from 20 MHz to 0.1 Hz with 11 points per decade.

Nowadays, the researchers that are working on the SOFC technology, are agree that it is necessary to decrease the operating temperature at 700°C(650-750 °C) of IT-SOFC technology, which currently is around 850-900°C for electrolyte supported cell used by the three main operators –Bloom, Hexis and Sun Fire. At this temperature the reactivity and the component cost of the cell decrease. Nevertheless, some interactions between the conventional electrolyte material (YSZ) and the cathode material (lanthanum based) are still present and it is necessary to include a ceria buffer layer to avoid the possible formation of an insulating pyrochlore structure La2Zr2O7 layer at the electrolyte-cathode interface. In ceria family, the best material regarding the ionic conductivity is the samaria doped ceria. However, the gadolinia doped ceria is the most employed from the cost point of view and the availability of gadolinium in comparison with samarium. This buffer layer avoids the reactivity between electrolyte and cathode, and presents a good anionic conductivity. It must be dense, thin and adherent on electrolyte, in order to be suitable for the surface treatment process. In this paper, we present some recent results obtained on the gadolinia doped ceria coatings deposited by magnetron sputtering from metallic targets in argon-oxygen reactive gas mixtures with different substrate bias voltage. After a description of the experimental device, a first part will be dedicated to their chemical, microstructural and structural characterization (SEM, XRD,…) in relation with the magnetron sputtering deposition parameters. In a second part, the ionic transport characteristics of the half cell (Ni-YSZ/YSZ/GDC) will be investigated via impedance spectroscopy measurements performed at various temperatures up to 800°C under Ar-H2 gas mixtures. Finally, a complete cell test ((Ni-YSZ/YSZ/GDC/LSC) was performed with the Fiaxell Open Flanges test bench. This study is carried out within the framework of the European territorial cooperation program INTERREG V A France-Switzerland. It has benefited from financial support from the EU through the European Regional Development Fund (ERDF- € 139,176) and the Swiss Confederation's contribution of CHF 134,173

Although HiPIMS technology has been widely studied, its optimization still remains in the adjustment of the experimental parameters acting on the ions, such as impulse mode, due to the inherent complexity of partially magnetized plasma of HiPIMS. Herein, recapture and re-energy of electrons by the assistance of the A-type magnetic field configuration, constructed by field coupling of the cathode magnetron and the auxiliary magnets mounted behind the substrate holder, was proposed. The dynamic behavior of the ions is attempted to be guided by exploiting electron recapture. The studies on the plasma diagnosis by optical emission spectroscopy and magnetic field simulation revealed that when the cathodic discharge remains constant, the characteristics of the deposition plasma in front of the substrate can be altered. Zirconium films were prepared under the a-HiPIMS mode (operated with the A-type magnetic configuration) and the conventional HiPIMS mode. Results showed that the Zr films prepared in the a-HiPIMS mode exhibited smoother surface, denser morphology, finer grains, higher homogenous thickness distribution, higher hardness, enhanced elastic recovery and higher value of the ratios H/E⁎ and H3/E⁎2. The mechanism of microstructure evolution of Zr film was discussed. It demonstrated that the action of the A-type magnetic configuration can densify the Zr film, without the need for high energy ion bombardment. The A-type magnetic field configuration provided an alternative strategy for compensating for the shortcoming of substrate bias in HiPIMS, invalidity to electrical insulating substrates, in terms of the dense film.

International audience; Yttria Stabilized Zirconia (YSZ) coatings were synthesized by reactive magnetron sputtering under different bias powers applied to the substrate holder and different thickness. All as-deposited coating presents a face centered cubic (f.c.c) structure of zirconia with dense and adhesive morphology. All coatings are adherent and the density increase with the bias power applied on the porte substrate holder. The best performance of the cell obtain in this study is 1060 mW.cm-2 at 650°C when the electrolyte thickness is 1.8 μm.

International audience; Recent progress in the activity improvement of anode catalysts for acidic electrochemical water splitting is largely achieved through empirical studies of iridium-based bimetallic oxides. Practical, experimentally accessible, yet general predictors of catalytic OER activity have remained scarce. This study investigates iridium and iridium–nickel thin film model electrocatalysts for the OER and identifies a set of general ex situ properties that allow the reliable prediction of their OER activity. Well-defined Ir-based catalysts of various chemical nature and composition were synthesized by magnetron sputtering. Correlation of physicochemical and electrocatalytic properties revealed two experimental OER activity descriptors that are able to predict trends in the OER activity of unknown Ir-based catalyst systems. More specifically, our study demonstrates that the IrIII+- and OH-surface concentration of the oxide catalyst constitute closely correlated and generally applicable OER activity predictors. On the basis of these predictors, an experimental volcano relationship of Ir-based OER electrocatalysts is presented and discussed.

International audience; Coatings with thicknesses between a few microns and similar to 10 mu m deposited on a Zircaloy-4 substrate have been studied with the objective to provide a significant reduction in the oxidation-induced embrittlement of the nuclear fuel cladding, especially in accidental conditions, such as LOss-of-Coolant-Accident (LOCA) conditions. This paper deals with the early studies carried out at CEA, several years before the Fukushima-Daiishi events, on different types of coatings obtained by a physical vapor deposition process. The studied coatings included ceramic, nitride and metallic multi-layered ones. The results of this screening analysis showed that the first generation of chromium-based coatings exhibited the most promising behavior: good compromise between oxidation resistance and adhesion to the metallic substrate, good fretting resistance and improved resistance to oxidation in steam at high temperature (Design Basis Accident LOCA conditions and slightly beyond).

International audience; • FeO films were synthesized by pulsed-DC magnetron sputtering from metallic target. • The film oxidation was controlled with a plasma emission monitoring system. • Special attention was paid to the sample position relative to the target axis. • Structural features depend on the oxidation rate of the growing films. • FeO behaviors are tuned from hematite semiconductor to magnetite semimetal properties. A R T I C L E I N F O Keywords: FeO Reactive sputtering Plasma emission monitoring Hematite Magnetite A B S T R A C T Iron oxide films were synthesized by pulsed-DC magnetron sputtering from a metallic target in Ar and O 2 gas mixtures. Plasma emission monitoring was implemented to accurately control the metal-to-oxygen ratio in the coating through the chemical state of the iron target. The intensity of the Fe* emission line was maintained at a given value (setpoint) by regulating the introduced oxygen flow rate. In addition, the oxidation rate of the growing film was adjusted by controlling the oxidation-to-deposition rate ratio as a function of the position of the substrates relative to the magnetron axis. The iron oxide films were characterized by X-ray diffraction, UV-VIS spectrophotometry, electrical measurement and vibrating sample magnetometry. In addition to the crys-tallization of pure hematite and magnetite phases, both phases coexist in a transition domain for a short range of setpoint depending on the oxidation-to-deposition rate ratio. The electrical, optical and magnetic behaviors of the FeO x films suggest that the relative proportion of phases can be tailored in this range. The FeO x film behaviors can then be tuned from the hematite semiconductor properties to the semi-metallic magnetite properties .

In order to improve the mechanical properties of TiN–Cu coatings, such as their hardness, adhesion and wear resistance, C atoms are proposed to be introduced into TiN–Cu coatings. In the current work, TiCN–Cu coatings with various carbon content were deposited on the high-speed steel by reactive multi-arc ion plating. The coatings' morphology, structure and mechanical properties were analyzed. The results show that with increase in C content, the coating's crystallinity degrades. The optimal hardness and adhesion strength of 37 GPa and 58 N can be achieved. A relatively low friction coefficient of about 0.11 is realized when C content is 34.14 at.%. Compared with TiN–Cu coatings without carbon doping, the mechanical properties of TiCN–Cu coatings are improved significantly.

In this work, the influences of the temperature and the air residual pressure during post-annealing treatment on the structural, optical and electrical properties of copper iron oxide thin films were investigated. The films were co-sputtered from metallic Cu and Fe targets in the presence of argon and oxygen gas mixture. The powers dissipated on the metallic targets were adjusted to fix the Cu/Fe metallic ratio close to 1 in the films. The as-deposited thin films were initially amorphous, and they were annealed under different oxidizing conditions as a function of the temperatures (380, 450 and 550°C) and of the air residual pressures (secondary vacuum, primary vacuum, and air atmosphere corresponding to the air residual pressures of 10−4, 10−1 and 105 Pa respectively). Spinel CuFe2O4 were clearly detected by X-ray diffraction analysis after air-annealing. With the diminishing of the air residual pressure, the films are reduced. It was shown that the delafossite CuFeO2 phase growth is possible in a limited range of temperature and pressure and is accompanied by the crystallization of phase mixture in which the nature of secondary phases depends on the air residual pressure. The optical and electrical properties of Cu-Fe-O thin films were then detailed and discussed according to the structural evolution with the treatment conditions.

International audience; The crystalline and magnetic properties of micron thick magnetron sputtered Co1−x Crx and Co1−x Nix alloy films are analyzed in the view of their implementation as semi-hard magnets. All of the tested films crystallize in an hcp lattice, at least up to 35 at% of alloying elements (Cr or Ni). The structural study shows that the ratio of hcp phase with [0001] axis orientated perpendicular to the film as compared with in-plane orientation increases (resp. decreases), when Ni (resp. Cr) concentration increases independently of the post-annealing temperature. The orientation of the magnetization results from the competition between the demagnetization field which tends to align the magnetization in plane and the crystalline anisotropy which tends to maintain the magnetization along the [0001] axis. Interestingly, we find that, although Co and Ni are very similar atoms, Co1−x Nix alloys crystalline anisotropy can be strongly increased and reach up to twice the anisotropy of the best Co1−x Crx alloy, while maintaining a magnetization at saturation above 1200 kA/m. The thermal stability of the structural and magnetic properties of both alloys is demonstrated for an annealing temperature up to 300 °C.

Pure V thin films were dc sputtered with different pressures (0.4 and 0.6 Pa) and particle incident angles α of 0°, 20° and 85°, by using the GLancing Angle Deposition (GLAD) technique. The sputtered films were characterized regarding their electrical resistivity behaviour in atmospheric pressure and in-vacuum conditions as a function of temperature (40–550 °C), in order to control the oxidation process. Aiming at comprehending the oxidation behaviour of the samples, extensive morphological and structural studies were performed on the as-deposited and annealed samples. Main results show that, in opposition to annealing in air, the columnar nanostructures are preserved in vacuum conditions, keeping metallic-like electrical properties.

International audience; High power impulse magnetron sputtering (HiPIMS) technology is employed to prepare HfC/a-C:H nanocomposite films in Ar/C2H2 atmosphere. The gas flow rate is varied to modulate the carbon content and nanocomposite structure of the film. The correlations between the carbon content and nanocomposite structure and the mechanical properties, thermal stability and oxidation resistance of HfC/a-C:H films are investigated. Mechanical properties analysis revealed that the optimal hardness 34.8 GPa is obtained at the HfC/a-C:H film with C content of 63.6 at.%. The Young’s modulus is related to the C–Hf∗ bond, which effectively toughens the film. The thermal stability of the film performs well when the annealing temperature reaches 800 °C and is gradually enhanced as the amorphous carbon content increases. Moreover, films with higher amorphous carbon content have greater potential for further hardening after annealing (from 31.8 to 38.4 GPa). The oxidation resistance of the film is governed by the synergistic effect of HfC grain size and amorphous carbon content. It is demonstrated that the two factors of fine grains and narrow mean grain separation are necessary to achieve enhanced oxidation resistance. These results may open up a new possible way to design other nc-MeC/a-C:H films for optimizing the toughness, thermal stability, and oxidation resistance.

The SOFC/SOEC community is now convinced that it is necessary to reduce the operating temperature of fuel cells to make the systems more robust, more reliable and thus to consider large-scale development. At the material level, the change of the reference electrolyte (YSZ) by a cerium compounds allows a significant performance gain for lower temperatures of use. It is obviously necessary to keep in mind the constraints related to the electrolyte application in solid electrolyte device, namely: good ionic conductivity unlike the electrical conductivity which must be low, electrochemical compatibility with the electrodes, be dense and covering on porous substrates. In this study, Gadolinia doped ceria coatings were deposited by cathodic arc evaporation from a metallic Ce-Gd (90/10 at%) target inserted into a conventional multiarc Ti evaporation target in the presence of a reactive argon-oxygen gas mixture. The structural and chemical features of these films were determined by X-ray diffraction and scanning electron microscopy. Their electrical properties were characterised using impedance spectroscopy measurements. It is shown that the as-deposited coatings crystallise in the fluorite type fcc structure of ceria and that their composition is the same than that of the target. The morphology of the coatings is influenced by the evaporation parameter (stress and droplet). The electrical measurements showed two contributions in Nyquist representation (figure1) and the activation energy is slightly higher than that given in the literature data for the bulk material. Figure 1 : Nyquist impedance plots of GDC coating, registered at 400°C, for two a.c. signal amplitudes. Logarithms of frequencies are indicated in the figure. Figure 1

Lanthanum perovskites are promising candidates to replace platinum group metal (PGM), especially regarding catalytic oxidation reactions. We have prepared thin catalytic coatings of Sr and Ag doped lanthanum perovskite by using the cathodic co-sputtering magnetron method in reactive condition. Such development of catalytic films may optimize the surface/bulk ratio to save raw materials, since a porous coating can combine a large exchange surface with the gas phase with an extremely low loading. The sputtering deposition process was optimized to generate crystallized and thin perovskites films on alumina substrates. We found that high Ag contents has a strong impact on the morphology of the coatings. High Ag loadings favor the growth of covering films with a porous wire-like morphology showing a good catalytic activity for CO oxidation. The most active composition displays similar catalytic performances than those of a Pt film. In addition, this porous coating is also efficient for CO and NO oxidation in a simulated Diesel exhaust gas mixture, demonstrating the promising catalytic properties of such nanostructured thin sputtered perovskite films. Fil: Arab Pour Yazdi, Mohammad. Universite de Bourgogne; Francia Fil: Lizarraga, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. Universite Claude Bernard Lyon 1. Institut de Physique Nucléaire de Lyon.; Francia. Universite Lyon 2; Francia Fil: Vernoux, Philippe. Universite Claude Bernard Lyon 1. Institut de Physique Nucléaire de Lyon.; Francia. Universite Lyon 2; Francia Fil: Billard, Alain. Universite de Bourgogne; Francia Fil: Briois, Pascal. Universite de Bourgogne; Francia

International audience; Mg-Sn thin films (21 ≤ at. % Sn ≤ 42.5) were deposited by magnetron sputtering in the argon atmosphere. The structure and morphology of the films were characterized as a function of the composition. Mg2Sn structure was changed from stable face-centered cubic to metastable orthorhombic structure while the content of Sn in the films increased. The influence of this structural modification on thermoelectric properties was discussed in a wide range of temperatures (30–200 °C). The film carrier concentration and mobility were measured to explain the electronic transport behavior as a function of the film structural modifications. The maximum figure of merit ZT ≈ 0.26 at 200 °C was reached for the film with 36 at. % Sn while a mixture of cubic and orthorhombic Mg2Sn structures coexisted. An annealing treatment was performed under vacuum (∼10−4 Pa) at different temperatures (up to 600 °C) to determine the limit of structural and morphological stability of this film.

Inclined, zigzag and spiral Ti1-xCux films were co-sputtered by the Glancing Angle Deposition technique. Two distinct titanium (Ti) and copper (Cu) targets were used and the films were grown with a particle flow incidence angle α of 80°. The thin films had Cu contents ranging from 36 to 76 ± 5 at. %. The effect of increasing Cu incorporation on the electrical anisotropy, as well as the effect of columnar architecture variations on the morphological, structural and electrical properties of the films was evaluated and correlated with the particular their architectures. Main results show well-defined and highly inclined columns (with an average column angle β = 45° ± 5°) for all sputtering conditions. Quasi-amorphous thin films were obtained with low Cu contents (36 at. %), while crystalline Cu (111) + Ti3Cu (114) bi-component structures were achieved at high Cu concentrations (76 at. %). No permanent oxidation of the films was detected after a two-cycle RT-200 °C-RT (RT – room temperature) annealing in air. The two-dimensional representation of the resistivity anisotropy of the columnar and 2 zigzags films is shaped as an elongated ellipse along the xx direction, with a variation of the effective anisotropy, Aeff, at 200 °C from 1.4 to 2.9. The samples prepared with 2 spirals and the same Cu content (36 at. %) exhibit an isotropic behavior, with an Aeff value at 200 °C of 1.1. The overall results demonstrate the possibility to tune the thin films' morphology and electrical characteristics in order to obtain a set of properties that are suitable for the development of high performance materials, such as the case of resistance temperature detectors., This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2013 and project PTDC/EEI-SII/5582/2014. Armando Ferreira acknowledges the FCT for the SFRH/BPD/102402/2014 grant. Funding was also provided by the Region of Franche-Comte, the French RENATECH network and performed in cooperation with the Labex ACTION Program (contract ANR-11-LABX-01-01). Financial support from the Basque Government Industry Department under the ELKARTEK and HAZITEK programs is also acknowledged.

International audience; Tungsten oxide thin films exhibiting an oriented columnar architecture were prepared by reactive co-sputtering. Two opposite W and WO3 targets focused on the center of the substrate were simultaneously sputtered using opposite and oblique angles of 80° from the substrate normal. The reactive gas pulsing process was used to adjust the films electrical resistivity. Different inclined columnar structures were produced and applied as gas sensors for dodecane detection. Morphology, structure and resistivity of the films were investigated and connected to the sensing performances measured from 373 to 773 K.

International audience; Hydrogen solid storage in intermetallic compounds has attracted great attention in the recent decades; TiFe-basedmetal hydride is one of the most important candidate materials to hold atomic hydrogen because of its significant storage capacity (about 1.9 wt. %) and its moderate operating pressure and temperature. The main hindrance to an effective and large use of this metal forming hydride is the difficult activation process i.e. the initial hydriding attempt. In this paper an experimental study about the first hydrogenation process of TiFe0.9Mn0.1 is carried out with a Sievert apparatus. At first, powder fabrication protocol then materials and methods used for the experimental characterizations are described. Secondly, a literature survey is presented about the activation processes of TiFe based alloys. Finally experimental results, discussions and conclusions are exposed. Those results lead to a comparison between the hydrogenation behaviors of two TiFe0.9Mn0.1 powder types: the ‘as received’ powder and the same powder after a thermo-chemical treatment. A wide improvement in the hydrogen activation response is noticed when the powder is submitted to this thermo-chemical treatment under specific operating conditions of gas pressure, temperature and time-duration. Plotted PCI curves and XRD patterns demonstrate that the material bulk is not affected by this thermo-chemical treatment. Then, the operating conditions are optimized, and SEM visualizations are performed in order to point out the effects of the treatment on the surface properties of TiFe0.9Mn0.1 particles. At the end, a conclusion summarizes the main results and outlines the perspectives of such thermo-chemical treatment.

International audience; Cu–Fe–O thin films were prepared via vacuum thermal evaporation of Fe and Cu after what the obtained bilayer Fe\Cu was annealed in free air at different temperatures during 2 h. The obtained Cu–Fe–O thin films were characterized using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), electrical and spectrophotometric measurements. X-ray diffraction (XRD) analysis revealed the presence of Fe2O3, CuO and CuFeO2 phases. Cu–Fe–O thin films exhibit rough surfaces by analyzing the film morphologies by scanning electron microscopy. Energy dispersive spectroscopy (EDS) technique was used to evaluate Cu–Fe–O thin films stoichiometry. The optical properties reveal that the absorption coefficient of Cu–Fe–O thin films is larger than 105 cm−1 and two optical direct band gaps in the range 1.65–2.2 eV were found. The Wemple and DiDomenico model was used to study the dispersion of the refractive index in terms of the single oscillator model. So, optical parameters such as refractive index, extinction coefficient, oscillator energy and dispersion energy were calculated. In addition and by using the model of Spitzer and Fan, the electrical free carrier susceptibility and the carrier concentration on the effective mass ratio were evaluated. All the samples present relatively high electrical resistivity.

International audience; Innovation in thin-film deposition processes, thermal spraying and cladding technologies mostly rely on evolutions of their previous iteration. Along with other examples, five case studies of emerging elaboration processes for metallurgical coatings are described coupled with their applications. In the frame of the lifetime extension of components exposed to aggressive media or their functionalization, this article depicts all the developments of the detailed processes. Physical vapor deposition (PVD) of coatings with exceptional properties is possible thanks to sources generating highly ionized metallic vapors. The control of the average energy per incident species and particularly metallic ions strongly influences the characteristics of the deposited layer obtained, for example, with HiPIMS (High Power Impulse Magnetron Sputtering). While PVD techniques are mainly directive regarding the growth of the coating, chemical vapor deposition (CVD) processes manage to homogeneously coat complex 3D shapes. The use of specific precursors in DLI–MOCVD (Direct Liquid Injection – MetalOrganic CVD), carefully selected from the whole metalorganic chemistry, allows one to efficiently treat heat-sensitive substrates and broadens their application range. The third detailed example of emerging technology is suspension plasma spraying (SPS). Projection of various solutions containing nanoparticles leads to the growth of unusual morphologies and microstructures and to the generation of porous coatings with multi-scaled porosity. On the other hand, cold-spray uses metallic powders with higher granulometry and does not modify them during the deposition process. As a result, high-purity and dense materials are deposited with properties similar to those of wrought materials. Whereas cold-spray is suitable only for ductile metals, laser cladding can be applied to ceramics, polymers and of course metals. Laser cladding is a key technology for advanced metallurgical engineering and alloy development due to its capability for functionally graded materials production and combinatorial synthesis.

International audience; Nanostructuration has opened the way for designing materials with improved properties by taking advantage of multiple interfaces providing enhanced local physical properties. In this frame, nanostructured materials are envisioned for nuclear applications due to severe environmental conditions (radiation, temperature, corrosion…). Here we report a study based on IBA (RBS and NRA) of a nanometric Cr/Ta multilayer coating demonstrating an extremely high radiation tolerance. TEM was also performed to confirm RBS results. Multilayer coated samples were firstly implanted with helium ions, and NRA analyses revealed that an optimized geometry can accommodate up to 20 at. % of gas without noticeable damage, implanted atoms being probably stored at the Cr/Ta interfaces. Heavy ion irradiation was also performed at room temperature (RT) and 400°C, mimicking nuclear reactor neutron bombardment. Although we detected the growth of mixing layers at the Cr/Ta interfaces upon irradiation, these newly created layers remain much thinner than those produced at a single interface, preserving the initial multilayer arrangement.

In this paper, we present the construction and preliminary experimental results of a MOEMS fiber-based integrated probe for endoscopic optical imaging of stomach tissue using a Swept-Source Optical Coherence Tomography (SSOCT). The probe consists of a Mirau micro-interferometer, combined with a GRIN lens collimator and a micromirror scanner. We describe the building blocks of the probe, especially the monolithically integrated Mirau mirointerferometer, fabricated by wafer-level vertical stacking and anodic bonding of Si/glass components, and the electrothermal 2-axis MEMS microscanner allowing large swept angles (up to ±22°) at high frequencies (&gt kHz) for low driving voltages (

ZnO with dense, porous, nano-wire and nano-tree morphologies was successfully synthesized via reactive magnetron sputtering at high pressure (10 Pa) and with different deposition temperatures (RT → 1273 K). The morphological properties of prepared ZnO coatings were revealed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis was performed to determine crystalline structure of the films in relation with their deposition temperature. Hall effect measurements were used to investigate the electrical resistivity, free carrier concentration and mobility in the coatings as a function of their morphology in a temperature range from 293 K to 473 K. Finally, C12H26 dodecane gas sensing properties of ZnO nano-trees were investigated at different temperatures (from 323 K to 566 K) and the results were discussed depending on dodecane concentration. A remarkable response of 39% was observed at 415 K for a low concentration of dodecane in air [1 ppm(v)]. High response to low concentrations of C12H26 as well as good chemical stability of ZnO nano-trees make this kind of structure a potential candidate as sensing layer for practical sensor applications.