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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.

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.

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.

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; 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; • 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.

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.

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

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.

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.

Two kinds of co-planar sensor cells based on Bi 2 Ta n V 1 − n O 5.5 (BITAVOX.n, where n corresponds to the substitution rate of V by Ta multiplied by 100) electrolytes were built by reactive magnetron sputtering. A sensor configuration exploited LASCO (La 1 − x − y Ag x Sr y CoO 3 -δ ) and platinum electrodes (Pt/BITAVOX.16/LASCO). However, due to the activity of both of them with different response times, this sensor exhibited a complex behaviour under 723 K. The second cell, Pt/BITAVOX.08/Au, exhibits a response at 473 K, and its intensity increases up to 623 K. At 673 K, polarisation changes, and the absolute value of the response increases dramatically, which can be explained by the competition with catalytic reaction over the platinum electrode.

International audience; wo series of W-Cu thin films were developed by the GLAD co-sputtering technique. The films were produced with two separated W and Cu targets. Both targets were focused on the centre of the substrate and were simultaneously sputtered using opposite and oblique angles of 80° from the substrate normal. In the first series, the W and Cu target currents were inversely changed from 50 to 140. mA in order to tune the elemental concentrations and the microstructure. For the second series, a shield was added between W and Cu targets, perpendicularly to the substrate surface in order to prevent the cross-contamination of the targets. The target currents were varied similarly to the first series. Two argon sputtering pressures were used (0.42 and 1.0. Pa) in each series, with and without the shield.Microstructure showed a tuneable inclined columnar microstructure, which become normal to the substrate at high pressure. The crystallographic structure was not significantly influenced by the shield implementation but rather by the sputtering pressure. The W/Cu atomic concentration ratio varied between 0.2 and 5.5 as a function of the sputtering pressure and target currents and an anisotropic chemical composition was measured inside the columns. The wide range of DC electrical resistivities (3.6×10⁻⁷ to 5.7×10⁻⁵ Ωm) was discussed considering W and Cu target currents, high and low sputtering pressures and the use of a cross-contamination shield. The role of the microstructure was clearly shown since significantly higher resistivity was obtained at high pressure, as a function of the W/Cu atomic concentration ratio. W-Cu sputtered thin films grown at... (PDF Download Available). Available from: https://www.researchgate.net/publication/320080270_W-Cu_sputtered_thin_films_grown_at_oblique_angles_from_two_sources_Pressure_and_shielding_effects [accessed Apr 09 2018].

cited By 13; International audience; The PVD co-sputtering technology is an efficient way to deposit Zr-Cu thin film metallic glass in a wide composition range. The structural stability and crystallization behavior of metallic glass films are investigated by in situ X-ray diffraction (XRD) via heating up to 873 K. The glassy films within the 33.3-89.1 at.% Cu range maintained their amorphous structure at temperatures higher than 550 K. Within this chemical composition range, films exhibit a smooth and dense surface morphology with 100 nm-sized grains and vein-like features. Glassy films revealed a high thermal stability as reflected by differential scanning calorimetry experiments and in situ high temperature XRD analysis. It was found that the structure evolved with the temperature and copper contents from a highly textured 1 1 1 crystallized fcc-Zr to intermetallic CuZr2, Cu10Zr7, Cu51Zr14phases to finally 1 1 1 crystallized fcc-Cu. Mechanisms involved in the structural changes of the glassy films together with the multi-stage crystallization process are discussed in the light of the copper contents. © 2014 Elsevier B.V. All rights reserved.

Pure chromium coatings have been deposited within a hollow cathode powered by means of a pulsed DC or a High Power Impulse Magnetron Sputtering (HiPIMS) supply. The discharge characterization by Optical Emission Spectroscopy (OES) has permitted to highlight that more Cr + are obtained with the HiPIMS mode. A deposition rate of 28 μm/h has been reached in pulsed DC mode and, in this case, the films present a columnar morphology whereas, in HiPIMS mode, a maximum deposition rate of 3 μm/h is obtained and the films have a compact morphology. X-ray diffraction (XRD) has shown a transition between {211} to random texture with pulsed DC mode when discharge current increases and a {110} texture for coatings deposited in the HiPIMS mode. The hardness is higher for the films deposited in the HiPIMS mode than for those obtained in the pulsed DC mode (1200 HV 0.025 and 400 HV 0.025 respectively). Oxidation resistance investigations show a barrier effect for all coatings.

In this paper, we investigate the feasibility of La1-xAgxCoO3-α nanowires by reactive magnetron sputtering. After a short description of the experimental and hydrocarbon sensing bench devices, a first part will be dedicated to the chemical, microstructural and structural characterization (SEM, XRD,...) of the coatings. As deposited coatings are amorphous and a post heat-treatment under air at 873 K is necessary to crystallise them in the perovskite structure. Finally, the performance as dodecane-sensors of these coatings with amorphous and crystalline structures will be discussed depending on dodecane concentrations and sensitive surfaces temperature and will be compared to those of La0.40Sr0.15Ag0.45CoO3-α nanowires.

Nanolayered TiN–CrN coatings were synthesized by cathodic arc deposition (CAD) on M2 tool steel substrates. The aim of this study was to establish a double-correlation between the influence of the bilayer period and the deposition temperature on the resulting mechanical–tribological properties. The superlattice hardening enhancement was observed in samples deposited at different temperatures — i.e. without additional heating, 300 °C and 400 °C. Nonetheless, the residual compressive stresses are believed to be the responsible for reducing the hardness enhancement when the deposition temperature was increased. For instance, sample deposited without additional heating presented a hardness of 48.5 ± 1.3 GPa, while by increasing the processing temperature up to 400 °C it was reduced down to 31.2 ± 4.1 GPa due to the stress relaxation. Indeed, the sample deposited at low temperature which possesses the thinnest bilayer period (13 nm) exhibited better mechanical properties. On the contrary, the role of the interfaces introduced when the period is decreased seems to rule the wear resistance.

Silicon oxynitride thin films were sputter deposited by the reactive gas pulsing process. Pure silicon target was sputtered in Ar, N 2 and O 2 mixture atmosphere. Oxygen gas was periodically and solely introduced using exponential signals. In order to vary the injected O 2 quantity in the deposition chamber during one pulse at constant injection time ( T ON ), the tau mounting time τ mou of the exponential signals was systematically changed for each deposition. Taking into account the real-time measurements of the discharge voltage and the I(O * )/I(Ar * ) emission lines ratio, it is shown that the oscillations of the discharge voltage during the T ON and T OFF times (injection of O 2 stopped) are attributed to the preferential adsorption of the oxygen compared to that of the nitrogen. The sputtering mode alternates from a fully nitrided mode ( T OFF time) to a mixed mode (nitrided and oxidized mode) during the T ON time. For the highest injected O 2 quantities, the mixed mode tends toward a fully oxidized mode due to an increase of the trapped oxygen on the target. The oxygen (nitrogen) concentration in the SiO x N y films similarly (inversely) varies as the oxygen is trapped. Moreover, measurements of the contamination speed of the Si target surface are connected to different behaviors of the process. At low injected O 2 quantities, the nitrided mode predominates over the oxidized one during the T ON time. It leads to the formation of Si 3 N 4− y O y -like films. Inversely, the mixed mode takes place for high injected O 2 quantities and the oxidized mode prevails against the nitrided one producing SiO 2− x N x -like films.

Zn1-xCoxO (0 < x < 14.6) diluted magnetic semiconductor coatings have been obtained by reactive DC magnetron sputtering of metallic Zn and Co targets at high pressure and high temperature. The coatings structural properties have been investigated by X-ray diffraction. All as-deposited coatings are crystalized in ZnO structure and neither traces of metallic nor oxide Co-rich clusters were detected in the films. The temperature dependence of the magnetization shows a paramagnetic Curie-Weiss behavior with antiferromagnetic interaction due to the associated spins and simple paramagnetic curie behavior of isolated free spins.

This paper reports results of dodecane-sensing studies with double-substituted LaCoO3perovskite oxide nanowires. La0.40Sr0.15Ag0.45CoO3-αnanowires were co-sputtered from metallic La, Sr, Ag and Co targets in the presence of a reactive argon-oxygen gas mixture. As deposited coatings are amorphous and crystallise in the perovskite structure after annealing at 873 K for 2 hours under air. Electrical response of the La0.40Sr0.15Ag0.45CoO3-αnanowires was measured at different temperature under air and under air containing 1 to 100 ppm (v) of dodecane vapour. The electrical signal of the nanowires was found to be high and it was possible to detect low concentrations of dodecane (under 5 ppm (v) ) at 573 K.

Cu x O thin films were deposited on glass and silicon substrates by High Power Impulse Magnetron Sputtering (HiPIMS) at room temperature from a metallic copper target. The influence of pulse off-time on the films’ structural, morphological and optoelectronic properties was investigated. It was found that the power intensity applied on the Cu target was strongly affected by pulse off-time, which had an important impact on the films’ composition. Upon increasing the pulse off-time from 500 μs to 3500 μs (pulse on-time fixed at 50 μs), the films’ crystallinity as well as transmittance in the visible region both ameliorate. Meanwhile, the conductivity type changed from n-type to p-type as the films’ composition changed. When the pulse off-time was fixed at 2000 μs, the optimal p-type conductivity of about 3 S × cm −1 was achieved, which is the highest p-type conductivity reported for Cu 2 O films in the last few years. The transition of the films’ conductivity type can be utilized for the fabrication of Cu 2 O-based p-n homojunction, and may also prove useful in developing other oxide films by using HiPIMS technology.

International audience; The effect of copper addition on the corrosion resistance and mechanical properties of binary Zr100-xCux (x = 30, 50, 80, 90 at.%) glassy coatings was investigated by means of electrochemical measurements, scanning electron microscopy (SEM), energy dispersive analysis spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and nano-indentation techniques. The corrosion resistance in 0.01 M deaerated H2SO4 solution and the mechanical properties of the Zr-Cu glassy coatings depend considerably upon the copper content in the glassy matrix. The top surfaces of the Zr-Cu coatings with lower Cu content were covered by a compact protective ZrO2 passive film. The competition between the oxidation of Zr atoms (ZrO2 film formation) and the oxidation-dissolution of Cu atoms assumed the most important role in the electrochemical behavior of the Zr-Cu glassy coatings. The generation of ZrO2 on the surface benefited the formation of passive film; and the corrosion resistance of the metallic glass coatings depended on the coverage degree of ZrO2 passive film. The evolution of free volume affected both the mechanical and corrosion behaviors of the Zr-Cu glassy coatings.

International audience; W-Cu thin films were co-deposited by magnetron sputtering using the glancing angle deposition (GLAD) method. The deposition angle of W and Cu targets was fixed at 80°, and their currents were inversely and systematically changed from 50 to 140 mA. Scanning electron microscopy, X-ray fluorescence spectroscopy, and X-ray diffraction were used to investigate the morphology and the elemental composition of the films. Electrical properties were also studied by the van der Pauw technique. An increase of the W target current and a decrease of the Cu target produced an improvement of the inclined columnar and porous structure. The W-to-Cu weight concentration ratio was tuned from 0.68 up to 19. Wsingle bondCu films exhibited a diffracted signal corresponding to the (100) planes of the bcc tungsten structure for the highest W current intensities whereas the (111) peak due to the fcc copper phase was measured when the Cu target current increased. The dc electrical resistivity measured at room temperature was gradually changed from 3.59 × 10− 7 up to 9.90 × 10− 6 Ωm by means of an inverse variation of W and Cu target currents. The Cu-rich films exhibited a non-reversible resistivity vs. temperature evolution due to thermal oxidation whereas those co-sputtered with the highest W target currents showed a sudden increase of resistivity when the temperature was above 400 K.

Titanium films were DC sputtered with a particle flux incidence angle of 80 degrees, using the Glancing Angle Deposition (GLAD) technique with increasing sputtering pressures from 0.2 to 1.5 Pa. This range of pressures is typically implemented for the deposition of thin films by the magnetron sputtering process. The main objective of this work was to study the anisotropic electrical resistivity behaviour of the different thin film nanostructures that were obtained. It is shown that low sputtering pressures (0.2-0.5 Pa) promote higher column angles beta with respect to the substrate normal (15 degrees, This work was supported by the Region of Franche-Comte, the French RENATECH network and performed in cooperation with the Labex ACTION program (contract ANR-11-LABX-0101). Funding was also provided 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. The authors thank financial support from the Basque Government Industry Department under the ELKARTEK Program., info:eu-repo/semantics/publishedVersion

International audience; The present study describes a sputtering and in situ vacuum electrical resistivity setup that allows a more efficient sputtering-oxidation coupling process for the fabrication of oxide compounds like vanadium dioxide, VO2. After the sputtering deposition of pure V thin films, the proposed setup enables the sample holder to be transferred from the sputtering to the in situ annealing + resistivity chamber without venting the whole system. The thermal oxidation of the V films was studied by implementing two different temperature cycles up to 550 °C, both in air (using a different resistivity setup) and vacuum conditions. Main results show that the proposed system is able to accurately follow the different temperature setpoints, presenting clean and low-noise resistivity curves. Furthermore, it is possible to identify the formation of different vanadium oxide phases in air, taking into account the distinct temperature cycles used. The metallic-like electrical properties of the annealed coatings are maintained in vacuum whereas those heated in air produce a vanadium oxide phase mixture.

Zr-59 at.% Cu glassy film was deposited by co-magnetron sputtering using pure metal targets. The film exhibits an XRD-amorphous structure and smooth surface morphology. Isothermal annealing at 370 °C, for 30 and 60 min, modify the local structural ordering and promote nucleation of Cu10Zr7 nanocrystalline-like domains as confirmed by TEM analysis. The mechanical properties of the film are far higher than those of pure metals, and are still improved after nanocrystallization. Keywords: Local nanocrystallization, Mechanical properties, Glassy films, Microstructure

International audience; TNTZ quaternary superelastic coatings with a beta structure were successfully deposited by magnetron sputtering of a Ti-Nb-Zr-Ta target. In this work, we discuss the effects of argon pressure and negative substrate bias voltage on the microstructure, morphology, texture, mechanical properties and superelastic behavior of these coatings. The results show that the texture is random at high deposition pressure and it becomes {110} at the lowest deposition pressure (i.e. 0.2 Pa). Applying negative bias voltage causes the disappearance of {110} texture and promotes the appearance of {100} and {111} textures. The texture evolution is related to the ion bombardment of the growing film and to the surface mobility of adatoms. The highest hardness and Young’s modulus are obtained for the Gum Metal (GM) film deposited at the lowest deposition pressure (i.e. 0.2 Pa) and a bias of −200 V. The Evolution of the mechanical properties is discussed as a function of the film density, the compressive stress and grains' size changes. It was found that the film deposited at 0.2 Pa and floating potential presents the greatest depth recovery ratio. It is due to the fact that the film is dense and its texture is {110}. The negative bias voltage seems to have an unfavorable effect on the superelasticity.

International audience; This work focuses on the structural, microstructural, electrical and electrochemical characterization of La–Ni–O coatings deposited by reactive magnetron sputtering under different argon partial pressures. Deposition was driven by Plasma Emission Monitoring system (PEM) which allows high deposition rate. For each pressure, the optimal regulation setpoint for lanthanum oxide deposition is determined and then the current dissipated on the nickel target is adjusted to obtain the convenient La/Ni ratio to achieve the K2NiF4 structure. After an appropriate annealing treatment, coatings crystallize in the desired structure with more or less impurities. Increasing the device's pressure from 0.4 to 4.8Pa produces more porous samples with different microstructures. Then, a coating with porosity gradient was built by using these four different total pressures. Its electrical performances were tested and allowed its utilization as cathode layer in intermediate temperature-solid oxide fuel cell (IT-SOFC). This modified architecture cathode allows better performances (71mW·cm−2) than dense cathode produced by the same technique (51mW·cm−2).

Aluminium based alloys were deposited on glass substrates by electron-beam evaporative PVD technique which is compatible with a roll to roll process on large flat substrates because of high deposition rates. Alloying elements (Cr, Gd) are added in order to improve both mechanical and corrosion behaviours of aluminium. This approach aims to develop sacrificial protection of steel flat products. Because of the components' vapor pressure difference, aluminium and alloying elements are co-evaporated from two separate sources. Nanohardness measurements and electrochemical characterizations in saline solution were carried out. It's shown that aluminium can be mechanically reinforced with preserving sacrificial behaviours.

In this study, SrZr0,84Y0,16O3-α (SZY16) coatings and pellets were synthesized by co-sputtering and solid state reaction, respectively, in order to compare their structural and electrical properties. The SZY16 as deposited coatings are amorphous and must be annealed at 623 K to crystallize in the convenient SrZrO3 perovskite structure. After annealing, the grain size of the coatings is about half that of the sintered pellets. SEM analysis shows that both pellets and coatings remain stable after several heating cycles. Activation energies of the total electrical conductivity are 0.68 eV for both the film and the pellet. Nyquist diagrams show that the pellet yields two contributions whereas only one can be detected for the film, attributed to interfacial processes. Finally, the conductivity of the film is about one order of magnitude lower than that of the corresponding bulk pellet.

BaCe 1− x Y x O 3−α coatings were synthesised by magnetron co-sputtering of metallic targets in the presence of reactive argon–oxygen gas mixtures. This material appears to be a valuable candidate for electrolyte in the novel concept of proton conductor fuel cells. In our knowledge, the single study concerning the deposition of this material was performed by radiofrequency sputtering of a perovskite target. In the present study, we focus on its feasibility by reactive magnetron (co-)sputtering. Hence, a first set of experiments was carried out using a single metallic target with the convenient metal content (Ba 0.50 Ce 0.45 Y 0.05 ) for the deposition of perovskite structure coatings. Whatever the deposition conditions, the cerium concentration in the coating is very low in comparison with that of the target. In a second set of experiments, the films were synthesised by co-deposition of Ce 0.9 Y 0.1 and Ba metallic targets to increase their Ce content. The composition of the coatings was then controlled by the discharge parameters. Whatever their composition in the range (Ce + Y)/Ba between 0.3 and 1.1, as-deposited coatings are amorphous and those with higher Ba content present a poor chemical stability against carbonation or hydration. As-deposited coatings with the convenient Ba content, i.e. Ba/(Ce + Y) ∼ 1, are also amorphous. They crystallise after annealing around 873 K for 2 h under air in a mixture of BaCO 3 and CeO 2 in spite of the targeted Y-substituted BaCeO 3 perovskite structure. Nevertheless, the crystallisation in the convenient perovskite structure was obtained after annealing under vacuum to prevent the carbonation of the coating.

Strontium-doped lanthanum manganite films were deposited on steel, silicon and yttria stabilised zirconia substrates by reactive co-sputtering of La0.85Sr0.15 and Mn targets in a Ar–O2 gas mixture. In this study, the discharge current applied to the manganese target was varied to adjust the film composition whereas that of the La–Sr target was maintained at a constant value of 1 A. The use of 0.4 A dissipated on the Mn target allowed the formation of a film with the La0.85Sr0.15MnO3 stoichiometric composition. As-deposited films were amorphous and exhibited a dense brittle fracture cross-section. Air annealing for 1 h at 700 °C induced the crystallisation in the expected perovskite structure of the coatings with a (La + Sr)/Mn atomic ratio ranging between 0.87 and 1. This crystallisation came with a strong improvement of the film electrical conductivity at room temperature.

Nanocomposite nc-(Zr, Ti)(B, N)/a-BN coatings were deposited on AISI M2 HSS substrates by reactive arc evaporation of a composite target constituted of a Zr–ZrB 2 (60–40 mol%) disc inserted into a conventional multiarc Ti target. The influence of the nitrogen flow rate and of the substrate bias voltage was investigated in relation to the chemical, structural, microstructural, mechanical and physicochemical features of the coating. It is shown that the coating hardness is a function of its composition, characterised by the (B + N)/(Zr + N) atomic ratio, and of the substrate bias which significantly modifies the nature of B–N bonds in the amorphous BN phase. Hence, coatings with about 50 GPa hardness and a low polar component of the surface energy (6.5 mJ m −2 ) can be deposited with intermediate nitrogen flow rate (15 sccm N 2 ) and a significant bias of the substrate voltage (−200 V) which foreshadows future applications for anti-stick superhard coatings.

Photocatalyst TiO 2 coatings have been reactively sputtered at high pressure on cold glass substrates pre-coated by a SiN x sodium diffusion barrier. The as-deposited coatings were amorphous and the TiO 2 /SiN x /glass samples were subsequently heated at different temperatures under air. The TiO 2 films crystallise in the anatase structure above temperatures of 250 °C with a [001] preferential orientation. The structural analyses have demonstrated that the crystallites are elongated following the c axis direction, perpendicularly to the surface. No modifications of grain size and texture have been observed over the complete temperature range studied (250–550 °C). However, the lattice parameters evolution shows a decrease of the tensile stress with a rise in annealing temperature. The microstructure is then completely relaxed around 400 °C and finally compressive stress is observed at higher temperature. The study of the photo-induced (photocatalytic and hydrophilic) properties shows an activity maximum at 400 °C. These results suggest that the photo-induced properties would be favoured by a relaxed microstructural state of titanium dioxide.

Apatite-type La9.33Si6O26 thin films were elaborated by co-sputtering of two metallic La and Si targets powered, respectively, by high power impulse magnetron sputtering and direct current sources, in pure Ar atmosphere, followed by a subsequent high temperature oxidation treatment in air. The structural and chemical features of these films have been assessed by X-ray diffraction and scanning electron microscopy (SEM). The film with near lanthanum silicate La/Si atomic ratio deposited on a porous Ni-YSZ cermet substrates was initially amorphous. After thermal oxidation at 1,173 K in air, the coating crystallised under the expected apatite structure. SEM observation revealed that both film compactness and thickness increased after thermal oxidation. The conductivity evolution with temperature of the pure apatite-like lanthanum silicate coatings, as measured by complex impedance spectroscopy, showed that the activation energy of is quite low compared to the literature data.

The electrochemical promotion of catalysis (EPOC) of propene combustion was investigated using Pt sputtered thin film on an O2− conductor, 8 mol% Y2O3-stabilized-ZrO2 (YSZ). In order to separate the influence of the thermal migration of the O2− oxide ions from the electrolyte to the catalyst surface and the impact of an electrical polarization on the catalytic activity, several light-off experiments (cool down and heat up procedures) were successively performed under different polarizations, i.e. OCV, +2 and −2 V. These experiments have clearly shown that the presence of O2− (thermally or electrochemically induced) inhibits the catalytic activity of the platinum for the propene deep oxidation. These results demonstrate the importance to define a normalized rate enhancement ratio, ρ n , from a reference value of the catalytic rate corresponding to a Pt surface state free of O2− ions.

Thin films of various compositions in the Na 2 O–SiO 2 –P 2 O 5 –ZrO 2 system were deposited in glassy form by reactive magnetron sputtering. An analysis by spectrophotometry showed an increase of the extinction coefficient ( k ) with the amount of Fe contamination. This contamination, originating from parasitic plasmas, was suppressed when convenient protections were used. Therefore, it was possible to produce optical clear films. A structural study by X-ray diffraction and Raman spectroscopy proved a reorganization in the amorphous state at low temperature and the appearance of a NASICON structure around 750 °C. The ionic conductivity, measured by impedance spectroscopy, and the optical properties were strongly affected by the thermal annealing process. The reorganization in the amorphous state and strong modifications of the ionic conductivity values and the refractive index ( n ) appeared in the same range of temperatures. This suggested a strong correlation between these different phenomena.