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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.

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 .

The high temperature steam electrolysis (HTE) represents one of the most promising technologies for mass hydrogen production. A commercial K41X steel (AISI441) containing 18 wt. % of chromium was tested as interconnect for solid oxide electrolyser cells (SOEC). In a previous paper, it was shown that the uncoated alloy is not suitable for SOEC interconnect application at 800°C in O2-H2O atmosphere. It was also proved that the application of a LaNi0.6Fe0.4O3-δ coating on the surface by physical vapour deposition process improves the alloy electrical behaviour and reduces chromium species evaporation. For this study, the same coating was deposited on the alloy surface by screen-printing process. Moreover, two spinel-type oxides, Co2MnO4 and Co3O4, deposited by physical vapour deposition process, were also tested in O2-H2O atmosphere at 800°C. The electrical conductivity did not present any improvement, but the Cr species volatility was reduced, especially with the LaNi0.6Fe0.4O3-δ coating.

La 2 NiO 4 coatings were co-sputtered on rotating substrates from metallic La and Ni targets in the presence of a reactive argon–oxygen gas mixture. This material is a potential candidate as cathode material for Intermediate Temperature-Solid Oxide Fuel Cells. The structural and chemical features of these films have been determined by X-ray Diffraction and Scanning Electron Microscopy. Their electrical properties have been characterised using the four point probe method and by Complex Impedance Spectroscopy measurements. It is shown that the as-deposited coatings, initially amorphous, crystallise in the LaNiO 3 perovskite-type oxide or in the convenient K 2 NiF 4 structure as a function of their composition. The electrical measurements show a clear relation between resistivity and structure of the coatings. Despite electrical resistivity values close to the theoretical ones, the activation energy of a coating presenting the convenient K 2 NiF 4 structure is slightly higher than those given in the literature data.

K41X (AISI 441) stainless steel evidenced a high electrical conductivity after 3000 h ageing in H 2 /H 2 O side when used as interconnect for solid oxide electrolyser cells (SOEC) working at 800 °C. Perovskite (La 1 − x Sr x MnO 3 − δ ) and spinel (Co 3 O 4 ) oxides coatings were applied on the surface of the ferritic steel for ageing at 800 °C for 3000 h. Both coatings improved the behaviour of the steel and give interesting opportunities to use the K41X steel as interconnect for hydrogen production via high temperature steam electrolysis. Co 3 O 4 reduced into Co leading to a very good Area Specific Resistance (ASR) parameter, 0.038 Ω cm 2 . Despite a good ASR (0.06 Ω cm 2 ), La 1 − x Sr x MnO 3 − δ was less promising because it partially decomposed into MnO and La 2 O 3 during ageing in H 2 /H 2 O atmosphere.

International audience; High temperature water vapour electrolysis (HTE) is an efficient technology for hydrogen production. In this context, a commercial stainless steel, K41X (AISI 441), was chosen as interconnect. In a previous paper, the high temperature corrosion and the electrical conductivity were evaluated in both anode (O-2-H2O) and cathode (H-2-H2O) atmosphere at 800 degrees C. In O-2-H2O atmosphere, the formation of a thin chromia protective layer was observed. Nevertheless, the ASR parameter measured was higher than the maximum accepted value. These results, in addition with chromium evaporation measurements, proved that the K41X alloy is not suitable for HTE interconnect application. In this study, two perovskite-type oxides La0.8Sr0.2MnO3-delta and LaNi0.6Fe0.4O3-delta were tested as coatings in O-2-H2O atmosphere at 800 degrees C. Screen-printing and physical vapour deposition were used as coating processes. The high temperature corrosion resistance and the electrical conductivity were improved, especially with the LaNi0.6Fe0.4O3-delta coating. Cr specie volatility was also reduced. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Nd2CuO4 and La2CuO4 are potential candidates as cathode material for intermediate temperature-solid oxide fuel cells. Nd–Cu and La–Cu oxides were co-sputtered on rotating substrates from metallic La, Nd and Cu targets in the presence of a reactive argon–oxygen gas mixture. Structural and chemical features of these films have been determined by X-ray diffraction and energy-dispersive spectroscopy. Their electrical resistivity was measured using the four-point probe method. As-deposited Nd–Cu based coatings are amorphous and, after annealing, crystallise in K2NiF4+ d -type structure for Nd/Cu atomic ratio of 2, with more or less Nd2O3 or CuO, depending on whether Nd or Cu is in excess, respectively. As-deposited La–Cu based coatings are also amorphous and crystallise in La2CuO4 for La/Cu >2 or in LaCuO3±d perovskite-type structure when Cu is in excess. The electrical measurements show a clear relation between resistivity and structure of the coatings. After annealing, crystallised neodymium-based coatings show higher resistivity than lanthanum-based ones. Finally, LaCuO3±d exhibit higher resistivity than La2CuO4.