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New advanced fuel cell technologies are moving towards high-temperature proton conductors (HTPCs) to meet environmental issues. Their elaboration remains a challenge and micro-computed tomography (µCT) is an innovative way to control their quality. NiO-BZY anodic supports of a protonic ceramic electrochemical cell (PCEC), elaborated by co-tape casting and co-sintered at 1350 °C, were coated with a BZY20 electrolyte layer by DC magnetron sputtering. The µCT allowed to observe defects inside the volume of these PCEC half-cells and to show their evolution after an annealing treatment at 1000 °C and reduction under hydrogen. This technique consists in obtaining a 3D reconstruction of all the cross-sectional images of the whole sample, slice by slice. This allows seeing inside the sample at any desired depth. The resolution of 0.35 µm is perfectly adapted to this type of problem considering the thickness of the different layers of the sample and the size of the defects. Defects were detected, and their interpretation was possible thanks to the 3D view, such as the phenomenon of NiO grain enlargement explaining defects in the electrolyte, the effect of NiO reduction, and finally, some anomalies due to the shaping process. Ways to anticipate these defects were then proposed.

A complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process and tested in operating fuel cell conditions exhibited a strong degradation in performance over time. Study of the cathode–electrolyte interface after cell testing showed, on one hand, the diffusion of lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to a La- and Sm-doped ceria phase. On the other hand, Ce and Sm diffused into the perovskite phase of the cathode. The grain boundaries appear to be the preferred pathways of the cation diffusion. Furthermore, a strontium enrichment was clearly observed both in the (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ layer and at the interface with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich phase corresponded to SrCO3. These different phenomena led to a chemical degradation of materials and interfaces, explaining the decrease in electrochemical performance.

Structural and dielectric properties of PrSrNi 0.8 Mn 0.2 O 4 ceramics elaborated by a rapid method combining mechanical milling and heat treatment were studied for the first time. The raw materials are milled at different times ( t mil = 0, 5, 10, 20 and 30 h) and annealed at 1300 °C for 8 h to produce a revealed PrSrNi 0.8 Mn 0.2 O 4 single phase, exhibiting tetragonal structure with space group I 4/ mmm . This result was confirmed by using the TEM/ED pattern for sample milled at 30 h using the [001] orientation. The corresponding lattice images show a well-ordered compound, indicating the absence of stacking faults and the growth of the crystallites. Giant dielectric response was observed in these ceramics, and only one dielectric relaxation was found on the curve of a dielectric constant as a function of the temperature. The dielectric loss drops with increasing milling time. For 30 h milling it is divided by 100 at room temperature for low frequencies compared with 5 h milling. An equivalent circuit [R-C][R-CPE] was used to fit the experimental data and provide the activation energy of the thermally activated relaxation. Using the same nominal composition, the milling time has a major effect on the dielectric constant by significantly reducing the losses.

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.

High temperature water vapour electrolysis (HTE) is one of the most efficient technologies for mass hydrogen production. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800 °C enables the use of metallic materials as interconnects. High temperature corrosion behaviour and electrical conductivity of a commercial stainless steel, K41X (AISI 441), were tested in HTE dual atmosphere (95%O 2 -5%H 2 0/10%H 2 -90%H 2 O) at 800 °C. The alloy exhibits a very good oxidation resistance compared to single atmosphere tests. However, a supplied electrical current significantly changes the nature of the oxides that form during the test. A very good Area Specific Resistance (ASR) parameter was measured in dual atmosphere, much lower than the values obtained in single atmosphere tests.

In this study, facile tape casting process has been successfully carried out to fabricate an unit anode supported intermediate temperature solid oxide fuel cell (IT-SOFC) with four different layers: a composite cathode which is a mix of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF48) and Gd0.1Ce0.9O1.9 (GDC10), GDC10 as thin electrolyte layer, NiO-GDC10 without pore former as thin anode functional layer (AFL), and anode support layer of NiO-GDC10 with carbon pore former. The multi-layer was sintered once to produce an unit planar cell. An OCV of 1.002 V at 500 °C, and maximum power density of 466 mW cm–2 at 648 °C are obtained. These results indicate negligible leakage of fuel through electrolyte. Furthermore scanning electron microscope (SEM) revealed crack free dense electrolyte. The single step sintering process gives an unit planar cell, which exhibits good performance without use of sintering aids, co-pressing, and lamination of green tape.

Interface reactivity between La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode material and metallic interconnect (Crofer22APU) was investigated in laboratory air at 700 °C. Due to the interconnect geometry, two interfaces have been analysed: (i) interconnect rib/cathode interface (physically in contact); (ii) the interface under the channel of interconnect. In both cases, formation of a parasite phase was observed after various ageing treatments (20 h, 100 h and 200 h). However, the growth of the determined SrCrO4 parasite phase depends on interface type and on ageing time. Two different mechanisms have been established in function of interface type: (i) SrCrO4 phase was formed after solid state diffusion of Cr from metallic interconnect to the cathode; (ii) gas phase reaction induced formation of SrCrO4 under the channel of interconnect. Finally, the influence of a chemical etching on cathode/interconnect reactivity was evaluated.

Rare earth doped materials have many familiar applications (TV screens, solid lasers, scintillators…) thanks to their efficient and robust luminescence properties. In recent years, growing interest has been focused on the changes in their optical properties with the size of the host particles. In this work, nanomaterials were produced for the first time by using laser pyrolysis. Y, Gd, and Eu nitrates were dissolved in water and used as precursors. Cubic phases of Y2O3:Eu3+ and Gd2O3:Eu3+ were obtained with sizes ranging from 3 to 40 nm. The spectroscopic properties revealed a new and nanostructure-specific broad band in the excitation spectrum. The emission spectrum was found to be characteristic of nanostructured sesquioxides only when excited in this new band, which was finally assumed to be a new charge transfer band for the smallest nanoparticles in the sample.

International audience; Refractory carbide nanostructured ceramics appear to be promising materials for high temperature applications requiring hard materials such as nuclear energy industry. Such carbide materials are usually obtained with micrometric sizes from the high temperature carboreduction of an oxide phase in a raw mixture of C black and titania or zirconia. TiC and ZrC nanopowders were produced from an intimate mixture of oxide nanograins with free C synthesized by laser pyrolysis from the decomposition of a liquid precursor. The temperature and the duration of the thermal treatment leading to the carburization were decreased, allowing the preservation of the nanoscaled size of the starting grains. A solution of titanium isopropoxide was laser-pyrolysed with ethylene as sensitizer in order to synthesize Ti/C/O powders. These powders were composed of crystalline TiO2 nanograins mixed with C. Annealing under argon enabled the formation of TiC through the carburization of TiO2 by free C. The final TiC mean grain size was about 80 nm. Zr/O/C powders were prepared from a solution of zirconium butoxide and were composed of ZrO2 crystalline nanograins and free C. The same thermal treatment as for TiC, but at higher temperature, showed the formation of crystalline ZrC with a final mean grain size of about 40 nm. These two liquid routes of nanoparticles synthesis are also compared to the very efficient gaseous route of SiC nanopowders synthesis from a mixture of silane and acetylene.

Yttria stabilised zirconia (YSZ) nanocrystals, with a mean size between 5 and 10 nm, were prepared by microwave flash synthesis. Flash synthesis was performed in alcoholic solutions of yttrium, zirconium chloride and sodium ethoxide (EtONa) using a microwave autoclave (RAMO system) specially designed by authors. Energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), BET adsorption technique, photon correlation spectroscopy (PCS) transmission and scanning electron microscopy (TEM and SEM) are used to characterized these nanoparticles. Compared with conventional synthesis, nanopowders can be produced in a short period (e.g. 10 s), both high purity and stoechiometric control are obtained. Nevertheless, this mean of production is more cheaper and much faster than the ones commonly used to produce yttria stabilized zirconia (YSZ) by conventional sol-gel techniques.

International audience; Single Chamber Solid Oxide Fuel Cells (SCFC) show a growing interest and are the concern of more and more papers. In such device, anode and cathode are ex-posed to a gas mixture of fuel (hydrocarbon) and oxidant (air) so that no more sealing with electrolyte is necessary. Their operating principle is based on the different catalytic activities of anode and cathode: Ideally, the anode has to be active for the oxidation of fuel while the cathode should present only a strong electro-activity for oxygen reduction. In this paper, we present the development of an anode supported SCFC device running in air/methane mixture characterized by their volume ratio, Rmix = CH4/O2.

International audience; Single chamber anode-supported fuel cells are investigated under several methane-oxygen-nitrogen atmospheres at intermediate temperatures (500°C-700°C). Ce0.9Gd0.1O1.95 (CGO) is chosen as electrolyte and deposited by screen-printing onto NiO-CGO anode pellets. A cathode composed of 70 wt% La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and 30 wt% of CGO is screen-printed onto the electrolyte. Thermogravimetric analyses of anode reduction are performed at 700 °C. Carbon deposition is observed under diluted methane but a successful reduction is obtained after an initialization under diluted methane followed by a final treatment under methane-to-oxygen ratio (Rmix) of 2. Anode-supported fuel cells are investigated regarding the working temperature and Rmix. Two types of cells are prepared with modifications of the electrolyte microstructure. For both cells tested, the Open Circuit Voltage (OCV), the power density and the fuel utilization increase when Rmix and temperature decrease. The electrolytes of both cells have a porous microstructure and the electrolyte of the second cell, with the highest thickness, brings better performances. At 600 °C for Rmix = 0.6, the maximum power density is improved from 60 for the first cell to 160 mW cm−2 for the second cell. Comparing the fuel utilization, it increases from 3% for the first cell to 6% for the second one for the same testing conditions.

Nickel Oxide and Gadolinium Doped Ceria (10% Gd) powders, with -40 mesh and -100 mesh particle size respectively, were mechanically milled in a Turbular-(System Schatz Willy a Bachofeng) up to 24 to 48 hours. Half-cells, 28 mm of diameter, Ni-GDC composite anodes have been fabricated by slurry based tape casting (Elcometer4340 Automatic Film Applicator) method for anode supported solid oxide fuel cell [1]. The chosen ceramic powders in suspension was prepared with the mass ratio of 65:35 for NiO to GDC10 maintained constant. The microstructural evolution of powders (crystallite size) was followed by means of X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The anode porosity was examined by Archimedes method [2]. The pre-sintered anode green tape were coated with a GDC electrolyte film by reactive magnetron sputtering using PEM techniques [3]. 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. Finally, the EIS measurements were performed on Ni-GDC/GDC half-cells under 60 sccm nitrogen by the means of a Solartron SI 1260 impedance / gain analyzer from 20 MHz to 0.1 Hz with 11 points per decade. References [1] Fabrication and characterization of Ni-SSZ gradient anodes/SSZ electrolyte for anode-supported SOFCs by tape casting and co-sintering technique. Chao Jin, Yachun Mao, Naiqing Zhang, Kening Sun. Harbin, China. Institutional Journal of Hydrogen Energy. [2] Manufacturing and Characterization of Single cell Intermediate-Temperature Solid Oxide Fuel Cells for APU in transportation application. Visweshwar Sivasankaran. Dijon France. 2ICB- Département I.RM. Université de Bourgogne-CNRS [3] F. Perry, A. Billard, C. Frantz, Surface Coatings Technology 94-95 681 (1997).

International audience; The influence of the sintering conditions on the electrochemical properties of the proton conducting electrolyte BaCe0.85Y0.15O3-delta (BCY15) and Ni - based BCY15 cermet anode for application in high temperature proton conducting fuel cell are investigated by electrochemical impedance spectroscopy. The results show that at lower sintering temperatures due to the formation of parasitic Y2O3 phase an increase of both the electrolyte and electrode resistances is observed. This effect is strongly reduced by enhancement of the sintering temperature. The obtained BCY15 conductivity (sigma = 2.5x10(-2) S/cm at 700 degrees C) is comparable with that of the best proton conducting materials, while the BCY15-Ni cermet (with ASR = 2.5 Omega cm(2) at 700 degrees C) needs further optimization. The results of impedance investigations of BCY15 as proton conducting electrolyte and cermet anode have been applied in development of innovative high temperature dual membrane fuel cell.

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The IDEAL-Cell project aims at developing an innovative and competitive concept for fuel cell operating between 600-700 {degree sign}C. It is based on the junction between a PCFC anode/electrolyte part and a SOFC electrolyte/cathode, through a mixed porous ceramic membrane. Cathode materials are: La0.60Sr0.40CoO3-d (LSCF40) or La0.60Sr0.40Co0.20Fe0.80O3-d (LSCF48); electrolyte materials are: Ce0.85Y0.15O2-d (YDC15) and BaCe0.85Y0.15O3-d (BCY15). Ni-BCY15 cermet is the anode material. The central membrane is made of BCY15-YDC15 mixture. Good compatibility was observed at electrode/electrolyte cathode interface after long term ageing (20h/1100{degree sign}C following by 500h/700{degree sign}C) and no new phase was detected. Concerning the dual membrane BCY15-YDC15, a good adhesion was obtained between these two electrolyte materials. Finally, reactivity between LSCF40/48 and Crofer 22 APU (selected as first generation interconnect material) was studied in oxidizing atmosphere (1h/1000{degree sign}C following by 200h/700{degree sign}C). SrCrO4 formation was observed due to the diffusion of Cr and reaction with Sr from the cathode material.

International audience; Nanosized zirconium carbide was obtained by carburization of tetragonal zirconia/free carbon nanocomposites synthesized by laser pyrolysis technique using zirconium butoxide as precursor and ethylene as sensitizer gas. To achieve the carboreduction, the powder had to be annealed at high temperature under Ar atmosphere to reduce the oxygen and form zirconium carbide (ZrC). Different temperatures were investigated for the heat treatment to obtain the complete carburization while keeping the size as low as possible. The final ZrC grain size was as low as 35 nm. Powders were characterized using X-ray diffraction, thermogravimetric analysis and transmission electron microscopy.

International audience; Perovskite-oxide nanocrystals of La0.75Sr0.25Cr0.93Ru0.07O3–δ with a mean size around 10 nm were prepared by microwave flash synthesis. This reaction was performed in alcoholic solution using metallic salts, sodium ethoxide and microwave autoclave. The obtained powder was characterised after purification by energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), BET adsorption technique, photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM). The results show that integrated perovskite-type phase and uniform particle size were obtained in the microwave treated samples. At last the synthesised powder was directly used in a sintering process. A porous solid, in accordance with the expected applications, was then obtained at low sintering temperature (1000 °C) without use of pore forming agent.

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New data on the interest of ruthenium doped lanthanum strontium chromite La1-xSrxCr1-yRuyO3δ (LSCrRu) as anode in ITSOFC are presented. Microwave synthesis of mixed oxides allowed shaping of half-cells and complete cells using sputtering and screen printing methods. LSCrRu methane reforming property had been studied in a mono-chamber system coupled with a mass spectrometer in collaboration with Institut de REcherche Hydro-Québec. Anode/electrolyte interfacial reactivity had been analysed using SIMS and XRD on half cells models after ageing under H2 at 800°C. This experiment gave the chemical composition of the film after treatment. Complete cells, tested under working conditions, highlighted, after selective dissolution of LSCrRu film, a microstructure modification at anode/electrolyte interface. XPS and SEM-EDX techniques did not show chemical reactivity., Cette étude apporte des données sur l'intérêt des chromites de lanthane strontium dopés au ruthénium La1-xSrxCr1-yRuyO3δ (LSCrRu) comme anode de pile à combustible ITSOFC. La synthèse sous champ micro-onde d'oxydes mixtes a permis la mise en forme de demi-cellules et cellules complètes modèles par pulvérisation cathodique magnétron et par sérigraphie. Les propriétés de reformage de CH4 ont pu être étudiées dans un dispositif mono-chambre couplé à un spectromètre de masse en collaboration avec l'Institut de REcherche Hydro-Québec. La réactivité à l'interface anode/électrolyte a été analysée par SIMS et XRD sur demi-cellules modèles vieillies sous H2 à 800°C. Elle a permis de préciser la chimie du film après traitement. Les cellules complètes, testées en condition de fonctionnement, ont mis en évidence, après dissolution sélective de LSCrRu, une modification de la microstructure à l'interface anode/électrolyte. Des analyses XPS et SEM-EDX n'ont pas montré de réactivité chimique.

The fabrications of large area IT-SOFC planar cell by new simple and cost effective process were explained. The optimization of the new process with respect to pore formers, thickness of layers, sintering temperature were performed. The electrochemical results of 10cm2 performed in Fiaxell open flange set up were detailed with respect to different configuration. Long term ageing performance tests of single cells were conducted in Fiaxell device and results are discussed. Preparation of new test bench and stacking process performed till now were briefed., La fabrication de cellules de piles à combustible IT-SOFC de large dimension par un nouveau procédé simple et peu coûteux est présentée dans ce manuscrit. L’optimisation de ce nouveau procédé en regard de l’utilisation d’agents de porosité, d’épaisseur de couches et de température de frittage a été réalisée. Les résultats des tests électrochimiques sur des cellules de surface active 10 cm2 réalisés dans le dispositif Fiaxell semi-ouvert ont été détaillés pour différentes cellules. Des tests de performance de longue durée ont également été menés sur le dispositif Fiaxell, présentés et discutés. La préparation et la réalisation d’un nouveau banc de test de stack a également été mené et présenté dans ces travaux.