Nous présentons ici une méthode originale et sécurisée pour l'élaboration en une seule étape de films nanostructurés composés de nanoparticules enrobées dans une matrice. Ce procédé polyvalent combine sous vide la technologie des jets... more
Nous présentons ici une méthode originale et sécurisée pour l'élaboration en une seule étape de films nanostructurés composés de nanoparticules enrobées dans une matrice. Ce procédé polyvalent combine sous vide la technologie des jets de nanoparticules avec la pulvérisation magnétron classique. Le principal avantage de la technique est la possibilité de choisir indépendamment la nature chimique des nanoparticules et celle de la matrice. La capacité à réaliser la synthèse sur de grandes surfaces est fournie par l'utilisation d'une série de plusieurs lentilles aérodynamiques placées en parallèle entre la source des nanoparticules et la chambre de dépôt sur une machine prototype.
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In this work, different configurations of IT-SOFC complete cells: ITM porous support /Ni-YSZ/YSZ/La2NiO4 with and without GDC protective layers were realized by two different surface treatment processes. The porous anode layer was... more
In this work, different configurations of IT-SOFC complete cells: ITM porous support /Ni-YSZ/YSZ/La2NiO4 with and without GDC protective layers were realized by two different surface treatment processes. The porous anode layer was deposited by Atmospheric Plasma Spraying (APS). The thin, dense and columnar electrolyte layer was deposited by reactive magnetron sputtering (PVD) with PEM system. The K2NiF4 dense cathode layer and GDC protective layers were also deposited by PVD. Morphological characterizations were performed after each step of the cell manufacture.
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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or... more
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Nanostructured coatings on large surfaces Olivier Sublemontier, Youri Rousseau, Yann Leconte, C. Petit, E Monsifrot, F. Perry, J-P Gaston, P. Chapon, M Stchakovsky, P. Briois, et al.
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A new cell design with metallic porous support was selected in order to face with the reduction of IT-SOFC’s operation temperature. Nevertheless, the excessive roughness of the porous metallic interconnect induce additional problems when... more
A new cell design with metallic porous support was selected in order to face with the reduction of IT-SOFC’s operation temperature. Nevertheless, the excessive roughness of the porous metallic interconnect induce additional problems when a thin electrolyte layer is required. In this work, an anode material (NiO-TSZ) by Atmospheric Plasma Spraying was deposited on metallic supports (ITM) produced by PLANSEE able to cover the roughness of the support. Then, a second thin and dense electrolyte layer (YSZ) by reactive magnetron sputtering was produced on the anode material. In this study, for both processing routes, the optimal process parameters regarding the structural, morphological and electrical characterizations were investigated.
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Anode support cell is one the most common configuration fuel cell used in the SOFC technology. The major problem of this technology is the high reactivity between electrolyte (YSZ) and cathode (LSC). One solution to overcome this problem... more
Anode support cell is one the most common configuration fuel cell used in the SOFC technology. The major problem of this technology is the high reactivity between electrolyte (YSZ) and cathode (LSC). One solution to overcome this problem consists in applying a buffer layer to avoid reactivity phenomenon. Three different techniques were used to synthesize a Gadolinia doped Ceria (GDC) buffer layer. A significant improvement of the cell performances can be obtained replacing the screen printed Co-GDC buffer layer by a dense GDC film deposited via reactive magnetron sputtering.
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Research Interests: Materials Engineering, Condensed Matter Physics, Materials Science, Microstructure, Raman Spectroscopy, and 15 moreScanning Electron Microscopy, Electron Probe Micro Analysis, Optical Properties, Magnetron Sputtering, Scanning Electron Microscope, Cross Section, Microstructures, Brittle Fracture, Chemical Composition, Energy Dispersive Spectroscopy, Sputter Deposition, Argon, Chemical Structure, Reactive Magnetron Sputtering, and High Power Impulse Magnetron Sputtering
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Effect of Slight ZnO Addition on the Structural, Morphological and Electrical Properties of Barium Zirconate Pellets. [ECS Transactions 25, 1767 (2009)]. Pascal Briois, Mohammad Arab Pour Yazdi, Samuel Georges, Aliaksandr Shaula, Albano... more
Effect of Slight ZnO Addition on the Structural, Morphological and Electrical Properties of Barium Zirconate Pellets. [ECS Transactions 25, 1767 (2009)]. Pascal Briois, Mohammad Arab Pour Yazdi, Samuel Georges, Aliaksandr Shaula, Albano Cavaleiro, Alain Billard. Abstract. ...
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CrN/a-CNx nanolayered coatings have been deposited by DC reactive magnetron sputtering of pure Cr and graphite targets. The total thickness is 1μm and that of a-CNx layers is kept constant at 3.5nm. The period (bilayer thickness) is in... more
CrN/a-CNx nanolayered coatings have been deposited by DC reactive magnetron sputtering of pure Cr and graphite targets. The total thickness is 1μm and that of a-CNx layers is kept constant at 3.5nm. The period (bilayer thickness) is in the range 8–16nm. CrN and a-CNx layers are crystalline and amorphous respectively. The decrease of CrN layers’ thickness (decrease of period) in
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ABSTRACT An ageing investigation of LSCF/CGO/YSZ half-cell, at 700 degrees C in air at OCP, was performed for different CGO buffer layer thicknesses (0, 0.11, 0.45, 1.1 and 2 mu m), using impedance spectroscopy (IS). The ageing behavior... more
ABSTRACT An ageing investigation of LSCF/CGO/YSZ half-cell, at 700 degrees C in air at OCP, was performed for different CGO buffer layer thicknesses (0, 0.11, 0.45, 1.1 and 2 mu m), using impedance spectroscopy (IS). The ageing behavior of the half-cell has been found to be strongly dependent on the CGO thickness. With addition of the CGO buffer layer the initial apparent electrolyte resistance was significantly reduced, while the LSCF cathodes showed limited performance degradation over a period of 530 h. X-ray microanalyses have shown that the recorded degradation of the LSCF cathode without buffer layer is due to the diffusion and the segregation of Sr at the LSCF/YSZ interface.
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ABSTRACT La-Si metallic coatings with La/Si ratios between 1.55 and 1.66 were synthesized by Direct Current Magnetron Sputtering of lanthanum and silicon targets in pure argon atmosphere. After the deposition stage, the ceramic... more
ABSTRACT La-Si metallic coatings with La/Si ratios between 1.55 and 1.66 were synthesized by Direct Current Magnetron Sputtering of lanthanum and silicon targets in pure argon atmosphere. After the deposition stage, the ceramic apatite-structure coatings were obtained by thermal oxidation in air for 2 hours at 1173 K. The structural and chemical features of these films have been assessed by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS). The electrical properties were determined by Complex Impedance Spectroscopy in planar configuration. The films with near apatite structure La/Si atomic ratio in range of La(10)Si(6)0(27) and La(9.33)Si(6)0(26) deposited on different substrates were initially amorphous. After thermal oxidation at 1173 K in air, the coating crystallised under the expected apatite structure. SEM observation revealed that the film compactness and thickness increased after thermal oxidation. The film adhesion on SOFCs material is guaranteed if the anode support was not reduced before the deposition stage. A specific method was performed to measure the electrical conductivity, i.e. to determine the ionic conductivity of the film: it uses the four-point probe technique combined with ac impedance spectroscopy. The good agreement between measurements performed in this work (Ea = 0.75 eV, 973 K, sigma = 3-4 10(-3) S.cm(-1)) and literature data allows concluding that deposited layers are of good quality and should be used as electrolyte in an Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC). (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.026112jes]
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Research Interests: Chemical Engineering, Materials Science, Scanning Electron Microscopy, Impedance Spectroscopy, Optoelectronics, and 11 moreThin Film, Activation Energy, High Temperature, Magnetron Sputtering, High Power, X ray diffraction, Scanning Electron Microscope, Sputter Deposition, Electrolyte, Direct Current, and High Power Impulse Magnetron Sputtering
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ABSTRACT Amorphous and polycrystalline zirconium oxide thin films have been deposited by reactive rf magnetron sputtering in a mixed argon/oxygen or pure oxygen atmosphere with no intentional heating of the substrate. The films were... more
ABSTRACT Amorphous and polycrystalline zirconium oxide thin films have been deposited by reactive rf magnetron sputtering in a mixed argon/oxygen or pure oxygen atmosphere with no intentional heating of the substrate. The films were characterized by high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and capacitance versus voltage (C–V) measurements to investigate the variation of structure, surface morphology, thickness of SiO2-like interfacial layer as well as dielectric characteristics with different oxygen partial pressures. The films deposited at low oxygen partial pressures (less than 15%) are amorphous and dense with a smooth surface. In contrast, the films prepared at an oxygen partial pressure higher than 73% are crystallized with the microstructure changing from the mixture of monoclinic and tetragonal phases to a single monoclinic structure. The film structural transition is believed to be consequences of decrease in the oxygen vacancy concentration in the film and of increase of the energetically neutral particles in the plasma due to an increased oxygen partial pressure. SE measurements showed that significant interfacial SiO2 growth has taken place above approximately 51%. The best C–V results in terms of relative dielectric constant values are obtained for thin films prepared at an oxygen partial pressure of 15%.
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Ageing investigations of LSCF/CGO/YSZ systems were performed at 700°C in air at OCV up to 530h with different thicknesses of CGO layer (0, 0.11, 0.45, 1.1 and 2 µm). After 530 h, a low series resistance variation is observed and becomes... more
Ageing investigations of LSCF/CGO/YSZ systems were performed at 700°C in air at OCV up to 530h with different thicknesses of CGO layer (0, 0.11, 0.45, 1.1 and 2 µm). After 530 h, a low series resistance variation is observed and becomes weaker with CGO layer due to a better contact. The polarization resistance evolution is strongly reduced when the CGO layer is added, and the minimum is observed with a CGO thickness of only 0.11 µm. The increase of the polarisation resistance was related to the high frequency contribution which corresponds to the degradation of the ionic transfer at the electrode / electrolyte interface. X-ray microanalyses have shown the diffusion and segregation of Sr at this interface only in the sample without CGO layer.
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Apatite-type lanthanum silicates draw researchers' attention due to their good performance as electrolyte materials for IT-SOFC (intermediate temperature solid oxide fuel cells). In this paper we present the synthesis of Sr-doped... more
Apatite-type lanthanum silicates draw researchers' attention due to their good performance as electrolyte materials for IT-SOFC (intermediate temperature solid oxide fuel cells). In this paper we present the synthesis of Sr-doped La10Si6O27 obtained by optimizing a water-based sol–gel process. The relevant synthesis parameters have been investigated to get pure, highly crystalline powders. The mechanisms occurring in the sol–gel reactions are discussed to improve the process of the sol formation. Using this optimized sol–gel process, pure apatite powders have been obtained by calcination from a temperature as low as 800 °C for 2 h and characterized using scanning electron microscopy and X-ray diffraction. The sintering treatment was performed at the temperature of 1500 °C leading to well-crystallized electrolytes likely to be used in fuel cell applications. Ionic conductivities have been measured in order to investigate the effect of the Sr-doping. The results show that the ionic conductivity is thermally activated and its value lies between 3 × 10−2 and 1 × 10−6 S cm−1 at 873 K as function of the composition and powder preparation conditions.
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ABSTRACT
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In order to decrease the operating temperature of Solid Oxide Fuel Cells (SOFC) from about 1000 C to around 700 C, the thickness of commonly used electrolytes such as Yttria Stabilised Zirconia (YSZ) must be decreased for about one order... more
In order to decrease the operating temperature of Solid Oxide Fuel Cells (SOFC) from about 1000 C to around 700 C, the thickness of commonly used electrolytes such as Yttria Stabilised Zirconia (YSZ) must be decreased for about one order of magnitude in the range 1–10 m. In this paper, we investigate the suitability of reactive magnetron sputtering for deposition
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Solid electrolyte thin films of Yttria-Stabilised Zirconia (YSZ), Gadolinium-Doped Ceria (GDC) and Lanthanum-Molybdenum Oxide (LaMOx) are sputter-deposited or co-sputter-deposited on rotating substrates from metallic targets in reactive... more
Solid electrolyte thin films of Yttria-Stabilised Zirconia (YSZ), Gadolinium-Doped Ceria (GDC) and Lanthanum-Molybdenum Oxide (LaMOx) are sputter-deposited or co-sputter-deposited on rotating substrates from metallic targets in reactive argon–oxygen mixtures. Their chemical and structural features are investigated by Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD) and their morphology is observed by Scanning Electron Microscopy (SEM) of brittle-fracture cross sections. Relationships are established with their electrical behaviour determined by means of Complex Impedance Spectroscopy (CIS). It is shown that the activation energy of the different electrolytes is consistent with the literature data after stabilisation of their microstructure by annealing around 800°C.