Properties of ceria films grown on stainless steel by electrodeposition method

The study focuses on the elaboration of thin nanostructured ceria films, grown on the stainless steel, in view of high temperature fuel cell applications. Films were prepared electrochemically, via cathodic electrolytic deposition method, at low temperature (30 0C). Structural, morphological and composition analysis of the asgrown and annealed films were performed by means of XRD, Raman, SEM and EDX measurements

Architectured interfaces and electrochemical modelling in an anode supported SOFC

International audienceIncreasing the SOFC performances is many-fold: i/ at low current density, through the enhancement of the catalytic properties of the electrodes, ii/ at the ohmic loss region, through lower resistance, iii/ at the high current density region, via the optimization of the electrodes microstructure. The present work proposes to explore how the corrugation of electrode/electrolyte interfaces impacts the performances of SOFCs. Taking ideas from the battery community, this approach was applied to the anode/electrolyte interface of a SOFC based on standard compositions. Patterning of this interface was achieved with different geometries at the 10-100µm scale by cold pressing. Thin electrolyte layers have been deposited on top of these architectures by different techniques. In parallel, an electrochemical model was carried out and implemented throughout the interface in FEM (finite element method) with COMSOL Multiphysics. The results showed a 25 % increase in the total current density for a certain ellipsoid geometry

Ultrathin Eu- and Er-Doped Y2O3 Films with Optimized Optical Properties for Quantum Technologies

Atomic layer deposited (ALD) YO thin films have been thoroughly investigated for optical or electronic applications. The coherent spectroscopy of lanthanide ions doped into this material has also recently attracted increasing interest in the field of quantum technologies for which they are considered promising candidates in quantum memories or as spin-photon interfaces. However, these most demanding applications require a deep control over the local positioning of the ions and their close environment in the crystalline matrix. This study focuses on the structural as well as optical properties of Eu and Er dopants in YO using photoluminescence (PL), luminescence decay times, and inhomogeneous line width (Γ) measurements within this particular context. While as-grown ALD films do not provide an ideal host for the emitters, we demonstrate that by optimizing the deposition conditions and using appropriate annealing post treatments narrow inhomogeneous lines can be obtained for the F↔D transition of Eu even for nanoscale films. Furthermore, about 1.5 ms lifetime has been measured for the infrared telecom transition of Er in ultrathin films (<10 nm), which is an order of magnitude higher than in nanoparticles of the same size. These results validate optimized rare-earth-doped ALD YO films as a suitable platform for photonics applications where few-nanometer-thick films with well-localized emitters are mandatory. This approach provides the first building blocks toward the development of more complex devices for quantum sensing or hybrid structures coupled with other systems such as two-dimensional materials

Oxygen reaction on strontium-doped lanthanum cobaltite dense electrodes at intermediate temperatures

International audienceLa0.7Sr0.3CoO3−δ (LSC) powder was characterized by thermogravimetry. Thin, dense layers of LSC were deposited by RF magnetron sputtering on YSZ pellets. The electrochemical behavior was studied as functions of temperature (300–530°C) and oxygen partial pressure (0.21–2×10−5 bar) by impedance spectroscopy. Impedance diagrams were decomposed into two elements, characteristic of the electrode polarization. The low frequency contribution can be described either as a limiting Warburg diffusion loop or as a semi-circle. These results can be interpreted in terms of a progressive evolution of the limiting process as functions of oxygen pressure and temperature, i.e. a finite diffusion process in series with dissociative sorption process. Under low oxygen pressure, at temperatures higher than 475°C, gas-phase diffusion polarization becomes significant

Discussion on a Percolating Conducting Network of a Composite Thin-Film Electrode (<= 1 mu m) for Micro-Solid Oxide Fuel Cell Application

International audienceNi/Gd0.1Ce0.9O2-delta,5 (Ni/GDC) and La0.6Sr0.4Fe0.8Co0.2O3-delta/Gd0.1Ce0.9O2-delta (LSCF/GDC) porous thin-film electrodes with thicknesses between 120 and 500 nm were synthesized through templated sol-gel chemistry coupled with the dip-coating process and heat treatment. The thin films consist of two interpenetrated networks made of pores and inorganic materials. The porous structure was composed of multi-scale pores with dimensions ranging from macro- to nanosize and with an oriented columnar structure. The dimension of the percolation network is discussed as a function of the chemical nature of the percolating components and the particle/thickness ratio. A three-dimensional percolation network is achieved in the LSCF/GDC composite, while a two-dimensional percolation network is observed for the Ni/GDC composite. This difference is related to the microstructure of the composite thin film. An anisotropic columnar structure is observed for Ni/GDC, while an isotropic structure is achieved for LSCF/GDC

Synthesis, characterization and electrical properties of La0.7Sr0.3Co0.2Fe0.8O3/Gd-CeO2 thin films (<= 500 nm)

International audienceA simple route toward the synthesis of mesostructured composite La(0.7)Sr(0.3)Co(0.2)Fe(0.8)O(3)x/yGd-CeO2 (LSCFx/ yGDC) (with x and y representing the volumetric% of LSCF and GDC in the composite films) thin films exhibiting both high electrical conductivities and optimized bicontinuous pore-solid network is reported. Because of the size of the pore wall, the mesostructured composite film is crystalline with particle size in the nanometer range even after a heat-treatment at 700 degrees C in air. Crystallization of the film was studied by in situ impedance spectroscopy. This technique allows us to define the heattreatment, the LSCF content in the composite film and the thickness of the film to achieve good electrical conductivity. The highest electrical conductivity of 250 S cm(-1) was found for the pure, mesoporous LSCF film at 700 degrees C

Accelerated degradation of yttria stabilized zirconia electrolyte during high-temperature water electrolysis

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Atomic layer deposition of epitaxial CeO 2 thin layers for faster surface hydrogen oxidation and faster bulk ceria reduction/reoxidation

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Feasibility Synthesis and Characterization of Gadolinia Doped Ceria Coatings Obtained by Cathodic Arc Evaporation

International audienceGadolinia 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

Conduction Mechanisms in Oxide–Carbonate Electrolytes for SOFC: Highlighting the Role of the Interface from First-Principles Modeling

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