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Search results for: ceria
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Nanocrystalline undoped ceria oxygen sensor.
PublicationW pracy przedstawiono wyniki badań struktury i elektrycznych właściwości nanokrystalicznego czujnika na bazie niedomieszkowanego tlenku ceru. Zbadano wpływ ciśnienia parcjalnego tlenu na rezystancję cienkowarstwowego tlenku ceru. Konduktancja tlenku ceru w zakresie stężeń tlenu od 10ppm do 100% ma charakter eksponecjalny z parametrem -0.25. Zbadano szybkość odpowiedzi oraz wpływ dwutlenku azotu oraz dwutlenku siarki na odpowiedź...
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Electrical properties of nanocrystalline Sm-doped ceria ceramics
PublicationWłaściwości ceramiki z cerii zależa zwykle silnie od struktury ziaren. W pracy przedstawiono właściwości elektryczne ceramiki z cerii domieszkowanej samarem wykonanje w technologii 'net shape' posiadającej strukturę nanokrystaliczną.
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Nanocrystalline doped zirconia and ceria films for fuel cell application
PublicationW artykule przestawiono porównanie właścowości warstw nanokrystalicznych przygotowanych w technologii 'net-shape'. Materiały te mają zastosowanie w tlenkowychogniwach paliwowych.
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Electrical properties of poros nanocrystalline undoped ceria oxygen sensor
PublicationW pracy zaprezentowano wykonanie czujnika z niedomieszkowanego tlenku ceru o nanometrowych ziarnach krystalicznych. Zastosowana metoda nanoszenia warstw zalicza się do metod niskotemperaturowych. Wytworzone warstwy przebadano za pomocą dyfrakcji rentgenowskiej, mikroskopii elektronowej oraz spektroskopii impedancyjnej. Wykonane czujniki charakteryzują się szybkim czasem odpowiedzi i stabilnym zachowaniem przy zmianach ciśnienia...
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Electrical properties of ceria films prepared by net shape technology
PublicationW pracy przedtswiono procedurę przygotowania gęstych warstw elektrolitu z wykorzystaniem technologii Net Shpe. Technologia ta na znaczne obniżenie temperatury przygotania tego typu warst. Okresloślono parametry elektryczne warst domieszkowanego ceru przygotowanych w tej technologii.
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Nanocrystalline doped zirconia and ceria films for fuel cell application
PublicationW artykule przedstawiono i porównano właściwości nanokrystalicznych warstw ceramicznych przygotowanych na bazie tlenku ceru i tlenku cyrkonu.
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Ceria Based Protective Coatings for Steel Interconnects Prepared by Spray Pyrolysis
PublicationStainless steels can be used in solid oxide fuel/electrolysis stacks as interconnects. For successful long term operation they require protective coatings, that lower the corrosion rate and block chemical reactions between the interconnect and adjacent layers of the oxygen or the hydrogen electrode. One of the promising coating materials for the hydrogen side is ceria. Using standard sintering techniques, ceria sinters at around...
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Gigantic electro-chemo-mechanical properties of nanostructured praseodymium doped ceria
PublicationSome oxygen defective fluorites are non-Newnham electrostrictors, i.e., the electromechanical response does not depend on their dielectric properties. Here, we show gigantic electrostriction in nanocrystalline 25 mol% praseodymium doped ceria (PCO) bulk ceramics. The material was fabricated with a fieldassisted spark plasma sintering (SPS) process from high-purity nanoscale PCO powders (<20 nm). The SPS process consolidates the...
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Corrosion Study of Ceria Protective Layer Deposited by Spray Pyrolysis on Steel Interconnects
PublicationSingle fuel cells and electrolysis cells are assembled into stacks using interconnects in order to increase power and gas production capacity. The most common choice for the interconnect material is stainless steel. It has good electrical and mechanical properties and is also cost effective. One of the problems when using steel is the formation of a thermally grown oxide scale during use which has a lower electrical conductivity...
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Spray pyrolysis of doped-ceria barrier layers for solid oxide fuel cells
PublicationGadolinium doped ceria (Ce0.8Gd0.2O2 − x-CGO) layer fabricated by spray pyrolysis is investigated as the diffusion barrier for solid oxide fuel cell. It is deposited between the La0.6Sr0.4FeO3 − δ cathode and the yttria stabilized zirconia electrolyte to mitigate harmful interdiffusion of elements. The parameters of the fabrication process are linked to the measured area specific resistances of the symmetrical cells and the efficiency...
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Nanocomposite nickel ceria cermet with low nickel content for anode-supported SOFCs
PublicationW pracy przedstawiono badania nanokompozytowego cermetu z zawartościa niklu 7.5, 11, 14% niklu w cermecie. Cermet przygotowno z wykorzystanim technologii net shape.
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Copper and cobalt co-doped ceria as an anode catalyst for DIR-SOFCs fueled by biogas
PublicationThe nanocrystalline compounds of Co and Cu co-doped ceria (with up to 20 mol.% of dopants) were fabricated by the reverse microemulsion synthesis method. They were deposited in a form of layers on the surface of SOFC anode in an aim to act as electrochemically active materials for biogas reforming process. Fourier Transformed Infrared Spectroscopy was used to analyze a composition of outlet gases simultaneously with the tests of...
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Electrical conductivity of nanostructured acceptor-doped ceria fabricated by spark plasma sintering (SPS)
PublicationHigh purity nanoscale powders (~10–15 nm size) of two different compositions of ceria, doped with Gd3+ and Ca2+, have been consolidated by spark plasma sintering (SPS) at different temperatures. Fully-dense samples were observed only at a sintering temperature of 980 °C. The as-sintered samples showed rather fast grain growth with an average grain size below 300 nm. The electrical properties of the samples were evaluated by impedance...
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Structural and catalytic properties of ceria layers doped with transition metals for SOFCs fueled by biogas
PublicationThe aim of this paper was to investigate an influence of the nanocrystalline Ce0.8A0.2O2-δ (A = Mn, Fe, Co, Ni, Cu) materials on the direct internal reforming of biogas in SOFC. Structural analysis of fabricated compounds has been done. An in-situ analysis of a composition of outlet gases from operating SOFC was performed using FTIR spectroscopy with simultaneous electrical tests. It was found out, that type of dopant strongly...
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Analysis of the grain boundary conductivity for nanocrystalline doped ceria using the brick layer model.
PublicationW pracy przedstawiono wyniki badań elektrycznych i mikrostrukturalnych ceru domieszkowanego itrem. Gęste i nanokrystaliczne filmy przygotowane zostały z użyciem prekursorów polimerowych na szafirze. Konduktancja elektryczna była badana w funkcji temperatury syntezy, która jest skorelowana z wielkością ziaren. Otrzymano mniejszą konduktancję nanokrystalicznego filmu ceru w porównaniu z próbkami ceramicznymi.
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Investigation of praseodymium and samarium co-doped ceria as an anode catalyst for DIR-SOFC fueled by biogas
PublicationThe Pr and Sm co-doped ceria (with up to 20 mol.% of dopants) compounds were examined as catalytic layers on the surface of SOFC anode directly fed by biogas to increase a lifetime and the efficiency of commercially available DIR-SOFC without the usage of an external reformer. The XRD, SEM and EDX methods were used to investigate the structural properties and the composition of fabricated materials. Furthermore, the electrical...
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Electro-chemo-mechanical properties in nanostructured Ca-doped ceria (CDC) by field assisted sintering
PublicationRecent investigations have shown that highly oxygen defective cerium oxides generate non-classical electrostriction that is superior to lead-based ferroelectrics. In this work, we report the effect of field-assisted spark plasma sintering (SPS) on electro-chemo-mechanical properties of calcium doped ceria (CDC). Nanometric powders of Ca.10 nm are rapidly consolidated to form polycrystalline nanostructures with a high degree of...
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Evaluation of Praseodymium and Gadolinium Doped Ceria as a Possible Barrier Layer Material for Solid Oxide Cells
PublicationIn this work, nanocrystalline layers based on the Pr, Gd co-doped CeO2 were investigated. For the preparation of thin layers, lowtemperature spray pyrolysis technique was used. Different stoichiometries of the layers were produced for comparison on polished sapphire substrates. The microstructure of the prepared thin layers was studied by scanning electron microscopy (SEM), energydispersive X-ray spectroscopy (EDS) and X-ray diffractometry (XRD)....
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Investigation of thin perovskite layers between cathode and doped ceria used as buffer layer in solid oxide fuel cells
PublicationIn this paper, thin perovskite layers between cathode material of solid oxide fuel cells and gadolinia-doped ceria buffer layer are investigated. Thin layers made of LaNi0.6Fe0.4O3-δ (LNF), La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), or SrTi0.65Fe0.35O3-δ (STF) were symmetrically deposited by spin coating method from metallo-organic polymer precursors on a Ce0.8Gd0.2O2-δ (CGO) substrate. Porous and about 40-μm-thick LNF cathodes were deposited...
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La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ oxygen electrodes for solid oxide cells prepared by polymer precursor and nitrates solution infiltration into gadolinium doped ceria backbone
PublicationInfiltration is a method, which can be applied for the electrode preparation. In this paper oxygen electrode is prepared solely by the infiltration of La0.6Sr0.4Co0.2Fe0.8O3‐δ (LSCF) into Ce0.8Gd0.2O2-δ (CGO) backbone. The use a polymer precursor as an infiltrating medium, instead of an aqueous nitrate salts solution is presented. It is shown that the polymer forms the single-phase perovskite at 600 °C, contrary to the nitrates...
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Limited dissolution of transition metals in the nanocrystalline cerium (IV) oxide
PublicationNanocrystalline cerium (IV) oxides doped with transition metals have gained significant interest recently, mostly in the field of catalysis. Herein, we present the comprehensive studies on ceria doped with 10 mol.% of transition metals (Mn, Fe, Co, Ni or Cu) synthesized by the reverse microemulsion method. The aim of this work is to study the properties of those materials with the use of different complementary methods like XRD,...
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Interactions between components of SrTi0.98 Nb0.02O3-δ-YSZ and SrTi0.98 Nb0.02O3-δ -CeO2 composites
PublicationComposites consisting of SrTiO3-based perovskite and either yttria-stabilized zirconia or ceria were investigated. The mechanical compatibility and possible inter-diffusion between phases were characterized by scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. A gradual disappearance of Ce-containing phases with an increase in the temperature of reduction in hydrogen was noticed. Moreover,...
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Improved performance of LaNi0.6Fe0.4O3 solid oxide fuel cell cathode by application of a thin interface cathode functional layer
PublicationIn this work, novel functional layers were prepared by a low temperature spray pyrolysis method on the oxygen side of the solid oxide cells. Thin layers of Ce0.8Gd0.2O2 and LaNi0.6Fe0.4O3 are prepared between the electrolyte and the porous oxygen electrode. Additionally the influence of the sprayed ceria barrier layer on the zirconia based electrolyte with the new layers is evaluated. Impedance spectroscopy results show improvement...
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Three electrode configuration measurements of electrolyte-diffusion barrier-cathode interface
PublicationMeasurements of a system consisting of cathode/doped ceria diffusion barrier/doped zirconia electrolyte were made using two- and three-electrode configuration. Results obtained on a three-electrode measurement configuration were compared with and reflect the results obtained in two-electrode configuration. Three-electrode measurements allowed separating the impact of the symmetrical interface in the investigated system. They also...
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Ultrafast high-temperature sintering (UHS) of cerium oxide-based compound
PublicationUltrafast high-temperature sintering (UHS) is an innovative sintering technique that can densify ceramics in a few seconds, dramatically reducing the carbon footprint and firing costs. In this work, the feasibility of applying UHS in Gd-doped ceria (GDC) and GDC-Er-stabilized bismuth oxide (ESB) composite powders was investigated. At high UHS currents (22-24 A), a fully dense GDC sample with a large grain size was obtained. Nonetheless,...
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Electrochemical properties of porous Sr0.86Ti0.65Fe0.35O3 oxygen electrodes in solid oxide cells: Impedance study of symmetrical electrodes
PublicationThis work evaluates porous Sr0.86Ti0.65Fe0.35O3 (STF35) as a possible oxygen electrode material for Solid Oxide Cells. The powder synthesis was performed by solid state method. Characterization included DC electrical conductivity study of sintered bulk samples and impedance spectroscopy study of symmetrical electrodes deposited on gadolinium doped ceria substrates. Measurements were carried out in atmospheres with different pO2...
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Enhanced Mechanical and Electromechanical Properties of Compositionally Complex Zirconia Zr1–x(Gd1/5Pr1/5Nd1/5Sm1/5Y1/5)xO2−δ Ceramics
PublicationCompositionally complex oxides (CCOs) or high-entropy oxides (HEOs) are new multi-element oxides with unexplored physical and functional properties. In this work, we report fluorite structure derived compositionally complex zirconia with composition Zr1- x(Gd1/5Pr1/5Nd1/5Sm1/5Y1/5)xO2-δ (x = 0.1 and 0.2) synthesized in solid-state reaction route and sintered via hot pressing at 1350 °C. We explore the evolution of these oxides'...
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Characteristics of La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ -supported micro-tubular solid oxide fuel cells with LaCo 0.4 Ni 0.6-x Cu x O 3-δ cathodes
PublicationIn this study, micro-tubular solid oxide fuel cells (T-SOFCs) with extruded La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte as the mechanical support and LaCo0.4Ni0.6O3-δ (LCNO) or LaCo0.4Ni0.4Cu0.2O3-δ (LCNCO) as cathodes were prepared and characterized. Partial substitution of Cu for the Ni-ion positions in the LCNO lattices was found to significantly enhance the densification and accelerate the grain growth. The porosity-corrected...
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CGO FILMS ON YSZ ELECTROLYTE FABRICATED BY SPRAY PYROLYSIS FOR SOFC
PublicationINTRODUCTION Solid oxide fuel cells are one of the fastest developing energy converters. The advancement introduced by research community provides steady state progress is stability and performance of the fuel cells. Significant influence on the cell’s performance and stability is related to cell design. The simplest design just consists of an anode, a solid electrolyte and a cathode. However, in order to improve the properties,...
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Catalysts for advanced oxidation processes: Deep eutectic solvents-assisted synthesis – A review
PublicationNew catalyst synthesis techniques, including green materials, are extensively studied for heterogeneous photocatalytic advanced oxidation processes (AOPs) on spotlight of sustainable development. Deep eutectic solvents (DESs) started to be used in this field as environmentally friendly alternative to ionic liquids (ILs). During the catalyst synthesis, DESs can act as stabilizers, capping agents, structure directing agents, templates,...
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Effects of Ni-NCAL and Ni–Ag electrodes on the cell performances of low-temperature solid oxide fuel cells with Sm0.2Ce0·8O2-δ electrolyte at various temperatures
PublicationThree low-temperature solid oxide fuel cells are built using Sm0.2Ce0·8O2-δ (SDC) as the electrolyte. Cell A is symmetrical and features Ni–LiNi0.8Co0·15Al0·05O2 (Ni–NCAL) electrodes, Cell B comprises a Ni–NCAL anode and a Ni–Ag cathode, and Cell C is fabricated using a Ni–NCAL cathode and a Ni–Ag anode. The ohmic resistance and polarization resistance (Rp) of Cells B and C are significantly higher than those of Cell A. The reduction...
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Processing of Ce0.8Gd0.2O2-δ barrier layers for solid oxide cells: The effect of preparation method and thickness on the interdiffusion and electrochemical performance
PublicationCe0.8Gd0.2O1.9 (CGO) barrier layers are required to mitigate the chemical reactions between Sr-containing oxygen electrode materials and Zr-based oxygen ion conductors in high-temperature solid oxide cells. Barrier layers produced by different methods were studied in this work. As a reference, a cell with no barrier layer was measured. The application of the powder-processed barrier layers, considerably increases the performance....
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Interaction of SrTi0.65Fe0.35O3-δ with LaNi0.6Fe0.4O3-δ, La0.6Sr0.4Co0.2Fe0.8O3-δ and Ce0.8Gd0.2O2-δ
PublicationIron doped strontium titanates SrTi1-xFexO3-δ are perovskites of versatile properties. They can be used in solid oxide fuel cells or high temperature oxygen sensors. Their reactivity with electrolyte materials, cathode buffer layer materials, other cathode materials or current collector layers has not been fully tested. In this study we use X-ray diffraction to check SrTi0.65Fe0.35O3-δ compatibility with Ce0.8Gd0.2O2-δ (used as...
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Global variation in anastomosis and end colostomy formation following left‐sided colorectal resection
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Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy
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