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A complex study of regularities of oxidative reactions is carried out in subsurface layers of current collectors of solid oxide fuel cells manufactured of Crofer 22APU or Crofer 22H stainless steel. The methods of scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy are used to study the distribution of the main steel elements in subsurface layers of current collectors as dependent on the operation time under the conditions of a cathodic chamber of solid oxide fuel cells. A mechanism of the process is suggested and contact resistance between the current collector and LSM cathode is calculated using the model of a Schottky barrier for a metal–semiconductor junction.

The results of the development of procedures for forming membrane-electrode assemblies (MEAs) of solid oxide fuel cells (SOFCs) by co-sintering of electrodes and electrochemical tests of MEAs were described. Plates of Hionic™ material (Fuel Cell Materials, United States) with an area of 50 × 50 mm2 were used as a solid electrolyte membrane. The cathode layers were prepared from cation-deficient lanthanum-strontium manganite and the anion conductor 89 mol % ZrO2–10 mol % Sc2O3–1 mol % CeO2 (10Sc1CeSZ) with a carbon black addition for control over the microstructure. The anode layers were formed from the composite NiO/10Sc1CeSZ and by introducing rice starch as a pore-forming agent in the anode current-collecting layer. The thermal treatment mode was optimized based on thermogravimetry and scanning electron microscopy data and the results of testing the electrochemical characteristics of SOFCs to provide the formation of electrochemically active electrodes using one thermal cycle.

Single crystals of solid electrolytes of the (ZrO2)1–x–y (Sc2O3) x (Y2O3) y (x = 0.035–0.11, y = 0‒0.02) system were grown by selective melt crystallization. Stabilization of ZrO2 only with Sc2O3 in the concentration range 9–11 mol % Sc2O3 did not afford crystals with a cubic structure, and only the introduction of additional Y2O3 stabilizers afforded uniform transparent single-phase cubic crystals. All the crystals under study had high microhardness, but low crack resistance. The ion conductivity of crystals with 6 and 9 mol % Sc2O3 (6ScZr and 9ScZr, respectively) is comparable to that of 8 mol % Y2O3-stabilized ZrO2 (8YSZ), which is the most suitable electrolyte in the ZrO2–Y2O3 binary system. The specific conductivity of crystals containing 8–10 mol % Sc2O3 and 1–2 mol % Y2O3 exceeds that of other materials including 8YSZ. The maximum conductivity in the given range of compositions is inherent in the cubic phase with 10 mol % Sc2O3 and 1 mol % Y2O3 (10Sc1YZr).

The effect of the radius of the alkali-earth cation substituted into the A sublattice of La(0.5)A(0.5)Mn(0.5)Ti(0.5)O(3-delta) (D = DD degrees, Sr, Ba) perovskites on their stability and transport and thermomechanical properties is considered. The increase in the cation radius is shown to improve the phase stability and decrease the conductivity under both oxidative and reductive conditions. The thermal and chemical expansion of La(0.5)A(0.5)Mn(0.5)Ti(0.5)O(3-delta) ceramics is studied by dilatometry in controlled atmospheres and a wide temperature range at p(O-2)=10(-21)-0.21 atm. The coefficients of thermal expansion of La(0.5)A(0.5)Mn(0.5)Ti(0.5)O(3-delta) are in the interval of (10.7-14.3)x 10(-6) K-1, i.e., compatible with those of standard solid electrolytes of solid-oxide fuel cells. The maximum chemical expansion does not exceed 0.2% at isothermal reduction in the COaEuro'CO2 mixture.

The kinetics of nickel reduction and morphological changes in Ni–10Sc1CeSZ composite anodes in intermediate-temperature solid oxide fuel cells (SOFC) are studied using the Raman spectroscopy technique with the help of application of optically transparent single crystal solid electrolyte membranes and also the thermogravimetric analysis technique. It is shown that the first reduction cycle differs considerably from all the further ones, which is related to morphological changes of nickel grains occurring during the first reduction cycle. A general scheme of occurrence of the process is suggested in studies of model cells using the Raman spectroscopy technique and also in the case of thermogravimetric analysis of powders; it explains the causes for significant differences between the total duration of the process as measured using different techniques. The results of the work can be used for optimization of the mode of initial reduction of the anodic SOFC electrode.

Crystals of (ZrO 2 ) 1− x (Sc 2 O 3 ) x solid solutions with x =0.035, 0.06, 0.09 and 0.11 have been grown for the first time using the directional crystallization technique. Analysis of the scandium distribution along the crystal showed that the composition of all specimens is homogeneous, and the Sc 2 O 3 concentration is almost identical to its content in the charge. All specimens exhibit a little decline in the scandium concentration along the crystal, this indicating that the effective distribution coefficient Sc is slightly greater than 1. The structure of as-grown crystals has been studied as a function of the Sc 2 O 3 stabilising oxide concentration by X-ray diffraction, transmission electron microscopy and Raman spectroscopy. Crystals containing 3.5 mol% Sc 2 O 3 are a mixture of the monoclinic and tetragonal phases, the crystals containing 6 mol% Sc 2 O 3 have a tetragonal structure, those with 9 mol% Sc 2 O 3 have the tetragonal phase with inclusions of the rhombohedral one and the specimens with 11 mol% Sc 2 O 3 represent the rhombohedral phase with inclusions of the cubic phase. The electrical conductivity was measured as a function of temperature by electrochemical impedance spectroscopy. The conductivity of the scandia stabilized crystals, in spite of their inhomogeneity, presence of stresses and low fracture toughness, is comparable with that of the yttria stabilized zirconia crystals.

The possibility of using tape casting to produce solid electrolyte films with a thickness of 100–300 μm from zirconia stabilized with oxides of scandium and cerium is considered. A method of slip casting onto a moving tape is used to produce rather thin ceramic sheets with a thickness of less than 1 mm. An organic slip based on azeotropic mixture of isopropyl alcohol and methyl ethyl ketone is used in the present work. The effect of solvents on the properties of the obtained film and sintered ceramic is analyzed. Dibutylphthalate, polyethylene glycol, and benzyl butylphthalate are used as plasticizers. The effectiveness of these plasticizers is based on the possibility of producing a slip with a viscosity of 2000–4000 mPa s by using them. Polyvinyl butyral appears to be the most optimal temporary binder, because it is satisfactorily removed in a continuous mode of annealing of plated ceramic blanks. The maximum density of ceramic plates is achieved at the annealing temperature of 1500°C. It is shown that the working range of the obtained solid electrolyte is 800–850°C, as the maximum ionic conductivity (more than 0.15 Ω−1 cm−1) is registered in it.

We set out to establish the place of Weak Signals at the conceptual intersection between the fields of futures and complexity studies as a qualitative counterpart to the so-called Early Warning Signals (of regime shift). After briefly presenting the scope of the Weak Signal concept and associated problems with positioning such a controversial construct against the complexity field, we investigate how theoretical and practical implications of studying qualitative changes in a complex system’s state allow for particular classes of phenomena to announce impactful events in advance. Finally, we reflect on the prospective ways of augmenting the Weak Signals concept by fusing it with the notion of Early Warning Signals and the consequent opportunities provided by bridging the fields of complexity and futures studies.

Development of a reliable, easily scalable and economically feasible technology for thin-film solid electrolyte fabrication is critical for the industrial production of solid oxide fuel cells (SOFCs). In the present work, the aerosol deposition (AD) technique has been appraised for this role. The thin-film membranes of 8 mol.% yttria-stabilized zirconia (8YSZ) solid electrolyte were applied onto two-layer anode supports, with subsequent screen-printing of the composite cathodes made of (La0.8Sr0.2)0.95MnO3–δ (LSM) and zirconia co-stabilized with 10 mol.% scandia and 1 mol.% ceria (10Sc1CeSZ). High quality of the thin membranes produced by the aerosol deposition was confirmed by scanning electron microscopy and electrochemical measurements, including the measurements of current–voltage dependencies and impedance spectroscopy. At 850 °C, the anode-supported SOFCs with wet hydrogen as fuel and air as an oxidant demonstrated the open-circuit voltage above 1.04 V, whilst the power density was higher than 500 mW/cm2.

The effect of co-doping an impurity on the transport parameters and cubic phase stabilization of ZrO2–Sc2O3-based solid solutions has been compared for Y2O3 and Yb2O3 dopants. Solid solution crystals of (ZrO2)1-x-y(Sc2O3)x(Yb2O3)y and (ZrO2)1-x-y(Sc2O3)x(Y2O3)y (x = 0.08–0.10, y = 0.01, 0.02) were grown by directional melt crystallization in a cold crucible. Co-doping of the (ZrO2)1-x(Sc2O3)x crystals (x = 0.08–0.10) with 2 mol% Y2O3 or Yb2O3 for all experimental compositions produced transparent homogeneous single crystals of the t” phase or the cubic phase. For co-doping of the scandia-stabilized zirconia crystals with 1 mol% Y2O3 or Yb2O3, the stabilization of the high-temperature phases depended on the Sc2O3 content in the solid solutions. For co-doping of the solid solutions with 1 mol% Y2O3 or Yb2O3, the conductivity of the crystals increased with the Sc2O3 concentration. For co-doping of the crystals with 2 mol% Y2O3 or Yb2O3, the conductivity decreased with the Sc2O3 concentration. At scandia concentrations of 9–10 mol%, the high-temperature conductivity of the crystals co-doped with ytterbia were higher compared to those with yttria co-doping. The (ZrO2)0.9(Sc2O3)0.09(Yb2O3)0.01 crystals had the highest conductivity over the entire experimental temperature range.

In current work, we conducted comparative studies of electrolyte-supported and anode-supported solid oxide fuel cells by means of electrochemical techniques (studies of I-V curves and impedance spectroscopy) as well as using Raman spectroscopy from the inner interface of the anode electrode and solid electrolyte. Electrolyte-supported (ESC) SOFCs were based on thick single-crystalline 8YSZ anion conductor membrane and had multilayered composite electrodes. Anode-supported cells (ASC) were based on thick two-layered commercially available anode supports, the thin-film electrolyte was deposited using a magnetron sputtering technique. Comparative studies showed a significant dependence of 460 cm−1 Raman peak both on fuel mixture composition and current load applied to the cell. Linear dependences of OCV on normalized peak area gave an opportunity to estimate local anodic overpotential on the current load applied for both SOFC structures. Application of ASC model cells gave an opportunity to significantly extend a range of current loads applied. Analysis of impedance spectra gave the opportunity to study the structure of complex resistance as well as the structure of local anodic overpotential obtained.

The present work is centered on the developments of a new technique for in-situ Raman spectroscopy studies of local chemical and electrochemical reactions, phase transitions, strains and morphological alterations in the SOFC electrodes under working conditions, combined with electrochemical measurements. An appropriate selection of the electrodes geometry makes it possible to directly collect Raman spectra from the triple-phase boundary zone by passing the beam through transparent single-crystal solid electrolyte onto the interface, varying current density, temperature and atmosphere over the working electrode. The results of case studies, focused on reduction of Ni-containing cermet anodes, are presented.

Current collectors are a key component of planar SOFCs, separating air and fuel supplied onto the electrodes and connecting the cells in series. One of main challenges in the SOFC technology developments is to suppress degradation processes, often associated with the interconnect materials, and to provide low contact resistivity in oxidizing atmospheres. The present work is focused on the studies of near-surface interdiffusion phenomena in Crofer 22 APU ferritic steel interconnects with Ni-based protective layers. Particular emphasis was centered on the area-specific resistance (ASR) between the current collectors and La0.8Sr0.2MnO3 (LSM) cathodes, which exhibits time dependencies governed by the protective interlayer composition and interface microstructure alterations. The ASR changes, tested during over 30,000 hours at atmospheric oxygen pressure, can be described in terms of a model assuming that the current across the interconnector | LSM interface is essentially controlled by electron transfer via the interfacial Schottky barrier. The experimental observations validate this approach, explaining the junction resistivity and Schottky barrier height variations as a result of metal interdiffusion between the current collector and Ni-based protective coating.

The electrochemical performance of the Ni-containing cermet anodes, widely used for all types of SOFCs, is essentially governed by the triple phase boundary (TPB) formed by metal, solid electrolyte and gaseous phase. Although the TPB length and electrode surface area may be drastically increased using nanostructured components, information on the resultant effects in terms of the cermet properties and SOFC production technology is still scarce. The present work is centered on the appraisal of NiO morphologies and optimization of pre-treatment conditions for the powders used for anode screen-printing, with commercial nanocrystalline nickel (II) oxide as a model starting material. A series of NiO powders were prepared via annealing at various temperatures (300 – 1100oC) followed by chemical, structural and morphological characterization. The results of X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM/ TEM), thermogravimentry and Raman spectroscopy reveal core-shell structure of nanosized NiO grains, formed due to surface hydration and oxidation under ambient conditions. Thermally induced desorption, and likely oxidation of organic components of the screen-printing pastes by the hyperstoichiometric oxygen, lead to poor quality of the electrode layers, thus making it necessary to introduce an additional powder pre-annealing step. The optimum pre-treatment temperature enabling to remove the absorbates, simultaneously preserving submicron grain size in the electrodes, corresponds to approximately 700oC.

Internet project in Siberian Branch of Russian Academy of Sciences (SB RAS) in Novosibirsk was initiated by informal group of active scientists which suggested a plan approved by official organizations, that was necessary for success of the project. They managed to earn money from different sources and define areas of responsibilities of each participant. The Novosibirsk project was successfully completed, all institutes get access to global computer network, and then Internet was spread to all scientific centers of SB RAS. This paper is mainly concerned with social and managerial issues which were the most significant for success of the project.

This paper considers how and why the positive net effect of science-related activities substantially increases the value beyond what would be anticipated by the financial theory, which seems to work so well for other fields. A qualitative analysis of 25 small biotechnology R&D firms listed on a stock exchange illustrates that these firms do not follow the neo-classical expectation of Gaussian returns. To better understand this deviation from the expected Gaussian returns, the firms are compared to S&P 100 and the Thomson Reuters Global Innovator List. It is found that while these large firms have a higher than expected frequency of non-Gaussian events, the causes appear to be dominated by macro-economic or industrial events that impact a large number of firms. With the small R&D-intensive biotechnology firms, it is possible to identify specific events that appear to trigger a sudden increase or decrease in value. A better understanding of the nature and magnitude of these events allows policy makers, investors and managers to better comprehend the unusually large risks and new opportunities associated with biotechnology R&D. From this, a greater insight is afforded into the dynamic value of R&D in general.

Results are presented of studying electrochemical properties of perovskite-like solid solutions (La0.5 + x Sr0.5 − x )1 − y Mn0.5Ti0.5O3 − δ (x = 0–0.25, y = 0–0.03) synthesized using the citrate technique and studied as oxide anodic materials for solid oxide fuel cells (SOFC). X-ray diffraction (XRD) analysis is used to establish that the materials are stable in a wide range of oxygen chemical potential, stable in the presence of 5 ppm H2S in the range of intermediate temperatures, and also chemically compatible with the solid electrolyte of La0.8Sr0.2Ga0.8Mg0.15Co0.05O3 − δ (LSGMC). It is shown that transition to a reducing atmosphere results in a decrease in electron conductivity that produced a significant effect on the electrochemical activity of porous electrodes. Model cells of planar SOFC on a supporting solid-electrolyte membrane (LSGMC) with anodes based on (La0.6Sr0.4)0.97Mn0.5Ti0.5O3 − δ and (La0.75Sr0.25)0.97Mn0.5Ti0.5O3 − δ and a cathode of Sm0.5Sr0.5CoO3 − δ are manufactured and tested using the voltammetry technique.

A method is developed for modifying the surface of current collectors in solid-oxide fuel cells (SOFC) prepared from ferrite stainless steel (Crofer22APU). Diffusion of the protective coating material into the Crofer22APU bulk and reverse diffusion of steel components into the coating are studied. The cross-sectional microstructure and composition are studied by the electron-microscopic technique. The elemental composition of the junction between the current collector and the lanthanum-strontium manganite cathode is studied depending on the time of service-life tests in the SOFC working mode (50–6000 h). The formation of the Cr2O3 oxide islet structure on the current collector surface at the steel/coating interface is observed. It is shown that the mutual diffusion of coating components (Ni) and Crofer22APU steel together with the redox reaction at the interface prevent the chromium diffusion to the surface and protect the steel current collector from oxidation.

Results of studies of solid-electrolyte membranes with the composition of 89 mol % ZrO2-10 mol % Sc2O3-1 mol % CeO2 obtained using the technique of slip casting on a moving tape are presented. Optimization of technological parameters of membrane casting and sintering allowed manufacturing parallel plane gastight plates with the thickness of 200–250 μm that were tested in model solid oxide fuel cells (SOFC) of planar design with standard electrodes based on nickel-containing cermets and lanthanum-strontium manganite. It is shown that though conductivity of such membranes is lower as compared to that of compacted and sintered compacted samples due to diffusion of the aluminum oxide admixture in the course of the manufacturing process, power density of SOFC is sufficiently high and reaches 430 mW/cm2 at 850°C.

Studies of oxygen diffusion, interphase exchange, specific electric conductivity, and thermal expansion showed that perovskite-like Sr0.7Ce0.3MnO3 − δ (SCMO) as a potential cathode material for solid oxide fuel cells (SOFCs) has considerable advantages over the conventional materials based on lanthanum-strontium manganites. To prevent the interactions of SCMO with solid electrolyte membranes of stabilized zirconia and lanthanum gallate, it is necessary to deposit protective layers of solid solutions based on cerium oxide, which do not form new phases in contact with SCMO and electrolytes. The trials of model SOFCs with porous SCMO-based cathodes demonstrated satisfactory electrochemical and endurance characteristics of these electrodes.

Layered cuprates Pr2 - xSrxCuO4-delta with T* (x = 0.3, 0.4) and T (x = 1.0, 13) structures were prepared in air at 1273-1373 K. Oxygen content (4 - delta) of the as-prepared phases decreases from 3.96 (x = 03) and 3.98 (x = 0.4) to 3.69 (x = 1.0) and 3.49 (x = 1.3), respectively, as determined by chemical titration. Dilatometry measurements revealed non-linear expansion with low- and high-temperature regions occurring due to thermogravimetrically detected oxygen loss. Different expansion behaviors in low- and high-temperature regions of T- and T*-phases are attributed to various distributions of oxygen vacancies in their crystal structures. Both x = 0.4 and 1.0 ceramic samples exhibit lower conductivity values at high temperatures in comparison with undoped Pr2CuO4. The temperature dependences of the electrical conductivity at variable oxygen partial pressure (Po-2 = 10(-4)-0.21 atm) reveal different mechanisms of the holes generation in x = 0.4 and 1.0 compounds. The tracer diffusion coefficient of oxygen (D-T) in Pr1.6Sr0.4CuO3.98 determined by isotopic exchange depth profile (IEDP) technique using secondary ion mass spectrometry (SIMS) is in the range 6.7 x 10(-10)-5.7 x 10(-8) cm(2)/s at 973-1223 K. Obtained values are in between those for La2CuO4 and Pr2CuO4 with pure rock-salt and fluorite slabs in the crystal structure, respectively. This shows the importance of rock-salt slabs for high oxygen conductivity in R2MO4 oxides. AuthorCount:13

The role of Sr/Ca ratio, which was varied from 3/6 to 9/0, on the structure, crystallization behavior and properties of diopside-based glass and glass-ceramic sealants targeted to solid oxide fuel cell (SOFC) applications was evaluated. The structural changes undergone by glass-powder compacts during isothermal heat treatment at 850 degrees C for 1-1000 h were investigated using XRD (X-ray diffraction) analysis, including quantitative Rietveld refinement, and MAS-NMR (magic angle spinning nuclear magnetic resonance) techniques. The tendency towards crystallization was retarded with increasing Sr/Ca ratio. Diopside-based phases, strontium akermanite and magnesium silicate were developed under various heat-treatment conditions. MAS-NMR analysis of glasses heat treated for 1000 h revealed that with increasing Sr/Ca ratio, Q(1) and Q(4) structural units were formed at the expenses of Q(2) units. The good thermal stability and chemical compatibility of the new glass-ceramic compositions coupled with their mechanical reliability and high electrical resistivity make them attractive for further experimentation as sealants for SOFCs. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

One challenge for advancing solid oxide fuel cell (SOFC) technology is to develop interconnect materials with adequate conductivity and stability in oxidizing atmosphere for efficient long-term use. The objective of the present work is development of a two-step process which leads to the formation of internal barrier layer for Cr diffusion to the surface of current collector. ”Current collector with modified surface layer-LSM cathode” junctions were tested at 850ºC in air and current density 0,5A/cm2. Exposure time was up to 21000 hour. It was found that an irregularly shaped layer of thickness 2–5 mm was formed at a depth of 6–8 mm from the surface of current collector with modified near surface layer. Investigation of the composition showed that this irregularly shaped layer consists of a Cr2O3 phase and the thickness of such Cr2O3 islands increases as a function of operational time. The observed formation of such an internally oxidized Cr layer suppresses the formation of the insulating Cr2O3 phase on the current collector surface and improve electrical conductivity.

Novel complex oxides Sr2Ga1+x In1−x O5, x = 0.0–0.2 with brownmillerite-type structure were prepared in air at T = 1,273 K, 24 h. Study of the crystal structure of Sr2Ga1.1In0.9O5 refined using X-ray powder diffraction data (S.G. Icmm, a = 5.9694(1) A, b = 15.2091(3) A, c = 5.7122(1) A, χ 2 = 2.48, R F 2 = 0.0504, R p = 0.0458) revealed ordering of Ga3+ and In3+ cations over tetrahedral and octahedral positions, respectively. A partial replacement of Sr2+ by La3+ according to formula Sr1−y La y Ga0.5In0.5O2.5+y/2, leads to the formation of a cubic perovskite (a = 4.0291(5) A) for y = 0.3. No ordering of oxygen vacancies or cations was observed in Sr0.7La0.3Ga0.5In0.5O2.65 as revealed by electron diffraction study. The trace diffusion coefficient (D T) of oxygen for cubic perovskite Sr0.7La0.3Ga0.5In0.5O2.65 is in the range 2.0 × 10−9–6.3 × 10−8 cm2/s with activation energy 1.4(1) eV as determined by isotopic exchange depth profile technique using secondary ion mass spectrometry at 973–1,223 K. These values are close to those reported for Ca-doped ZrO2. High-temperature electrical conductivity of Sr0.7La0.3Ga0.5In0.5O2.65 studied by AC impedance was found to be nearly independent on oxygen partial pressure. Calculated values of activation energy at T

A simple continuum one-dimensional model of porous mixed-conducting electrode applied onto solid oxide electrolyte is proposed and discussed. Assuming linear relationships between the reaction overpotential and current, the model makes it possible to derive analytical solutions for the electrode thickness dependence of the overall electrode resistance. The least dissipation principle is used to determine the distribution of the ionic and electronic currents throughout the mixed-conducting layer. The area-specific resistance is expressed in terms of the electron and ion resistivities of the electrode material, its “reaction resistivity” as a slope of current–overpotential dependence, and geometric parameters. The solution is expanded to describe the electrode impedance and gas transport resistance under DC conditions.

A new experimental approach for in-situ Raman spectroscopy of the electrode | solid electrolyte interfaces in controlled atmospheres, based on the use of optically transparent single-crystal membranes of stabilized cubic zirconia, has been proposed and validated. This technique makes it possible to directly access the electrochemical reaction zone in SOFCs by passing the laser beam through single-crystal electrolyte onto the interface, in combination with simultaneous electrochemical measurements. The case study centered on the analysis of NiO reduction in standard cermet anodes under open-circuit conditions, demonstrated an excellent agreement between the observed kinetic parameters and literature data on nickel oxide. The porous cermet reduction kinetics at 400-600C in flowing H2-N2 gas mixture can be described by the classical Avrami model, suggesting that the reaction rate is determined by the metal nuclei growth limited by Ni diffusion. The advantages and limitations of the new experimental approach were briefly discussed., Comment: ISSFIT-12 conference paper

The performances of single cell solid oxide fuel cell (SOFC) stacks with Ni/8YSZ (8 mol% Y 2 O 3 doped ZrO 2 ) and Ni/10CGO (10 mol% Gd 2 O 3 doped CeO 2 ) anodes were compared with respect to sulfur poisoning (1–50 ppm) with H 2 /H 2 O/N 2 fuel mixture at 850 °C. The mechanisms of the sulfur poisoning and regeneration of Ni/8YSZ and Ni/10CGO anodes at the triple phase boundaries are discussed. The effects of various parameters as H 2 S contamination cycles, H 2 S concentration, current density, H 2 O concentration and contamination durations were examined. A mechanism for the progress of the sulfur poisoning in the anode is proposed. It is shown that theoretically it is possible to calculate the nickel surface area accessible for the sulfur adsorption in the anode using H 2 S poisoning behavior for Ni/8YSZ anodes. The sulfur poisoning mechanisms of Ni/8YSZ and of Ni/10CGO anodes are proposed by taking into account the different oxidation mechanisms of H 2 in the anodes considered in previous studies. The higher sulfur resistance of Ni/10CGO is explained with its high mixed ionic electronic conductivity as well as its ability to adsorb H 2 . Due to these properties CGO can continue electrochemical reactions even when nickel is covered with sulfur.

Strontium additions in (La1−x Sr x )1−y Mn0.5Ti0.5O3−δ (x = 0.15–0.75, y = 0–0.05) having a rhombohedrally distorted perovskite structure under oxidizing conditions lead to the unit cell volume contraction, whilst the total conductivity, thermal and chemical expansion, and steady-state oxygen permeation limited by surface exchange increase with increasing x. The oxygen partial pressure dependencies of the conductivity and Seebeck coefficient studied at 973–1223 K in the p(O2) range from 10−19 to 0.5 atm suggest a dominant role of electron hole hopping and relatively stable Mn3+ and Ti4+ states. Due to low oxygen nonstoichiometry essentially constant in oxidizing and moderately reducing environments and to strong coulombic interaction between Ti4+ cations and oxygen anions, the tracer diffusion coefficients measured by the 18O/16O isotopic exchange depth profile method with time-of-flight secondary-ion mass spectrometric analysis are lower compared to lanthanum–strontium manganites. The average thermal expansion coefficients determined by controlled-atmosphere dilatometry vary in the range 9.8–15.0 × 10−6 K−1 at 300–1370 K and oxygen pressures from 10−21 to 0.21 atm. The anodic overpotentials of porous La0.5Sr0.5Mn0.5Ti0.5O3−δ electrodes with Ce0.8Gd0.2O2-δ interlayers, applied onto LaGaO3-based solid electrolyte, are lower compared to (La0.75Sr0.25)0.95Cr0.5Mn0.5O3−δ when no metallic current-collecting layers are introduced. However, the polarization resistance is still high, ~2 Ω × cm2 in humidified 10 % H2–90 % N2 atmosphere at 1073 K, in correlation with relatively low electronic conduction and isotopic exchange rates. The presence of H2S traces in H2-containing gas mixtures did not result in detectable decomposition of the perovskite phases.

Increasing Sr2+ and Ti4+ concentrations in perovskite-type $$ {\left( {{\hbox{L}}{{\hbox{a}}_{0.{75} - x}}{\hbox{S}}{{\hbox{r}}_{0.{25} + x}}} \right)_{0.{95}}}{\hbox{M}}{{\hbox{n}}_{0.{5}}}{\hbox{C}}{{\hbox{r}}_{0.{5} - x}}{\hbox{T}}{{\hbox{i}}_x}{{\hbox{O}}_{{3} - }}_\delta \left( {x = 0 - 0.{5}} \right) $$ results in slightly higher thermal and chemical expansion, whereas the total conductivity activation energy tends to decrease. The average thermal expansion coefficients determined by controlled-atmosphere dilatometry vary in the range (10.8–14.5) × 10−6 K−1 at 373–1,373 K, being almost independent of the oxygen partial pressure. Variations of the conductivity and Seebeck coefficient, studied in the oxygen pressure range 10−18–0.5 atm, suggest that the electronic transport under oxidizing and moderately reducing conditions is dominated by p-type charge carriers and occurs via a small-polaron mechanism. Contrary to the hole concentration changes, the hole mobility decreases with increasing x. The oxygen permeation fluxes through dense ceramic membranes are quite similar for all compositions due to very low level of oxygen nonstoichiometry and are strongly affected by the grain-boundary diffusion and surface exchange kinetics. The porous electrodes applied onto lanthanum gallate-based solid electrolyte exhibit a considerably better electrochemical performance compared to the apatite-type La10Si5AlO26.5 electrolyte at atmospheric oxygen pressure, while Sr2+ and Ti4+ additions have no essential influence on the polarization resistance. In H2-containing gases where the electronic transport in $$ {\left( {{\hbox{L}}{{\hbox{a}}_{0.{75} - x}}{\hbox{S}}{{\hbox{r}}_{0.{25} + x}}} \right)_{0.{95}}}{\hbox{M}}{{\hbox{n}}_{0.{5}}}{\hbox{C}}{{\hbox{r}}_{0.{5} - x}}{\hbox{T}}{{\hbox{i}}_x}{{\hbox{O}}_{{3} - }}_\delta $$ perovskites becomes low, co-doping deteriorates the anode performance, which can be however improved by infiltrating Ni and $$ {\hbox{Ce}}{{\hbox{O}}_{{\rm{2}} - }}_\delta $$ v into the porous oxide electrode matrix.

The article views the phenomenon of philosophizing as a specific type of discourse, which uses the metalanguage of the third level of abstraction to verbalize the process of thinking. The research proves that the phenomenon of the translated philosophic text also appears to be the metascientific discourse of the reflection over the ontological and over its verbalization. The revealing of noematic hierarchy of sense bearing structures is necessary for the pure hermeneutical understanding of the philosophic text sense. The analysis shows that the new sense derivation and interpretation turns into a process of overflow and mutations that pervades the entire cognitive sphere.

The article studies basic functional communicative features of social work discourse. Assuming the actualization of triple communication bonds “a social worker – a client – a social service” in social work interaction, the authors study the key levels of communicative actions, which verbalize both institutional and personal elements in this communication domain. The approach provides an opportunity to specify social work discourse as a contaminated phenomenon combining the features of a social-ritual kind within the institutional type of discourse and an existential kind within personality-oriented type of discourse. The linguistic means of actualizing conventional components of this type of discourse are determined.

The modified method of electrostatic spray pyrolysis was designed to apply protective coatings based on Mn-Co spinel to ferritic stainless steels (Crofer22APU and 08X18T1). The comparative thermogravimetric (TG) studies of ferrite stainless steels with and without protective coatings were carried out. The electrochemical characteristics of protective coatings exposed to long current loading were studied. The formation of the Mn-Cr spinel observed and studied at the contact between the ferrite stainless steel and the Mn-Co spinel. The coatings of Mn-Co spinel were shown preventing formation of continuous Cr2O3 oxide film on the stainless steel surface.

Model SOFCs with Sr0.7Ce0.3MnO3 cathode were found to display nonlinear current-voltage characteristics resulting from changes in the interface resistance with varying current load. Short-term tests (~200 hours) of the cell performance were carried out at a current load of 81.5 mA/cm2. The resource tests demonstrated high stability of power performance of the model SOFCs. The Sr0.7Ce0.3MnO3 material was concluded to be a promising cathode for intermediate-temperature SOFCs.

The objective of this work was to use a "built-in" potential electrode method to measure the cathode overpotential in solid oxide fuel cells (SOFCs) directly. The studies were performed on yttria-stabilised zirconia (YSZ) electrolyte-supported SOFCs using La0.8Sr0.2MnO3 (LSM) and Sr0.75Y0.25Co0.5Mn0.5O3-y (SYCM) as cathodes and Ni-ScSZ cermet as the anode. The contributions of the cathode, anode and electrolyte to the total cell resistance were investigated using a combination of current-voltage and impedance measurements with the built-in potential electrode technique. The cathode overpotential was shown to be lower for the SYCM cathode than for the LSM cathode, and the difference increases as the current in the cell increases.

One challenge for advancing solid oxide fuel cell (SOFC) technology is to develop interconnect materials with adequate conductivity and stability for efficient long-term use. Proposed here is a technology for effectively modifying the surface of SOFC current collectors and significantly reducing the oxidation rate of ferritic stainless steel at elevated temperatures and high current densities. The formation of "Kirkendall voids" at the Crofer 22 APU ferritic stainless steel-intermetallic compound interface was observed and investigated. The Kirkendall voids play the role of a barrier layer blocking Cr diffusion to the surface and suppressing the formation of the resistive Cr2O3 surface layer. Long-term test measurements showed that the ASR value of the current collector-LSM junction decreases two times during the first 3000 hours and subsequently remains constant.

The method of electrostatic spray pyrolysis was designed to apply protective coatings based on Mn-Co spinel to ferrite stainless steels (Crofer22APU and 08Kh18T1). The comparative thermogravimetric (TG) studies of ferrite stainless steels with and without protective coatings were carried out. The electrochemical characteristics of protective coatings exposed to long current loading were studied. The formation processes of Cr2O3 oxide films were studied at the contact of ferrite stainless steel with La0.8Sr0.2MnO3 ionic and electronic conductor. The coatings of Mn-Co spinel were shown not preventing formation of continuous oxide film on the stainless steel surface.

The objective of the present work is the development of a “built-in” potential electrode method for direct measurements of the cathode and anode overpotentials and the corresponding interface resistances of solid oxide fuel cells (SOFC). The studies were performed on a yttria-stabilised zirconia (YSZ) electrolyte-supported SOFC using La0.8Sr0.2MnO3 as cathode, GDC as protecting layer and Ni-ScSZ cermet as anode. The mesh potential electrode was placed inside the YSZ membrane near the cathode side. Using the combination of the I-U and the impedance measurements with the built-in potential electrode technique, the temperature dependencies of the electrodes and electrolyte contributions to the total cell resistance were determined.

The electrochemical reduction of nitric oxide in the presence of the excess oxygen was reviewed. It was shown that the selectivity and activity of the cathodes is strongly dependent on the composition and on the microstructure of the cathode material. A concept of electrochemical reactor with multilayer electro-catalytic electrode was proposed and successfully designed in Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Japan. The typical values of current efficiency in such electrochemical reactors are of the order of 10–20% at gas composition: 1,000 ppm NO and 2% O2 balanced in He and at gas flow rate 50 ml/min. The value of current efficiency depends on the functional multi-layer electrode composition, structure, and operating temperature. Such electrochemical reactors show the value of NO/O2 selectivity (νsel) higher than 5 (νsel > 5) at intermediate temperature and up to νsel = 25 at low temperature operation. It was shown that multilayer electro-catalytic electrode should consist at list from three main functional layers: cathode, electro-catalytic electrode, covering layer, in order to operate as an electrode with high selectivity.

The possibilities of formation and details of architecture of bubblets that arise in an electrolyte in the presence of a hydrophobic effect at the vapor/liquid interface for one of the ions is discussed. It is demonstrated that the competition of this effect and the image forces leads to the emergence, around a cavity of radius R that materialized for some reason or another, of a charged double layer, which is capable of stabilizing the bubble dimensions. A relationship is determined between radius R and parameters pertaining to the problem: the energy of localization of “hydrophobic” ions, the surface tension at the vapor/liquid interface, the dielectric constant of the liquid, and so on. It is mentioned that the scenario under discussion has no threshold that would interfere with the emergence of dipole-charged bubblets in weak electrolytes.

The microstructure and chemical changes in the Ni-YSZ heterojunctions were studied by scanning, transmission, and high-resolution electron microscopy and X-ray diffraction. It was shown that new nano-size Ni grains are formed at Ni-YSZ interface at the cell operation. The following two stage reaction mechanism was proposed for hydrogen oxidation on the nano-size Ni grains: 1. NiO + Н2 Þ Н2О + Ni; 2. O2-(YSZ) + Ni Þ NiO + 2e. This mechanism implies that the SOFC will operate during some time even after switching off the hydrogen flow. We have observed and investigated current-voltage characteristics of SOFC after cutting off the hydrogen pass through anode chamber. Electrochemical properties of SOFC were investigated as a function of Ni volume content for two different geometry of anode current collector. Good correlations of experimentally measured SOFC characteristics with results of numeric calculations were found.

Microstructural and chemical changes in a NiO-YSZ electrocatalytic electrode were studied. The microstructural changes in the NiO-YSZ electrocatalytic electrode after the cell operation was compared with the electrode quenched under the applied voltage to suppress the oxidation process. The reversible reduction of NiO into Ni and the formation of intergranular Ni layers at the NiO/YSZ interface were investigated. It was shown that in a compositional range of the NiO-YSZ electrodes from 1/3 to 2/3 the value of the ambipolar conductivity increased with increasing voltage applied to the electrochemical cell. The observed reversible increase in the value of ambipolar conductivity of the electrocatalytic electrode is described in frames of the model of reversible reduction of NiO into Ni under the conditions of cell operation.

A new family of electrochemical cells ((Electro-catalytic electrode)|Pt(Cathode)|YSZ|Pt(Anode)) for NO decomposition in the presence of excess oxygen have been designed and investigated. It was shown that by control of the composition of the (NiO) x –(YSZ) 1− x electro-catalytic electrode, it was possible to minimize the values of the cell operating voltage. The electrochemical properties of an electrochemical cell for NO decomposition were investigated and correlated with the compositions of the (NiO) x –(YSZ) 1− x electro-catalytic electrode using the effective medium percolation theory (EMPT). The optimum NiO addition (35% by volume) to the electro-catalytic electrode resulted in a decrease of the cell operating voltage and in a decrease in the electrical power required for NO decomposition. A mechanism of NO decomposition by this new type of the electrochemical cell with composite electro-catalytic electrode was proposed and investigated.

Solid-state electrochemical cells with two cathode layers were designed for effective NO x decomposition. It was found that covering of the cathode by a mixed oxide electrode increased NO decomposition even in the presence of excess oxygen. A strong correlation between the microstructure of the working electrode and conversion rate of NO x gas was observed and studied. It was shown that there was a linear dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nano-porous working electrode and that the value of current efficiency depended on the NO and O 2 gas concentrations only. A mechanism for the process of NO decomposition on nano-porous ceramics electrode was proposed and the theoretical value of the current efficiency was calculated. A good numerical correlation between the calculated and measured characteristics of the electrochemical cell were observed.

In recent years, an intense research effort has been focused on electrochemical cells for reduction of gases of nitrogen oxide radicals (NOx) due to the need to design an effective method for the purification of the exhaust gas from lean burn and diesel engines. A new type of solid-state electrochemical cell with composite Pt–YSZ cathode and nano-porous NiO–YSZ working electrode for decomposition of NOx gas in the presence of excess oxygen was proposed and investigated. It was shown that the dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nano-porous NiO– YSZ working electrode was linear and that the value of current efficiency is dependent on the NO and O2 gas concentrations only. For the first time, an electrochemical cell for NO decomposition operating at dc voltage lower than 1.7 V in the temperature range of 550–700 jC was designed. The combination of the new type of composite cathode with a nano-porous working electrode provides the possibility of large reductions in the electrical power required for NO decomposition in the presence of excess oxygen. D 2002 Elsevier Science B.V. All rights reserved.

The data obtained by impedance spectroscopy (1 Hz to 32 MHz) and broad-band dielectric spectroscopy (30 GHz-150 THz) are presented for crystals based on zirconia doped by 1.5–30 mol % Y2O3 or 10 mol % Sc2O3 and 1 mol % Y2O3. The maximum of ionic conductivity is confirmed for the latter composition in the working temperature range of solid oxide fuel cells where the doping by scandium and yttrium oxides makes it possible to obtain isotropic single crystals. Dependences of dielectric permeability and high-frequency conductivity of materials on the composition of crystals and temperature are presented.

The oxygen tracer diffusion and surface exchange coefficients of Sr0.7Ce0.3MnO3-delta (SCM), measured by the O-18/O-16 isotopic exchange depth profile method with time-of-flight secondary-ion mass spectrometric analysis at 973-1123 K, are substantially higher than those of (La,Sr)MnO3-delta. Testing of model solid oxide fuel cells (SOFCs) with SCM cathodes, ceria-based protective interlayers and Ni-containing cermet anodes demonstrated a relatively good and stable performance. For 0.5 mm thick solid electrolyte membranes made of ZrO2- 10 mol% Sc2O3- 1 mol% Y2O3 and doped lanthanum gallate, the maximum power density at 1073 K was approximately 170 and 230 mW/cm(2), respectively, without microstructural optimization and surface modification of the electrodes. Compared to another promising family of SOFC cathode materials, (La,Sr)(Co,Fe)O3-delta, SCM exhibits significantly lower thermal and chemical expansion assessed by the controlled-atmosphere dilatometry. (C) 2013 Elsevier B.V. All rights reserved.

The structure and phase transitions of C60 crystals doped with lithium by injecting metal ions from the superionic crystal-C60 single crystal heterojunction under electrodiffusion conditions are reported. The sample experienced irreversible transitions resulting in the virtually complete disappearance of EPR signals and MW conduction in the temperature range 320–370 K. In this temperature interval, a new C60 phase was formed; the phase contained polymeric chains of C60 molecules along the crystallographic c axis and lithium clusters. The structure of this phase was determined. Annealing at 620 K restored the EPR signal and, according to the X-ray data, the initial cubic structure of pure C60. The X-ray pattern, however, contained additional diffraction peaks, which was evidence of the presence of one more phase with a structure yet unknown.