In the present work single-phase proton-conducting electrolyte CaZr0.95Sc0.05O3-δ (CZS) is synthesized by a conventional solid-state technique with different impurities content. Impurities are ...introduced by using different milling bodies during the synthesis. It is shown that milling by steel balls or grinding in a jasper mortar results in approximately 1 at.% of iron and silica respectively. Milling with ZrO2 balls does not lead to a noticeable increase in the level of impurities in CZS.
The influence of impurities on the bulk and grain boundary conductivity is studied by means of electrochemical impedance spectroscopy. The measurements are performed on symmetric cells with different electrodes: Pt|CZS|Pt, (Pt + PrO2)|CZS|(Pt + PrO2) and Ag|CZS|Ag. The data analyzed by the conventional equivalent circuit and distribution of relaxation times (DRT) techniques.
It is shown that impurities influence only the grain boundary conductivity which proves that the grain boundary segregation occurs. However, a large grain-boundary resistance could be an obstacle to determine the bulk resistance.
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•CaZr0.95Sc0.05O3-δ electrolytes with different impurities content were obtained.•Bulk and grain-boundary conductivities were distinguished using DRT technique.•The addition of Si decreases grain-boundary conductivity, while Fe – increases.
The Cosmic Microwave Background (CMB) radiation is the only observable that allows studying the earliest stage of the Universe. Radioastronomy instruments for CMB investigation require low working ...temperatures around 100 mK to get the necessary sensitivity. On-chip electron cooling of receivers is a pathway for future space missions due to problems of dilution fridges at low gravity. Here, we demonstrate experimentally that in a Cold-Electron Bolometer (CEB) a theoretical limit of electron cooling down to 65 mK from phonon temperature of 300 mK can be reached. It is possible due to effective withdrawing of hot electrons from the tunnel barrier by double stock, special traps and suppression of Andreev Joule heating in hybrid Al/Fe normal nanoabsorber.
In this work, the effect of the content of CuO, ZnO, Al2O3, NiO, Fe2O3, Co3O4 and MoO3 additives on the sinterability, microstructure, and electrical properties of La0.9Sr0.1ScO3-α proton-conducting ...oxide in a form of tubes produced by slip casting is studied. It is shown that the relative density of La0.9Sr0.1ScO3-α tubes without sintering aids is ~86%. The introduction of 1.0 wt % ZnO, Al2O3, NiO or 0.5 ÷ 1.0 wt % Co3O4 leads to a relative density of ceramics higher than 95%. Among dense ceramic tubes, LSS +0.5 wt % Co3O4 has the highest electrical conductivity. The introduction of 1 wt % Fe2O3 additive does not affect the sinterability of the LSS, and 1 wt % CuO and MoO3 inhibits LSS sintering. Single protonic ceramic fuel cells based on LSS +0.5 wt % Co3O4 and LSS +1.0 wt % NiO supporting electrolyte tubes with a thickness of 300 μm are studied. The maximum power density of about 30 mW/cm2 at 800 °C was obtained for a cell based on LSS +0.5 wt % Co3O4 using wet hydrogen as fuel and air as an oxidizing gas.
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•Co3O4 recognized to be the best sintering additive for La0.9Sr0.1ScO3-δ electrolyte.•The way of sintering additive introduction affects microstructure in case of Co3O4.•The optimal amount of Co3O4 additive was found to be 0.5 wt%.•Highly dense ceramic tubes of proton-conducting electrolyte were obtained.
This review is devoted to porphyrin-based film materials. Various technological and scientific applications of ones are close to surface and interface related phenomena. In the part I of review the ...following topics are discussed the recent progress in field of submonolayers, monolayers and multilayers films on the vapor-solid interfaces, including results on (i) conformational behavior of adsorbed molecules, (ii) aggregation and surface phases formation, (iii) on-surface coordination networks, and (iv) on-surface chemical reactions. The examples of combined approaches to developing materials and porphyrin-based film materials application are also presented.
From the precursor properties through the surface phenomena to molecular devices and functional films. Display omitted
•Conformation, aggregation and chemical processes of porphyrins at gas/solid interfaces•Characteristics of porphyrin structures on surfaces•Molecular devises; high scale films formation and its applications
An augmented reality display based on a planar waveguide made in photo-thermo-refractive glass had been demonstrated. The monolithic integration of multiplexed volume Bragg gratings with the ...waveguide platform provided in/out-coupling and image transmission from a portable projector. Design and calculation of the grating configuration was performed. The optical replication method was simulated and implemented for manufacturing the multiplexed coupling elements. Resulted field of view was limited by the projection system of the prototype, however can be expanded beyond 50
o
.
The usage of coal-water fuel instead of dry coal for heat and power generation is a promising way to decrease harmful emissions during power generation. Improvement of the coal-water fuel ignition ...and combustion parameters is important due to the specifics of the fuel. The use of glycerol as a flammable additive to the coal-water fuel is environmentally friendly and leads to reducing the ignition time and threshold temperature of that composition fuel. Generally accepted approximation of the dependence of the main combustion parameters includes the ignition temperature and the time delay before ignition on the glycerol content of the fuel composition does not correspond to the physical nature of the process and does not reflect the real nature of the change. To approximate the experimental data in the case of complex two-component fuel based on the coal-water slurry and glycerol, a more suitable and physically correct inverse sigmoid function is proposed. The applicability of the proposed function has been confirmed by experimental studies.
The Central part of the Oka Plateau lying in the East Sayan Mountains is still a poorly studied area of southern Siberia as regards its paleogeography. This gap can be partially replenished by the ...results of the present study. This study is focused on reconstruction of the central Oka Plateau environment in the Middle–Late Holocene. The pollen from bottom sediments of Sagan-Nur Lake provided a qualitative reconstruction of the vegetation in the catchment area of the lake as well as the quantitative reconstruction of dominant vegetation types obtained via the biomization method. The reconstruction suggests the dominance of the tundra vegetation consisting of dwarf birch, alder, and willow with patches of spruce and larch between about 8120 and 7000 cal. yr BP. The climate was sharp continental with high soil moisture resulting from summer permafrost thaw. The expansion of the forest biome began in the Central Oka Plateau at about 7000 cal. yr BP due to climate warming, hydrological network reconstruction resulting from complete thaw of regional glaciers and degradation of the permafrost rocks. Around 3200 cal. yr BP, the larch forests with the participation of Siberian pine started spreading across the Sagan-Nur Lake catchment area, thus suggesting colder conditions than before. The obtained reconstructions can help identifying the promising lakes and their catchment areas in the East Sayan Mountains for potential sustainable development through special projects (e.g., educational, tourist, environmentally protected).
Summary
For the fuel ignition, the thermal conductivity and heat capacity are the key properties that determine the pre‐ignition behavior of the drop of the fuel. The classic monophase fuels, such as ...natural gas, liquid propellants, or solid one‐component fuels, have been investigated for a long time; and their thermophysical properties are well known in most of the cases. Composite fuels, which have recently attracted the attention of the researchers, have complex contents. In many cases, composite fuel is a mixture of solid and liquid components in the form of a slurry. Coal‐water fuel and its derivatives with different additives are examples of such type fuels. For those fuels, the thermophysical properties are usually unknown. Nowadays, researchers use simple additivity theory for the calculation of the thermophysical properties of complex fuels for the first approach. Authors of this research believe that the simple additivity approach is not correct and can lead to the wrong results in the case of the numerical research of the ignition and burning processes of such a fuel. In the present research, the thermophysical properties of coal‐water fuel with glycerol additives were experimentally obtained. It was found that the coefficient of thermal conductivity increases with temperature and varies in the range of 0.45 to 0.53 W/(m·K). The heat capacity of the fuel also increases with the temperature and varies from 4.7 to 5.5 kJ/kg·K. The higher the glycerol content, the lower the thermal conductivity and heat capacity of the composite fuel in the investigated temperature range. The results confirm the failure of the approach of the additivity law usage. Neither, thermal conductivity coefficient or heat capacity of the coal‐water fuel with the addition of up to 20% glycerol complies with the additivity law. Differences between real values of the thermophysical properties and calculated ones are more than 30% to 50%. Empirical expressions for calculation of the thermophysical properties of coal‐water fuel with the addition of up to 20% glycerol are presented.
Glycerol affects thermophysical properties of the resulting suspension; thermophysical properties of CWF with glycerol do not obey law of additivity changes in thermophysical properties and can eliminate improvements in CWF combustion.
Ni cermets have been widely investigated as anode materials for solid oxide fuel cells (SOFCs), particularly for those based on O
2−
-conducting electrolytes, e.g., yttria-stabilized zirconia (YSZ). ...However, proton ceramic fuel cells (PCFCs) are increasingly attracting research attention, considered to be another developmental step in high-temperature fuel cell technologies. Ni cermets with a ceramic matrix capable of performing proton transfer are believed to be prospective anode materials for PCFCs. This work is aimed at investigating materials that can be used as supporting anodes with LaScO
3
-based proton-conducting electrolytes. La
0.95
Sr
0.05
ScO
3−
δ
(LSS5) as a potential ceramic component was synthesized by solid-phase and co-precipitation methods. Ni-LSS5 composites were obtained by solid-state mixing of the respective powders followed by reduction in hydrogen. Effects of the LSS5 powder production technique and sintering temperature (1400, 1450, and 1500 °С) on the microstructural features and phase composition were studied using both oxidized and reduced samples. The temperature dependencies of resistivity, as well as of thermal and chemical expansions, were investigated in situ. It is found that the electrical conductivity and chemical expansion of Ni-LSS is largely determined by its porosity rather than by the selected synthesis method. The materials under study are shown to exhibit relatively small values of chemical expansion and resistivity, making them promising for application in anode-supported PCFCs with LaScO
3
-based proton-conducting electrolytes.
Graphical abstract
.
In this work, we synthesized the glasses of the SiO
2
–Al
2
O
3
–CaO–Na
2
O–MgO–K
2
O–B
2
O
3
–Y
2
O
3
system and investigated their thermal properties under changes in the ratios between the ...components in both modifying (MgO/CaO) and glass-forming (SiO
2
/B
2
O
3
) oxides. In addition, the effects of crystallization on both the properties of sealants and their behaviour at the boundary with ceramic yttria-stabilized zirconia (YSZ) electrolyte have been studied. X-ray diffraction analysis was used to determine the phase composition of the glasses both after quenching, dilatometric measurements and sealing of the glasses with the YSZ ceramic support. The thermal expansion coefficients (CTEs) found for the glasses and glass–ceramics are shown to be in good agreement with those of other cell components. The sealing temperatures of these materials are found to be lower than the operating temperature limit of the interconnector alloy. It is shown that Mg-rich glasses exhibit higher resistance to interaction with Cr compared to other compositions under study. The scanning electron microscopy and energy dispersive spectroscopy studies have confirmed the formation of gas-tight connections by the sealants under investigation. The glass demonstrating the highest stability in contact with the Crofer22APU alloy has been tested as a sealant for a tubular cell. This material is established to ensure a tight connection without cracks during operation at 850 °C for 250 h. The materials are thus found to be promising candidates for use as sealants for solid oxide fuel cells (SOFCs).
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