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All 1-25 26-50 51-75 76-100 101-125 126-150 151-175 176-200 201-225 226-250 251-275 276-300 301-325 326-350 351-375 376-400 401-425 426-450 451-475 476-500 501-525 526-550 551-575 576-600 601-625 626-650 651-675 676-Reaction Sintering of Ca3Co4O9 with BiCuSeO Nanosheets for High-Temperature Thermoelectric Composites
ID=665| Authors |
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Journal of Electronic Materials volume
Volume: 51,
Pages: 532–542 Time of Publication: 2022 |
| Abstract | Ceramic composites composed of oxide materials have been synthesized by reaction sintering of Ca3Co4O9 with BiCuSeO nanosheets. In situ x-ray diffraction and thermogravimetric analyses of the compound powders were conducted to understand the phase transformations during heating up to 1173 K. Further thermogravimetric analyses investigated the thermal stability of the composites and the completion of reaction sintering. The microstructure of the formed phases after reaction sintering and the composition of the composites were investigated for varying mixtures. Depending on the amount of BiCuSeO used, the phases present and their composition differed, having a significant impact on the thermoelectric properties. The increase of the electrical conductivity at a simultaneously high Seebeck coefficient resulted in a large power factor of 5.4 μW cm−1 K−2, more than twice that of pristine Ca3Co4O9. |
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High-performance anode-supported solid oxide fuel cells with co-fired Sm0.2Ce0.8O2-δ/La0.8Sr0.2Ga0.8Mg0.2O3−δ/Sm0.2Ce0.8O2-δ sandwiched electrolyte
ID=664| Authors |
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International Journal of Hydrogen Energy
Volume: 47,
Issue: 8,
Pages: 5429-5438 Time of Publication: 2022 |
| Abstract | In this study, intermediate-temperature solid oxide fuel cells (IT-SOFCs) with a nine-layer structure are constructed via a simple method based on the cost-effective tape casting-screen printing-co-firing process with the structure composed of a NiO-based four-layer anode, a Sm0.2Ce0·8O2-δ(SDC)/La0·8Sr0.2Ga0.8Mg0·2O3−δ (LSGM)/SDC tri-layer electrolyte, and an La0·6Sr0·4Co0·2Fe0·8O3-δ (LSCF)-based bi-layer cathode. The resultant SDC (4.14 μm)/LSGM (1.47 μm)/SDC (4.14 μm) tri-layer electrolyte exhibits good continuity and a highly dense structure. The Ro and Rp values of the single cell are observed to be 0.15 and 0.08 Ω cm2 at 800 °C, respectively, and the MPD of the cell is 1.08 Wcm-2. The high MPD of the cell appears to be associate with the significantly lower area-specific resistance and the reasonably high OCV. Compared to those with a similar electrolyte thickness reported in prior studies, the nine-layer anode-supported IT-SOFC with a tri-layer electrolyte developed by the study demonstrates superior cell properties. |
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Synthesis, structure and ionic conductivity of nanocrystalline Ce1−xLaxO2−δ as an electrolyte for intermediate temperature solid oxide fuel cells
ID=663| Authors |
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Journal of Alloys and Compounds
Volume: 896,
Pages: 163012 Time of Publication: 2022 |
| Abstract | La-doped CeO2 nanoparticles of composition Ce1−xLaxO2−δ (0 ≤ x ≤ 0.1) have been studied here as prospective electrolytes for intermediate temperature solid oxide fuel cells (IT-SOFCs). They were synthesized by auto-combustion method and the powder samples were calcined at 700 °C to get ultrafine nanocrystalline particles. They were characterized by XRD, Raman, FTIR, XPS, DRS, FESEM/EDX, particle size analyzer and ac-impedance techniques. Ionic conductivity was measured from 350 − 750 °C. The Ce0.90La0.1O2−δ (0.1 LDC) and Ce0.95La0.05O2−δ (0.05 LDC) showed a maximum conductivity of 8.89 × 10−3 and 8.32 × 10−3 S cm−1 at 700 °C, respectively. The σt of 0.1 LDC = 1.01 × 10−2 S cm−1 at 750 °C. The activation energy of 0.1 LDC and 0.05 LDC was found to be 0.70 eV and 0.87 eV, respectively. These values are higher than those reported for La-doped CeO2 in literature. The SOFC performance with 0.05 LDC as electrolyte showed open circuit voltage of 0.81 V and maximum power density of 41 mW cm−2 at 650 °C using hydrogen as fuel. |
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Unlocking bulk and surface oxygen transport properties of mixed oxide-ion and electron conducting membranes with combined oxygen permeation cell and oxygen probe method
ID=662| Authors |
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Journal of Membrane Science Volume: 644, Pages: 120082 Time of Publication: 2022 |
| Abstract | Surface exchange kinetics and bulk diffusion of oxygen are of paramount importance to the activity of oxygen electrocatalysis and performance of electrochemical devices such as fuel cell, metal-air batteries, and oxygen separation membranes. Conventional approaches to obtaining these transport properties are often limited to single property under a specific non-operation related condition. Here we use a combined oxygen permeation cell and oxygen probe methodology to simultaneously attain rates of oxygen surface exchange and bulk conductivity/chemical diffusivity of three representative mixed oxide-ion and electron conductors, namely SrCo0.9Ta0.1O3-δ (SCT), La0.6Sr0.4CoO3-δ (LSC) and La0.6Sr0.4FeO3-δ (LSF), operated under a steady-state oxygen flux. The results explicitly show that SCT exhibit the highest oxide-ion conductivity/chemical diffusivity, fastest rates of surface oxygen exchange kinetics, thus promising to be the best oxygen electrocatalyst. We have also mapped out the distribution of oxygen chemical potential gradient across the membranes and applied B-transport number concept to illustrate the rate-limiting steps in the overall oxygen permeation process. |
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Improved thermoelectric properties in ceramic composites based on Ca3Co4O9 and Na2Ca2Nb4O13
ID=661| Authors |
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Open Ceramics
Volume: 8,
Pages: 100198 Time of Publication: 2021 |
| Abstract | The oxide materials Ca3Co4O9 and Na2Ca2Nb4O13 were combined in a new ceramic composite with promising synergistic thermoelectric properties. Both compounds show a plate-like crystal shape and similar aspect ratios but the matrix material Ca3Co4O9 with lateral sizes of less than 500 nm is about two orders of magnitude smaller. Uniaxial pressing of the mixed compound powders was used to produce porous ceramics after conventional sintering. Reactions between both compounds and their compositions were thoroughly investigated. In comparison to pure Ca3Co4O9, mixing with low amounts of Na2Ca2Nb4O13 proved to be beneficial for the overall thermoelectric properties. A maximum figure-of-merit of zT = 0.32 at 1073 K and therefore an improvement of about 19% was achieved by the ceramic composites. |
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https://doi.org/10.1016/j.oceram.2021.100198 Link |
Glass-ceramic composites as insulation material for thermoelectric oxide multilayer generators
ID=660| Authors |
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Time of Publication: 2021
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| Abstract | Thermoelectric generators can be used as energy harvesters for sensor applications. Adapting the ceramic multilayer technology, their production can be highly automated. In such multilayer thermoelectric generators, the electrical insulation material, which separates the thermoelectric legs, is crucial for the performance of the device. The insulation material should be adapted to the thermoelectric regarding its averaged coefficient of thermal expansion α and its sintering temperature while maintaining a high resistivity. In this study, starting from theoretical calculations, a glass-ceramic composite material adapted for multilayer generators from calcium manganate and calcium cobaltite is developed. The material is optimized towards an α of 11 × 10−6 K−1 (20–500°C), a sintering temperature of 900°C, and a high resistivity up to 800°C. Calculated and measured α are in good agreement. The chosen glass-ceramic composite with 45 vol.% quartz has a resistivity of 1 × 107 Ωcm and an open porosity of <3%. Sintered multilayer samples from tape-cast thermoelectric oxides and screen-printed insulation show only small reaction layers. It can be concluded that glass-ceramic composites are a well-suited material class for insulation layers as their physical properties can be tuned by varying glass composition or dispersion phases. |
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https://doi.org/10.1111/jace.18235 Link |
Electrical properties of yttria-stabilised hafnia ceramics
ID=659| Authors |
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Phys. Chem. Chem. Phys.
Volume: 23,
Pages: 25951 Time of Publication: 2021 |
| Abstract | Cubic, yttria-stabilised hafnia, YSH, ceramics of general formula, YxHf1xO2x/2: x = 0.15, 0.30 and 0.45 were sintered at 1650–1750 1C and characterised by impedance spectroscopy. All three compositions are primarily oxide ion conductors with a small amount of p-type conductivity that depends on atmospheric conditions and appears to increase with x. The electronic conductivity is attributed to hole location on under-bonded oxide ions and the absorption of oxygen molecules by oxygen vacancies, both of which occur on substitution of Hf4+ by Y3+. Composition x = 0.15 has the highest total conductivity and shows curvature in the Arrhenius plot at high temperatures, similar to that of the most conductive yttria-stabilised zirconia. |
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Electrochemical Performance of SrWO4 Electrolyte for SOFC
ID=658| Authors |
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The International Journal of Integrated Engineering
Volume: 13,
Issue: 1,
Pages: 74-80 Time of Publication: 2021 |
| Abstract | cheelite structured SrWO4 material was synthesized by the solid-state sintering method and studied with respect to phase stability and ionic conductivity under condition of technological relevance for SOFC applications. The resulting compound was crystallized in the single phase of tetragonal scheelite structure with the space group of I41/a. Room temperature X-ray diffraction and subsequent Rietveld analysis confirms its symmetry, space group and structural parameters. Analysis by SEM illustrated a highly dense structure. SrWO4 sample shows lower conductivity compared to the raditional BCZY perovskite structured materials. SrWO4 sample exhibited an ionic conductivity of 1.93 × 10−6 S cm-¹ at 1000°C in dry Ar condition. Since this scheelite type compound demonstrated significant conductivity and a dense microstructure, it could serve in SOFC as a mixed ion-conducting electrolyte. |
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Electrical properties and charge compensation mechanisms of Cr-doped rutile, TiO2
ID=657| Authors |
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Phys. Chem. Chem. Phys.
Volume: 23,
Pages: 22133-22146 Time of Publication: 2021 |
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Protonic Transport Properties of Perovskite Heterostructures A Thin Film Study
ID=656| Author |
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Time of Publication: 2021
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Master Thesis Materials Science for Energy and Nanotechnology Link |
Expanded Chemistry and Proton Conductivity in Vanadium-Substituted Variants of γ-Ba4Nb2O9
ID=655| Authors |
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Chem. Mater.
Volume: 33,
Issue: 18,
Pages: 7475–7483 Time of Publication: 2021 |
| Abstract | We have substantially expanded the chemical phase space of the hitherto unique γ-Ba4Nb2O9 type structure by designing and synthesizing stoichiometric ordered analogues γ-Ba4V1/3Ta5/3O9 and γ-Ba4V1/3Nb5/3O9 and exploring the solid-solution series γ-Ba4VxTa2–xO9 and γ-Ba4VxNb2–xO9. Undoped Ba4Ta2O9 forms a 6H-perovskite type phase, but with sufficient V doping the γ-type phase is thermodynamically preferred and possibly more stable than γ-Ba4Nb2O9, forming at a 200 °C lower synthesis temperature. This is explained by the fact that Nb5+ ions in γ-Ba4Nb2O9 simultaneously occupy 4-, 5-, and 6-coordinate sites in the oxide sublattice, which is less stable than allowing smaller V5+ to occupy the former two and larger Ta5+ to occupy the latter. The x = 1/3 phase γ-Ba4V1/3Ta5/3O9 shows greatly improved ionic conduction compared to the x = 0 phase 6H-Ba4Ta2O9. We characterized the structures of the new phases using a combination of X-ray and neutron powder diffraction. All compositions hydrate rapidly and extensively (up to 1/3 H2O per formula unit) in ambient conditions, like the parent γ-Ba4Nb2O9 phase. At lower temperatures, the ionic conduction is predominately protonic, while at higher temperatures it is likely other charge carriers make increasing contributions. |
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https://doi.org/10.1021/acs.chemmater.1c02340 Link |
Electrical transport in a molten-solid V2O5–ZrV2O7 composite
ID=654| Authors |
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J. Mater. Chem. A
Volume: 9,
Pages: 18537-18545 Time of Publication: 2021 |
| Abstract | Molten-solid composite oxides are candidates as oxygen transport membranes (OTMs) at intermediate temperatures (500–700 °C). Effects of the constituent phases and interphases on surface reactions and transport processes in these composites are elusive. Here we contribute fundamental insight to such materials systems, applying electrochemical impedance spectroscopy (EIS) and electromotive force (emf) measurements to investigate the electrical conductivity characteristics of a 30 mol% V2O5–ZrV2O7 composite with a eutectic melting point at ∼670 °C. When V2O5 melts and increases the V2O5 volume percolation, the electrical conductivity increases by a factor of 10 and the activation energy increases from 0.21 to ∼0.7 eV. The oxygen red-ox reaction at the surface changes from being rate limited by charge transfer processes to mass transfer processes as a consequence of fast oxygen exchange in molten V2O5 as compared to the all-solid composite. These effects coincide with the ionic transport number rising from essentially zero to ∼0.4, reflecting a significant increase in the relative oxide ion conductivity. Oxygen permeation across a 30 mol% V2O5–ZrV2O7 membrane was estimated to be in the same order as for several dual-phase membranes, but one magnitude lower than for single-phase mixed conducting membranes at intermediate temperatures. |
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DOI: 10.1039/D1TA03750A Link |
Evaluation of Materials for Use in Open-Cycle Magnetohydrodynamic Power Generation
ID=653| Author |
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Time of Publication: 2021
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Michael S. Bowen for the degree of Master of Science in Mechanical Engineering Link |
Anode-supported solid oxide fuel cells with multilayer LSC/CGO/LSC cathode
ID=652| Authors |
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Fuel Cells
Volume: 21,
Issue: 4,
Pages: 408-412 Time of Publication: 2021 |
| Abstract | The multilayer La0.6Sr0.4CoO3/Ce0.9Gd0.1O2/La0.6Sr0.4CoO3 (LSC/CGO/LSC) thin film cathode of the solid oxide fuel cell (SOFC) with the different thickness of the LSC and CGO layers are obtained by magnetron sputtering. Cathodes are deposited onto the NiO/8YSZ anode-supported 8YSZ/CGO bilayer electrolyte. The influence of the deposited multilayer cathode on the SOFC performance is investigated in the temperature range between 800 and 600°C. It is shown that the thin-film multilayer cathode allows increasing the SOFC efficiency, and the obtained optimum thickness of the LSC and CGO layers provides the maximum power density for SOFCs. The maximum power density of 2430, 1170, and 290 mW cm–2 is obtained respectively at 800, 700, and 600°C for the SOFCs with the LSC/CGO/LSC layer 50/50/50 nm thick. The polarization resistance measured at 800 and 750°C on the symmetric SOFC with the CGO electrolyte and LSC/CGO/LSC cathode is 0.17 and 0.3 Ω cm2, respectively. |
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Performance and Processes of Pure CO2 Electrolysis in Solid Oxide Cells
ID=651| Authors |
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ECS Transactions
Volume: 103,
Issue: 1,
Pages: 501 Time of Publication: 2021 |
| Abstract | Pure carbon dioxide (CO2) electrolysis presents a sustainable method for the production of carbon monoxide (CO). CO is an important feedstock for producing base chemicals for the chemical industry. High-temperature CO2 electrolysis in solid oxide electrolysis cells (SOECs) make it possible to recycle climate-damaging CO2 and utilize renewable energy sources for the conversion to CO. We thoroughly investigated the direct CO2 electrolysis electrochemically with respect to the process parameters temperature, fuel utilization, load, flow rates, and CO2:CO feed gas ratio. With faradaic efficiencies of about 100% and high current densities of up to 1.5 Abold dotcm,-2 the results show the high potential of pure CO2 electrolysis. |
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Metal Supported Proton Conducting Ceramic Cell with Thin Film Electrolyte for Electrolysis Application
ID=650| Authors |
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ECS Transactions
Volume: 103,
Issue: 1,
Pages: 693 Time of Publication: 2021 |
| Abstract | Manufacturing of metal supported proton conducting ceramic cells is investigated in the present study. A low temperature fabrication route was chosen to avoid metal corrosion during the fabrication process, in which pulsed laser deposition (PLD) was employed to apply the thin-film BaZr0.7Ce0.2Y0.1O3-δ electrolyte layer. The surface condition of the support layer is a critical aspect to produce a dense and gas-tight electrolyte layer by PLD. In order to decrease the average size of the 10-30 µm large pores in metal substrate down to the nano-scale, different powders with different particles size were successfully fabricated and integrated into a pore-size graded structure to form a homogeneous porous surface whose size distribution meets the requirements for making a dense PLD coating layer. An electrolyte layer with the intended phase is achieved with a thickness of around 1 µm. Initial electrochemical investigation with a Pt oxygen electrode showed a total resistance of 4.92 Ω cm2 at 600°C at OCV. |
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Boundaries of High-Temperature Co-Electrolysis Towards Direct CO2-Electrolysis
ID=649| Authors |
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ECS Transactions
Volume: 103,
Issue: 1,
Pages: 493 Time of Publication: 2021 |
| Abstract | In this work, the transition boundary of high-temperature co-electrolysis towards pure CO2-electrolysis was investigated. AC and DC measurements with H2O concentrations from 0.0%eq to 39.7%eq led to the identification of the underlying electrochemical processes. Comparison of CO2 conversion in the (R)WGS reaction with electrochemical CO2 reduction by means of area specific resistance (ASR) showed that gas composition determines the dominant reduction reaction (H2O or CO2 reduction). The cell performance of CO2-electrolysis was found to be comparable to co-electrolysis in the boundary region up to around 4.7 %eq H2O. The threshold for the perception of CO2-electrolysis during co-electrolysis has been established to be around 31.7 %eq H2O. The hypothesis that pre-domination of CO2-electrolysis increases with decreasing H2O concentrations below this boundary limit was underlined by measurement results. |
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The Electrochemical Society, find out more The Electrochemical Society, find out more Metal Supported Proton Conducting Ceramic Cell with Thin Film Electrolyte for Electrolysis Application
ID=647| Authors |
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ECS Transactions
Volume: 103,
Pages: 693 Time of Publication: 2021 |
| Abstract | Manufacturing of metal supported proton conducting ceramic cells is investigated in the present study. A low temperature fabrication route was chosen to avoid metal corrosion during the fabrication process, in which pulsed laser deposition (PLD) was employed to apply the thin-film BaZr0.7Ce0.2Y0.1O3-δ electrolyte layer. The surface condition of the support layer is a critical aspect to produce a dense and gas-tight electrolyte layer by PLD. In order to decrease the average size of the 10-30 µm large pores in metal substrate down to the nano-scale, different powders with different particles size were successfully fabricated and integrated into a pore-size graded structure to form a homogeneous porous surface whose size distribution meets the requirements for making a dense PLD coating layer. An electrolyte layer with the intended phase is achieved with a thickness of around 1 µm. Initial electrochemical investigation with a Pt oxygen electrode showed a total resistance of 4.92 Ω cm2 at 600°C at OCV. |
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Syngas production with CO2 utilization through the oxidative reforming of methane in a new cermet-carbonate packed-bed membrane reactor
ID=646| Authors |
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Journal of Membrane Science
Volume: 637,
Pages: 119607 Time of Publication: 2021 |
| Cermet; Gas Separation; Membrane reactor; Oxidative reforming of methane | |
| Remark |
https://doi.org/10.1016/j.memsci.2021.119607 Link |
Structural and Electrochemical Properties of Scandia Alumina Stabilized Zirconia Thin Films
ID=645| Authors |
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Coatings
Volume: 11,
Issue: 7,
Pages: 800 Time of Publication: 2021 |
| Abstract | This work presents a systematic investigation of scandia alumina stabilized zirconia (ScAlSZ, composition: ZrO2:Sc2O3:Al2O3 93:6:1 wt.%) thin films (~2 μm). Thin films were formed by the e-beam evaporation method on 450 °C substrates. The influence of Al concentration on thin film microstructure, structure, and electrochemical properties was characterized by EDS, XRD, Raman, and EIS methods. It was found that the aluminum concentration in the deposited thin films decreased with an increase in the deposition rate. The concentration of Al changed from 15.9 to 3.8 at.% when the deposition rates were 0.2 and 1.6 nm/s, respectively. The crystallinity of the thin films depended strongly on the concentration of Al, resulting in an amorphous phase when Al concentration was 22.2 at.% and a crystalline phase when Al concentration was lower. ScAlSZ thin films containing 15.9 at.% of Al had monoclinic and tetragonal phases, while thin films with 1.6 and 3.8 at.% of Al had a mixture of cubic, tetragonal, and monoclinic phases. The phase transition was observed during the thermal annealing process. Cubic and rhombohedral phases formed in addition to monoclinic and tetragonal phases appeared after annealing ScAlSZ thin films containing 15.9 and 22.2 at.% of aluminum. The highest total ionic conductivity (σbulk = 2.89 Sm−1 at 800 °C) was achieved for ScAlSZ thin films containing 3.8 at.% of Al. However, thin films containing a higher concentration of aluminum had more than 10 times lower total conductivity and demonstrated changes in activation energy at high temperatures (>560 °C). Activation energies changed from ~1.10 to ~1.85 eV. |
| Keywords | electron beam deposition; scandia alumina stabilized zirconia (ScAlSZ); solid oxide fuel cells (SOFC); ionic conductivity |
| Remark |
https://doi.org/10.3390/coatings11070800 Link |
Anomalous grain boundary conduction in BiScO3-BaTiO3 high temperature dielectrics
ID=644| Authors |
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Acta Materialia
Volume: 216,
Pages: 117136 Time of Publication: 2021 |
| Remark |
https://doi.org/10.1016/j.actamat.2021.117136 Link |
Preparation of NdBaCo2O5+δ–Ce0.9Gd0.1O1.95 composite cathode by in situ sol-mixing method and its high-temperature electrochemical properties
ID=643| Authors |
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Journal of Alloys and Compounds
Volume: 885,
Pages: 160901 Time of Publication: 2021 |
| Abstract | NdBaCo2O5+δ-xCe0.9Gd0.1O1.95 (NBCO-xCGO, x = 0 ~ 8 wt%) composite materials are prepared by novel sol-mixing method and evaluated as cathodes for intermediate-temperature solid oxide fuel cells. The chemical compatibility, thermal expansion behavior and electrochemical performance of NBCO-xCGO composite cathodes are studied. There is no chemical reaction between NBCO and CGO after sintering at 1100 °C for 12 h. Introducing CGO leads to the decrease of both thermal expansion coefficient and conductivity. Among all the composites, NBCO-5CGO shows the lowest polarization resistance of 0.034 Ω cm2 at 700 °C. The anode-supported single-cell with NBCO-5CGO cathode exhibits a maximum power density of 1.0 W cm−2 at 700 °C. The electrochemical impedance spectrum measurement combining with the distribution of relaxation times analysis proves that the addition of CGO nanoparticles significantly improves the surface oxygen dissociation process, and the charge transfer process is identified to be the reaction limiting step to control the oxygen reduction kinetics on NBCO-5CGO composite cathode. |
| Keywords | Intermediate-temperature solid oxide fuel cell; Composite cathode; Distribution of relaxation times analysis; Oxygen reduction kinetics |
| Remark |
https://doi.org/10.1016/j.jallcom.2021.160901 Link |
Valence state of europium and samarium in Ln2Hf2O7 (Ln = Eu, Sm) based oxygen ion conductors
ID=642| Authors |
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Ceramics International
Volume: 47,
Issue: 19,
Pages: 26898-26906 Time of Publication: 2021 |
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Impedance spectroscopy studies of the chlorophosphate glasses
ID=641| Authors |
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Materials Today: Proceedings
Time of Publication: 2021
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| Remark |
https://doi.org/10.1016/j.matpr.2021.06.041 Link |
Optical properties and frequency-dependent conductivity of K2O-BaO-TiO2-P2O5 glasses
ID=640| Authors |
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Materials Today: Proceedings
Time of Publication: 2021
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| Abstract | The glass compositions (20-x)K2O-xBaO–30TiO2–50P2O5 with (0�¯≤�¯x�¯≤�¯20�¯mol%) were elaborated using the conventional quenching method. Their related glass-ceramics were developed by controlled crystallization under heat treatments. UV–visible absorption was employed to study the optical properties of the glasses. This technique showed the reduction of Ti4+ to Ti3+ ion content with the substitution of K2O by BaO, and it was found that the BaO addition reduces the structural disorder in the studied glasses. The electrical properties of the glass-ceramics were carried out by impedance spectroscopy in the frequency range from 10�¯Hz to 1�¯MHz under various temperatures from room temperature to 550�¯K. The obtained results showed that the electrical conductivity follows Jonscher’s universal power law and the electrical motion process in the glass-ceramics is provided by the hopping mechanism. |
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