Published references
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ID=564| Authors |
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Chem. Mater.
Volume: 32,
Issue: 10,
Pages: 4347–4357 Time of Publication: 2020 |
| Abstract | A series of Zn-substituted compounds, Sr2Sc1–xZnxGaO5–0.5x, based on the brownmillerite-type oxide ion conductor Sr2ScGaO5 have been synthesized, and a single-phase region has been identified at 0.4 ≤ x < 0.6. The structure and dynamics of Sr2Sc0.6Zn0.4GaO4.8 were investigated by X-ray and neutron diffraction, neutron total scattering and pair distribution function (PDF) analysis, impedance spectroscopy, and neutron spectroscopy. The material was found to be a highly disordered cubic perovskite with a remarkable level of oxygen deficiency across a large temperature range. These structural properties lead to an increase of oxide ion conductivity of about two orders of magnitude relative to the parent Sr2ScGaO5. The presence of proton conductivity and some water uptake was suggested by the impedance data and corroborated by thermogravimetric analysis (TGA), solid state nuclear magnetic resonance (NMR), variable temperature X-ray diffraction, and neutron spectroscopy. Both proton and oxide ion conductivity produced a measurable quasi-elastic neutron scattering (QENS) signal, and the onset of each dynamic process could be observed by monitoring the temperature dependence of the elastic and inelastic scattering intensities measured in fixed window scans. Neutron total scattering and PDF studies revealed a local structure that is markedly different from the perovskite average structure, and we propose that Sr2Sc0.6Zn0.4GaO4.8 contains a rare one-coordinate or terminal oxygen site. |
| Remark | Link |
High-performing electrolyte-supported symmetrical solid oxide electrolysis cells operating under steam electrolysis and co-electrolysis modes
ID=563| Authors |
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International Journal of Hydrogen Energy
Volume: 45,
Issue: 28,
Pages: 14208-14217 Time of Publication: 2020 |
| Abstract | Symmetrical solid oxide cells (s-SOC) present several advantages compared to typical configuration, as a reduction of sintering steps or a better thermomechanical compatibility between the electrodes and the electrolyte. Different mixed ionic-electronic conductors (MIEC) have been reported as suitable candidates for symmetrical configuration, allowing operations under steam electrolysis (SOEC) or co-electrolysis (co-SOEC) without the use of reducing safe gas (typically employed in SoA nickel based cells). In the present study, Sr2Fe1.5Mo0.5O6−δ (SFM) electrodes are deposited on both sides of YbScSZ tapes previously coated with a Ce1-xGdxO1.9 (GDC) barrier layer grown by PLD. Electrode sintering temperature is optimized and fixed at 1200 °C by means of electrochemical impedance spectroscopy (EIS) measurements in symmetrical atmosphere. The cell is then characterized at 900 °C in SOEC and co-SOEC modes without the use of any safe gas obtaining high current densities of 1.4 and 1.1 A cm−2 at 1.3 V respectively. Short-term reversibility is finally proven by switching the gas atmosphere between the cathode and anode sides while keeping the electrolysis conditions. Similar performances are obtained in both configurations. |
| Keywords | Solid oxide electrolyser, SOEC, Co-electrolysis, Symmetrical, Energy storage, Safe gas |
| Remark |
https://doi.org/10.1016/j.ijhydene.2020.03.144 Link |
Defect Chemistry of Sodium Bismuth Titanate and itsSolid Solutions
ID=562| Author |
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Time of Publication: 2019
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Dissertation Link |
Mixed-conducting ceramic-carbonate dual-phase membranes: Gas permeation and counter-permeation
ID=561| Authors |
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Journal of Membrane Science
Volume: 605,
Pages: 118093 Time of Publication: 2020 |
| Abstract | CO2 and O2 permeable ceramic-carbonate dual-phase membranes can be used in membrane reactors for applications such as selective oxidation of hydrocarbons. Two ceramic-carbonate dual-phase membranes consisting of mixed electronic-ionic conducting perovskite-type ceramics of Pr0.6Sr0.4Co0.2Fe0.8 and SrFe0.9Ta0.1O3-δ are studied for CO2 and O2 permeation and counter-permeation. The geometric factors for the carbonate phase and ceramic phase, obtained from the data of helium permeation and electrical conductivity, are used to calculate the effective carbonate and oxygen ionic conductivity in the carbonate and ceramic phase. Without counter-permeation, O2 permeation through the dual-phase membrane is controlled by oxygen ionic conduction in the ceramic phase and CO2 permeation is determined by the total conductance including effective carbonate and oxygen ionic conductivities in both phases. When the dual-phase membrane is exposed to CO2 on one side and O2 on the other side, counter-permeation of CO2 and O2 occurs in the opposite directions across the membrane. With CO2 counter-permeation, the oxygen ionic flux is higher than that without counter-permeation due to an increase in the driving force for oxygen transport. CO2 permeation consumes oxygen ions transporting through the membrane, resulting in a lower O2 permeation flux compared with the O2-only permeation case. However, O2 counter-permeation has negligible effect on CO2 permeation flux for the dual-phase membranes. |
| Remark |
https://doi.org/10.1016/j.memsci.2020.118093 Link |
Reaction mechanism of low-temperature catalysis by surface protonics in an electric field
ID=560| Author |
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Faraday Discuss.
Time of Publication: 2020
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| Abstract | The process combining heterogeneous catalysts and DC electric field can achieve high catalytic activities, even under mild conditions (<500 K) with less electrical energy consumption. Hydrogen production by steam reforming of methane, aromatics and alcohol, dehydrogenation of methylcyclohexane, dry reforming of methane, and ammonia synthesis are known to proceed at low temperatures in an electric field. In-situ/operando analyses have been conducted using IR, Raman, XAFS, electrochemical impedance spectroscopy, and isotopic kinetic analyses to elucidate the reaction mechanism for these reactions at low temperatures. Results show that surface proton hopping by a DC electric field, called surface protonics, is important for these reactions at low temperatures because of higher surface adsorbate concentrations at lower temperatures. |
| Remark |
Accepted Manuscript, https://doi.org/10.1039/C9FD00129H Link |
Peculiar Properties of Electrochemically OxidizedSmBaCo2−xMnxO5+δ(x=0; 0.5 and 1) A-SiteOrdered Perovskites
ID=559| Authors |
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Crystals
Volume: 10,
Pages: 205 Time of Publication: 2020 |
| Abstract | Fully-stoichiometric SmBaCo2-xMnxO6oxides (x=0, 0.5, 1) were obtained through theelectrochemical oxidation method performed in 1 M KOH solution from starting materials having closeto equilibrium oxygen content. Cycling voltammetry scans allow us to recognize the voltage range(0.3–0.55 V vs. Hg/HgO electrode) for which electrochemical oxidation occurs with high efficiency.In a similarly performed galvanostatic experiment, the value of the stabilized voltage recorded duringthe oxidation increased with higher Mn content, which seems to relate to the electronic structure ofthe compounds. Results of the iodometric titration and thermogravimetric analysis prove that theproposed technique allows for an increase in the oxygen content in SmBaCo2-xMnxO5+δmaterialsto values close to 6 (δ≈1). While the expected significant enhancement of the total conductivitywas observed for the oxidized samples, surprisingly, their crystal structure only underwent slightmodification. This can be interpreted as due to the unique nature of the oxygen intercalation process at room temperature. |
| Remark |
doi:10.3390/cryst10030205 Link |
Dielectric properties of new oxide phases Ln0.65Sr1.35Co0.5Ti0.5O4 (Ln = La, Nd, Pr) with the K2NiF4 - type structure
ID=558| Authors |
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Ceramics International
Volume: 46,
Issue: 10, Part A,
Pages: 15305-15313 Time of Publication: 2020 |
| Abstract | New complex oxides of the composition Ln0.65Sr1.35Co0.5Ti0.5O4 (Ln = La, Nd, Pr) with the K2NiF4 – type structure were synthesized using the citrate-nitrate method. Their crystal chemical characteristics and dielectric properties are researched. Different values of frequency-independent dielectric constants are observed in a wide frequency range of 103–107 Hz in ceramics prepared at a temperature of 1300 °C. The highest permittivity ε is about 102 (at ambient temperature) in the frequency range from 1 kHz to 1 MHz for La0.65Sr1.35Co0.5Ti0.5O4 and Pr0.65Sr1.35Co0.5Ti0.5O4 samples. Co3+ and rare earth elements (La, Nd, Pr) co-doping Sr2TiO4 solid solution distorts the coordination polyhedra (Co,Ti)O6 and SrO9, which leads to an Re ε increase by several times. The surface microstructure of ceramics was investigated. The samples relative density correlates with the dielectric constant value. A sample of the Nd0.65Sr1.35Co0.5Ti0.5O4 composition has a lower relative density and, accordingly, a lower Re ε value. The results of dielectric properties researches show that the structure anisotropy and the samples morphology have a significant effect on the value of the dielectric constant. |
| Keywords | Sol–gel processes Grain size Perovskites Dielectric properties |
| Remark |
https://doi.org/10.1016/j.ceramint.2020.03.071 Link |
Activation of C−H Bond of Propane by Strong Basic Sites Generated by Bulk Proton Conduction on V‐Modified Hydroxyapatites for the Formation of Propene
ID=557| Authors |
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ChemCatChem
Volume: 12,
Issue: 9,
Pages: 2506-2521 Time of Publication: 2020 |
| Abstract | Insights into the catalytic transformation of propane to propene on V‐apatite catalysts are provided based on structure‐reactivity relationships. Substitution of phosphates by vanadates in the hydroxyapatite structure leads to the formation of Ca10(PO4)6‐x(VO4)x(OH)2‐yOy V‐oxy‐hydroxy‐apatite solid solutions (x=0→6). Bulk vanadium incorporation promotes (i) calcium rich terminations (XPS, CO adsorption), (ii) proton deficiency inside the OH− channels (1H NMR) giving rise to O2− native species, (iii) the thermally‐activated formation of additional O2− species along the OH− channels resulting in H‐bonding interaction (in situ DRIFT) and (iv) the proton conduction process that eventually results in the surface exposure of O2− species (in situ impedance spectroscopy). The exposure of Ca2+−O2− surface acid‐base pairs allows the dissociation of hydrogen, emphasizing the strong basicity of the related O2− species. Whereas an increasing vanadium content is beneficial to propene selectivity, it scarcely impacts propane conversion. The reaction proceeds mainly upon oxidative dehydrogenation, even if the minor dehydrogenation route is also observed. Surface O2− generated thanks to proton mobility are involved in the C−H bond activation, as shown by the synergistic effect between the oxidative dehydrogenation of propane reaction and the bulk proton conduction measured under operando conditions. This puts emphasis on the key role of strong basic sites for propane activation. |
| Remark |
https://doi.org/10.1002/cctc.201902181 Link |
First observation of surface protonics on SrZrO3 perovskite under a H2 atmosphere
ID=556| Authors |
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Chem. Commun.
Volume: 56,
Pages: 2699-2702 Time of Publication: 2020 |
| Abstract | This is the first direct observation that surface proton hopping occurs on SrZrO3 perovskite even under a H2 (i.e. dry) atmosphere. Understanding proton conduction mechanisms on ceramic surfaces under a H2 atmosphere is necessary to investigate the role of proton hopping on the surface of heterogeneous catalysts in an electric field. In this work, surface protonics was investigated using electrochemical impedance spectroscopy (EIS). To extract the surface proton conduction, two pellets of different relative densities were prepared: a porous sample (R.D. = 60%) and a dense sample (R.D. = 90%). Comparison of conductivities with and without H2 revealed that only the porous sample showed a decrease in the apparent activation energy of conductivity by supplying H2. H/D isotope exchange tests revealed that the surface proton is the dominant conductive species over the porous sample with H2 supply. Such identification of a dominant conductive carrier facilitates consideration of the role of surface protonics in chemical reactions. |
| Remark | Link |
Mixed-conducting ceramic-carbonate membranes exhibiting high CO2/O2 permeation flux and stability at high temperatures
ID=555| Authors |
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Journal of Advanced Ceramics
Volume: 9,
Issue: 1,
Pages: 94-106 Time of Publication: 2020 |
| Abstract | This investigation demonstrates the feasibility to fabricate high quality ceramic–carbonate membranes based on mixed-conducting ceramics. Specifically, it is reported the simultaneous CO2/O2permeation and stability properties of membranes constituted by a combination of ceramic and carbonate phases, wherein the microstructure of the ceramic part is composed, in turn, of a mixture of fluorite and perovskite phases. These ceramics showed ionic and electronic conduction, and at the operation temperature, the carbonate phase of the membranes is in liquid state, which allows the transport of CO32– and O2– species via different mechanisms. To fabricate the membranes, the ceramic powders were uniaxially pressed in a disk shape. Then, an incipient sintering treatment was carried out in such a way that a highly porous ceramic was obtained. Afterwards, the piece is densified by the infiltration of molten carbonate. Characterization of the membranes was accomplished by SEM, XRD, and gas permeation techniques among others. Thermal and chemical stability under an atmosphere rich in CO2 was evaluated. CO2/O2 permeation and long-term stability measurements were conducted between 850 and 940 °C. The best permeation–separation performance of membranes of about 1 mm thickness, showed a maximum permeance flux of about 4.46×10 -7 mol?m -2 ?s -1 ?Pa -1 for CO 2 and 2.18×10 -7 mol?m -2 ?s -1 ?Pa -1 for O 2 at 940 ?. Membranes exhibited separation factor values of 150–991 and 49–511 for CO2/N2and O2/N2 respectively in the studied temperature range. Despite long-term stability test showed certain microstructural changes in the membranes, no significant detriment on the permeation properties was observed along 100 h of continuous operation. |
| Keywords | CO2 separation; O2 separation; ceramic–carbonate membrane; selectivity |
| Remark | Link |
Indium doping in SrCeO3 proton-conducting perovskites
ID=554| Authors |
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Journal of Solid State Chemistry
Volume: 248,
Pages: 121210 Time of Publication: 2020 |
| Abstract | In this work we present results of studies of In3+ doping in strontium cerate, comprising structural aspects, and oxygen as well as proton conductivity. Crystal structure analysis of single-phase SrCe1-xInxO3-a (x = 0.1, 0.2 and 0.3) materials in 25–900 °C temperature range indicates presence of strong orthorhombic distortion of the perovskite-type structure, similar as for the undoped SrCeO3. Limited sinterability of the obtained powders was mitigated by addition of 1 wt% of NiO, which allowed to manufacture dense sinters at 1400 °C. Electrochemical impedance spectroscopy measurements done in dry synthetic air show decrease of the ionic (oxygen) conductivity with the increase of In content, as well as associated increase of the activation energy. This indicates that formed oxygen vacancies are trapped in the structure. Overall, electrical conductivity for SrCe1-xInxO3-a in H2O- and D2O-containing atmospheres decreases with In content, but respective H+ and D+ transference numbers are larger for samples with higher indium doping. At 500 °C the highest proton and deuterium conductivity was recorded for SrCe0.9In0.1O3-a, reaching up to 0.70·10−4 S cm−1 and 0.26·10−4 S cm−1, respectively. Derived diffusion and surface exchange coefficients are 10−7-10−6 cm2 s−1 and 10−6-10−5 cm s−1, respectively in 500–700 °C temperature range. |
| Keywords | Strontium cerate, In doping, Crystal structure, Hydration, Transport properties, Proton conductivity |
| Remark |
https://doi.org/10.1016/j.jssc.2020.121210 |
A detailed kinetic model for the reduction of oxygen on LSCF-GDC composite cathodes
ID=553| Authors |
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Electrochimica Acta
Time of Publication: 2020
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| Abstract | A kinetic investigation of the Oxygen Reduction Reaction (ORR) is performed on LSCF-GDC composite cathodes (La0.4Sr0.6Co0.2Fe0.8O3-δ/Ce0.9Gd0.1O2-δ 50/50) spanning a wide range of operating conditions. EIS tests are carried out on symmetric cells between 700 °C and 560 °C at OCV, with O2/N2 mixtures at varying O2 molar fraction (5–21%). A dynamic, one-dimensional, physic model of the LSCF-GDC electrode is applied to rationalize the experimental results. The model simulates the spectra by solving mass and charge conservation equations, including terms for gas diffusion in the porous electrode and solid state transport in both the LSCF and the GDC lattice. A thermodynamically consistent, detailed kinetic scheme is applied to describe the ORR mechanism, which takes into account elementary steps of adsorption and desorption, first and second electronation at the gas/electrode interface, interfacial and lattice ion transfer. A full set of rate parameters (pre-exponential factors and activation energies) is derived by fitting to inhouse-measured impedance data, and validated against a well-established literature dataset. The sensitivity analysis supports the prevailing role of the TPB route over the 2 PB route, and highlights that the transfer of a single-charged oxygen adatom from the LSCF surface to the GDC lattice governs the ORR. The model clarifies the origin of distortions in measured impedance arcs, and captures the effect of O2 pressure on the observed electrochemical activity. |
| Remark |
https://doi.org/10.1016/j.electacta.2020.135620 Link |
High performance and toxicity assessment of Ta3N5 nanotubes for photoelectrochemical water splitting
ID=552| Authors |
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Catalysis Today
Time of Publication: 2019
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| Abstract | In this work, Co-based cocatalysts are electrodeposited on mesoporous Ta3N5 nanotubes. The electrodeposition time is varied and the optimized photoelectrode reaches a photocurrent density of 6.3 mA/cm2 at 1.23 V vs. SHE, under simulated solar illumination of 1 Sun, in 1 M NaOH. The best performing electrode, apart from the high photocurrent density, shows improved stability under intense photoelectrochemical water splitting conditions. The dual function of the cocatalyst to improve not only the photoelectrochemical performance, but also the stability, is highlighted. Moreover, we adopted a simple protocol to assess the toxicity of Co and Ta contained nanostructured materials (representing used photoelectrodes) employing the human cell line HeLa S3 as target cells. |
| Remark |
https://doi.org/10.1016/j.cattod.2019.12.031 Link |
A CO2-Tolerant Perovskite Oxide with High Oxide Ion and Electronic Conductivity
ID=551| Authors |
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Adv. Mater.
Time of Publication: 2019
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| Abstract | Mixed ionic–electronic conductors (MIECs) that display high oxide ion con-ductivity (σo) and electronic conductivity (σe) constitute an important family of electrocatalysts for a variety of applications including fuel cells and oxygen sepa-ration membranes. Often MIECs exhibit sufficient σe but inadequate σo. It has been a long-standing challenge to develop MIECs with both high σo and stability under device operation conditions. For example, the well-known perovskite oxide Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) exhibits exceptional σo and electrocatalytic activity. The reactivity of BSCF with CO2, however, limits its use in practical applications. Here, the perovskite oxide Bi0.15Sr0.85Co0.8Fe0.2O3−δ (BiSCF) is shown to exhibit not only exceptional bulk transport properties, with a σo among the highest for known MIECs, but also high CO2 tolerance. When used as an oxygen separation membrane, BiSCF displays high oxygen permeability comparable to that of BSCF and much higher stability under CO2. The combination of high oxide transport properties and CO2 tolerance in a single-phase MIEC gives BiSCF a significant advantage over existing MIECs for practical applications. |
| Remark |
DOI: 10.1002/adma.201905200 Link |
Coexistence of three types of sodium motion in double molybdate Na9Sc(MoO4)6: 23Na and 45Sc NMR data and ab initio calculations
ID=550| Authors |
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Phys. Chem. Chem. Phys.
Volume: 22,
Pages: 144-154 Time of Publication: 2020 |
| Abstract | The rechargeable Na-ion batteries attract much attention as an alternative to the widely used but expensive Li-ion batteries. The search for materials with high sodium diffusion is important for the development of solid state electrolytes. We present the results of experimental and ab initio studies of the Na-ion diffusion mechanism in Na9Sc(MoO4)6. The ion conductivity reaches the value of 3.6 × 10−2 S cm−1 at T ∼ 850 K. The 23Na and 45Sc NMR data reveal the coexistence of three different types of Na-ion motion in the temperature range from 300 to 750 K. They are activated at different temperatures and are characterized by substantially different dynamics parameters. These features are confirmed by ab initio calculations of activation barriers for sodium diffusion along various paths. |
| Remark | Link |
Long-term (4 year) degradation behavior of coated stainless steel 441 used for solid oxide fuel cell interconnect applications
ID=549| Authors |
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Journal of Power Sources
Time of Publication: 2019
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| Abstract | The present work aims to investigate the long-term stability of Ce/Co coated AISI 441 used as an interconnect material in solid oxide fuel cells (SOFC). Being a commercially available alloy the use of AISI 441 would greatly reduce the cost of SOFCs in comparison to tailor-made interconnect materials such as Crofer 22 APU. To analyze the long-term stability Ce/Co coated AISI 441 is exposed in air at 800 °C for up to 38 000 h. Mass gain values are recorded continuously. After 7 000, 23 000, and 35 000 h area specific resistance (ASR) measurements are performed, and cross-sections are prepared and analyzed using scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. Cr-evaporation measurements are conducted on samples exposed for up to 38 000 h. |
| Keywords | SOFC, Interconnect, Corrosion, Ce/Co coating, AISI 441, Long-term |
| Remark |
https://doi.org/10.1016/j.jpowsour.2019.227480 Link |
Identification of barium-site substitution of BiFeO3–Bi0.5K0.5TiO3 multiferroic ceramics: X-ray absorption near edge spectroscopy
ID=548| Authors |
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Radiation Physics and Chemistry
Volume: 170
Time of Publication: 2020
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| Abstract | In this work, the effects of barium substitution on the local structure, dielectric and magnetic properties of the polycrystalline ceramics 0.6BiFeO3–0.4(Bi0.5K0.5)TiO3 (0.6BFO–0.4BKT) system was investigated. A solid-state reaction technique was used to synthesize the materials with barium (Ba) doping of 1, 3, 5, 7, and 10 mol%. XRD analysis reveals the coexistence between tetragonal and rhombohedral phases of single-phase perovskite in pure 0.6BFO–0.4BKT and the rhombohedral reach phase was found with increasing Ba content. XANES simulations indicate that the majority of Ba atoms occupy A-site in BKT lattice of Ba-doped 0.6BFO-0.4BKT, the oxidation state of Fe, Ti, and Ba ions are +3, +4 and+2, respectively. At 5 mol% of Ba doping content, the dielectric measurement shows the morphotropic phase boundary (MPB) and the maximum value of ferromagnetic characteristic were observed, indicating an optimum composition, properties and production conditions. |
| Keywords | X-ray absorption near edge spectroscopy; Barium-doped; Multiferroic ceramics; XANES simulations |
| Remark |
https://doi.org/10.1016/j.radphyschem.2019.108621 Link |
Tuning of Mg content to enhance the thermoelectric properties in binary Mg2+δ Si (δ = 0, 0.1, 0.15, 0.2)
ID=547| Authors |
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Materials Research Express
Volume: 6
Time of Publication: 2019
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| Abstract | We report the enhanced thermoelectric properties of binary Mg2Si by tuning the Mg content. Polycrystalline Mg2+δ Si (where δ is the excess Mg content in the starting composition of the samples and δ = 0, 0.1, 0.15, 0.2) samples were processed by solid-state synthesis route using ball milling followed by rapid spark plasma sintering in order to minimize the Mg loss during processing. Microstructural and x-ray diffraction analysis revealed that, Mg content (δ) of 0.1–0.15 is required to get the binary Mg2Si phase without any elemental Mg/Si phase. Hall effect measurement and Fourier Transform Infrared Spectroscopy analysis show that, the excess Mg content helps to enhance the carrier concentration and charge carrier effective mass due to the occupancy of Mg at the interstitial site in Mg2Si structure. The influence of Mg content on thermoelectric properties, viz., electrical resistivity, Seebeck coefficient and thermal conductivity is investigated from 300 K to 780 K. A marked enhancement in thermoelectric power factor (~1.6 mW m−2K−2) is obtained for Mg2.15Si sample at 780 K. The occupancy of excess Mg at interstitial sites reduces the lattice thermal conductivity by lowering lattice symmetry. A maximum figure of merit (ZT) ~ 0.39 ± 0.03 at 780 K has been achieved in Mg2.15Si sample, the highest among that reported in n-type binary Mg2Si system. This suggests that excess Mg content in the starting composition of Mg2+δ Si helps in stabilizing the phase as well as improves the thermoelectric properties of the Mg2Si. |
| Remark |
https://doi.org/10.1088/2053-1591/ab58fb Link |
Exploring the Role of Manganese on Structural, Transport, and Electrochemical Properties of NASICON-Na3Fe2–yMny(PO4)3–Cathode Materials for Na-Ion Batteries
ID=546| Authors |
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ACS Applied Materials & Interfaces
Volume: 11,
Issue: 46
Time of Publication: 2019
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| Abstract | Given the extensive efforts focused on protecting the environment, eco-friendly cathode materials are a prerequisite for the development of Na-ion battery technology. Such materials should contain abundant and inexpensive elements. In the paper, we present NASICON-Na3Fe2–yMny(PO4)3 (y = 0, 0.1, 0.2, 0.3, and 0.4) cathode materials, which meet these requirements. Na3Fe2–yMny(PO4)3 compounds were prepared via a solid-state reaction at 600 °C, which allowed to obtain powders with submicron particles. The presence of manganese in the iron sub-lattice inhibits phase transitions, which occurs at ∼95 and ∼145 °C in Na3Fe2(PO4)3, changing the monoclinic structure to rhombohedral and affecting the structural and transport properties. The chemical stability of Na3Fe2–yMny(PO4)3 was thus higher than that of Na3Fe2(PO4)3, and it also exhibited enhanced structural, transport, and electrochemical properties. The observed correlation between the chemical composition and electrochemical properties proved the ability to precisely tune the crystal structure of NASICONs, allowing cathode materials with more desirable properties to be designed. |
| Keywords | Na-ion batteries, XRD, crystal structure |
| Remark |
https://doi.org/10.1021/acsami.9b10184 Link |
Intriguing electrochemistry in low-temperature single layer ceramic fuel cells based on CuFe2O4
ID=545| Authors |
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International Journal of Hydrogen Energy
Time of Publication: 2019
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| Abstract | A composite of CuFe2O4 and Gd-Sm co-doped CeO2 is studied for a single layer ceramic fuel cell application. In order to optimize the cell performance, the effects of sintering temperatures (600 °C, 700 °C, 800 °C, 900 °C and 1000 °C) were investigated for the fabrication of the cells. It was found that the cells sintered at 700 °C outperformed other cells with a maximum peak power density of 344 mW/cm2 at 550 °C. The electrochemical impedance spectroscopy analysis on the best cell revealed significant ohmic losses (0.399 Ω cm2) and polarization losses (0.174 Ω cm2) in the cell. The HR-TEM and SEM gave microstructural information of the cell. The HT-XRD spectra showed the crystal structures in different sintering temperatures. The cell performance was stable and the composite material did not degrade during an 8 h stability test under open-circuit condition. This study opens up new avenues for the exploration of this nanocomposite material for the low temperature single component ceramic fuel cell research. |
| Keywords | Catalysis; Ceramic; Composite; Fuel cell; Single component |
| Remark |
https://doi.org/10.1016/j.ijhydene.2019.09.175 Link |
Mn-rich SmBaCo0.5Mn1.5O5+δ double perovskite cathode material for SOFCs
ID=544| Authors |
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International Journal of Hydrogen Energy
Volume: 44,
Issue: 50
Time of Publication: 2019
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| Abstract | SmBaCo0.5Mn1.5O5+δ oxide with Sm-Ba cation-ordered perovskite-type structure is synthesized and examined in relation to whole RBaCo0.5Mn1.5O5+δ series (R: selected rare earth elements). Presence of Sm and 3:1 ratio of Mn to Co allows to balance physicochemical properties of the composition, with moderate thermal expansion coefficient value of 18.70(1)·10−6 K−1 in 300–900 °C range, high concentration of disordered oxygen vacancies in 600–900 °C range (δ = 0.16 at 900 °C), and good transport properties with electrical conductivity reaching 33 S cm−1 at 900 °C in air. Consequently, the compound enables to manufacture catalytically-active cathode, with good electrochemical performance measured for the electrolyte-supported laboratory-scale solid oxide fuel cell with Ni-Gd1.9Ce0.1O2-δ|La0.4Ce0.6O2-δ|La0.8Sr0.2Ga0.8Mg0.2O3-δ|SmBaCo0.5Mn1.5O5+δ configuration, for which 1060 mW cm−2 power density is observed at 900 °C. Furthermore, the tested symmetrical SmBaCo0.5Mn1.5O5+δ|La0.8Sr0.2Ga0.8Mg0.2O3-δ|SmBaCo0.5Mn1.5O5+δ cell delivers 377 mW cm−2 power density at 850 °C, which is a promising result. |
| Keywords | Mn-rich layered perovskites; Physicochemical properties; Cathode materials; SOFC; Symmetrical SOFC |
| Remark |
https://doi.org/10.1016/j.ijhydene.2019.08.254 Link |
Simultaneous CO2 and O2 separation coupled to oxy-dry reforming of CH4 by means of a ceramic-carbonate membrane reactor for in situ syngas production
ID=543| Authors |
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Chemical Engineering Science
Volume: 210
Time of Publication: 2019
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| Abstract | It is reported the use of a ceramic-carbonate membrane exhibiting CO2 and O2 permeation, coupled with the oxy-carbon dioxide reforming of methane to produce syngas in a membrane reactor arrangement. The studied membrane is made of a porous fluorite/perovskite mixed conducting ceramic infiltrated with molten carbonates. The CO2 and O2 gas mixture used to perform the oxy-dry reforming process is the membrane’s permeate, which reacts with CH4 supplied in the sweep gas with the assistance of a catalyst. The reactor converts from 74 to 99% of CH4 under the studied separation and reaction conditions. The total rate of syngas production reaches 6.25 mL∙min−1∙cm−2 at 875 °C and a H2/CO ratio ranging from 2.1 to 1.3 between 800 and 875 °C. A long-term test shows a stable performance for 300 h. This work suggests the feasibility of this capture-conversion concept for the valorization of CO2 by the efficient production of syngas. |
| Keywords | Inorganic membrane; Gas permeation; Ceramic-carbonate membrane; Oxy-CO2 reforming of methane; Syngas production |
| Remark |
https://doi.org/10.1016/j.ces.2019.115250 Link |
Factors Limiting the Apparent Hydrogen Flux in Asymmetric Tubular Cercer Membranes Based on La27W3.5Mo1.5O55.5 and La0.87Sr0.13CrO3
ID=542| Authors |
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| Source |
Membranes
Volume: 9
Time of Publication: 2019
|
| Abstract | Asymmetric tubular ceramic–ceramic (cercer) membranes based on La27W3.5Mo1.5O55.5-La0.87Sr0.13CrO3 were fabricated by a two-step firing method making use of water-based extrusion and dip-coating. The performance of the membranes was characterized by measuring the hydrogen permeation flux and water splitting with dry and wet sweep gases, respectively. To explore the limiting factors for hydrogen and oxygen transport in the asymmetric membrane architecture, the effect of different gas flows and switching the feed and sweep sides of the membrane on the apparent hydrogen permeability was investigated. A dusty gas model was used to simulate the gas gradient inside the porous support, which was combined with Wagner diffusion calculations of the dense membrane layer to assess the overall transport across the asymmetric membrane. In addition, the stability of the membrane was investigated by means of flux measurements over a period of 400 h. |
| Keywords | hydrogen permeation; water splitting; surface kinetics; asymmetric tubular membrane; lanthanum tungstate; lanthanum chromite |
| Remark |
doi:10.3390/membranes9100126 Link |
Thermoelectric properties of A-site deficient La-doped SrTiO3 at 100–900 °C under reducing conditions
ID=541| Authors |
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| Source |
Journal of the European Ceramic Society
Volume: 40,
Issue: 2,
Pages: 401-407 Time of Publication: 2020 |
| Abstract | Lanthanum doped strontium titanate is a potential n-type thermoelectric material at moderate and high temperatures. (La0.12Sr0.88)0.95TiO3 ceramics were prepared by two different routes, conventional sintering at 1500 °C and spark plasma sintering at temperatures between 925 and 1200 °C. Samples with grain size between 40 nm and 1.4 μm were prepared and characterized with respect to their thermoelectric transport properties at temperatures between 100 and 900 °C under reducing conditions (H2/H2O-buffer mixtures). The thermal conductivity was significantly reduced with decreasing grain size reaching a value of 1.3 W m−1. K−1 at 600 °C for grain size of 40 nm and porosity of 19%. Electrical conductivity increased with increasing grain size showing a maximum of 500 S cm−1 at 200 °C for a grain size of 1.4 μm. The highest figure-of-merit (zT) was measured for samples with 1.4 μm average grain size reaching 0.2 at 500 °C. |
| Remark |
https://doi.org/10.1016/j.jeurceramsoc.2019.09.024 Link |
Ceria-Based Dual-Phase Membranes for High-Temperature Carbon Dioxide Separation: Effect of Iron Doping and Pore Generation with MgO Template
ID=540| Authors |
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| Source |
Membranes
Volume: 9,
Issue: 9,
Pages: 108 Time of Publication: 2019 |
| Abstract | Dual-phase membranes for high-temperature carbon dioxide separation have emerged as promising technology to mitigate anthropogenic greenhouse gases emissions, especially as a pre- and post-combustion separation technique in coal burning power plants. To implement these membranes industrially, the carbon dioxide permeability must be improved. In this study, Ce0.8Sm0.2O2−δ (SDC) and Ce0.8Sm0.19Fe0.01O2−δ (FSDC) ceramic powders were used to form the skeleton in dual-phase membranes. The use of MgO as an environmentally friendly pore generator allows control over the membrane porosity and microstructure in order to compare the effect of the membrane’s ceramic phase. The ceramic powders and the resulting membranes were characterized using ICP-OES, HSM, gravimetric analysis, SEM/EDX, and XRD, and the carbon dioxide flux density was quantified using a high-temperature membrane permeation setup. The carbon dioxide permeability slightly increases with the addition of iron in the FSDC membranes compared to the SDC membranes mainly due to the reported scavenging effect of iron with the siliceous impurities, with an additional potential contribution of an increased crystallite size due to viscous flow sintering. The increased permeability of the FSDC system and the proper microstructure control by MgO can be further extended to optimize carbon dioxide permeability in this membrane system. |
| Keywords | samarium doped ceria; SDC; FSDC; CO2 separation membranes; scavenging effect of iron; permeability |
| Remark |
https://doi.org/10.3390/membranes9090108 Link |
