NORECS / Support / References Search FAQ Order and Enquiry Contact Language
Published references

These publications have a reference to ProboStat™ or other NORECS products

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-  

MOX-Based Resistive Gas Sensors with Different Types of Sensitive Materials (Powders, Pellets, Films), Used in Environmental Chemistry

ID=716
Author Paul Chesler and Cristian Hornoiu
Source
Chemosensors
Volume: 11, Issue: 2, Pages: 95
Time of Publication: 2023
Abstract The identification of an unknown gaseous species or the composition of a gaseous mixture can be performed using various experimental techniques such as: mass spectrometry, chromatography, nuclear magnetic resonance (NMR), infrared (IR), X-Rays, or by combining these analytical techniques (in automated analyzers). Unfortunately, these techniques use highly expensive equipment and require the use of qualified personnel. Using gas sensors is a viable and inexpensive alternative. The most commonly used sensors in the field are resistive type chemosensors (chemiresistors), due to their simple detection mechanism and low manufacturing costs. The detection principle of these sensors is based on the catalytic reaction between the sensitive material of the sensor and the target gas. This reaction occurs with the release or consumption of electrons, influencing the overall electrical resistance of the sensor. This review describes various MOX-based chemiresistors, which contain different types of sensitive substrates, such as powders, pellets or films, as well as a clear tendency towards sensor miniaturization and the constant improvement of the fabrication techniques towards greener and more cost-effective synthesis routes over time. The goal of this research was to obtain sensors with high 3S parameters (sensitivity, selectivity, and stability), that can be mass-produced and implemented on a wide scale.
Keywords resistive gas sensors; chemiresistors; sensitivity; selectivity; stability; eco-friendly; low-cost; miniaturized; micro-sensors; mass-produced
Remark https://doi.org/10.3390/chemosensors11020095
Link

Two Types of Negative Thermal Expansion Observed in PbCr1–xTixO3

ID=715
Authors Yuki Sakai, Kana Matsuno, Takumi Nishikubo, Masayuki Fukuda, Shogo Wakazaki, Masahito Ikeda, Kazuki Takahashi, Zhao Pan, Lei Hu, and Masaki Azuma
Source
Chem. Mater.
Time of Publication: 2023
Abstract Two negative thermal expansions (NTEs) with different mechanisms were observed in solid solutions of perovskite-type oxides PbCrO3 and PbTiO3. PbCr1–xTixO3 was found to adopt a cubic structure the same as that of PbCrO3 for x ≤ 0.6 and a PbTiO3-type tetragonal structure for x ≥ 0.7. The NTE observed at x ≤ 0.6 was accompanied by a cubic-to-cubic phase transition originating from the rearrangement of Pb2+/Pb4+ in a complex local structure called a charge glass. The volume shrinkage of −2.5% observed in PbCrO3 is sufficiently large despite the absence of intermetallic charge transfer, which is the origin of pressure-induced cubic-to-cubic phase transition and 9.8% volume collapse. The NTE in the tetragonal phase was caused by the ferroelectric-to-paraelectric phase transition, the same as in PbTiO3. We succeeded in significantly lowering the working temperature of PbTiO3 as an NTE material by Cr substitution while retaining a large volume shrinkage of 0.6%.
Remark https://doi.org/10.1021/acs.chemmater.2c02896
Link

General characterization and potential use of Moroccan lizardite clay in ceramics: Technological and dielectric studies

ID=714
Authors Youssef Arkame, Achraf Harrati, Yassine Et-Tayea, Ahmed Manni, Fahd Oudrhiri Hassani, Abdeslam El Bouari, Ali Sdiri, Iz-Eddine El Amrani El Hassani, Chaouki Sadik
Source
Open Ceramics
Volume: 13, Pages: 100332
Time of Publication: 2023
Abstract This work focuses on the characterization of lizardite and studying the technological and dielectric features of ceramics based on this geomaterial by experimental measurements. Note that, the physical evaluation (dielectric properties) of magnesian clay has never been studied. Natural lizardite was extracted from the Beni Boussera massif (Rif, Morocco), and was characterized in terms of chemical, physical, mineralogical and thermal aspects. A purification process was carried out to identify the mineral phases present in this material. The results showed that the studied material is mainly composed of silica (47.16 wt%) and magnesia (31.21 wt%), it is also richer in clay minerals such as lizardite and chlorite. The ceramic specimens were prepared by the uniaxial pressing method, followed by sintering to different temperatures (i.e., 900, 1000, 1100, and 1200 °C). The influence of the sintering temperature on porosity, density, shrinkage, water absorption, mechanical and microstructural properties of ceramics was evaluated, as well as chemical resistance and dielectric properties were studied. The evaluation of the optimized ceramic materials shows that good dielectric properties are obtained when sintered at a temperature of 1100 °C with a dielectric constant of 1.33, a dielectric loss of around 0.08, and a conductivity of 4.86 E−8 S/cm, at high frequency. Furthermore, the obtained ceramic specimen has a porosity of 17%, a density of 2.02 g/cm3, a water absorption of 9.86%, and a mechanical strength of 19.3 MPa. As a consequence, the results obtained have provided ceramics based on a natural resource with favorable technological and mechanical properties, and very interesting dielectric properties.
Remark https://doi.org/10.1016/j.oceram.2023.100332
Link

Effect of Steam to Carbon Dioxide Ratio on the Performance of a Solid Oxide Cell for H2O/CO2 Co-Electrolysis

ID=713
Authors Naouma Bimpiri, Argyro Konstantinidou, Dimitrios Tsiplakides, Stella Balomenou and Kalliopi Maria Papazisi
Source
Nanomaterials
Volume: 13, Issue: 2, Pages: 299
Time of Publication: 2023
Abstract The mixture of H2 and CO, the so-called syngas, is the value-added product of H2O and CO2 co-electrolysis and the feedstock for the production of value-added chemicals (mainly through Fischer-Tropsch). The H2/CO ratio determines the process in which syngas will be utilized and the type of chemicals it will produce. In the present work, we investigate the effect of H2O/CO2 (steam/carbon dioxide, S/C) ratio of 0.5, 1 and 2 in the feed, on the electrochemical performance of an 8YSZ electrolyte-supported solid oxide cell and the H2/CO ratio in the outlet, under co-electrolysis at 900 °C. The B-site iron doped lanthanum strontium chromite La0.75Sr0.25Cr0.9Fe0.1O3-δ (LSCF) is used as fuel electrode material while as oxygen electrode the state-of-the art LSM perovskite is employed. LSCF is a mixed ionic-electronic conductor (MIEC) operating both under a reducing and oxidizing atmosphere. The cell is electrochemically characterized under co-electrolysis conditions both in the presence and absence of hydrogen in the feed of the steam and carbon dioxide mixtures. The results indicate that under the same concentration of hydrogen and different S/C ratios, the same electrochemical performance with a maximum current density of approximately 400 mA cm−2 is observed. However, increasing p(H2) in the feed results in higher OCV, smaller iV slope and Rp values. Furthermore, the maximum current density obtained from the cell does not seem to be affected by whether H2 is present or absent from the fuel electrode feed but has a significant effect on the H2/CO ratio in the analyzed outlet stream. Moreover, the H2/CO ratio seems to be identical under polarization at different current density values. Remarkably, the performance of the LSCF perovskite fuel electrode is not compromised by the exposure to oxidizing conditions, showcasing that this class of electrocatalysts retains their reactivity in oxidizing, reducing, and humid environments.
Keywords Co-electrolysis; perovskite oxide; doping; lanthanum chromite; LSCF; solid oxide; SOEC; syngas; steam to carbon dioxide ratio
Remark https://doi.org/10.3390/nano13020299
Link

Centrosymmetric Tetragonal Tungsten Bronzes A4Bi2Nb10O30 (A = Na, K, Rb) with a Bi 6s Lone Pair

ID=712
Authors Inger-Emma Nylund, Caren Regine Zeiger, Ding Peng, Per Erik Vullum, Julian Walker, Mari-Ann Einarsrud, and Tor Grande*
Source
Chem. Mater.
Volume: 35, Issue: 1, Pages: 17–26
Time of Publication: 2023
Abstract A first-principles study of the tetragonal tungsten bronze (TTB) K4Bi2Nb10O30 has suggested that the Bi 6s lone pair causes in-plane polarization (within the a–b plane), corresponding to the one found in Pb5Nb10O30 (PN), in contrast to the out-of-plane polarization (along c) found in most TTBs. Replacing PN with KBN potentially opens for a lead-free analogue to morphotropic phase boundaries known in TTBs based on PN. Here, we report on the synthesis and properties of A4Bi2Nb10O30 (ABN, A = Na, K, Rb) with the objective to determine the structure and electrical properties, paying particular attention to the role of the Bi 6s lone pair. The ABN materials were synthesized via conventional solid-state synthesis in a two-step process. Convergent-beam electron diffraction demonstrated a centrosymmetric tetragonal space group for the two compounds KBN and RBN, and ferroelectric polarization–electric field measurements confirmed the lack of hysteretic behavior in line with the observed centrosymmetric symmetry. Non-ambient powder X-ray diffraction demonstrated the signature of a phase transition for KBN and RBN, as several weak satellite reflections vanished during heating and reappeared upon cooling. Dielectric spectroscopy supported the observation of an anomaly due to the presence of a weak maximum in the electrical permittivity at temperatures corresponding to the disappearance of the satellite reflections. Possible explanations for the absence of polarization in ABN TTBs are discussed with particular attention to the suppression of the 6s2 lone pair effect of Bi and the size of A-site cations in the TTB crystal structure.
Remark https://doi.org/10.1021/acs.chemmater.2c01944
Link

The Role of Strain in Proton Conduction in Multi-Oriented BaZr0.9Y0.1O3−δ Thin Film

ID=711
Authors Muhammad Shahrukh Saleem, Qianli Chen, Nick A. Shepelin, Simone Dolabella, Marta D. Rossell, Xuhai Zhang, Coleman X. Kronawitter, Fabio La Mattina, and Artur Braun
Source
ACS Appl. Mater. Interfaces
Volume: 14, Issue: 50, Pages: 55915–55924
Time of Publication: 2022
Abstract Within the emerging field of proton-conducting fuel cells, BaZr0.9Y0.1O3−δ (BZY10) is an attractive material due to its high conductivity and stability. The fundamentals of conduction in sintered pellets and thin films heterostructures have been explored in several studies; however, the role of crystallographic orientation, grains, and grain boundaries is poorly understood for proton conduction. This article reports proton conduction in a self-assembled multi-oriented BZY10 thin film grown on top of a (110) NdGaO3 substrate. The multiple orientations are composed of different lattices, which provide a platform to study the lattice-dependent conductivity through different orientations in the vicinity of grain boundary between them and the substrate. The crystalline stacking of each orientation is confirmed by X-ray diffraction analysis and scanning transmission electron microscopy. The transport measurements are carried out under different gas atmospheres. The highest conductivity of 3.08 × 10–3 S cm–1 at 400 °C is found under a wet H2 environment together with an increased lattice parameter of 4.208 Å, while under O2 and Ar environments, the film shows lower conductivity and lattice parameter. Our findings not only demonstrate the role of crystal lattice for conduction properties but also illustrate the importance of self-assembled strategies to achieve high proton conduction in BZY10 thin films.
Keywords BaZrO3 thin film; BaZr0.9Y0.1O3−δ strained structure; proton conduction; crystallographic orientation
Remark https://doi.org/10.1021/acsami.2c12657
Link

Low temperature ammonia synthesis by surface protonics over metal supported catalysts

ID=710
Author Yasushi Sekine
Source
Faraday Discussions
Time of Publication: 2023
Abstract Low-temperature ammonia synthesis by applying an electric field to a solid heterogeneous catalyst was investigated to realize an on-demand, on-site catalytic process for converting distributed renewable energy into ammonia. By applying an electric field to the catalyst, even at low temperatures, the reaction proceeds efficiently by an "associative mechanism" in which proton-conducting species on the support surface promote the formation of N2Had intermediates through surface protonics. Kinetics, isotope exchange, infrared spectroscopy, X-ray spectroscopy, and AC impedance analysis were performed to clarify the effect of metal and catalyst support structure on the reaction, and an evaluation method for the surface protonics of the support was established to analyze the reaction mechanism, and further analysis using computational chemistry was also conducted. The elementary step determining catalytic activity changed from N2 dissociation to N2H formation, and this difference resulted in high activity for ammonia synthesis at low temperatures even when using base metal catalysts such as Fe and Ni.
Remark DOI: 10.1039/x0xx00000x
Link

Experimental application of a laser-based manufacturingprocess to develop a free customizable, scalablethermoelectric generator demonstrated on a hot shaft

ID=709
Authors Marvin Abt, Katharina Kruppa, Mario Wolf, Armin Feldhoff, Ludger Overmeyer
Source
Engineering Reports
Time of Publication: 2022
Abstract Geometry, design, and processing in addition to the thermoelectric materialproperties have a significant influence on the economic efficiency and perfor-manceofthermoelectricgenerators(TEGs).WhileconventionalBULKTEGsareelaborate to manufacture and allow only limited variations in geometry, printedTEGs are often restricted in their application and processing temperature due totheuseoforganicmaterials.Inthiswork,aproof-of-conceptforfabricatingmod-ular, customizable, and temperature-stable TEGs is demonstrated by applyingan alternative laser process. For this purpose, low temperature cofired ceram-ics substrates were coated over a large area, freely structured and cut withoutmasks by a laser and sintered to a solid structure in a single optimized thermalpost-processing.Ascalabledesignwithcomplexgeometryandlargecoolingsur-face for application on a hot shaft was realized to prove feasibility. Investigationson sintering characteristics up to a peak temperature of 1173K, thermoelec-tric material properties and temperature distribution were carried out for aCa3Co4O9/Ag-based prototype and evaluated using profilometer, XRD, and IRmeasurements. For a combined post-processing, an optimal sintering profilecould be determined at 1073K peak temperature with a 20min holding time.Temperaturegradientsofupto100Kcouldbeachievedalongathermocouple.Asingle TEG module consisting of 12 thermocouples achieved a maximum powerof0.224μWandopen-circuitvoltageof134.41mVatanaveragehot-sidetemper-ature of 413.6 K and temperature difference of 106.7 K. Three of these modulescombined into a common TEG with a total of 36 thermocouples reached a maxi-mumpowerof0.58Kandopen-circuitvoltageof319.28mVwithalesseraveragehot-side temperature of 387.8 K and temperature difference of 83.4 K.
Remark https://doi.org/10.1002/eng2.12590
Link

A New Electroactive and Stable Electrode Based on Praseodymium Molybdate for Symmetrical SOFCs

ID=708
Authors N.V. Lyskov, A.I. Kotova, D.I. Petukhov, S.Ya. Istomin, G.N. Mazo
Source
Russian Journal of Electrochemistry
Volume: 58, Pages: 989–997
Time of Publication: 2022
Abstract The electrochemical activity of a new electrode material based on Pr5Mo3O16 + δ (РМž) within the composition of a symmetrical solid oxide fuel cell (S-SOFC) of the electrolyte-supported design is studied. The model S-SOFC of the РМž/Ce0.9Gd0.1O1.95(GDC)/Zr0.84Y0.16O1.92(YSZ)/GDC/PMO composition demonstrated the maximum power density of 28 mW/cm2 at 900°С. To improve the power characteristics of S-SOFC, the porous buffer GDC layer is modified by the method of Pr6O11 infiltration. It is found that the addition of electroactive Pr6O11 into the GDC buffer layer provides the three-fold increase in the fuel-cell power density with the maximum of 90 mW/cm2 at 900°С. The 10 h life-time test of the model S-SOFC with the РМž/GDC + Pr6O11/YSZ/GDC + Pr6O11/PMO composition carried out at a load of 0.7 V reveals the absence of any considerable degradation in fuel cell power characteristics. The results obtained suggest that the new electrode material based on PMO holds promise for the development of S-SOFC.
Remark Link

Surface protonic conductivity in chemisorbed water in porous nanoscopic CeO2

ID=707
Authors Xinwei Sun, Einar Vøllestad, Per Martin Rørvik, Sebastian Prodinger, Georgios N. Kalantzopoulos, Athanasios Chatzitakis, Truls Norby
Source
Applied Surface Science
Volume: 611, Issue: A, Pages: 155590
Time of Publication: 2023
Abstract CeO2 surfaces play decisive roles in heterogeneous catalysis of important processes. Here, we investigate adsorption and dissociation of water and migration of protons on internal surfaces of nanoscopic porous CeO2. Sorption and thermogravimetry confirm literature suggestions that the surface is hydrogenated to Ce3+ ions and protons H+. The following chemisorption is dissociative, yet weak, and physisorption sets in only at the very highest relative humidities, reflecting hydrophobic behaviour. We link sample conductivities to surface protonic conductances via a brick layer model and show that behaviours at high, intermediate, and low temperatures with, respectively, positive, close to zero, and negative apparent activation energies and pH2O1/2, pH2O1, and pH2O3/2 dependences, can be attributed to different models of migration all within the chemisorbed layer, without contribution from physisorbed water. While CeO2 may special in this respect due to the effect of the hydrogenated surface, we believe the extended models of transport in the chemisorbed layer may apply also to other oxides. Unsaturated chemisorption may play an important role for CeO2 as catalyst in that the surface is left available for reactant molecules, still with availability of dissociated and mobile protons in the chemisorbed layer and electronic defects by Ce3+ in the surface.
Keywords Ceria; CeO2; Porous; Hydrogenation; Water adsorption; Chemisorption; Conductivity; Protonic; Surface; Brick layer model
Remark https://doi.org/10.1016/j.apsusc.2022.155590
Link

Ni-doped A-site excess SrTiO3 thin films modified with Au nanoparticles by a thermodynamically-driven restructuring for plasmonic activity

ID=706
Authors Kevin G. Both, Vilde M. Reinertsen, Thomas M. Aarholt, Ingvild J.T. Jensen, Dragos Neagu, Øystein Prytz, Truls Norby, Athanasios Chatzitakis
Source
Catalysis Today
Time of Publication: 2023
Abstract Plasmonically active nanoparticles offer a promising pathway to extend the absorption range of photocatalysts. While not necessarily catalytically active themselves, these particles allow the absorption of lower energy photons in wide band gap photocatalysts. Here, we present A-site excess SrTiO3 thin films, doped with Ni, where through a subsequent exsolution process we created well-socketed Ni nanoparticles in the surface of SrTiO3. These were galvanically replaced by Au, resulting in well-socketed Au nanoparticles with variable size on the surface, depending on the galvanic replacement time. Photoelectrochemical measurements and electron energy loss spectroscopy revealed the improved photoresponse of the thin films by plasmonic activity of the nanoparticles. The energy of the plasmon peak suggests that the main improvement results from the injection of hot charge carriers. Our study opens new avenues for the design and synthesis of the next generation of photocatalytic materials.
Remark In press, https://doi.org/10.1016/j.cattod.2022.11.011
Link

Structural, Optical, and Sensing Properties of Nb-Doped ITO Thin Films Deposited by the Sol–Gel Method

ID=705
Authors Madalina Nicolescu, Daiana Mitrea, Cristian Hornoiu, Silviu Preda, Hermine Stroescu, Mihai Anastasescu, Jose Maria Calderon-Moreno, Luminita Predoana, Valentin Serban Teodorescu, Valentin-Adrian Maraloiu, Maria Zaharescu and Mariuca Gartner
Source
Gels
Volume: 8, Issue: 11, Pages: 717
Time of Publication: 2022
Abstract The aim of the present study was the development of Nb-doped ITO thin films for carbon monoxide (CO) sensing applications. The detection of CO is imperious because of its high toxicity, with long-term exposure having a negative impact on human health. Using a feasible sol–gel method, the doped ITO thin films were prepared at room temperature and deposited onto various substrates (Si, SiO2/glass, and glass). The structural, morphological, and optical characterization was performed by the following techniques: X-ray diffractometry (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV/Vis/NIR spectroscopic ellipsometry (SE). The analysis revealed a crystalline structure and a low surface roughness of the doped ITO-based thin films. XTEM analysis (cross-sectional transmission electron microscopy)showed that the film has crystallites of the order of 5–10 nm and relatively large pores (around 3–5 nm in diameter). A transmittance value of 80% in the visible region and an optical band-gap energy of around 3.7 eV were found for dip-coated ITO/Nb films on SiO2/glass and glass supports. The EDX measurements proved the presence of Nb in the ITO film in a molar ratio of 3.7%, close to the intended one (4%). Gas testing measurements were carried out on the ITO undoped and doped thin films deposited on glass substrate. The presence of Nb in the ITO matrix increases the electrical signal and the sensitivity to CO detection, leading to the highest response for 2000 ppm CO concentration at working temperature of 300 ◦C.
Remark https://doi.org/10.3390/gels8110717
Link

Ultrafast Crystallization and Sintering of Li1.5Al0.5Ge1.5(PO4)3 Glass and Its Impact on Ion Conduction

ID=704
Authors Antonino Curcio, Antonio Gianfranco Sabato, Marc Nuñez Eroles, Juan Carlos Gonzalez-Rosillo, Alex Morata, Albert Tarancón, and Francesco Ciucci
Source
ACS Appl. Energy Mater.
Volume: 5, Issue: 11, Pages: 14466–14475
Time of Publication: 2022
Abstract Li1.5Al0.5Ge1.5(PO4)3 (LAGP) is among the most promising solid electrolytes for the next generation’s all-solid-state lithium batteries. However, preparing LAGP electrolytes is time- and energy-intensive. In this work, LAGP glassy powders were sintered and crystallized in 180 s by ultrafast high-temperature sintering (UHS) under conditions attractive for continuous industrial processes (i.e., ambient pressure and atmosphere). The fast heating rates characteristic of UHS significantly delay crystallization, potentially decoupling crystallization and sintering. Furthermore, electrochemical impedance spectroscopy (EIS) characterizations reveal that LAGP sintered and crystallized by UHS has an ionic conductivity of 1.15 × 10–4 S/cm, slightly lower than conventionally annealed samples (1.75 × 10–4 S/cm). The lower conductivity can be attributed to poorer intergrain contact. To overcome this issue, additives such as B2O3 and Li3BO3 are used, resulting in ∼2 and ∼5 times higher grain boundary conductivity for LAGP+1 wt % B2O3 and LAGP+1 wt % Li3BO3, respectively, compared to LAGP. Overall, this work provides insights into unraveling the impact of UHS sintering on the LAGP Li+ conduction mechanism.
Remark https://doi.org/10.1021/acsaem.2c03009
Link

Development and characterization of highly stable electrode inks for low-temperature ceramic fuel cells

ID=703
Authors Sanaz Zarabi Golkhatmi, Muhammad Imran Asghar, Peter D. Lund
Source
Journal of Power Sources
Volume: 552, Pages: 232263
Time of Publication: 2022
Abstract Inkjet printing is a potential contactless and mask-free additive manufacturing approach for solid oxide fuel cells. Here, a highly stable cathode ink using La0.6Sr0.4Co0.2Fe0.8O3 was developed and characterized with particle size analysis, viscosity, surface tension, density, and thermal analysis. Both fresh and 6-months stored inks showed excellent jetability behavior with a Z number of 2.77 and 3.45, respectively. The ink was successfully inkjet-printed on a (LiNaK)2CO3-Gd:CeO2 porous electrolyte substrate to fabricate a symmetric cell. The electrochemical impedance spectroscopy measurements showed that at 550 °C the inkjet printing lowered the ohmic resistance to one-third (from 1.05 Ω cm2 to 0.37 Ω cm2) and the mass diffusion resistance by 4.25 times (from 6.09 Ω cm2 to 1.43 Ω cm2) as compared to drop-casted cell by creating a hierarchical porous structure and increasing reaction sites. Successful inkjet printing of the functional electrode material opens up a new avenue for the fabrication of the low-temperature ceramic fuel cells.
Keywords Inkjet printing; Ceramics; Electrode; Solid oxide fuel cell; Stability
Remark https://doi.org/10.1016/j.jpowsour.2022.232263
Link

Native point defects and polaron transport in zirconium pyrovanadate

ID=702
Authors Linn Katinka Emhjellen, Xin Liu, Jonathan M. Polfus, Reidar Haugsrud
Source
Solid State Ionics
Volume: 386, Pages: 116033
Time of Publication: 2022
Abstract Density functional theory calculations and electrochemical impedance spectroscopy have been combined to derive a defect model for ZrV2O7 to rationalize its electrical conductivity behavior. ZrV2O7 shows slight vanadium over-stoichiometry, yielding the predominant defect pair: V5+ on Zr sites (VZr•) charge-compensated by electron polarons as V4+ on V sites (VV′). Small polaron hopping is the dominating conduction mechanism with a calculated polaron self-trapping energy of −0.22 eV. The polarons can, however, be strongly bound as V4+ substituted on Zr sites (VZr×), with a calculated binding energy of −0.97 eV with respect to free polarons. The temperature dependency of the electrical conductivity exhibits a crossover between two regimes at 550 °C, and the apparent activation energy increases with increasing temperature from 0.3 to 0.86 eV. According to the defect model, which includes the concentration ratio of free and bound polarons, free polaron hopping predominates the electrical conductivity at lower temperatures while the thermally activated transition from bound to free polarons predominates at higher temperatures.
Keywords Point defects; Free polarons; Bound polarons; Zirconium pyrovanadate
Remark https://doi.org/10.1016/j.ssi.2022.116033
Link

Surface kinetics and bulk transport in La2Ni0.5Cu0.5O4+δ membranes from conductivity relaxation

ID=701
Authors Zuoan Li, Reidar Haugsrud
Source
Journal of European Ceramic Society
Volume: 43, Issue: 2, Pages: 462-467
Time of Publication: 2023
Abstract This work reports conductivity relaxation measurements on both uncoated (1.2 mm thick) and coated (2.0 mm thick) La2Ni0.5Cu0.5O4+δ membranes in the temperature range between 550 and 850 °C and oxygen partial pressures from 0.01 to 1.0 atm. The results show that surface kinetics has a significant effect on the relaxation profiles, especially at low temperatures and should not be neglected when extracting transport parameters. Oxygen chemical diffusion and surface exchange coefficients have been determined by transient conductivity with surface modification. Higher activation energy of surface exchange compared to bulk diffusion is observed for La2Ni0.5Cu0.5O4+δ, similar to that for La2NiO4+δ. Based on the oxygen partial pressure dependence of the surface exchange coefficient, it has been revealed that oxygen dissociative adsorption rate-limits the surface exchange.
Keywords Conductivity relaxation; Surface modification; Surface exchange mechanisms; Oxygen diffusion; La2Ni0.5Cu0.5O4+δ; La2NiO4+δ
Remark https://doi.org/10.1016/j.jeurceramsoc.2022.10.046
Link

Sintering and electrical properties of proton conducting BSZCY151020

ID=700
Author Sjur Storhaug
Source
Time of Publication: 2022
Remark Master Thesis
Link

Electrospun Ca3Co4−xO9+δ nanofibers and nanoribbons: Microstructure and thermoelectric properties

ID=699
Authors Katharina Kruppa, Itzhak I. Maor, Frank Steinbach, Vadim Beilin, Meirav Mann-Lahav, Mario Wolf, Gideon S. Grader, Armin Feldhoff
Source
J Am Ceram Soc.
Volume: 106, Pages: 1170–1181
Time of Publication: 2023
Abstract Oxide-based ceramics offer promising thermoelectric (TE) materials for recy- cling high-temperature waste heat, generated extensively from industrial sources. To further improve the functional performance of TE materials, their power factor should be increased. This can be achieved by nanostructuring and texturing the oxide-based ceramics creating multiple interphases and nanopores, which simultaneously increase the electrical conductivity and the Seebeck coef- ficient. The aim of this work is to achieve this goal by compacting electrospun nanofibers of calcium cobaltite Ca3 Co 4−xO 9+δ, known to be a promising p-type TE material with good functional properties and thermal stability up to 1200 K in air. For this purpose, polycrystalline Ca3 Co 4−xO 9+δ nanofibers and nanorib- bons were fabricated by sol–gel electrospinning and calcination at intermediate temperatures to obtain small primary particle sizes. Bulk ceramics were formed by sintering pressed compacts of calcined nanofibers during TE measurements. The bulk nanofiber sample pre-calcined at 973 K exhibited an improved Seebeck coefficient of 176.5 S cm−1 and a power factor of 2.47 μW cm−1 K−2 similar to an electrospun nanofiber-derived ceramic compacted by spark plasma sintering.
Remark DOI: 10.1111/jace.18842
Link

Effects of Ni-NCAL and Ni–Ag electrodes on the cell performances of low-temperature solid oxide fuel cells with Sm0.2Ce0·8O2-δ electrolyte at various temperatures

ID=698
Authors Sea-Fue Wang, Yi-Le Liao, Yung-Fu Hsu, Piotr Jasinski
Source
International Journal of Hydrogen Energy
Volume: 47, Issue: 94, Pages: 40067-40082
Time of Publication: 2022
Abstract Three low-temperature solid oxide fuel cells are built using Sm0.2Ce0·8O2-δ (SDC) as the electrolyte. Cell A is symmetrical and features Ni–LiNi0.8Co0·15Al0·05O2 (Ni–NCAL) electrodes, Cell B comprises a Ni–NCAL anode and a Ni–Ag cathode, and Cell C is fabricated using a Ni–NCAL cathode and a Ni–Ag anode. The ohmic resistance and polarization resistance (Rp) of Cells B and C are significantly higher than those of Cell A. The reduction of NCAL at the anodes of Cells A and B yields LiOH and Li2CO3 phases, and the Ni particles generated on the surfaces of the NCAL particles improve the catalytic activity of the cells. Li2CO3–LiOH melts at temperatures >450 °C and penetrates the porous SDC electrolyte layer, causing its densification and abnormal grain growth and increasing its ionic conductivity to >0.2 S/cm at low temperatures. The high open-circuit voltages (OCVs) (0.970–1.113 V) of the cells during electrochemical measurements are ascribed to the Li2CO3–LiOH phase which serves as an electron-blocking layer for the SDC electrolytes. As the reduction of NCAL approaches completion, the anode comprises only Ni phase, which hinders the charge transfer process. The triple-phase-boundary (TPB) area at cathode of Cell B is significantly lower than that of Cell A; therefore, the catalytic activity of Cell B for the oxygen reduction reaction is lower than that of Cell A. Consequently, the maximum power density (MPD) of Cell B is less than half of that of Cell A. The large Rp value of Cell C is ascribed to its low TPB area at Ni–Ag anode which has no reaction with H2 during operation. No visible sintering of the SDC electrolyte layer is observed for Cell C; therefore, its ionic conductivity is considerably smaller than those of the electrolyte layers of Cells A and B. The OCVs of Cell C (0.281–0.495 V) are significantly lower than the typical OCVs of ceria-based SOFCs. This is attributed to the porous SDC electrolyte layer of Cell C. The large Rp values and the low OCVs contribute to the low MPDs of Cell C at various temperatures.
Keywords Solid oxide fuel cell; NCAL electrode; Polarization; Cell performance
Remark https://doi.org/10.1016/j.ijhydene.2022.09.148
Link

Tuning the Thermoelectric Performance of CaMnO3-Based Ceramics by Controlled Exsolution and Microstructuring

ID=697
Authors Nikola Kanas, Benjamin A. D. Williamson, Frank Steinbach, Richard Hinterding, Mari-Ann Einarsrud, Sverre M. Selbach, Armin Feldhoff, and Kjell Wiik
Source
CS Appl. Energy Mater.
Volume: 5, Issue: 10, Pages: 12396–12407
Time of Publication: 2022
Abstract The thermoelectric properties of CaMnO3−δ/CaMn2O4 composites were tuned via microstructuring and compositional adjustment. Single-phase rock-salt-structured CaO–MnO materials with Ca:Mn ratios larger than unity were produced in reducing atmosphere and subsequently densified by spark plasma sintering in vacuum. Annealing in air at 1340 °C between 1 and 24 h activated redox-driven exsolution and resulted in a variation in microstructure and CaMnO3−δ materials with 10 and 15 vol % CaMn2O4, respectively. The nature of the CaMnO3−δ/CaMn2O4 grain boundary was analyzed by transmission electron microscopy on short- and long-term annealed samples, and a sharp interface with no secondary phase formation was indicated in both cases. This was further complemented by density functional theory (DFT) calculations, which confirmed that the CaMnO3−δ indeed is a line compound. DFT calculations predict segregation of oxygen vacancies from the bulk of CaMnO3−δ to the interface between CaMnO3−δ and CaMn2O4, resulting in an enhanced electronic conductivity of the CaMnO3−δ phase. Samples with 15 vol % CaMn2O4 annealed for 24 h reached the highest electrical conductivity of 73 S·cm–1 at 900 °C. The lowest thermal conductivity was obtained for composites with 10 vol % CaMn2O4 annealed for 8 h, reaching 0.56 W·m–1K–1 at 700 °C. However, the highest thermoelectric figure-of-merit, zT, was obtained for samples with 15 vol % CaMn2O4 reaching 0.11 at temperatures between 800 and 900 °C, due to the enhanced power factor above 700 °C. This work represents an approach to boost the thermoelectric performance of CaMnO3−δ based composites.
Remark https://doi.org/10.1021/acsaem.2c02012
Link

Magnetron sputtered LSC-GDC composite cathode interlayer for intermediate-temperature solid oxide fuel cells

ID=696
Authors A.A. Solovyev, A.V. Shipilova, S.V. Rabotkin, E.A. Smolyanskiy, A.N. Shmakov
Source
International Journal of Hydrogen Energy
Volume: 47, Issue: 89, Pages: 37967-37977
Time of Publication: 2022
Abstract The paper investigates the influence of the La0.6Sr0.4CoO3-δ-Gd0.1Ce0.9O1.95 (LSC-GDC) composite cathode interlayer on the operation of solid oxide fuel cells (SOFCs). Thin composite layers with the different GDC content are obtained by the reactive magnetron sputtering. The impact of the high-temperature annealing on the LSC-GDC phase composition is studied by the X-ray diffraction instrument using additionally a synchrotron radiation. The NiO-YSZ anodes with the YSZ electrolyte thin film and GDC barrier layer are used for the SOFC fabrication. The current-voltage curves and impedance spectra of SOFCs are obtained in the temperature range of 700–800°С. It is shown that not annealed composite layers with ∼50 vol% GDC content possess the most efficient electrochemical activity. The maximum power density of the SOFC with the LSC-GDC interlayer is 1322, 1041 and 796 mW/cm2 at 800, 750 and 700 °C, respectively, which is 20–35% higher than that of the cell without cathode interlayer.
Remark https://doi.org/10.1016/j.ijhydene.2022.08.281
Link

Dealing with degradation in solid oxide electrochemical cells: novel materials and spectroscopic probes

ID=695
Authors Robles Fernández, Adrián Merino Rubio, Rosa Isabel (dir.) ; Orera Utrilla, Alodia (dir.)
Source
Universidad de Zaragoza, PhD thesis
Time of Publication: 2022
Remark Link

Nanostructured La0.75Sr0.25Cr0.5Mn0.5O3–Ce0.8Sm0.2O2 Heterointerfaces as All-Ceramic Functional Layers for Solid Oxide Fuel Cell Applications

ID=694
Authors Juan de Dios Sirvent, Albert Carmona, Laetitia Rapenne, Francesco Chiabrera, Alex Morata, Mónica Burriel, Federico Baiutti, and Albert Tarancon
Source
ACS Appl. Mater. Interfaces
Volume: 14, Issue: 37, Pages: 42178–42187
Time of Publication: 2022
Abstract The use of nanostructured interfaces and advanced functional materials opens up a new playground in the field of solid oxide fuel cells. In this work, we present two all-ceramic thin-film heterostructures based on samarium-doped ceria and lanthanum strontium chromite manganite as promising functional layers for electrode application. The films were fabricated by pulsed laser deposition as bilayers or self-assembled intermixed nanocomposites. The microstructural characterization confirmed the formation of dense, well-differentiated, phases and highlighted the presence of strong cation intermixing in the case of the nanocomposite. The electrochemical properties─solid/gas reactivity and in-plane conductivity─are strongly improved for both heterostructures with respect to the single-phase constituents under anodic conditions (up to fivefold decrease of area-specific resistance and 3 orders of magnitude increase of in-plane conductivity with respect to reference single-phase materials). A remarkable electrochemical activity was also observed for the nanocomposite under an oxidizing atmosphere, with no significant decrease in performance after 400 h of thermal aging. This work shows how the implementation of nanostructuring strategies not only can be used to tune the properties of functional films but also results in a synergistic enhancement of the electrochemical performance, surpassing the parent materials and opening the field for the fabrication of high-performance nanostructured functional layers for application in solid oxide fuel cells and symmetric systems.
Keywords thin films, hydrogen oxidation reaction, symmetric functional layers, solid oxide cells, nanocomposites
Remark https://doi.org/10.1021/acsami.2c14044
Link

Correlations between structure, microstructure and ionic conductivity in (Gd,Sm)-doped ceria†

ID=693
Authors Cristina Artini, Massimo Viviani, Sabrina Presto, Sara Massardo, Maria Maddalena Carnasciali, Lara Gigli, and Marcella Pani
Source
Physical Chemistry Chemical Physics
Volume: 24, Issue: Cristina Artini, Massimo Viviani, Sabrina Presto, Sara Massardo, Maria Maddalena Carnasciali, Lara Gigli and Marcella Pani , Pages: 23622-23633
Time of Publication: 2022
Remark https://doi.org/10.1039/D2CP03255D
Link

High-temperature electrical conductivity and electrochemical activity in oxygen redox reaction of La-doped Sr2FeCo0.5Mo0.5O6-δ

ID=692
Authors M. M. Abdullaev, N. V. Lyskov, S. Ya. Istomin, E. V. Antipov
Source
Journal of Solid State Electrochemistry volume
Volume: 26, Pages: 2771–2779
Time of Publication: 2022
Abstract High-temperature electrical conductivity and electrochemical activity in the oxygen redox reaction of Sr2FeCo0.5Mo0.5O6-δ (SFCM) and Sr1.6La0.4FeCo0.5Mo0.5O6-δ (LSFCM) at variable oxygen partial pressure have been studied. We have found that the partial replacement of Sr2+ by La3+ results in a substantial decrease in the total electrical conductivity due to a decrease in the hole charge carrier concentration. Detailed analysis of the high- and low-frequency parts of the impedance spectra at pO2 = 0.1–1 atm and 873–1173 K has revealed different rate-limiting steps in the oxygen redox reaction for SFCM and LSFCM resulted from different oxygen vacancy concentrations in these materials. For SFCM, the oxygen redox reaction is limited by the processes of adsorption and dissociation of oxygen molecules, while for LSFCM by the charge transfer occurring at the triple phase boundary.
Remark Link
norecs.com

This article is the property of its author, please do not redistribute or use elsewhere without checking with the author.