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Effects of LiNi0.8Co0.15Al0.05O2 electrodes on the conduction mechanism of Sm0.2Ce0.8O2−δ electrolyte and performance of low-temperature solid oxide fuel cells

ID=691
Authors Sea-Fue Wang, Yi-Le Liao, Yung-Fu Hsu, Piotr Jasinski,
Source
Journal of Power Sources
Volume: 546, Pages: 231995
Time of Publication: 2022
Abstract In this study, three low-temperature solid oxide fuel cells are constructed using Ce0.8Sm0.2O2−δ (SDC) as the electrolyte and Ni–LiNi0.8Co0.15Al0.05O2 (Ni–NCAL) and Ni–Ag as the electrodes. Cell A with symmetrical Ni–NCAL electrodes exhibits the best electrochemical performance. During operation, the Ni–NCAL anode is reduced by H2 atmosphere to form LiOH and Li2CO3. The Li2CO3–LiOH melt produced at >450 °C permeates the SDC electrolyte layer, causing its densification and grain growth in addition to the Li+-ion doping of SDC grains. The maximum electrical conductivity of the Li+-ion-doped SDC at 550 °C is at least one order of magnitude smaller than that of the SDC–Li2CO3–LiOH composite electrolyte (0.331 S cm−1). The ohmic and polarization resistances of Cell A at 550 °C are 0.168 and 0.256 Ω cm2, respectively, and its open-circuit voltage is 1.065 V, indicating the presence of dense SDC electrolyte and electron-blocking layers. The maximum power density of the cell at 550 °C is 535.2 mW·cm−2, which is primarily due to the high catalytic activity for the hydrogen oxidation and oxygen reduction reactions at the electrodes and large electrical conductivity of the SDC–Li2CO3–LiOH composite electrolyte at low temperatures.
Remark https://doi.org/10.1016/j.jpowsour.2022.231995
Link

Efficiencies of cobalt- and copper-based coatings applied by different deposition processes for applications in intermediate-temperature solid oxide fuel cells

ID=690
Authors M. Tomas, V. Asokan, J. Puranen, J.-E. Svensson, J. Froitzheim
Source
International Journal of Hydrogen Energy
Volume: 47, Issue: 76, Pages: 32628-32640
Time of Publication: 2022
Abstract Solid Oxide Fuel Cells (SOFCs) are electrochemical conversion devices that produce electricity directly by oxidising a fuel. The interconnects between the individual cells need to be coated to limit Cr(VI) evaporation from the steel and to preserve electrical conductivity. Physical Vapour Deposition (PVD)-coated samples with Ce/Co, Ce/Cu, and Ce/MnCu, and Thermal Spray (TS)-coated Mn/Co, Cu and Mn/Cu and AISI 441 steel samples were exposed at 650 °C for up to 1000 h. The PVD Ce/Co and Ce/Cu coatings, as well as the TS Mn/Co coating, exhibited the formation of a thin protective Cr2O3 scales underneath the coating. These samples also exhibited the lowest area-specific resistance (ASR) values. The remainder of the samples exhibited much higher mass gains and higher ASR values. Cr(VI) evaporation measurements showed that all the coatings behaved approximately the same despite the PVD coatings being only about one-tenth of the thickness of the TS coatings.
Remark https://doi.org/10.1016/j.ijhydene.2022.07.168
Link

Synthesis of a Novel Nanoparticle BaCoO2.6 through Sol-Gel Method and Elucidation of Its Structure and Electrical Properties

ID=689
Authors Fareenpoornima Rafiq, Parthipan Govindsamy, and Selvakumar Periyasamy
Source
Journal of Nanomaterials
Time of Publication: 2022
Abstract The physical properties of cobalt oxide with varied oxidation states, and coordination numbers, in the transition series, have numerous applications. The present study explores the physical properties of BaCoO2.6 nanoparticles synthesized through the sol-gel method. The X-ray diffraction figure exhibits a 25 nm crystallite size hexagonal phase. The observational data shows the reduction in the real part of impedance (), dielectric constant (), dielectric loss (), and a raise in ac conductivity of mixed type of conduction with an elevation in frequency analyzed through impedance spectroscopy. The conductivity due to grain and grain boundaries is shown foremost in the complex impedance analysis. The plot of (Seebeck coefficient) in the low-temperature range indicates p-type behavior and the metal-insulator transition in the as-synthesized sample. The sample characteristics suggest applications in optical and switching devices. The Seebeck coefficient is the generation of potential difference when subjected to temperature difference. Thermoelectric materials are associated with the concept of high electrical conductivity like crystals and low thermal conductivity to that of glass. Nanothermoelectric materials can decrease further the thermal conductivity through phonon scattering. Electrical characterization suggests the presence of both NTCR and PTCR behavior in the sample, and hence, it explores the application in thermistor/resistance temperature detector’s (RTD) and low dielectric constant and loss to electro-optical and higher conversion efficiency to storage devices. Additionally, impedance spectroscopy helps in the study of electrochemical systems and solid-state devices wherein the transition of metal-insulator is an add-on to the research.
Remark https://doi.org/10.1155/2022/3877879
Link

Conduction mechanism of donor and acceptor doped sodium niobate-based ceramics

ID=688
Authors Luting Lu, Linhao Li, Xiuzi Che, Gaoyang Zhao
Source
Ceramics International
Volume: 48, Issue: 21, Pages: 32073-32080
Time of Publication: 2022
Abstract Recently, NaNbO3 (NN) has become a hot topic of current research due to its antiferroelectric energy storage properties, which demand that the ceramics withstand large applied electric fields. The breakdown strength is dependent on conduction properties, but there is limited research on the conduction mechanisms of NN. Here we report that A-site donor-doping of Bi3+ (BixNa1-3xNbO3) and B-site acceptor-doping of Mg2+ (NaNb1-2/5yMgyO3) in NN lead to dramatic changes in the magnitude of the bulk conductivity (σb) and the conduction mechanism of NN ceramics. Undoped NN exhibits mixed conduction behavior with an oxide ion transport number (tion) of ∼0.44, and σb of ∼10−6 S/cm at 600 °C. A low level of Bi3+ doping (x = 0.06) suppresses the NN mixed conduction mechanism to electron conduction (tion ∼ 0), and the bulk conductivity increases significantly, σb > 10−4 S/cm at 600 °C. On the other hand, Mg2+ doping (y = 0.06) samples mainly change the σb, with the mixed ion/hole conduction (tion ∼ 0.43) and σb > 10−4 S/cm at 700 °C. The results show that the conductivity of NN increases and exhibits different conduction mechanisms with the doping of Bi3+ and Mg2+. Aliovalent doping is not beneficial to improving the insulation properties. Thus, this work provides theoretical guidance for the study of energy storage characteristics and the suppression of leakage behavior of high-temperature dielectric capacitors.
Keywords NaNbO3; Conduction mechanisms; Chemical doping; Defect
Remark https://doi.org/10.1016/j.ceramint.2022.07.146
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Effect of high pressure-high temperature treatment on the microstructure and dielectric properties of cobalt doped СaСu3Тi4ž12

ID=687
Authors N.I. Kadyrova, N.V. Melnikova, A.A. Mirzorakhimov
Source
Journal of Physics and Chemistry of Solids
Volume: 169, Pages: Journal of Physics and Chemistry of Solids
Time of Publication: 2022
Abstract The results of studying the effect of high pressures and high temperatures (8 GPa, 1273 K) used in the process of thermobaric treatment of CaCu3-xCoxTi4O12 ceramics (x = 0; 0.4; 0.6), initially prepared by solid-phase synthesis, on the structure and electrical characteristics are presented. The dielectric parameters were evaluated in a temperature interval (293–1000) K in a frequency range 1 Hz–32 MHz. It was established that the value of dielectric permittivity ε of samples upon thermobaric treatment is an order of magnitude higher than ε of samples prepared by solid-phase synthesis. The main reasons for the high values of dielectric permittivity are both the intragrain effects related, among other things, to hopping mechanism of polaron motion, and the polarization effects provided by the presence microstructure inhomogeneities. The latter are nonconducting boundaries of conducting grains and, in some examined materials, microscopic-scale surfaces of inhomogeneities, which appeared due to deformation during thermobaric treatment. At high temperatures, oxygen vacancies make the main contribution to the observed values of dielectric permittivity.
Keywords Oxide ceramics; Synthesis; High pressure-high temperature; Microstructure; Dielectric properties
Remark https://doi.org/10.1016/j.jpcs.2022.110870
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Characterization of Y and Mn co-substituted BaZrO3 ceramics: Material properties as a function of the substituent concentration

ID=686
Authors Maria Balaguer, Yoo Jung Sohn, Dietmar Kobertz, Sergey Kasatikov, Andrea Fantin, Michael Muller, Norbert H. Menzler, Olivier Guillon, Mariya E. Ivanova
Source
Solid State Ionics
Volume: 382, Pages: Mariya E. Ivanova
Time of Publication: 2022
Abstract Innovations in materials science are the key element for solving technological challenges. Various energy and environmental applications require designing materials with tailored compositions, microstructures and specific target-oriented performance. Y and Mn co-substituted BaZrO3, e.g. BaZr0.85Y0.15Mn0.05O3-δ, has previously attracted attention as a membrane material for H2 separation from gas mixtures due to its mixed proton-electron conductivity leading to appreciable levels of H2-flux at elevated temperatures and its good thermo-chemical stability under reducing environments. In the present work, we developed ceramic materials within the BaZr0.8Y0.2-xMnxO3-δ series, where x = 0.02–0.15. The study of their functional properties in dependence of the Y-to-Mn ratio disclosed that thermal expansion and hydration decrease by increasing the Mn content as well as the total electrical conductivity. In addition to that, XPS analysis and near edge X-ray absorption fine structure spectra (NEXAFS) in the vicinity of O K-edge and Mn L2,3-edges indicated that the Mn atoms oxidation state in the surface and in the bulk range from Mn2+ to Mn4+ depending on the ambient conditions that can be encountered in MPEC electrodes, which it is suggested to be related with a hydration mechanism mediated by Mn oxidation and subsequent proton attachment to oxygen neighbors, similar to LSM.
Remark https://doi.org/10.1016/j.ssi.2022.115959
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Effect of Mn doping on the structural, spectral, electrical, ferromagnetic and piezoelectric properties of 0.7BFO-0.3BTO lead-free ceramics

ID=685
Authors Farha Jabeen, Raza Shahid, M. Shahid Khan, Raghvendra Pandey
Source
Journal of Alloys and Compaunds
Volume: 917, Pages: 165303
Time of Publication: 2022
Abstract Lead-free 0.7BiFeO3-0.3BaTi1−xMnxO3 ceramics, where x ranges from 1% -- 10%, were prepared by conventional solid state reaction method. Effect of addition of MnO2 on the structural, spectral, electrical, magnetic and piezoelectric properties of 0.7BiFeO3-0.3BaTiO3 material were studied systematically. The previous studies have emphasized on the doping in BiFeO3 rather than doping in BaTiO3 in BiFeO3-BaTiO3 system. Our work focuses on the influence of Mn doping in BaTiO3 in the BiFeO3-BaTiO3 system. All the ceramics were calcined at the optimum temperature of 800 °C to minimize the impurity phases to a great extent. The synthesized ceramics have a co-existence of R and T phases with a space group of R3c and P4mm respectively with a small amount of Bi25FeO40 impurity. The sample for x = 0.01 has R as the host phase rather than T phase, but as the concentration of Mn increases to 0.10, the R phase and T phase start forming a more stable solid solution. Additionally, the doping effect of Mn on grain and grain boundary was studied at 300 °C and illustrated by their equivalent circuits with the help of ZView 2 software. The grain resistance decreased significantly for the sample with x = 0.10. Hence, the addition of MnO2 significantly enhanced the electrical and piezoelectric properties of the 0.7BiFeO3-0.3BaTiO3 material. The improved electrical properties at high temperature and low frequencies εr =1.8 × 109, σ = 4.1 × 10−3 S cm−1 and piezoelectric property d33 = 128 pC/N was obtained for x = 0.10.
Remark https://doi.org/10.1016/j.jallcom.2022.165303
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From quaternary to senary high entropy antimonide nanoparticles by a facile and scalable thermal treatment method

ID=684
Authors Nayereh Soltani, Jamil Ur Rahman, Patricia Almeida Carvalho, Calliope Bazioti, Terje Finstad
Source
Materials Research Bulletin
Volume: 153, Pages: 111873
Time of Publication: 2022
Abstract Transition metal antimonides form a class of intermetallic compounds, which has drawn considerable attention due to their potential applications in various fields. However, the formation of nanostructures containing multiple transition metal elements has been a challenge. Here, a new class of multicomponent antimonide nanoparticles with chemical composition ranging from quaternary to senary were synthesized via a simple, reproducible, and scalable thermal treatment method. This method allows uniform elemental distributions in a single nanoparticle, demonstrating the ability to obtain medium- and high-entropy antimonide nanostructures. The mechanism of formation was proposed and the characteristics of obtained nanoparticles were investigated by X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. Under the achieved optimal synthesis conditions, the formation of a single-phase with a hexagonal structure (P63/mmc) was observed for the quaternary and quinary samples, whereas in the case of the senary samples, a trace of minor impurity can be observed.
Keywords Intermetallic compounds; Nanostructures; Electron microscopy; X-ray diffraction; Crystal structure
Remark https://doi.org/10.1016/j.materresbull.2022.111873
Link

Performance of membranes based on novel Ce0.8Sm0.2O2-δ /Ag cermet and molten carbonates for CO2 and O2 separation

ID=683
Authors C.G. Mendoza-Serrato, R. Lopez-Juarez, A. Reyes-Montero, J.A. Romero-Serrano, C. Gomez-Yanez, J.A. Fabian-Anguiano, J. Ortiz-Landeros
Source
Chemical Engineering Science
Volume: 255, Pages: 117673
Time of Publication: 2022
Abstract This work proposes a cermet infiltrated with a mixture of Li2CO3/Na2CO3/K2CO3 as a dense membrane to selectively separate CO2 and O2 at high temperatures. The cermet consisted of a mixture of the Ce0.8Sm0.2O2-δ (SDC) ceramic and silver as the metallic phase. This type of membrane is a novel design of the ceramic/carbonates type and represents an improvement of state-of-art designs by avoiding microstructural changes in the metallic phase and improving chemical inertness and wettability with the carbonate phase. First, an SDC nanostructured powder was chemically synthesized by direct combustion of urea: lanthanide nitrates-based deep eutectic solvent; then, SDC and silver powders were mixed in a 50:50 vol% ratio by using high energy ball milling. The mixture was uniaxially pressed and sintered to form a support. This cermet exhibited excellent wettability properties against the ternary molten carbonate phase; therefore, it readily allowed infiltration of the molten salts to form a dense membrane. Hence, the cermet showed excellent electronic conductivity as well as corrosion resistance in contact with carbonates for 200 h of continuous immersion. The cermet-carbonate membrane showed permselectivity by separating CO2 and O2 at high temperatures. It reaches simultaneous permeation values of 0.49 and 0.26 ml·min−1·cm−2, for CO2 and O2, respectively, at 850 °C. Finally, continuous permeation tests at 825 °C for 85 h proved the excellent chemical stability of the cermet-carbonate membrane. Any chemical reactivity was not observed between the cermet and the carbonates.
Keywords Cermet; Molten carbonate membrane; CO2 separation; O2 separation
Remark https://doi.org/10.1016/j.ces.2022.117673
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La1-xSrxMO3 (M = Co, Mn, Cr) interconnects in a 4-leg all-oxide thermoelectric generator at high temperatures

ID=682
Authors Reshma K. Madathil, Raphael Schuler, Truls Norby
Source
Journal of Physics and Chemistry of Solids
Volume: 167, Pages: 110739
Time of Publication: 2022
Abstract We herein report tests at high temperatures of a 4-leg oxide thermoelectric generator consisting of two pairs of p-type Ni0.98Li0.02O (Li–NiO) and n-type Zn0.98Al0.02O (Al–ZnO), assembled with various conducting perovskite oxides as interconnects. Using a custom-built testing system, we evaluated performance and stability at a hot side (furnace) temperature of up to 1000 °C under temperature differences up to ΔT = 600 °C in air. With a La0.6Sr0.4CoO3 (LSC) interconnect, a maximum power output of 18 mW was achieved with TH = 940 and TC = 340 °C (ΔT = 600 °C). Power maxima with La0.8Sr0.2MnO3 (LSM) and La0.8Sr0.2CrO3 (LSCr) as interconnects were lower, 6 mW and 2 mW, respectively, under similar conditions, attributed to their lower thermal and electrical conductivities. This demonstrates the requirements and potential of oxide interconnects for stable use of all-oxide thermoelectric generators at high temperatures in ambient air.
Keywords Thermoelectric generator; Oxide; Interconnect; NiO; ZnO; La0.6Sr0.4CoO3 (LSC)
Remark https://doi.org/10.1016/j.jpcs.2022.110739
Link

The effect of alkaline earth metal substitution on thermoelectric properties of A0.98La0.02MnO3-δ (A = Ca, Ba)

ID=681
Authors Sathya Prakash Singh, Nikola Kanas, Mari-Ann Einarsrud, Kjell Wiik
Source
Processing and Application of Ceramics
Volume: 16, Issue: 1, Pages: 78–82
Time of Publication: 2022
Abstract The thermoelectric properties of ceramics with composition A0.98La0.02MnO3-δ are anticipated to vary with the basicity and atomic portion of the alkaline earth metal, A. In the present investigation ceramic powder precursors with composition A0.98La0.02MnO3-δ (A = Ca, Ba) were synthesized by the solid-state method and sintered in air at 1400 °C. Seebeck coefficient, electrical and thermal conductivities were characterized for both materials from 100 to 900 °C in air. The highest zT of 0.10 at 900 °C was reached for Ca0.98La0.02MnO3-δ. The high zT is attributed to the enhanced electronic conductivity (∼90 S/cm at 900 °C) due to La doping. zT for Ba0.98La0.02MnO3-δ reached its highest value (0.02) at 800 °C corresponding to a low electronic conductivity (∼2 S/cm), while the thermal conductivity was significantly reduced compared to Ca0.98La0.02MnO3-δ reaching ∼1 W/(m·K) combined with a high Seebeck coefficient, −290 μV/K. The present data represent a valuable basis for further development of these materials with respect to applications in thermoelectric devices.
Remark https://doi.org/10.2298/PAC2201078S
Link

Boundary Investigation of High-Temperature Co-Electrolysis Towards Direct CO2 Electrolysis

ID=680
Authors Stephanie E. Wolf, Lucy Dittrich, Markus Nohl, Tobias Duyster, Izaak C. Vinke, Rüdiger-A. Eichel, and L. G. J. (Bert) de Haart
Source
Journal of The Electrochemical Society
Volume: 169, Pages: 034531
Time of Publication: 2022
Abstract In the temperature range of high temperature co-electrolysis of both steam and carbon dioxide, the reverse water-gas shift reaction (RWGS) takes place. Prior studies were conducted with a narrow gas composition range to investigate the role of RWGS during co-electrolysis. The results for steam electrolysis, CO 2 electrolysis, and co-electrolysis caused different conclusions regarding the role of electrochemical CO2 and H 2 O conversion compared to RWGS during co-electrolysis. This work aims to resolve the role of CO2 conversion as part of RWGS in co-electrolysis. The boundary is characterized by AC and DC measurements over a broad gas composition range from CO 2 electrolysis towards co-electrolysis with nearly 50%eq H 2 O. Especially, the electrochemical CO2 reduction and CO2 conversion in the RWGS are compared to clarify their role during co-electrolysis. The results revealed that gas composition determined the predominant reaction (H 2 O or CO2 reduction). The cell performance of co-electrolysis in the boundary region up to 5% eq H2 O was similar to the performance of CO2 electrolysis. Up to 30%eq H 2 O, the performance increases with H 2 O concentration. Here, both CO2 and H 2 O electrolysis occur. Above 30% eq H 2 O, steam electrolysis and the RWGS reaction both dominate the co-electrolysis process.
Remark Link

Site occupancy, luminescence and dielectric properties of β-Ca3(PO4)2-type Ca8ZnLn(PO4)7 host materials

ID=679
Authors Yu.Yu. Dikhtyar, D.A. Spassky, V.A. Morozov, D.V. Deyneko, A.A. Belik, O.V. Baryshnikova, I.V. Nikiforov, B.I. Lazoryak
Source
Journal of Alloys and Compounds
Volume: 908, Pages: 164521
Time of Publication: 2022
Abstract Phosphates of Ca8ZnLn(PO4)7 (Ln3+ = La – Nd, Sm – Lu) with β-Ca3(PO4)2-type structure were prepared by high-temperature solid-state technique on air. All compounds of Ca8ZnLn(PO4)7 are centrosymmetric and have Rc space group, which has been proved by several methods such as second-harmonic generation, dielectric spectroscopy, and Rietveld analysis. The influence of Ln3+ on the structure, luminescent properties and temperature of phase transitions, which corresponds with “tetrad” effect, has been investigated. The bandgap width and location of 4f Ln3+ and Ln2+ levels relatively to the energy bands were determined using the data of luminescent spectroscopy.
Remark https://doi.org/10.1016/j.jallcom.2022.164521
Link

Tuning of the microstructural and electrical properties of undoped BaTiO3 by spark plasma sintering

ID=678
Authors Jon G. Bell, T. Graule, M. Stuer
Source
Open Ceramics
Volume: 9, Pages: 100244
Time of Publication: 2022
Abstract The distribution of oxygen vacancies in BaTiO3 specimens can greatly affect material electrical properties. Spark plasma sintering followed by annealing in controlled pO2 atmospheres offers the potential to control the oxygen vacancy distribution. Impedance spectroscopy has been used to study the electrical characteristics of undoped BaTiO3 specimens prepared at 1200 °C under a pressing pressure of 5 MPa and 50 MPa using spark plasma sintering (SPS). For both samples, at temperatures greater than 750 °C, the total conductivity is determined by the bulk conductivity (σb), while at temperatures between 550 °C–750 °C the total conductivity is determined by the grain boundary conductivity (σgb). Below 550 °C, the total conductivity is determined by the BaTiO3–Pt interface conductivity (σel). The bulk, grain boundary and electrode interface resistances and activation energies are lower for samples sintered and pressed at 50 MPa, compared to specimens sintered and pressed at 5 MPa. Plots of grain boundary conductivity (σgb) vs. oxygen partial pressure (pO2) (log(σgb) vs. log(pO2)), over the temperature range 517 °C–683 °C, have slopes of approximately 4.0 indicating that doubly charged oxygen vacancies () are located at the grain boundaries. The grain boundary region and BaTiO3–Pt interface conductivities are highly sensitive to the oxygen partial pressure. Therefore, SPS sintered BaTiO3 specimens that have been subjected to controlled annealing could be used to tailor BaTiO3 dielectric properties, as well as have potential applications in high temperature O2 sensing. Furthermore, analysis of a.c. conductivity using the Jonscher model reveals that the governing charge transport mechanism is via quantum mechanical tunneling (QMT), which operates at temperatures when grain boundaries control the total conductivity. The mechanism switches to the correlated barrier hopping (CBH) model at temperatures when the bulk controls the total conductivity.
Remark https://doi.org/10.1016/j.oceram.2022.100244
Link

Mesophase Transitions in [(C2H5)4N][FeBrCl3] and [(CH3)4N][FeBrCl3] Ferroic Plastic Crystals

ID=677
Authors Julian Walker, Kenneth P. Marshall, Jorge Salgado-Beceiro, Benjamin A. D. Williamson, Nora S. Løndal, Socorro Castro-Garcia, Manuel Sánchez Andújar, Sverre M. Selbach, Dmitry Chernyshov, and Mari-Ann Einarsrud
Source
Chem. Mater.
Volume: 34, Issue: 6, Pages: 2585–2598
Time of Publication: 2022
Abstract Plastic crystals are supramolecular materials that possess a unique high entropy mesophase at elevated temperatures, where a long-range structural symmetry coexists with a local molecular orientational disorder. The transition to mesophase can involve a large entropy change useful for thermal energy storage and influences the temperature range of ferroelectric and piezoelectric properties, important for sensor applications. Synchrotron X-ray diffraction and pair distribution function analysis were used to study the structure, while calorimetry, dielectric, leakage current measurements, and density functional theory were used to investigate the influence of the organic cation on the structure and properties of tetraethylammonium bromotrichloroferrate(III) [(C2H5)4N][FeBrCl3] and tetramethylammonium bromotrichloroferrate [(CH3)4N][FeBrCl3]. The [(C2H5)4N][FeBrCl3] mesophase transition had an entropy change of 151.5 J·K–1·kg–1, while [(CH3)4N][FeBrCl3] had only 49 J·K–1·kg–1. This was explained by the [(C2H5)4N][FeBrCl3] mesophase having less long-range structural symmetry and more local orientational disorder, of both the cations and anions, compared to [(CH3)4N][FeBrCl3]. Both materials exhibited at least two conductive mechanisms below the transition, vacancy-mediated ionic and electronic conduction. The introduction of anion orientational freedom, as opposed to cation orientational freedom, at the mesophase transition was most influential for the electrical properties. Introduction ARTICLE SECTIONS
Remark https://doi.org/10.1021/acs.chemmater.1c03778
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Contact angle screening and asymmetric dual-phase CO2 separation membranes

ID=676
Authors Wen Xing, Anne Store
Source
Journal of Membrane Science
Volume: 652, Pages: 120447
Time of Publication: 2022
Abstract Dual-phase CO2 separation membrane consisting of molten carbonates confined in a solid matrix can separate CO2 at high temperatures. The contact angle of molten carbonates to different oxides that can potentially serve as membrane supports was screened between 450 and 650 °C. These oxides have different electrical transport properties, including oxide ion, mixed, and electronic conducting. The contact angles vary between 80° and 10° for different materials. Asymmetric membranes were fabricated using wettable oxide ion conductors BTM and CGO (Bi0.8Tm0.2O1.5 and Ce0.8Gd0.2O2-δ) infiltrated with molten carbonates supported by the most "non-wetting" oxide BPR (Bi0.8Pr0.2O1.5) selected in the contact angle screening. The membranes show CO2 flux in the range of 0.035–0.35 ml/min cm2 at temperatures from 500 to 650 °C. Compared to a symmetric membrane with similar total membrane thickness, the asymmetric architecture significantly reduces the effective membrane thickness and increases CO2 flux. After the CO2 flux measurements, the membrane was examined with SEM and EDS mapping, showing that the molten carbonates were mainly confined within the top membrane and sealing area without penetrating the support layer.
Remark https://doi.org/10.1016/j.memsci.2022.120447
Link

NaMn0.2Fe0.2Co0.2Ni0.2Ti0.2O2 high-entropy layered oxide – experimental and theoretical evidence of high electrochemical performance in sodium batteries

ID=675
Authors Katarzyna Walczak, Anna Plewa, Corneliu Ghica, Wojciech Zajac, Anita Trenczek-Zajac, Marcin Zajac, Janusz Tobota, Janina Molenda
Source
Energy Storage Materials
Volume: 47, Pages: 500-514
Time of Publication: 2022
Abstract Li-ion batteries, widely used in portable electronics, electric vehicles, and energy storage systems, are an integral element of our daily life. However, the limitation of lithium sources, which leads to high prices, prompts the search for alternatives. Recently there has been noticed a rapid interest in Na-ion batteries technology. Especially, suitable cathode structures are investigated to accumulate larger sodium ions. In this paper, the high entropy layered oxide NaMn0.2Fe0.2Co0.2Ni0.2Ti0.2O2 is presented which achieves superior electrochemical properties with a stable capacity of ca. 180 mAh g−1. The understanding of its high performance is based on a complex study of the multiphase intercalation mechanism. The combination of advanced structural analysis by XAS, in situ XRD, TEM, and computational DFT modelling gives a new concept on the nature of O3-P3 structure reorganization. The presented experimental and theoretical evidence indicates that the P3 phase of layered oxides is energetically favourable for a lower sodium content for specific transition metal-oxide pair distance. Fundamental understanding of the nature of phase transformation is crucial for tailoring structural composition, where the desirable O3-P3 reorganization will occur, resulting in achieving high-performance cathodes.
Remark https://doi.org/10.1016/j.ensm.2022.02.038
Link

Investigation of magnetic properties and converse magnetoelectric effect in the composite of doped barium hexaferrite with potassium niobate, 0.5BaFe10Sc2O19-0.5KNbO3 and 0.5BaFe10In2O19-0.5KNbO3

ID=674
Authors Surbhi Gupta, S.K. Deshpande, V.G. Sathe, V. Siruguri
Source
Physica B: Condenced Matte
Volume: 663, Pages: 413736
Time of Publication: 2022
Abstract This study investigates the magnetic and electric properties of the 0.5BaFe10Sc2O19-0.5KNbO3 (0.5BFSc2O-0.5KNO) and 0.5BaFe10In2O19-0.5KNbO3 (0.5BFIn2O-0.5KNO) composite samples. Refined X-ray diffraction (XRD) studies substantiate the presence of both ferrimagnetic (BFSc2O and BFIn2O) and ferroelectric KNbO3 phase with the ratio (0.5:0.5) in both the compounds without any impure phase. By electric poling the samples with an electric field of 2.5 kV/cm, magnetization shows a different behaviour (decreasing in Sc and increasing in doped composite), can be attributed to the electric field induced changes of spin states due to stress induced at the interface of ferrimagnetic (FM)/ferroelectric (FE) regions. Strong converse magnetoelectric coupling (CME) was observed in both the compounds, with a large electric field modulation in magnetism (80%) in the 0.5BFInO-0.5KNO composite. Dielectric studies reveal the presence of ferroelectric (FE-Tc) transition around the magnetic Curie temperature (FM-Tc) of respective composites, further indicates the presence of converse magnetoelectric coupling in both systems.
Remark https://doi.org/10.1016/j.physb.2022.413736
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Tailored and Improved Protonic Conductivity through Ba(ZxCe10−x)0.08Y0.2O3−δ Ceramics Perovskites Type Oxides for Electrochemical Devices

ID=673
Authors Dr. Kwati Leonard, Prof. Yuji Okuyama, Dr. Mariya E. Ivanova, Prof. Wilhelm A. Meulenberg, Prof. Hiroshige Matsumoto
Source
ChemElectroChem
Time of Publication: 2022
Abstract Acceptor-doped barium zirconate cerate electrolytes constitute prospective materials for highly efficient and environmentally friendly electrochemical devices. This manuscript employs a systematic approach to further optimize ionic conductivity in Ba(ZrxCe10−x)0.08Y0.2O3−δ, (1≤x≤9) oxides for moderate temperature electrolysis. We found two new composition variants by fixing a cerium/zirconium ratio of 5/4 at the perovskite B-site with incremental zirconium, an observation that contrasts many reports suggesting a linear decrease in conductivity with increasing zirconium. As a result, the composition BaZr0.44Ce0.36Y0.2O3−δ demonstrates a superior ionic conductivity (10.1 mS cm−1 at 500 °C) to stability trade-off whereas, BaZr0.16Ce0.64Y0.2O3−δ exhibits the highest conductivity (11.5 mS cm−1 at 500 °C) among the studied pellets. The high protonic conductivity is associated with a high degree of hydration, as confirmed by thermo-gravimetric analysis. In addition, both compositions as electrolytes allow successful hydrogen production in a steam electrolyzer prototype. Electrolysis voltage as low as 1.3 V is attainable at current densities of 600 and 500 mA/cm2 respectively at 600 °C, achieving 82 % current efficiencies with the later electrolyte.
Keywords https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/celc.202101663
Remark https://doi.org/10.1002/celc.202101663
Link

On the mechanism of Mn(II)-doping in Scandia stabilized zirconia electrolytes

ID=672
Authors Einar Vøllestad, Vegar Øygarden, Joachim Seland Graff, Martin Fleissner Sunding, John D. Pietras, Jonathan M. Polfus, Marie-Laure Fontaine
Source
Acta Materialia
Volume: 227, Pages: 117695
Time of Publication: 2022
Abstract Cubic Scandia-stabilized zirconia (ScSZ) is an attractive electrolyte material for solid oxide cells due to its significant ionic conductivity, provided that the phase transition to its rhombohedral polymorph upon cooling is suppressed. The latter is achieved with addition of a secondary co-dopant, albeit it may be at the detriment of its ionic conductivity Here, we thoroughly investigate how MnO2 (0.5–10 mol%) as a co-dopant impacts on the sinterability, thermal expansion, crystal structure and ionic conductivity of ZrO2 doped with 10 mol% Scandia (10ScSZ), and we provide new insight on the chemistry of dissolved manganese in the fluorite lattice. Reactive sintering of 2 mol% MnO2 mixed with 10ScSZ enables to produce dense electrolyte with significant reduction of the peak sintering temperature and stabilisation of the cubic structure down to room temperature. Combined density functional theory and X-ray photoelectron spectroscopy analyses reveal that manganese predominantly enters the structure as Mn2+ during reactive sintering, with a prevalence of higher valence states at the surface and grain boundaries. The highest oxide ion conductivity is achieved for 2 mol% doped 10ScSZ (120 mScm−1 at 800 °C) and it decreases with increasing Mn concentration. For all compositions, the bulk conductivity remains independent of pO2 – corroborating a limited electronic conductivity contribution from Mn-doping. The grain boundary conductivity is found to decrease with sintering time and pO2, which is attributed to the chemistry and concentration of segregated manganese at the surface and grain boundaries, yielding depletion of oxygen vacancies in the space charge layer.
Keywords Electrical conductivity; SOFC; Reactive sintering; ScSZ; Stability
Remark https://doi.org/10.1016/j.actamat.2022.117695
Link

Detailed characterization of oxide-ion and proton transport numbers in Sr–Ti layered perovskites using an improved electromotive force method

ID=670
Authors Yutaro Yagi, Isao Kagomiya & Ken-ichi Kakimoto
Source
Journal of Materials Research
Time of Publication: 2022
Abstract Numerous Sr–Ti-based layered perovskite-structured compounds exhibit protonic conductivity. In a previous study, we found that a new Sr2Ti0.95Al0.05O4−δ (STA05) layered perovskite also shows evidence of protonic conductivity. However, Sr–Ti-based layered perovskites are also potential oxide-ion conductors. Detailed transport numbers for both protons and oxide-ions in Sr–Ti-based layered perovskites remain unclear. To solve this problem, we here propose an improved approach based on electromotive force (emf) measurements to account for the contributions of thermal emf and polarization to the total conductivity. In the first step of this study, the conditions for investigating actual emfs were evaluated using measurements of yttria-stabilized zirconia as a typical oxide-ion conductor. The optimized emf technique was subsequently used to evaluate the transport numbers of STA05, which was found to exhibit no oxide-ion transport. Thus, STA05 is concluded to be a mixed proton and electron conductor..
Remark Link

Impedance spectroscopy study of Au electrodes on Gd-doped CeO2 (GDC) – Molten Li2CO3+Na2CO3 (LNC) composite electrolytes

ID=669
Authors Vijayan Sobhana Dilimon, Ragnar Strandbakke, Truls Norby
Source
Journal of Power Sources
Volume: 522, Pages: 230986
Time of Publication: 2022
Abstract We herein report an impedance spectroscopy study of Au electrodes on Gd-doped CeO2 (GDC) – molten Li2CO3+Na2CO3 (LNC) composite electrolytes in O2 and O2+CO2 atmospheres. Complementary measurements of Au on GDC alone are provided for supporting insight. We find that the adsorption of CO2 on GDC in O2+CO2 atmospheres effectively blocks oxygen adsorption and severely slows oxygen reduction kinetics. The conductivity of the composite is dominated by the GDC phase in the solid-solid temperature region, while the LNC phase dominates above its melting point, and no further enhancement e.g. by interfacial effects are found. The incorporation of LNC melt into GDC results in a significant reduction in the polarisation resistance of Au electrodes in O2 atmospheres, as the melt mediates the reaction by a peroxide mechanism. In O2+CO2 atmospheres, however, the polarisation resistance of Au electrodes on GDC-LNC membranes is significantly higher, higher even than that on GDC. This we assign again to the blocking adsorption of CO2 (or carbonate) on the surfaces of ceria and the sluggish transport and reactions now mediated by carbonate-carried oxide species (CO42−) instead of peroxide species.
Keywords Molten carbonate fuel cells; MCFC; CeO2; Gd-doped; GDC; GDC-Molten carbonate composite electrolyte; Oxygen electrode; Mechanism
Remark Link

Lanthanum strontium cobaltite as interconnect in oxide thermoelectric generators

ID=668
Authors Reshma K.Madathil, TrulsNorby
Source
Solid State Sciences
Volume: 124, Pages: 106801
Time of Publication: 2022
Abstract Issues related to use of metallic interconnects in oxide thermoelectric generators (TEGs) need to be addressed to secure performance and durability. Metal interconnects suffer from high cost of noble metals or chemical instability and contact resistance of non-noble metals, arising from oxidation, evaporation, and delamination in the oxidising conditions of ambient air at high operating temperatures. This work introduces the use of a stable and highly conducting ceramic oxide, in our case p-type lanthanum strontium cobaltite (La0.6Sr0.4CoO3, LSC) as interconnect. We verified the thermochemical stability of LSC in contact with p-type Ni0.98Li0.02O (Li–NiO) and n-type Zn0.98Al0.02O (Al–ZnO) and examined the electrical characteristics. An area specific contact resistance (ASRc) of ∼1800 Ω cm2 for a direct p-n junction was reduced to ∼400 mΩ cm2 for a p-LSC-n junction at a temperature of 300 °C, validating the concept. The use of a screen-printed LSC/Al–ZnO composite as a thin interconnect layer was found to decrease the contact resistance of the junction further to ∼260 mΩ cm2 at 300 °C, attributed to increased effective area of the LSC/Al–ZnO p-n junction.
Keywords Thermoelectric generator; All-oxide; Thermoelectric materials; Oxides; Interconnect; Oxide; p-n-junction; Ohmic; LaCoO3; Sr-substituted; La0.6Sr0.4CoO3
Remark Link

Oxide Ion and Proton Conductivity in a Family of Highly Oxygen-Deficient Perovskite Derivatives

ID=667
Authors Chloe A. Fuller, Douglas A. Blom, Thomas Vogt, Ivana Radosavljevic Evans, and John S. O. Evans
Source
J. Am. Chem. Soc.
Volume: 144, Issue: 1, Pages: 615–624
Time of Publication: 2022
Abstract Functional oxides showing high ionic conductivity have many important technological applications. We report oxide ion and proton conductivity in a family of perovskite-related compounds of the general formula A3OhTd2O7.5, where Oh is an octahedrally coordinated metal ion and Td is a tetrahedrally coordinated metal ion. The high tetrahedral content in these ABO2.5 compositions relative to that in the perovskite ABO3 or brownmillerite A2B2O5 structures leads to tetrahedra with only three of their four vertices connected in the polyhedral framework, imparting a potential low-energy mechanism for O2– migration. The low- and high-temperature average and local structures of Ba3YGa2O7 (P2/c, a = 7.94820(5) Å, b = 5.96986(4) Å, c = 18.4641(1) Å, and β = 91.2927(5) ° at 22 °C) were determined by Rietveld and neutron pair distribution function (PDF) analysis, and a phase transition to a high-temperature P1121/a structure (a = 12.0602(1) Å, b = 9.8282(2) Å, c = 8.04982(6) Å, and γ = 107.844(3)° at 1000 °C) involving the migration of O2– ions was identified. Ionic conductivities of Ba3YGa2O7.5 and compositions substituted to introduce additional oxide vacancies and interstitials are reported. Most phases show proton conductivity at lower temperatures and oxide ion conductivity at high temperatures, with Ba3YGa2O7.5 retaining proton conductivity at high temperatures. Ba2.9La0.1YGa2O7.55 and Ba3YGa1.9Ti0.1O7.55 appear to be dominant oxide ion conductors, with conductivities an order of magnitude higher than that of the parent compound.
Remark https://doi.org/10.1021/jacs.1c11966
Link

Advanced metal oxide infiltrated electrodes for boosting the performance of solid oxide cells

ID=666
Authors Alodia Orera, Alejandro Betato, Jorge Silva-Trevino, Angel Larrea and Miguel A. Laguna-Bercero
Source
J. Mater. Chem. A
Time of Publication: 2021
Abstract An efficient way for boosting the performance of solid oxide electrodes is the infiltration of metallic nanoparticles into both electrodes. In this work we will focus on improving the performance of standard lanthanum strontium manganite oxygen electrodes, by the addition of different metal oxide nanoparticles. First studies will be performed using cerium oxide nanoparticles, as this is the classic oxide already proposed in the literature. Other novel metal oxides such as praseodymium or manganese oxide will be explored, as studies in the literature for these two metal oxides are very scarce. The effect of metal oxide infiltration into LSM/YSZ oxygen electrodes will be studied in both symmetrical cells and complete microtubular cells using conventional fuel electrodes (NiO-YSZ) and electrolytes (YSZ). The obtained current densities in both fuel cell and electrolysis modes are significantly enhanced in comparison with other results in the literature for microtubular configuration.
Remark DOI: 10.1039/D1TA07902F
Link
norecs.com

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