jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Nunzia Coppola | Pierpaolo Polverino | G. Carapella | Regina Ciancio | Piu Rajak | Dario Montinaro | Francesca Martinelli | L. Maritato | Cesare Pianese
Source: Materials (article, 2021-10-05)
Field: Materials Science — Materials Chemistry

Large Area Deposition by Radio Frequency Sputtering of Gd0.1Ce0.9O1.95 Buffer Layers in Solid Oxide Fuel Cells: Structural, Morphological and Electrochemical Investigation We investigate the influence of position, under large circular sputtering targets, on the final electrochemical performance of 35 mm diameter button solid oxide fuel cells with sputter-deposited Gadolinium doped Ceria barrier layers, positioned in order to almost cover the entirety of the area associated with a 120 × 80 mm<sup>2</sup> industrial cell. We compare the results obtained via structural and morphological analysis to the Electrochemical Impedance Spectroscopy (EIS) measurements performed on the button cells, disentangling the role of different parameters. The Atomic Force Microscopy analysis makes it possible to observe a decrease in the roughness values from the peripheral to the central zones under the sputtering target, with peak-to-valley roughness values, respectively, decreasing from 380 nm to 300 nm, while Scanning Electron Microscopy and Energy Dispersive Spectroscopy show a dependence of the layer coverage from the position. The electrochemical performances of button cells with buffer layers of only 200 nm in thickness, and with negligible thickness gradients across them, show current density values of up to 478 mA/cm<sup>2</sup> at 0.8 V and 650 °C, with an improvement of more than 67% with respect to button cells with standard (screen printed) buffer layers. These results point out the major influence exerted by parameters such as the thickness gradient and the coverage of the sputtered buffer layers in determining the final electrochemical performances. Materials science ; Sputtering ; Dielectric spectroscopy ; Scanning electron microscope ; Oxide ; Surface roughness ; Buffer (optical fiber) ; Surface finish ; Electrochemistry ; Analytical Chemistry (journal) ; Composite material ; Thin film ; Nanotechnology ; Chemistry ; Electrode ; Metallurgy Advancements in Solid Oxide Fuel Cells ; Electronic and Structural Properties of Oxides ; Magnetic and transport properties of perovskites and related materials
Authors: Yu‐Cheng Shao | Bhupendra Karki | Wen-Cheng Huang | Xuefei Feng | Gamini Sumanasekera | Jinghua Guo | Yi‐De Chuang | Byron Freelon
Source: The Journal of Physical Chemistry Letters (article, 2021-01-05)
Field: Materials Science — Materials Chemistry

Spectroscopic Determination of Key Energy Scales for the Base Hamiltonian of Chromium Trihalides The van der Waals (vdW) chromium trihalides (CrX<sub>3</sub>) exhibit field-tunable, two-dimensional magnetic orders that vary with the halogen species and the number of layers. Their magnetic ground states with proximity in energies are sensitive to the degree of ligand-metal (p-d) hybridization and relevant modulations in the Cr d-orbital interactions. We use soft X-ray absorption (XAS) and resonant inelastic X-ray scattering (RIXS) spectroscopy at Cr <i>L</i>-edge along with the atomic multiplet simulations to determine the key energy scales such as the crystal field 10 <i>Dq</i> and interorbital Coulomb interactions under different ligand metal charge transfer (LMCT) in CrX<sub>3</sub> (X= Cl, Br, and I). Through this systematic study, we show that our approach compared to the literature has yielded a set of more reliably determined parameters for establishing a base Hamiltonian for CrX<sub>3</sub>. Chromium ; Chemistry ; van der Waals force ; Multiplet ; Hamiltonian (control theory) ; Scattering ; Coulomb ; Atomic physics ; Magnetic field ; Metal ; Physics ; Electron ; Molecule ; Optics ; Spectral line ; Quantum mechanics 2D Materials and Applications ; Inorganic Chemistry and Materials ; MXene and MAX Phase Materials
Authors: Martino Aldrigo | Mircea Dragoman | S. Iordănescu | Andrei Avram | Octavian‐Gabriel Simionescu | Cătălin Pârvulescu | H. El Ghannudi | Simone Montori | L. Nicchi | S. Arockia Edwin Xavier | A. Ziaei
Source: IEEE Access (article, 2021-01-01)
Field: Materials Science — Materials Chemistry

Tunable 24-GHz Antenna Arrays Based on Nanocrystalline Graphite In this work, we present a tunable 24-GHz antenna array based on a CMOS-compatible 110-nm-thick nanocrystalline graphite film grown by plasma enhanced chemical vapor deposition. The film has a nominal bulk conductivity exceeding 16000 S/m (hence, greater than any graphene monolayer or industrially available graphene multilayer) but still able to show an outstanding modulation of its charge carrier density in the upper microwave spectrum. The manufactured layer was used to design, simulate, fabricate, and test a 24-GHz patch antenna array, with each radiating element having overall dimensions of just λ0/8×λ0/7. The fabricated array exhibits a measured maximum gain of about 3 dBi around 24 GHz (unbiased state), with a half-power beam width of only 14.5° (suitable in wireless links where a high directivity is envisaged). Spanning the dc bias voltage between -25 V and 25 V at 24 GHz, the gain can be tuned continuously between -1.5 dBi and 4 dBi, whereas the resonance frequency undergoes a maximum shift of 166 MHz. This voltage-dependent tuning of the gain represents a first step in developing carbon-based applications to control amplitude and phase simultaneously and independently. These results (never reported) demonstrate the big potential of nanocrystalline graphite for high-performance microwave components that are CMOS compatible (a highly desirable characteristic for high fabrication yield and large-scale production), with unprecedented tunability for next-generation high-capacity communications. Materials science ; Optoelectronics ; Nanocrystalline material ; Antenna (radio) ; Microwave ; Biasing ; Voltage ; Electrical engineering ; Nanotechnology ; Telecommunications Graphene research and applications ; Electromagnetic wave absorption materials ; Interconnection Networks and Systems
Authors: Kenneth Tuul | Rasmus Palm
Source: Reactions (article, 2021-01-18)
Field: Materials Science — Materials Chemistry

Influence of Nanoconfinement on the Hydrogen Release Processes from Sodium Alanate Sodium alanate (NaAlH4) is a prospective H2 storage material for stationary and mobile applications, as NaAlH4 contains 7.4 wt% of H2, and it is possible to do multiple H2 release and accumulation cycles. Nanoconfinement is a potential solution to enhance the H2 release properties of NaAlH4. To optimize the supporting material and the synthesis method used for the nanoconfinement of NaAlH4, a better understanding of the influence of nanoconfinement on the H2 release processes is necessary. Thus, the H2 release from bulk, purely nanoconfined, and intermediate NaAlH4 is measured at different temperature ramp rates, and the characteristic parameters for each hydrogen release process are determined. Activation energies for each process are determined using the Kissinger method, and the effect of nanoconfinement on the activation energies is analysed. The impact of nanoconfinement on the H2 release processes from NaAlH4 and the limitations of each process in case of bulk and nanoconfined NaAlH4 are presented and discussed. Nanoconfinement of NaAlH4 decreases activation energies of the initial reversible H2 release steps to between 30 and 45 kJ mol−1 and increased the activation energy of the last irreversible H2 release step to over 210 kJ mol−1. Hydrogen storage ; Activation energy ; Chemical engineering ; Materials science ; Hydrogen ; Process (computing) ; Nanotechnology ; Chemistry ; Physical chemistry ; Computer science ; Organic chemistry Hydrogen Storage and Materials ; Hybrid Renewable Energy Systems ; Fuel Cells and Related Materials
Authors: Jan Maier | Todd B. Marder
Source: Chemistry - A European Journal (review, 2021-03-30)
Field: Chemistry — Organic Chemistry

Mechanistic and Kinetic Factors of <i>ortho</i>‐Benzyne Formation in Hexadehydro‐Diels‐Alder (HDDA) Reactions With the rapid development of the hexadehydro-Diels-Alder reaction (HDDA) from its first discovery in 1997, the question of whether a concerted or stepwise mechanism better describes the thermally activated formation of ortho-benzyne from a diyne and a diynophile has been debated. Mechanistic and kinetic investigations were able to show that this is not a black or white situation, as minor changes can tip the balance. For that reason, especially, linked yne-diynes were studied to examine steric, electronic, and radical-stabilizing effects of their terminal substituents on the reaction mechanism and kinetics. Furthermore, the influence of the nature of the linker on the HDDA reaction was explored. The more recently discovered photochemical HDDA reaction also gives ortho-arynes, which display the same reactivity as the thermally generated ones, but their formation might not proceed by the same mechanism. This minireview summarizes the current state of mechanistic understanding of the HDDA reaction. Aryne ; Steric effects ; Reactivity (psychology) ; Chemistry ; Reaction mechanism ; Mechanism (biology) ; Kinetics ; Computational chemistry ; Photochemistry ; Stereochemistry ; Organic chemistry ; Catalysis Cyclization and Aryne Chemistry ; Chemical Reactions and Mechanisms ; Catalytic Alkyne Reactions
Authors: Robert J. Green | V. B. Zabolotnyy | M. Zwiebler | Zhaoliang Liao | S. Macke | Ronny Sutarto | Feizhou He | Mark Huijben | Guus Rijnders | Gertjan Koster | J. Geck | V. Hinkov | G. A. Sawatzky
Source: Physical Review Materials (article, 2021-06-29)
Field: Materials Science — Materials Chemistry

Intrinsic versus extrinsic orbital and electronic reconstructions at complex oxide interfaces The interface between the insulators ${\mathrm{LaAlO}}_{3}$ (LAO) and ${\mathrm{SrTiO}}_{3}$ accommodates a two-dimensional electron liquid (2DEL)---a high-mobility electron system exhibiting superconductivity as well as indications of magnetism and correlations. While this flagship oxide heterostructure shows promise for electronics applications, the origin and microscopic properties of the 2DEL remain unclear. The uncertainty remains in part because the electronic structures of such nanoscale-buried interfaces are difficult to probe and is compounded by the variable presence of oxygen vacancies and coexistence of both localized and delocalized charges. These various complications have precluded decisive tests of intrinsic electronic and orbital reconstruction at this interface. Here we overcome prior difficulties by developing an interface analysis based on the inherently interface-sensitive resonant x-ray reflectometry. We discover a high-charge density of 0.5 electrons per interfacial unit cell (u.c.) for samples above the critical LAO thickness and extract the depth dependence of both the orbital and the electronic reconstructions near the buried interface. We find that the majority of the reconstruction phenomena are confined to within 2 u.c. of the interface, and we quantify how oxygen vacancies significantly affect the electronic system. Our results provide strong support for the existence of polarity-induced electronic reconstruction, clearly separating its effects from those of oxygen vacancies. Materials science ; Heterojunction ; Delocalized electron ; Condensed matter physics ; Oxide ; Electronic structure ; Electron ; Superconductivity ; Chemical physics ; Nanotechnology ; Optoelectronics ; Physics Electronic and Structural Properties of Oxides ; Magnetic and transport properties of perovskites and related materials ; Advanced Condensed Matter Physics
Authors: Donghan Shin | Gang Wang | Mengjiao Han | Zeyu Lin | Andrew O’Hara | Feiyu Chen | Junhao Lin | Sokrates T. Pantelides
Source: Physical Review Materials (article, 2021-04-08)
Field: Materials Science — Materials Chemistry

Preferential hole defect formation in monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi mathvariant="normal">W</mml:mi><mml:msub><mml:mi>Se</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> by electron-beam irradiation A unique dense network of multi-member-ring round hole defects is formed in monolayer WSe${}_{2}$ from the evolution of multivacancies by suitable control of a scanning focused electron beam, whereas the same process leads predominantly to chalcogen-vacancy line defect array in other trigonal-prismatic transition metal dichalcogenide (TMDC) monolayers. Density functional theory (DFT) calculations track the formation of the observed complex multivacancy structures and find that the underlying atomic-scale processes are quasi-thermodynamic, which elaborates the formation mechanism of dense round hole defects in WSe${}_{2}$ monolayers. The high-density round holes in WSe${}_{2}$ hold promise for novel applications such as atomic and molecular sieving. Monolayer ; Materials science ; Vacancy defect ; Density functional theory ; Crystallography ; Chalcogen ; Condensed matter physics ; Nanotechnology ; Physics ; Quantum mechanics ; Chemistry 2D Materials and Applications ; Chalcogenide Semiconductor Thin Films ; Advanced Photocatalysis Techniques
Authors: Hassan Ghani | Emad͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏͏ Yousif
Source: Al-Nahrain Journal of Science (article, 2021-09-01)
Field: Chemistry — Organic Chemistry

Chemistry of Some Organotin Compounds Organotin compounds (OTCs) are characterized as having at minimum one covalent bond between carbon and tin atoms, and are usually denoted by the formula RnSnX4-n (n =1-3, R =aryl or alkyl, X =halogen ion or a carboxylate, etc.). There are several methods to synthesis organotin compounds, they are Grignard and Kocheshkov reactions, Wurtz reaction and alkylation method. The tin has two stable state,(II) and (IV). Sn(II) forms pyramidal sp3complexes as well as trigonal bipyramidal sp3d complexes, whereas Sn(IV) forms trigonal bipyramidal sp3d complexes or octahedral sp3d2complexes. Chemistry ; Trigonal bipyramidal molecular geometry ; Tin ; Carboxylate ; Alkyl ; Aryl ; Halogen ; Octahedron ; Covalent bond ; Medicinal chemistry ; Stereochemistry ; Ion ; Molecule ; Organic chemistry Organometallic Compounds Synthesis and Characterization ; Marine Biology and Environmental Chemistry ; Corrosion Behavior and Inhibition
Authors: Thomas Gaudisson | Sophie Nowak | Zeinab Nehme | Nicolas Menguy | Nader Yaacoub | Jean−Marc Grenèche | Souad Ammar
Source: Frontiers in Materials (article, 2021-10-08)
Field: Materials Science — Materials Chemistry

Polyol-Made Spinel Ferrite Nanoparticles—Local Structure and Operating Conditions: NiFe2O4 as a Case Study We report the effect of a polyol-mediated annealing on nickel ferrite nanoparticles. By combining X-ray fluorescence spectroscopy, X-ray diffraction, and 57 Fe Mössbauer spectrometry, we showed that whereas the as-prepared nanoparticles (NFO) are stoichiometric, the annealed ones (a-NFO) are not, since Ni 0 -based crystals precipitate. Nickel depletion from the spinel lattice and reduction in the polyol solvent are accompanied with an important cation migration. Indeed, thanks to Mössbauer hyperfine structure analysis, we evidenced that the cation distribution in NFO departs from the thermodynamically stable inverse spinel structure with a concentration of tetrahedrally coordinated Ni 2+ of 20 wt-% ( A sites). After annealing, and nickel demixing, originated very probably from the A sites of NFO lattice, the spinel phase accommodates with cation and anion vacancies, leading to the (Fe 3+ 0.84 □ 0.16 ) A [Ni 2+ 0.80 Fe 3+ 1.16 □ 0.04 ] B O 4-0.20 formula, meaning that the applied polyol-mediated treatment is not so trivial. Spinel ; Polyol ; Mössbauer spectroscopy ; Materials science ; Annealing (glass) ; Nanoparticle ; Nickel ; Stoichiometry ; Chemical engineering ; Crystallography ; Analytical Chemistry (journal) ; Chemistry ; Physical chemistry ; Metallurgy ; Nanotechnology ; Chromatography ; Composite material Magnetic Properties and Synthesis of Ferrites ; Electromagnetic wave absorption materials ; Iron oxide chemistry and applications
Authors: Jianwen Zhang | Dongwei Wang | Lujia Wang | Wanwan Zuo | Lijun Zhou | Xue Hu | Dingyu Bao
Source: Polymers (article, 2021-07-26)
Field: Materials Science — Polymers and Plastics

Effect of Terminal Groups on Thermomechanical and Dielectric Properties of Silica–Epoxy Composite Modified by Hyperbranched Polyester To study the effect of hyperbranched polyester with different kinds of terminal groups on the thermomechanical and dielectric properties of silica-epoxy resin composite, a molecular dynamics simulation method was utilized. Pure epoxy resin and four groups of silica-epoxy resin composites were established, where the silica surface was hydrogenated, grafted with silane coupling agents, and grafted with hyperbranched polyester with terminal carboxyl and terminal hydroxyl, respectively. Then the thermal conductivity, glass transition temperature, elastic modulus, dielectric constant, free volume fraction, mean square displacement, hydrogen bonds, and binding energy of the five models were calculated. The results showed that the hyperbranched polyester significantly improved the thermomechanical and dielectric properties of the silica-epoxy composites compared with other surface treatments, and the terminal groups had an obvious effect on the enhancement effect. Among them, epoxy composite modified by the hyperbranched polyester with terminal carboxy exhibited the best thermomechanical properties and lowest dielectric constant. Our analysis of the microstructure found that the two systems grafted with hyperbranched polyester had a smaller free volume fraction (FFV) and mean square displacement (MSD), and the larger number of hydrogen bonds and greater binding energy, indicating that weaker strength of molecular segments motion and stronger interfacial bonding between silica and epoxy resin matrix were the reasons for the enhancement of the thermomechanical and dielectric properties. Epoxy ; Materials science ; Polyester ; Composite number ; Composite material ; Dielectric ; Terminal (telecommunication) ; Gelcoat ; Polymer chemistry Synthesis and properties of polymers ; Polymer Nanocomposites and Properties ; Tribology and Wear Analysis
Authors: Myneni Sukesh Babu | R. Sarathi | Takahiro Imai | Toshikatsu Tanaka
Source: Polymers (review, 2021-03-22)
Field: Materials Science — Materials Chemistry

Influence of Gamma Irradiation and Water Aging on the Space Charge Characteristics of Epoxy Micro-Nano Composites Epoxy micro-nano composites are well-known to exhibit enhanced electrical, mechanical as well as thermal properties compared to base epoxy resin. Yet, a clear understanding need to be achieved on the long-term aging performance of the epoxy micro-nano composites. The present review article is a comprehensive study on the impact of gamma irradiation and water aging on the space charge characteristics of epoxy micro-nano composites that are applicable as insulant in high-voltage power apparatus. Ion-trapping nanoparticles, which possess good oxidation resistance and high ion trapping ability, are being chosen as nanofillers along with silica micro fillers in epoxy micro-nano composite material for improving the reliability of electrical insulation structures. The epoxy micro-nano composite specimens were subjected to gamma irradiation (4 kGy and 8 kGy) and water aging (under room temperature and at 90 °C), to analyze the effect of aging on space charge accumulation and charge decay characteristics. The mean magnitude of accumulated space charge density of epoxy micro-nano composites tends to increase with an increase in gamma irradiation dose as well as an increment in water diffusion coefficient. The mean lifetime of the space charge decay during depoling has significantly reduced after gamma irradiation and is converse with water aged specimen. Voltage polarity reversal studies have indicated that a part of homo-charge injected from electrodes remained as hetero-charge just after polarity reversal and could result in the distortion of electric field thereby increasing the electric field enhancement factor. Epoxy ; Materials science ; Composite material ; Space charge ; Irradiation ; Composite number ; Nano- ; Electron High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Electrical Fault Detection and Protection
Authors: Zhenzhen Ou | Feng Gao | Lingjian Zhu | Huaijun Zhao | Zihan Xun
Source: PLoS ONE (article, 2021-06-01)
Field: Materials Science — Materials Chemistry

Study on aluminum nitride/addition-cure liquid silicone rubber composite for high-voltage power encapsulation In view of the development direction of high power and miniaturization of high-voltage power supply, higher requirements are put forward for the breakdown strength, thermal conductivity of packaging materials for its high voltage output module. An electric-insulated heat-conducted material with aluminium nitride as heat conducting filler and addition-cure liquid silicone rubber (ALSR) as matrix for high voltage power encapsulation has been studied. Initially, the thermal conductivity and breakdown strength of composites were explored at different filler fractions. With increase of filler fraction, the thermal conductivity increased and the breakdown strength decreased. Then, with the packaging module volume as the optimization objective and the working temperature as the optimization condition, the temperature distribution of high voltage power supply was studied by using the finite element method, and 40wt% filling fraction was selected as the optimal ratio. Finally, the actual packaging experiment of the high voltage module is carried out. and the variation of the output voltage and temperature with the working time is obtained. According to the experimental results, the output voltage of the high voltage module is basically stable, and the maximum surface temperature is 40.4°C. The practicability of the electric-insulated heat-conducted material has been proved. Materials science ; Silicone rubber ; Composite material ; Thermal conductivity ; Voltage ; High voltage ; Liquid nitrogen ; Composite number ; Breakdown voltage ; Electrical engineering High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Advanced Sensor and Energy Harvesting Materials