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SSRN 2022年

作者： Silva, Argos Soares de Albuquerque Sousa, Sarah Maria de Gouveia, Guilherme Lisboa Garcia, Amauri Spinelli, José Eduardo Department of Materials Engineering Federal University of São Carlos UFSCar SP São Carlos13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil Department of Manufacturing and Materials Engineering University of Campinas SP Campinas13083-860 Brazil

The Al-4Cu-Mg 2017 alloy is a significant Al extrusion alloy. As a result, knowing its behavior in terms of grain refining during casting stages becomes critical for the next processing steps. In the face of the shortcomings exhibited by TiB inoculants, the addition of NbB could be tested for this alloy as an alternative. The present article investigates the effects of NbB addition on grain size (GS), on secondary dendrite arm spacing (λ2) and on hardness of centrifugally cast (CC) and directionally solidified (DS) 2017 alloy samples, encompassing a broad range of cooling rates and solidification conditions. The λ2 did not change much as a result of the NbB inoculation, either for DS or CC samples, decreasing from 7.2 μm to 7.0 μm in the case of the 4 mm-thick CC samples and increasing from 17.0 μm to 22.5 μm in the case of the DS samples. The average GS, on the other hand, reduced from 293 μm to 136 μm for the NbB-containing CC samples and from 756 μm to 313 μm for the DS samples associated with cooling rates of 10 K/s. Both processes can achieve nearly the same GS reduction ratio, namely 2.2 for the CC and 2.5 for the DS. This implies that GS reduction ratio was barely affected if similar cooling rates were compared while taking the experimental range for both processes into account. Moreover, Vickers hardness results revealed that GS had little influence on this property for both alloys studied. The experimentally obtained data translated a variety of solidification condition outlines for the 2017 alloy. Through this data, understanding of an alternative inoculant in a significant Al alloy series advanced significantly. © 2022, The Authors. All rights reserved.

关键词： Solidification

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Cyclic ferroelectric switching and quantized charge transport in CuInP2S6

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Physical Review B 2023年第18期108卷 L180101-L180101页

作者： Daniel Seleznev Sobhit Singh John Bonini Karin M. Rabe David Vanderbilt Department of Physics and Astronomy Center for Materials Theory Rutgers University Piscataway New Jersey 08854 USA Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New York New York 10010 USA

The van der Waals layered ferroelectric CuInP2S6 has been found to exhibit a variety of intriguing properties arising from the fact that the Cu ions are unusually mobile in this system. While the polarization switching mechanism is usually understood to arise from Cu ion motion within the monolayers, a second switching path involving Cu motion across the van der Waals gaps has been suggested. In this work, we perform zero-temperature first-principles calculations on such switching paths, focusing on two types that preserve the periodicity of the primitive unit cell: “cooperative” paths preserving the system's glide mirror symmetry, and “sequential” paths in which the two Cu ions in the unit cell move independently of each other. We find that CuInP2S6 features a rich and varied energy landscape, and that sequential paths are clearly favored energetically both for cross-gap and through-layer paths. Importantly, these segments can be assembled to comprise a globally insulating cycle with the out-of-plane polarization evolving by a quantum as the Cu ions shift to neighboring layers. In this sense, we argue that CuInP2S6 embodies the physics of a quantized adiabatic charge pump.

关键词： Electric polarization Electronic structure Ferroelectricity Phonons Structural phase transition

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Flexible Trilayer Cellulosic Paper Separators engineered with BaTiO3 ferroelectric fillers for High Energy Density Sodium-ion Batteries

arXiv

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arXiv 2024年

作者： Sapra, Simranjot K. Das, Mononita Raja, M. Wasim Chang, Jeng-Kuei Dhaka, Rajendra S. Department of Physics Indian Institute of Technology Delhi Hauz Khas New Delhi110016 India International College of Semiconductor Technology National Yang Ming Chiao Tung University 1001 University Road Hsinchu30010 Taiwan Department of Materials Science and Engineering National Yang Ming Chiao Tung University 1001 University Road Hsinchu30010 Taiwan Energy Materials and Devices Division CSIR-Central Glass and Ceramic Research Institute Kolkata700032 India Department of Chemical Engineering Chung Yuan Christian University 200 Chung Pei Road Taoyuan32023 Taiwan

Cellulose-based paper separators are employed in sodium-ion batteries (SIBs) as a viable and economical substitute of conventional separators, owing to their sustainability, scalability, safety and cost-effectiveness. We design a full cell configuration having Na3V2(PO4)3 as cathode and pre-sodiated hard carbon as an anode with different separators and compare the electrochemical performance of these ceramic-impregnated polymer-coated cellulose paper separators with commercial glass fiber separator. Notably, the paper-based multilayer separators provide desirable characteristics such as excellent electrolyte wettability, thermal stability up to 200◦C, and ionic conductivity, which are essential for the efficient operation of SIBs. The cellulose separator is coated by a layer of polyvinylidene fluoride polymer, followed by a second layer of styrene butadiene rubber (SBR) polymer in which ferroelectric fillers BaTiO3 are integrated, which interacts with the polymer hosts through Lewis acid-base interactions ion and improves the conduction mechanism for the Na+ ions. The final lamination is performed by varying the SBR concentrations (0.5, 0.75, and 1.0 w/v%). The incorporated polymer matrices improve the flexibility, adhesion and dispersion of the nanoparticles and affinity of the electrolyte to the electrode. The morphology of the paper separators shows the uniform interconnected fibers with the porous structure. Interestingly, we find that the paper separator with 0.75 w/v% content of SBR exhibit decreased interfacial resistance and improved electrochemical performance, having retention of 62% and nearly 100% Coulombic efficiency up to 240 cycles, as compared to other concentrations. Moreover, we observe the energy density around 376 Wh kg−1 (considering cathode weight), which found to be comparable to the commercially available glass fiber separator. Our results demonstrate the potential of these multilayer paper separators towards achieving sustainability and safe

关键词： Sodium-ion batteries

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Lambda Theta Reflectometry for protein biosensing 17

Lambda Theta Reflectometry for protein biosensing

引用

Frontiers in Biological Detection: From Nanosensors to Systems XVII 2025

作者： Klose, Alanna M. Katz, Joseph D. Boni, Robert Miller, Benjamin L. Department of Dermatology University of Rochester RochesterNY14627 United States Materials Science Program University of Rochester RochesterNY14627 United States Laboratory of Laser Energetics University of Rochester RochesterNY14627 United States Department of Biomedical Engineering University of Rochester RochesterNY14627 United States

ISBN: (纸本)9781510684249

Label-free reflectometry sensors detect proteins by measuring the reflectance properties of a thin film on a substrate. As light encounters a thin film layer stack, reflections from the layer boundaries interfere with each other encoding information about layer properties onto the reflected light. Existing reflectometric techniques measure changes in thin film thickness by observing a change in the interference spectrum, polarization state or reflectance relative to an initial antireflective condition at fixed angle and wavelength. These techniques are used for biosensing by detecting changes in film thickness as analyte binds to surface-bound ligand. Existing approaches are limited by low multiplexing capability, limited sensitivity, or by requiring high manufacturing tolerances of the detector substrates. Lambda Theta Reflectometry (LTR) is a novel reflectometric technique that measures changes in film thickness by measuring the location of null reflectivity as a function of wavelength (lambda) and angle of incidence (theta). The substrate is simultaneously illuminated with a range of angles and wavelengths and reflected light is angularly and spectrally resolved. The optical thickness of the thin film is retrieved by fitting the location of the null in lambda theta space. A prototype LTR reflectometer has demonstrated the ability to measure SiO2 layer thickness with milli-Ångstrom precision. LTR measurements of SiO2/Si oxide films are in excellent agreement with spectroscopic ellipsometry for films thickness ranging from 1390-1465 Å. LTR enables sensitive measurements across a range of analyte concentrations without requiring stringent control over initial layer stack thickness. © 2025 SPIE.

关键词： Ellipsometry

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Tunable Optical Beam Focusing Using Static Water Droplets on an Electrospun Polymer Fiber

SSRN

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SSRN 2024年

作者： Budlayan, Marco Laurence M. Palangyos, Dina C. Patricio, Jonathan N. Arco, Susan D. Guerrero, Raphael A. Department of Physics College of Mathematics and Natural Science Caraga State University Butuan City8600 Philippines Department of Physics School of Science and Engineering Ateneo de Manila University Quezon City1108 Philippines Mathematics and Natural Sciences Department College of Computing Pangasinan State University Pangasinan Urdaneta2428 Philippines Materials Science and Engineering Program College of Science University of the Philippines Diliman Quezon City1101 Philippines Institute of Chemistry College of Science University of the Philippines Diliman Quezon City1101 Philippines Ateneo de Manila University Philippines

This work explores the use of static water microdroplets on a microfiber to vary the width of an optical beam. Varying the water droplet volume changes the beam width without replacing any optical components. A surface derived from glass deposited with polyvinyl chloride (PVC) microfibers via electrospinning was used to sustain the droplet shape on the surface. Scanning electron microscopy revealed the presence of randomly intertwined microfibers with diameters of less than 3 µm which afforded the surface a hydrophobic property. A decrease in the optical transmittance of the films and an increase in the water contact angle were also observed as fiber density increases. Results revealed an increase in the beam size with increasing droplet volume manifesting a defocusing or magnifying effect as the beam passed through the droplets. The beam maintained its Gaussian profile, confirming that the presence of the deposited fibers did not significantly alter the beam type. By using droplets with different liquid volumes (5-60 µL), we replicate the action of a convex lens with varying focal length. © 2024, The Authors. All rights reserved.

关键词： Microfibers

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A single n-type semiconducting polymer-based photo-electrochemical transistor

arXiv

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arXiv 2023年

作者： Druet, Victor Ohayon, David Petoukhoff, Christopher E. Zhong, Yizhou Alshehri, Nisreen Koklu, Anil Nayak, Prem D. Salvigni, Luca Almulla, Latifah Surgailis, Jokubas Griggs, Sophie McCulloch, Iain Laquai, Frédéric Inal, Sahika Biological and Environmental Science and Engineering Division Organic Bioelectronics Laboratory Thuwal23955-6900 Saudi Arabia KAUST Solar Center Physical Science and Engineering Division Materials Science and Engineering Program KAUST Thuwal23955-6900 Saudi Arabia Physics and Astronomy Department College of Sciences King Saud University Riyadh12372 Saudi Arabia Department of Chemistry Chemistry Research Laboratory University of Oxford OxfordOX1 3TA United Kingdom

Conjugated polymer films that can conduct ionic and electronic charges are central to building soft electronic sensors and actuators. Despite the possible interplay between light absorption and mixed conductivity of these materials in aqueous biological media, no polymer film has ever been used to realize a solar-switchable organic bioelectronic circuit relying on a fully reversible, redox reaction-free mechanism. Here we show that light absorbed by an electron and cation-transporting polymer film reversibly modulates its electrochemical potential and conductivity in an aqueous electrolyte, leveraged to design an n-type photo-electrochemical transistor (n-OPECT). We generate transistor output characteristics by solely varying the intensity of light that hits the n-type polymeric gate electrode, emulating the gate voltage-controlled modulation of the polymeric channel current. The micron-scale n-OPECT shows a high signal-to-noise ratio and an excellent sensitivity to low light intensities. We demonstrate three direct applications of the n-OPECT, i.e., a photoplethysmogram recorder, a light-controller inverter circuit, and a light-gated artificial synapse, underscoring the suitability of this platform for a myriad of biomedical applications that involve light intensity changes. © 2023, CC BY.

关键词： Polymer films

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Microscopic picture of paraelectric perovskites from structural prototypes

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Physical Review Research 2022年第1期4卷 L012042-L012042页

作者： Michele Kotiuga Samed Halilov Boris Kozinsky Marco Fornari Nicola Marzari Giovanni Pizzi Theory and Simulation of Materials (THEOS) National Centre for Computational Design and Discovery of Novel Materials (MARVEL) École Polytechnique Fédérale de Lausanne CH-1015 Lausanne Switzerland Designed Material Technologies LLC P.O. Box 14548 Richmond Virginia 23221-9998 USA John A. Paulson School of Engineering and Applied Sciences Harvard University 29 Oxford Street Cambridge Massachusetts 02138 USA Robert Bosch LLC Research and Technology Center Cambridge Massachusetts 02139 USA Department of Physics and Science of Advanced Materials Program Central Michigan University Mt. Pleasant Michigan 48859 USA

We highlight with first-principles molecular dynamics the persistence of intrinsic 〈111〉 Ti off-centerings for BaTiO3 in its cubic paraelectric phase. Intriguingly, these are inconsistent with the Pm3¯m space group often used to atomistically model this phase using density-functional theory or similar methods. Therefore, we deploy a systematic symmetry analysis to construct representative structural models in the form of supercells that satisfy a desired point symmetry but are built from the combination of lower-symmetry primitive cells. We define as structural prototypes the smallest of these that are both energetically and dynamically stable. Remarkably, two 40-atom prototypes can be identified for paraelectric BaTiO3; these are also common to many other ABO3 perovskites. These prototypes can offer structural models of paraelectric phases that can be used for the computational engineering of functional materials. Last, we show that the emergence of B-cation off-centerings and the primitive-cell phonon instabilities is controlled by the equilibrium volume, in turn, dictated by the filler A cation.

关键词： Crystal symmetry Ferroelectricity Structural order parameter Paraelectrics

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Mitigating oxygen reduction reaction barriers: An in-depth first-principles exploration of high-entropy alloy as catalysts

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Electrochemistry Communications 2024年 166卷

作者： Chen, Ming-Yi Thanh Thuy Tran, Ngoc Hsu, Wen-Dung Department of Materials Science and Engineering National Cheng Kung University 1 University Road Tainan701 Taiwan Research Center National Cheng Kung University Tainan701 Taiwan Program on Semiconductor Packaging and Testing Academy of Innovative Semiconductor and Sustainable Manufacture National Cheng Kung University Tainan701 Taiwan

This study investigates the effectiveness of high-entropy alloys (HEAs) as catalysts for reducing the energy barrier of the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Four HEAs—IrPdPtRh, CoCrFeNi, NbMoTaW, and TiZrNbTa—are analyzed as potential catalysts. This superiority arises from the shift in the overall d-band center position towards negative energy in HEAs. The study suggests that an increased standard deviation of atomic valences within HEAs correlates positively with improved ORR efficiency, indicating it as a potential design indicator for cost-effective catalysts. Moreover, predictions of valence variations based on differences in electronegativity between individual elements are proposed. Additionally, the research highlights that additional surface adsorption of Pt on HEAs would further enhance ORR activity. © 2024

关键词： Catalysts

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Long-Term Stability of NaOCl Passivation on CZTS Crystals Investigated via SEM-EDS

Long-Term Stability of NaOCl Passivation on CZTS Crystals In...

引用

IEEE Symposium on Nuclear science (NSS/MIC)

作者： J. Seo J. Byun K. Kim Y. Kim B. Park Department of Health and Safety Convergence Science Korea University Seoul Republic of Korea Interdisciplinary program in precision public health Korea University Seoul Republic of Korea Department of Materials Science and Engineering Korea University Seoul Republic of Korea School of Health and Environmental Science Korea University Seoul Republic of Korea Marine Radioactivity Monitoring Group Korea University Busan Republic of Korea

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

This study investigates the efficient passivation of CdTe-based semiconductor crystals, focusing on the long-term stability and underlying mechanisms of NaOCl passivation. CdZnTeSe crystals were grown, processed, and passivated with NaOCl, and their surface characteristics were studied using SEM-EDS and XPS. The passivation was found to significantly enhance the surface resistance, with a sustained effect for more than 90 s, attributed to the formation of a tellurium oxide layer. The passivation process was further elucidated through detailed morphological and compositional analyses. The NaOCl-passivated crystals exhibited improved electrical and spectroscopic properties in radiation detection, with a prolonged stability of 60-90 days, which are longer compared to other passivants. Additionally, the feasibility of NaOCl passivation on a CdZnTeSe detector was explored, showcasing enhanced resistivity and spectroscopic performance. The study concludes with insights into the potential industrial application of NaOCl passivation for CdTe-based radiation detectors.

关键词： Microwave integrated circuits Semiconductor detectors Surface resistance Radiation detectors Surface morphology Crystals Stability analysis

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Coherent X-ray Spectroscopy Elucidates Nanoscale Dynamics of Plasma-Enhanced Thin-Film Growth

arXiv

引用

arXiv 2023年

作者： Myint, Peco Woodward, Jeffrey M. Wang, Chenyu Zhang, Xiaozhi Wiegart, Lutz Fluerasu, Andrei Headrick, Randall L. Eddy, Charles R. Ludwig, Karl F. Department of Physics Division of Materials Science and Engineering Boston University BostonMA United States Electronics Science and Technology Division U.S. Naval Research Laboratory WashingtonDC United States Department of Physics and Materials Science Program University of Vermont Burlington United States National Synchrotron Light Source II Brookhaven National Laboratory Upton United States

Sophisticated thin film growth techniques increasingly rely on the addition of a plasma component to open or widen a processing window, particularly at low temperatures. However, the addition of the plasma into the growth environment also complicates the surface dynamical evolution. Taking advantage of continued increases in accelerator-based X-ray source brilliance, this real-time study uses X-ray Photon Correlation Spectroscopy (XPCS) to elucidate the nanoscale surface dynamics during Plasma-Enhanced Atomic Layer Deposition (PE-ALD) of an epitaxial indium nitride film. XPCS examines the evolution of the coherent X-ray scattering speckle pattern, which is a fingerprint of the unique sample microstructure at each moment in time. In PE-ALD, ultrathin films are synthesized from repeated cycles of alternating self-limited surface reactions induced by temporally-separated pulses of material precursor and plasma reactant, allowing the influence of each on the evolving morphology to be examined. During the heteroepitaxial 3D growth examined here, sudden changes in surface structure during initial film growth, consistent with numerous overlapping stress-relief events, are observed. When the film becomes continuous, the nanoscale surface morphology abruptly becomes long-lived with correlation time spanning the period of the experiment. Throughout the growth experiment, there is a consistent repeating pattern of correlations associated with the cyclic growth process, which is modeled as transitions between different surface states. The plasma exposure does not simply freeze in a structure that is then built upon in subsequent cycles, but rather there is considerable surface evolution during all phases of the growth cycle. © 2023, CC BY.

关键词： Ultrathin films

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