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SSRN 2022年

作者： Akbarpour, Mohammad Reza Ahmadi, M. Gharamaleki Ebadzadeh, Touradj Kim, Hyoung Seop Department of Materials Engineering Faculty of Engineering University of Maragheh P.O. Box 83111- Maragheh55181 Iran Ceramic Division Materials and Energy Research Center P.O. Box 14155-4777 Karaj Alborz Iran Department of Materials Science and Engineering Pohang University of Science and Technology Pohang Korea Republic of

Equiatomic Ni-Ti alloy reinforced with 0, 2.5, 5, and 10 vol. % SiC nanoparticles was synthesized through mechanical alloying and microwave sintering process. In this method, a mixture of Ti and Ni powders and SiC nanoparticles (0-10 vol.%) were mechanically milled for 30h, compressed under 1 GPa pressure, and then sintered at 900-1100 °C by microwave heating. Microstructural analysis of the synthesized samples was performed using X-ray diffraction and scanning / transmission electron microscopy, and their hardness was determined using a Vickers microhardness tester. Structural studies revealed the formation of a complex phase structure consisting of the austenite (B2-NiTi), the martensite (B19'-NiTi), and the nickel-rich (Ni 3 Ti(and titanium-rich)NiTi 2 (phases. HR-TEM investigations confirmed an increased Ni 3 Ti phase in the austenitic NiTi matrix nearby the martensitic NiTi phase. It was found that adding SiC nanoparticles to Ni-Ti increased the amount of hard Ni 3 Ti phase, promoted the stability of the martensite phase at room temperature, and retarded the matrix grain growth during the sintering process. Microhardness tests showed that when the content of SiC nanoparticles increased up to 5 vol. %, the microhardness increased considerably to 9 GPa and then declined. The high microhardness of synthesized nanocomposites is due to the formation of Ni 3 Ti and NiTi martensitic phases and their nanocrystalline structure. © 2022, The Authors. All rights reserved.

关键词： Silicon carbide

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On-Chip Unidirectional Waveguiding for Surface Acoustic Waves along a Defect Line in a Triangular Lattice

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Physical Review Applied 2023年第2期19卷 024053-024053页

作者： Yun Zhou Naiqing Zhang Dia’aaldin J. Bisharat Robert J. Davis Zichen Zhang James Friend Prabhakar R. Bandaru Daniel F. Sievenpiper Department of Mechanical Engineering University of California San Diego La Jolla 92093-0411 California USA Department of Electrical Engineering University of California San Diego La Jolla 92093-0411 California USA Program in Materials Science University of California San Diego La Jolla 92093-0411 California USA

The latest advances in topological physics have yielded a toolset for highly robust wave-propagation modalities for overcoming obstacles involving beam steering and lateral diffraction in surface acoustic waves (SAWs). However, extant proposals are limited to the exploitation of spin- or valley-polarized phases and rely on nonzero Berry curvature effects. Here, we propose and experimentally demonstrate a highly robust guiding principle, which instead employs an intrinsic chirality of phase vortices and maintains a zero Berry curvature for SAWs. Based on a line defect within a true triangular phononic lattice, the guided SAW mode spans a wide bandwidth [(Δω/ωcenter) ∼ 10%] and is well confined in the lateral direction with 3-dB attenuation within half of a unit cell. SAW routing around sharp bends with negligible backscatter is demonstrated. The on-chip integrated design permits unidirectional SAW modes that can enable considerable miniaturization of SAW-based devices, with applications ranging from radio-frequency devices to quantum information transduction.

关键词： Line defects Ultrasonics Acoustic metamaterials Phononic crystals Topological insulators Triangular lattice Waveguides Surface acoustic wave

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Enhancing Gravimetric and Volumetric Capacitance in Supercapacitors with Nanostructured Partially Graphitic Activated Carbon

SSRN

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SSRN 2023年

作者： Lee, Jeong Han Kang, Yong-Mook Roh, Kwang Chul Emerging Materials R&D Division Korea Institute Ceramic Engineering & Technology Jinju-Si52851 Korea Republic of Department of Materials Science and Engineering Korea University Seoul02841 Korea Republic of KU-KIST Graduate School of Converging Science and Technology Korea University Seoul02841 Korea Republic of Seoul02792 Korea Republic of

The volumetric and gravimetric capacitance of supercapacitors are primarily influenced by the specific surface area and porosity required for the formation of electric double layers in the electrode material, and these capacitance are known to have a trade-off relationship. To address this issue, additional capacitance enhancement mechanisms are needed not only at the electrode material surface but also within the limited mass and volume, which can be achieved through structural improvements of the material. In this study, we produce partially graphitic activated carbon with low specific surface area but nano-sized crystalline regions from petroleum pitch, a soft carbon precursor. This approach allows for improvements in gravimetric capacitance. The resulting activated carbon with a specific surface area of 1122 m2 g−1 exhibits volumetric specific capacitance of 27.9 F cc−1 and gravimetric specific capacitance of 38 F g−1 in an organic electrolyte, indicating a new direction for electrode materials in supercapacitors. © 2023, The Authors. All rights reserved.

关键词： Supercapacitor

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Plasmonic Nanolaser by Silver Nanowire Embedded in CsPbBr3 Quantum Dots

Plasmonic Nanolaser by Silver Nanowire Embedded in CsPbBr3 Q...

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JSAP-OSA Joint Symposia, JSAP 2021

作者： Xing, Di Lin, Cheng-Chieh Won, Phillip Xiang, Rong Chen, Tzu-Pei A. Kamal, A. Syazwan Lee, Yang-Chun Ho, Ya-Lun Maruyama, Shigeo Ko, Seung Hwan Chen, Chun-Wei Delaunay, Jean-Jacques School of Engineering The University of Tokyo Japan International Graduate Program of Molecular Science and Technology National Taiwan University Taiwan Department of Materials Science and Engineering National Taiwan University Taiwan Department of Mechanical Engineering Seoul National University Korea Republic of Center of Atomic Initiative for New Materials National Taiwan University Taiwan

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Reliability of Deployed Organic Photovoltaic Modules

Reliability of Deployed Organic Photovoltaic Modules

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IEEE Conference Photovoltaic Specialists (PVSC)

作者： Hafiz K. M. Sheriff Yongxi Li Sammy Saad Stephen R. Forrest Applied Physics Program University of Michigan Ann Arbor Michigan USA Department of Electrical Engineering University of Michigan Ann Arbor Michigan USA Department of Physics University of Michigan Ann Arbor Michigan USA Department of Materials Science and Engineering University of Michigan Ann Arbor Michigan USA

ISBN: (数字)9781665464260

ISBN: (纸本)9781665475822

The commercial future of organic photovoltaics (OPVs) relies on their efficiency and reliability. Recent progress in the field has ensured the achievement of device efficiency comparable to those of commercial silicon-based photovoltaics (Si-PVs) [1]. In pursuit of reliable devices, recent works have demonstrated the intrinsic stability of both small-molecule, vacuum deposited [2] and non-fullerene acceptor (NFA) – polymer-based devices [3] under controlled laboratory conditions. The final step for outdoor deployment is therefore a demonstration of the reliability of large area OPV modules in the field, subjected to fluctuating environmental conditions such as humidity, temperature, rainfall, snow, and solar intensity. In this work, we develop a customized test facility intended for the study of the reliability of large area OPV modules deployed in outdoor environments. The facility is designed for automated in-situ measurements calibrated to 1 sun solar intensity, AM 1.5 G illumination. Initial data show the modules retain more than 95% of their initial performance for 150 h when exposed to varying solar intensities, temperature fluctuations of -2°C to 10°C, and relative humidity as high as 90%. The only significant extrinsic challenge to device stability observed was the ingress of water into the package. This is mitigated by improved packaging which utilizes polyisobutylene (PIB) encapsulation and a customized insulated glass unit (IGU).

关键词： Temperature measurement Temperature distribution Test facilities Rain Snow Humidity Solar panels Polymers Sun Thermal stability

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Assessment of Simple Adhesive Substrates as a Method for Quantifying Microplastics and the Factors Influencing Capture

SSRN

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SSRN 2022年

作者： Rieland, Julie M. Hu, Zeyuan Deese, Julian S. Love, Brian J. Department of Materials Science and Engineering United States Department of Biomedical Engineering United States Macromolecular Science and Engineering Graduate Program 2300 Hayward St Ann ArborMI48109 United States

Microplastics are a growing environmental concern, with a large body of evidence documenting substantial distribution of plastic material in virtually all environmental compartments. Countermeasures that help to bind, aggregate, or coalesce these distributed particles might result in lower human and animal exposures. Pressure sensitive adhesives (PSAs) have been identified as a viable microplastic (MP) capture mechanism with a range of potential use conditions. As with any countermeasure, there is a need to evaluate their collection efficiency, cost, ease of installation, etc. Expanding on previous work, submerged, spray-coated PSAs were investigated as a quick and low-cost quantitative method to assess MP binding in water. Two molecular weights of poly(2-ethylhexyl acrylate) PSA (92k, 950k, and 50:50 bimodal distribution) were applied as spray-coated substrates to compare MP-adhesive interactions. Thin films of PSA (92k 6 ± 1 μm, 950k 4 ± 2 μm, 50:50 BD 6.5 ± 1 μm) were sprayed on borosilicate glass slides using a commercial air brush. Polydisperse nylon-12 particles varying in size from 15-30 µm in diameter were dispersed in aqueous solution between 0.01 and 5 mg mL -1 and agitated under ambient conditions as quantitative comparisons of adhesive wettability and net capture. Mixed assays were also performed comparing binding of common MP species including polyethylene, polystyrene, and polyester particles and fibers to understand how varying composition, size, and form factor affect adsorption. The glass slide method demonstrated linear trends associated with the MP binding to glass slides with respect both to exposure time and MP concentration. The adhesive wettability demonstrates bounding parameters under which high wettability adhesives excel at MP capture but may compromise the integrity of the adhesive film. © 2022, The Authors. All rights reserved.

关键词： Adhesives

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Enhanced Pore Formation in Petroleum Pitch by Steam and Co2 Hybrid Physical Activation: A Synergistic Approach

SSRN

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SSRN 2023年

作者： Lee, Jeong Han Kang, Yong-Mook Roh, Kwang Chul Emerging Materials R&D Division Korea Institute Ceramic Engineering & Technology Jinjusi52851 Korea Republic of Department of Materials Science and Engineering Korea University Seoul02841 Korea Republic of KU-KIST Graduate School of Converging Science and Technology Korea University Seoul02841 Korea Republic of Seoul02792 Korea Republic of

Creating effective pore formation in petroleum pitch (PP) is challenging due to its transformation into a stable graphitic structure at high temperatures, typical of soft carbon materials. While the use of transformations into carbon nanofibers and chemical activation can mitigate these inherent properties, they entail complex methodologies and present environmental risks. This study introduces a hybrid physical activation process using steam and CO2 as a simpler alternative. The effect of hybrid physical activation on the pore structure formation of PP is investigated and the effect of activator ratio and temperature on pore formation is analyzed, focusing on the specific surface area, degree of graphitization and pore structure change. The results demonstrates that activated carbons achieved a maximum specific surface area of 2506 m2 g−1 through a synergistic effect of hybrid physical activation. Moreover, we confirme that the milling process is crucial for effective stabilization of PP, and that controlling the ratio of steam and CO2 can optimize pore formation. This study demonstrates that the hybrid physical activation method overcomes the limitations of conventional activation techniques, thereby providing a valuable strategy for producing activated carbon from petroleum pitch and expanding its application to similar materials. © 2023, The Authors. All rights reserved.

关键词： Activated carbon

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Customizable wave tailoring materials enabled by nonlinear bilevel inverse design

arXiv

引用

arXiv 2024年

作者： MacNider, Brianna Xiu, Haning Qian, Kai Frankel, Ian Kim, Hyunsun Alicia Boechler, Nicholas Department of Mechanical and Aerospace Engineering University of California La Jolla San DiegoCA92093 United States Department of Structural Engineering University of California La Jolla San DiegoCA92093 United States Program in Materials Science and Engineering University of California La Jolla San DiegoCA92093 United States

Passive transformation of waves via nonlinear systems is ubiquitous in settings ranging from acoustics to optics and electromagnetics. Passivity is of particular importance for responding rapidly to stimuli and nonlinearity enormously expands signal transformability compared to linear systems due to the breaking of superposition. It is well known that different types of nonlinearity yield vastly different effects on propagating signals, which raises the question of "what precise nonlinearity is the best for a given wave tailoring application?" Considering a one-dimensional spring-mass chain as a testbed, we couple the shape optimization of structures for tailored nonlinear constitutive responses with reduced-order nonlinear dynamical inverse design. Using minimization of peak kinetic energy transmission from impact as a case study, we identify ideal nonlinear constitutive responses and the geometries needed to achieve them. As part of this, we show the large sensitivity of this metric to small changes in nonlinearity, and thus the need for high precision, free-form nonlinearity tailoring. We validate our predictions using impact experiments in a chain of nonlinear springs and masses. This work sets the foundation for broader passive nonlinear mechanical wave tailoring material design, with applications to computing, signal processing, shock mitigation, and autonomous materials. © 2024, CC BY-NC-ND.

关键词： Kinetic energy

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Improved Band Gaps and Structural Properties from Wannier-Fermi-Löwdin Self-Interaction Corrections for Periodic Systems

arXiv

引用

arXiv 2022年

作者： Shinde, Ravindra Yamijala, Sharma S.R.K.C. Wong, Bryan M. Department of Chemical & Environmental Engineering Materials Science & Engineering Program Department of Chemistry Department of Physics & Astronomy University of California-Riverside RiversideCA United States

The accurate prediction of band gaps and structural properties in periodic systems continues to be one of the central goals of electronic structure theory. However, band gaps obtained from popular exchange-correlation functionals (such as LDA and PBE) are severely underestimated partly due to the spurious self-interaction error (SIE) inherent to these functionals. In this work, we present a new formulation and implementation of Wannier function-derived Fermi-Löwdin (WFL) orbitals for correcting the SIE in periodic systems. Since our approach utilizes a variational minimization of the self-interaction energy with respect to the Wannier charge centers, it is computationally more efficient than the HSE hybrid functional and other self-interaction corrections that require a large number of transformation matrix elements. Calculations on several (17 in total) prototypical molecular solids, semiconductors, and wide-bandgap materials show that our WFL self-interaction correction approach gives better band gaps and bulk moduli compared to semilocal functionals, largely due to the partial removal of self-interaction errors. © 2022, CC BY.

关键词： Energy gap

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Ultra-thin Carbon Biphenylene Network as an Anisotropic Thermoelectric Material with High Temperature Stability Under Mechanical Strain

arXiv

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arXiv 2024年

作者： Sargın, Gözde Özbal Demirci, Salih Gong, Kai Özçelik, V. Ongun Faculty of Engineering and Natural Sciences Sabanci University Istanbul34956 Turkey Department of Physics Kırıkkale University Kırıkkale71450 Turkey Department of Civil and Environmental Engineering Rice University TX77005 United States Materials Science and Nano Engineering Program Sabanci University Istanbul34956 Turkey

Carbon biphenylene network (C-BPN), which is an ultra-thin material consisting of carbon atoms arranged in square-hexagonal-octagonal (4-6-8) periodic rings, has intriguing properties for nano-scale device design due to its unique crystal structure. Here, using the Landauer formalism in combination with first-principles calculations, we show that C-BPN is a highly stable thermoelectric material at elevated temperatures under mechanical strain, where its thermoelectric efficiency can be anisotropically engineered. Transport calculations reveal that C-BPN’s transmission spectrum has significant degrees of directional anisotropy and it undergoes a metal-insulator transition under strain, which leads to an increase in its Seebeck coefficient. C-BPN’s lattice thermal conductance can be selectively tuned up to 35% bidirectionally at room temperature by strain engineering. Enhancement in its power factor and the suppression of its lattice thermal conductance improves the p-type figure of merit up to 0.31 and 0.76 at 300 and 1000 K, respectively. Our findings reveal that C-BPN has high potency to be used in thermoelectric nano devices with selective anisotropic properties at elevated temperatures. Copyright © 2024, The Authors. All rights reserved.

关键词： Metal insulator transition

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