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Low-Temperature Mechanical Alloying Of Cu-Fe and Cu-Ta Powders

MRS Online Proceedings Library 2020年第1期481卷 637-642页

作者： He, J.-H. Ma, E. Materials Science and Engineering Program Department of Mechanical Engineering Louisiana State University Baton Rouge USA

A model analysis is presented which explains ball-milling induced alloying in positive-heatof- mixing systems in terms of a dynamic balance between externally forced mixing and thermal phase decomposition mediated by deformation-enhanced population of defects. The possibility of eliminating the thermal decomposition to force single phase formation is examined by milling Cu-Fe and Cu-Ta powder mixtures at the liquid nitrogen temperature (LN2T). Over a range of compositions for Cu-Fe and almost the entire composition range for Cu-Ta, the two-phase region observed for room-temperature (RT) milling persisted after cryomilling. The moderate temperature dependence of milling-induced alloying is interpreted by analyzing the dynamics of the generation and annihilation of the nonequilibrium vacancies during deformation and impacts in a SPEX mill.

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Defect engineering Centrosymmetric 2D Material Flexocatalysts

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Small 2024年第31期20卷 2401116-2401116页

作者： Chen, Yu-Ching Chen, Po-Han Liao, Yin-Song Chou, Jyh-Pin Wu, Jyh Ming Department of Materials Science and Engineering National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Ph.D. Program in Prospective Functional Materials Industry National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Tsing Hua Interdisciplinary Program National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan Department of Physics National Changhua University of Education No. 1 Jin-De Road Changhua500 Taiwan High Entropy Materials Center National Tsing Hua University 101 Section 2 Kuang Fu Road Hsinchu300 Taiwan

In this study, the flexoelectric characteristics of 2D TiO2 nanosheets are examined. The theoretical calculations and experimental results reveal an excellent strain-induced flexoelectric potential (flexopotential) by an effective defect engineering strategy, which suppresses the recombination of electron–hole pairs, thus substantially improving the catalytic activity of the TiO2 nanosheets in the degradation of Rhodamine B dye and the hydrogen evolution reaction in a dark environment. The results indicate that strain-induced bandgap reduction enhances the catalytic activity of the TiO2 nanosheets. In addition, the TiO2 nanosheets degraded Rhodamine B, with kobs being ≈1.5 × 10−2 min−1 in dark, while TiO2 nanoparticles show only an adsorption effect. 2D TiO2 nanosheets achieve a hydrogen production rate of 137.9 µmol g−1 h−1 under a dark environment, 197% higher than those of TiO2 nanoparticles (70.1 µmol g−1 h−1). The flexopotential of the TiO2 nanosheets is enhanced by increasing the bending moment, with excellent flexopotential along the y-axis. Density functional theory is used to identify the stress-induced bandgap reduction and oxygen vacancy formation, which results in the self-dissociation of H2O on the surface of the TiO in the dark. The present findings provide novel insights into the role of TiO2 flexocatalysis in electrochemical reactions. © 2024 Wiley-VCH GmbH.

关键词： Titanium dioxide

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Freeform Direct-write and Rewritable Photonic Integrated Circuits in Phase-Change Thin Films

arXiv

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arXiv 2023年

作者： Wu, Changming Deng, Haoqin Huang, Yi-Siou Yu, Heshan Takeuchi, Ichiro Ríos Ocampo, Carlos A. Li, Mo Department of Electrical and Computer Engineering University of Washington SeattleWA98195 United States Department of Materials Science and Engineering University of Maryland College ParkMD20742 United States School of Microelectronics Tianjin University Tianjin300072 China Institute for Research in Electronics and Applied Physics University of Maryland College ParkMD20742 United States Department of Physics University of Washington SeattleWA98195 United States

Photonic integrated circuits (PICs) with rapid prototyping and reprogramming capabilities promise revolutionary impacts on a plethora of photonic technologies. Here, we report direct-write and rewritable photonic circuits on a low-loss phase change material (PCM) thin film. Complete end-to-end PICs are directly laser written in one step without additional fabrication processes, and any part of the circuit can be erased and rewritten, facilitating rapid design modification. We demonstrate the versatility of this technique for diverse applications, including an optical interconnect fabric for reconfigurable networking, a photonic crossbar array for optical computing, and a tunable optical filter for optical signal processing. By combining the programmability of the direct laser writing technique with PCM, our technique unlocks opportunities for programmable photonic networking, computing, and signal processing. Moreover, the rewritable photonic circuits enable rapid prototyping and testing in a convenient and cost-efficient manner, eliminate the need for nanofabrication facilities, and thus promote the proliferation of photonics research and education to a broader community. © 2023, CC BY.

关键词： Phase change materials

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Strength and Toughness of Silicide Matrix materials Consolidated by Hot Isostatic Pressing

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MRS Online Proceedings Library 2020年第1期322卷 191-196页

作者： R. Suryanarayanan S. M. L. Sastry K. L. Jerina Materials Science & Engineering Program Department of Mechanical Engineering Washington University St. Louis USA

Substantial improvements have been reported in high temperature strength and creep resistance, and room temperature fracture toughness of molybdenum disilicide (MoSi2) reinforced with ductile or brittle reinforcements. The influence of Hot Isostatic Pressing (HIP) process parameters on the mechanical properties of MoSi2 based alloys was studied. Monolithic MoSi2 powder and MoSi2 powder blended with either niobium powder or silicon carbide whisker reinforcements were consolidated by HIP at 1200–1400°C, 207 MPa, and 1–4 hrs. The HIP’ed compacts were characterized for compression strength and creep resistance at 1100–1300°C. Fracture toughness was measured on single edge notched rectangular specimens at room temperature. Mechanical properties were correlated with post-HIP microstructural features.

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Interface-Induced Ferromagnetism in lateral NiBr2 and NiCl2 Heterostructure

arXiv

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arXiv 2024年

作者： Ozdemir, Ilkay Seyedmohammadzadeh, Mahsa Yüksel, Yusuf Aktürk, Olcay Uzengi Akinci, Ümit MiloševiĆ, Milorad V. Tongay, Seth Ariel Barth, Johannes V. Aktürk, Ethem Physics Department Adnan Menderes University Aydin09100 Turkey Department of Physics University of Antwerp Groenenborgerlaan 171 AntwerpB-2020 Belgium Physics Department Faculty of Science Dokuz Eylul University Tinaztepe Campus Izmir35390 Turkey Department of Electrical Electronic Engeneering Adnan Menderes University Aydin09010 Turkey Materials Science and Engineering School for Engineering of Matter Transport and Energy Arizona State University TempeAZ85287 United States James Franck Strasse1 Garching85748 Germany Nanotechnology Application and Research Center Adnan Menderes University Aydin09010 Turkey

Magnetic skyrmions are promising candidates for future information storing and processing devices. There are different routes for stabilizing the skyrmions. Understanding the interplay mechanism between different scenarios of skyrmion formation is one key factor that can reveal new paths for controlling skyrmion phases. Inspired by the flexibility of two-dimensional materials that offer an exciting playground for manipulating spin textures, we conducted ab initio simulations and utilized four-state spin framework to determine magnetic parameters of lateral heterostructure formed by NiBr2 and NiCl2 Monolayers. The obtained spin interaction parameters are utilized to determine the skyrmionic phases via Monte Carlo simulation. Monte Carlo simulation results suggest three distinct phase transition mechanisms exist in the present system. Namely, examination of heat capacity versus temperature curve obtained from average anisotropic exchange energy yields a phase transition between paramagnetic and spin-spiral states at 5K for pristine NiBr2, a paramagnetic-mixed skyrmion state transition occurs at 17K for pristine NiCl2, and a high-temperature ferromagneticparamagnetic transition at T = 80K is observed for the heterostructure region, indicating that some kind of intrinsic ferromagnetism may originate at the interface of pristine Janus structures. © 2024, CC BY.

关键词： Textures

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Utilization of plastic waste processing for oil fuel at Tambaan Beach, Pasuruan City

Utilization of plastic waste processing for oil fuel at Tamb...

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2019 International Conference on Innovation and Technology, ICIT 2019

作者： Rudianto, R. Yudaningtyas, E. Lelono, T.D. Kasitowati, R.D. Marine Science Study Program Faculty of Fisheries and Marine Science Universitas Brawijaya Malang Indonesia Department of Electrical Engineering Faculty of Engineering Universitas Brawijaya Malang Indonesia Fisheries Resource Utilization Study Program Faculty of Fisheries and Marine Science Universitas Brawijaya Malang Indonesia

The amount of waste in Indonesia is estimated to reach 68 million tons in 2019, of which 9.52 million tons is a plastic waste. With this amount, Indonesia is ranked second in the world as the largest producer of plastic waste. One area that suffers from plastic waste is the coastal area. This plastic waste is difficult to decompose and cause environmental problems. Likewise, it happened on the Tambaan coast in Tambaan sub-district, Panggungrejo subdistrict, Pasuruan city. Currently, accumulation of plastic waste is evident throughout the coastal area. The accumulation of scattered plastic waste and its proximity to the residents' settlements has become a hotbed of mosquitoes and caused a pungent smell. The Serving Doctoral program at Universitas Brawijaya offers a solution to process plastic waste into fuel oil such as diesel, kerosene, and premium. The technology used was Muryani's distillation from Wlingi, Blitar Regency. The technology can change certain types of plastic waste to produce fuel. Karang Taruna Bina Hang Tuah was acted as a reliable partner to assist the implementation of the technology on site. This study aims to strengthen the capacity of Karangtaruna in Tambaan Village to be more concerned about the environmental problems of Tambaan beach by processing waste that has been polluted by plastic waste. The results of plastic waste treatment showed that 10 kg of dried plastic waste can be transformed into diesel, premium and kerosene with the efficiency value of 60%, 35%, and 15%, respectively. © Published under licence by IOP Publishing Ltd.

关键词： Distillation

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Tensor-Monopole-Induced Topological Boundary Effects in Four-Dimensional Acoustic Metamaterials

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Physical Review Letters 2025年第18期134卷 186601-186601页

作者： Qingyang Mo Shanjun Liang Cuicui Lu Jie Zhu Shuang Zhang New Cornerstone Science Laboratory Department of Physics University of Hong Kong 999077 Hong Kong China School of Professional Education and Executive Development The Hong Kong Polytechnic University Hong Kong China Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurements of Ministry of Education Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems Center for Interdisciplinary Science of Optical Quantum and NEMS Integration School of Physics Beijing Institute of Technology Beijing 100081 China Institute of Acoustics School of Physics Science and Engineering Tongji University 200092 Shanghai China Department of Electrical & Electronic Engineering University of Hong Kong 999077 Hong Kong China Quantum Science Center of Guangdong-Hong Kong-Macao Great Bay Area 3 Binlang Road Shenzhen China Materials Innovation Institute for Life Sciences and Energy (MILES) HKU-SIRI Shenzhen People’s Republic of China

Gauge field theory provides the mathematical and conceptual framework to describe and understand topological singularities such as Weyl points and magnetic monopoles. While singularities associated with vector electromagnetic gauge fields have been well studied, those of higher-form tensor gauge fields, like the four-dimensional (4D) tensor monopoles predicted by string theory, have remained largely theoretical or limited to experimental demonstration in pure synthetic dimensions, thereby not allowing investigations of the associated boundary effects. Here, we present a 4D system with tensor monopoles using engineered acoustic metamaterials. Our momentum space combines three real momentum dimensions and a geometric parameter as the fourth. By varying this fourth momentum, we experimentally reveal two distinct topological surface states in 3D subsystems: Fermi-arc surface states in a gapless subsystem and Dirac-cone surface states in a gapped subsystem. Our work introduces a novel platform for exploring new topological structures associated with tensor gauge field and topological phenomena in higher dimensions.

关键词： Momentum

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AlPO4 in Silica Glass Optical Fibers: Deduction of Additional Material Properties

IEEE Photonics Journal

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IEEE Photonics Journal 2019年第5期11卷 1-13页

作者： Yu, Nanjie Hawkins, Thomas W. Bui, Thao-Vien Cavillon, Maxime Ballato, John Dragic, Peter D. Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign UrbanaIL United States Center for Optical Materials Science and Engineering Technologies Department of Materials Science and Engineering Clemson University AndersonSC United States

A silica clad optical fiber with a core comprised of SiO2, P2O5, Al2O3, and AlPO4 is analyzed in order to determine the impact of AlPO4 when added to silica. A chromatic dispersion curve is presented, from which the nonlinear refractive index is estimated to be similar to that of silica. When doped into SiO2, AlPO4 decreases the thermo-optic coefficient (slightly), decreases the acoustic velocity, broadens the Brillouin spectral width through increased viscoelastic damping, and reduces the strength of the dependence of Brillouin frequency on temperature. Findings herein indicate that AlPO4 has a near-zero value of p12. It also is found that the fiber does not have complete AlPO4 formation, with some P2O5 formation in Al2O3-rich regions of the fiber. Given the relevance of AlPO4 to high power active fiber technology, the presented data can be used for designing fibers with enhanced performance characteristics, such as those with elevated threshold for the onset of stimulated Brillouin scattering. © 2009-2012 IEEE.

关键词： Silica

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Topological Phases on Quantum Trees

arXiv

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arXiv 2023年

作者： Westström, Alex Duan, Wenbu Yao, Kangpei Wang, Xiaonan Liu, Jie Li, Jian Department of Physics School of Science Westlake University Zhejiang Hangzhou China Key Laboratory for Quantum Materials of Zhejiang Province School of Science Westlake University Zhejiang Hangzhou China Institute of Natural Sciences Westlake Institute for Advanced Study Zhejiang Hangzhou China College of Electrical and Information Engineering Hunan University Hunan Changsha China

In this work, we present a theory for topological phases for quantum systems on tree graphs. Conventionally, topological phases of matter have been studied in regular lattices, but also in quasicrystals and amorphous settings. We consider specific generalizations of regular tree graphs, and explore their topological properties. Unlike conventional systems, infinite quantum trees are not finite-dimensional, allowing for novel phenomena. We find a proliferation of topological zero modes present throughout the entire system, indicating that the bulk also acts as a boundary. We then go on to show that only three symmetry classes host stable topological phases in contrast to the usual five symmetry classes per dimension. Finally, we introduce what we call the Su-Schrieffer-Heeger tree which is topologically non-trivial even in the absence of inner degrees of freedom and does not possess any gapped trivial phases. We realize this system in an electronic circuit and show that our theory matches with experiments. Copyright © 2023, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Local and global measures of the shear moduli of jammed disk packings

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Physical Review E 2023年第5期107卷 054903-054903页

作者： Shiyun Zhang Weiwei Jin Dong Wang Ding Xu Jerry Zhang Mark D. Shattuck Corey S. O'Hern Department of Physics University of Science and Technology of China Hefei Anhui 230026 China Department of Mechanical Engineering and Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA Graduate Program in Computational Biology and Bioinformatics Yale University New Haven Connecticut 06520 USA

Strain-controlled isotropic compression gives rise to jammed packings of repulsive, frictionless disks with either positive or negative global shear moduli. We carry out computational studies to understand the contributions of the negative shear moduli to the mechanical response of jammed disk packings. We first decompose the ensemble-averaged, global shear modulus as 〈G〉=(1−F−)〈G+〉+F−〈G−〉, where F− is the fraction of jammed packings with negative shear moduli and 〈G+〉 and 〈G−〉 are the average values from packings with positive and negative moduli, respectively. We show that 〈G+〉 and 〈|G−|〉 obey different power-law scaling relations above and below pN2∼1. For pN2>1, both 〈G+〉N and 〈|G−|〉N∼(pN2)β, where β∼0.5 for repulsive linear spring interactions. Despite this, 〈G〉N∼(pN2)β′ with β′≳0.5 due to the contributions from packings with negative shear moduli. We show further that the probability distribution of global shear moduli P(G) collapses at fixed pN2 and different values of p and N. We calculate analytically that P(G) is a Γ distribution in the pN2≪1 limit. As pN2 increases, the skewness of P(G) decreases and P(G) becomes a skew-normal distribution with negative skewness in the pN2≫1 limit. We also partition jammed disk packings into subsystems using Delaunay triangulation of the disk centers to calculate local shear moduli. We show that the local shear moduli defined from groups of adjacent triangles can be negative even when G>0. The spatial correlation function of local shear moduli C(r⃗) displays weak correlations for pnsub2<10−2, where nsub is the number of particles within each subsystem. However, C(r⃗) begins to develop long-ranged spatial correlations with fourfold angular symmetry for pnsub2≳10−2.

关键词： Jamming Packing & jamming problems Granular materials

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