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Observation of possible excitonic charge density waves and metal–insulator transitions in atomically thin semimetals

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Nature Physics 2024年第4期20卷 597-602页

作者： Gao, Qiang Chan, Yang-Hao Jiao, Pengfei Chen, Haiyang Yin, Shuaishuai Tangprapha, Kanjanaporn Yang, Yichen Li, Xiaolong Liu, Zhengtai Shen, Dawei Jiang, Shengwei Chen, Peng Shenyang National Laboratory for Materials Science Shanghai Center for Complex Physics School of Physics and Astronomy Shanghai Jiao Tong University Shanghai China Institute of Atomic and Molecular Sciences Academia Sinica Taipei Taiwan Physics Division National Center for Theoretical Sciences Taipei Taiwan Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai China College of Engineering International Advanced Technology Program National Taiwan University of Science and Technology Taipei Taiwan Chinese Academy of Sciences Shanghai China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei China

In solids, the condensation of electron and hole pairs with finite momentum leads to an ordered state known as a charge density wave, in which the charge has spatial modulation. However, lattice symmetry breaking and the accompanying relocation of the ions, which changes the charge distribution, can also occur simultaneously, making it difficult to disentangle the origin of the transition. Here we demonstrate a condensed phase in low-dimensional HfTe2. Angle-resolved photoemission spectroscopy measurements reveal a metal–insulator transition upon lowering the temperature. The observation of an opening gap, the renormalization of the bands and the emergence of replica bands in the low-temperature regime suggests that a charge density wave formed in the ground state. Raman spectroscopy shows no sign of lattice distortion within the detection limit. A small amount of electron doping substantially raises the transition temperature due to a reduced screening effect and a more balanced carrier density for electrons and holes. Our results indicate that the formation mechanism of the charge density wave is consistent with the excitonic insulator phase in low-dimensional HfTe2 without any structural modification. © The Author(s), under exclusive licence to Springer Nature Limited 2024.

关键词： Charge density waves

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Infrared Spectra Prediction for Diazo Groups Utilizing a Machine Learning Approach with Structural Attention Mechanism

arXiv

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arXiv 2024年

作者： Liu, Chengchun Mo, Fanyang School of Materials Science and Engineering Peking University Beijing100871 China -Preferred Program Peking University Shenzhen Graduate School Shenzhen518055 China

Infrared (IR) spectroscopy is a pivotal technique in chemical research for elucidating molecular structures and dynamics through vibrational and rotational transitions. However, the intricate molecular fingerprints characterized by unique vibrational and rotational patterns present substantial analytical challenges. Here, we present a machine learning approach employing a Structural Attention Mechanism tailored to enhance the prediction and interpretation of infrared spectra, particularly for diazo compounds. Our model distinguishes itself by honing in on chemical information proximal to functional groups, thereby significantly bolstering the accuracy, robustness, and interpretability of spectral predictions. This method not only demystifies the correlations between infrared spectral features and molecular structures but also offers a scalable and efficient paradigm for dissecting complex molecular interactions. Copyright © 2024, The Authors. All rights reserved.

关键词： Molecular structure

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Porous FeAl alloys via powder sintering:Phase transformation,microstructure and aqueous corrosion behavior

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Journal of materials science & Technology 2021年第27期86卷 64-69页

作者： Gang Chen Klaus-Dieter Liss Chao Chen Yuehui He Xuanhui Qu Peng Cao Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing100083PR China Materials and Engineering Science Program Guangdong Technion-Israel Institute of TechnologyShantouGuangdong515063PR China Technion-Israel Institute of Technology Haifa32000Israel School of Mechanical MaterialsMechatronic and Biomedical EngineeringFaculty of Engineering&Information SciencesUniversity of WollongongWollongongNSW2522Australia State Key Laboratory for Powder Metallurgy Central South UniversityChangsha410083PR China Department of Chemical and Materials Engineering The University of AucklandPrivate Bag 92019Auckland1142New Zealand MacDiarmid Institute of Advanced Materials and Nanotechnology Victoria University of WellingtonPO Box 600Wellington6140New Zealand

This study investigates the phase transformation and microstructure of porous Fe Al parts sintered from elemental powder mixtures using in-situ neutron diffraction and in-situ thermal dilatometry.A single B2 structured Fe Al phase was determined in the sintered Fe Al *** combined effects of the Kirkendall porosity,transient liquid phase,and phase transformations associated with powder sintering all contribute to the swelling phenomenon of the final sintered *** aqueous corrosion test indicates that the corrosion products include iron oxides in the porous Fe Al *** accumulation of corrosion products blocks the pore channel and decreases pore size and permeability over the soaking time.

关键词： Powder sintering Intermetallic Porous Corrosion Neutron diffraction

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Novel ruthenium-based catalysts with atomic dispersion for oxygen evolution reaction in water electrolysis

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materials Today Chemistry 2024年 35卷

作者： Liao, Kuo-Wei Chen, Hsueh-Yu Wei, Wen-Hui Chen, Guan-Cheng Yamanaka, Ichiro Liu, Bo-Tau Hong, Ting-Fu Chiang, Tai-Chin Huang, Hsin-Chih Wang, Chen-Hao Department of Materials Science and Engineering National Taiwan University of Science and Technology Taipei106335 Taiwan Department of Chemical Science and Engineering School of Materials and Chemical Technology Tokyo Institute of Technology Meguro-ku Tokyo152-8552 Japan Department of Chemical and Materials Engineering National Yunlin University of Science and Technology Yunlin640301 Taiwan Department of Materials Engineering National Pingtung University of Science and Technology Pingtung912301 Taiwan Global Development Engineering Program National Taiwan University of Science and Technology Taipei106335 Taiwan Advanced Manufacturing Research Center National Taiwan University of Science and Technology Taipei106335 Taiwan

This study introduces a method for fabricating ultra-high-performance catalysts designed for the oxygen evolution reaction (OER), employing a combination of ball-milling, autoclave heat treatment procedures, and a two-step heat treatment approach. This method produces catalysts characterized by an atomic dispersion of ruthenium on nitrogen-doped carbon sheets (Ru–O/N–C–NH3). The Ru–O/N–C–NH3 catalyst exhibits exceptional OER activity in alkaline conditions, achieving a mass activity of 16842 A g−1Ru at 1.52 V, and a minimal overpotential of 290 mV at a current density of 10 mA cm−2. Moreover, this catalyst demonstrates enduring stability, showing no significant decay after a 100-h stability test in anion exchange membrane water electrolysis (AEMWE), with a mass activity approximating 62000 A g−1PGM. This is nearly three orders of magnitude greater than the AEMWE that utilizes commercial IrO2 as an anode. The atomic dispersion and the Ru–O/N bonding of the catalyst are substantiated to contribute to the notable enhancement in OER activity. © 2023 Elsevier Ltd

关键词： Ruthenium

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Reconfiguring Surface Acoustic Wave Microfluidics via In Situ Control of Elastic Wave Polarization

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Physical Review Letters 2025年第3期134卷 037002-037002页

作者： Yu Gao (郜煜) Thomas Voglhuber-Brunnmaier Yuekang Li Leyla Akh Nicholas H. Patino Apresio Kefin Fajrial Massimo Ruzzene Bernhard Jakoby Xiaoyun Ding Paul M. Rady Department of Mechanical Engineering University of Colorado Boulder Colorado 80309 USA Institute for Microelectronics and Microsensors Johannes Kepler University Linz Austria Biomedical Engineering Program University of Colorado Boulder Colorado 80309 USA Materials Science and Engineering Program University of Colorado Boulder Colorado 80309 USA BioFrontiers Institute University of Colorado Boulder Colorado 80309 USA

We demonstrate in situ control of the elastic wave polarization in a surface acoustic wave (SAW). It allows us to create highly reconfigurable SAW microfluidics that can be switched on demand between the acoustohydrodynamic (AHD) regime and electrohydrodynamic (EHD) regime for manipulating particles and cells. The control of wave polarization comes from our experimental and theoretical identification of an unexpected shear-horizontal (SH) wave mode in a conventional Rayleigh (R) wave design, which is stereotyped to excite only vertically polarized Rayleigh SAWs. The SH wave mode is predominantly horizontally polarized and can be selectively excited to propagate in the same direction as the Rayleigh SAW. Such a selective wave generation between the SH mode and R mode allows for reconfiguration between AHD and EHD regimes that leads to unprecedented colloidal patterns and assembly dynamics. Such a reconfiguration of the particle manipulation mechanism can be explained by the controllable competition or synergism between the coexisting acoustic and electric fields. Remarkably, in the EHD regime, a virtual zero-boundary electric quadrupole is created, and a novel colloidal diamond-shaped assembly is observed in this piezoelectric-quadrupole trap, which was rarely reported in acoustic or electric microfluidics. The presented in situ control of polarization revolutionizes our understanding of SAW and acoustofluidics, expands its potential by assuming the advantages of AHD and EHD on demand, and inspires new strategies in micro- and nanoscale manufacturing and manipulation, with applications beyond fundamental scientific interest.

关键词： Microfluidics

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The Effect of air carbon arc gouging on the mechanical and electrochemical properties of AISI 316L submerged arc welds 11

The Effect of air carbon arc gouging on the mechanical and e...

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11th European Stainless Steel Conference science and Market, ESSC 2022 and 7th European Duplex Stainless Steel Conference and Exhibition, DUPLEX 2022

作者： Campesan, Gabriel Roberto de Bribean Guerra, Ana Paula Koga, Guilherme Yuuki Bolfarini, Claudemiro Federal University of São Carlos Department of Materials Science and Engineering Rod. Washington Luis São Carlos SP CEP 13565-905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luis São Carlos SP CEP 13565-905 Brazil

ISBN: (纸本)9788898990269

In the maintenance and manufacturing practices of equipment in the petrochemical industry, the air carbon arc gouging-ACG is used in the preparation of carbon steel joints to be repaired or joined by welding. However, the Standards impose several restrictions to the use of this cost-effective process to stainless steels. The main concern is the pick-up of carbon and sensitization of the steels against corrosion. Therefore, this paper aimed to evaluate the effect of ACG of AISI 316L steel on its electrochemical and mechanical properties. The repaired/welded joints were studied in three different situations, namely: i) any type of cleaning, ii) brushing and iii) machining after gouging. The 20-mm-thick plate was submerged arc welded. Different regions on cross-section of welds were inspected to assess the degree of sensitization by double-loop electrochemical potentiokinetic reactivation (DL-EPR) method, and the risk of intergranular corrosion by oxalic acid etching tests. The electrochemical techniques and mechanical tests (only welded joints) such as tensile, hardness and impact measurements showed no impairing of such properties with the use of ACG, irrespective to the cleaning method used. © ESSC and DUPLEX 2022. All rights reserved.

关键词： Welds

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Approach to nonisothermal crystallization kinetics of poly(4-methyl-1-pentene) melt: Effect of gamma-ray

SPE Polymers

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SPE Polymers 2021年第1期2卷 50-61页

作者： Chang, Yuan-Hsiang Zhang, Yulin Chiang, Donyau Yang, Fuqian Lee, Sanboh Department of Materials Science and Engineering National Tsing Hua University Hsinchu Taiwan Materials Program Department of Chemical and Materials Program University of Kentucky Lexington KY United States Taiwan Instrument Research Institute National Applied Research Laboratories Hsinchu Taiwan

Understanding the effect of gamma-ray irradiation on the nonisothermal crystallization of polymer during cooling is of practical importance for the applications and manufacturing of crystallized polymer. In this work, we expose poly(4-methyl-1-pentene) (PMP) to gamma-ray with different irradiation doses and study the crystallization of the gamma-ray irradiated PMPs. All the PMPs exhibit a doublet peak in the differential scanning calorimeter thermograms for the cooling rates in a range of 2.5–20°C/min. We use linear superposition of two inverse Gaussian functions to decompose the doublet peak into two individual peaks and analyze the crystallization kinetics of the crystallization processes associated with individual peaks. The Avrami exponent decreases with the decrease of the crystallization temperature and is in a range of 0.96–2.43 for the crystallization near the melting point and a range of 0.72–1.68 for the crystallization away the melting temperature. The activation energy for the crystallization near the melting temperature decreases with the increase of the irradiation dose. For the crystallization away from the melting temperature, the activation energy for the PMPs without gamma-ray irradiation is smallest. © 2021 The Authors. SPE Polymers published by Wiley Periodicals LLC. on behalf of Society of Plastics Engineers.

关键词： activation energy crystallization doublet peak gamma-ray irradiation poly(4-methyl-1-pentene)

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Perspective on the perovskite quantum dots for flexible photovoltaics

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Journal of Energy Chemistry 2021年第11期30卷 505-507,I0011页

作者： Jiabei Yuan Nopporn Rujisamphan Wanli Ma Jianyu Yuan Youyong Li Shuit-Tong Lee Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory of Carbon-Based Functional Materials and DevicesSoochow UniversitySuzhou 215123JiangsuChina Macao Institute of Materials Science and Engineering Macao University of Science and TechnologyTaipa 999078MacaoChina Nanoscience and Nanotechnology Graduate Program Faculty of ScienceKing Mongkut’s University of Technology ThonburiBangkok 10140Thailand

Owing to the ever-increasing charging demand for portable electronics,display devices and wearable electronic textiles,flexible and lightweight solar cells are highly urgent to be ***-generation solution-processable photovoltaic(PV)devices attracted great attentions due to their unique properties of low-cost,lightweight,and large-area printing compatibility with flexible substrates[1].

关键词： printing perovskite compatibility

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PBF-AMP-Onto: an ontology for powder bed fusion additive manufacturing processes 1

PBF-AMP-Onto: an ontology for powder bed fusion additive man...

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1st International Workshop on Semantic materials science: Harnessing the Power of Semantic Web Technologies in materials science, SeMatS 2024

作者： Pour, Mina Abd Nikooie Tarafder, Prithwish Wiberg, Anton Li, Huanyu Moverare, Johan Lambrix, Patrick Department of Computer and Information Science Linköping University Linköping Sweden Swedish e-Science Research Centre Linköping University Linköping Sweden Department of Management and Engineering Linköping University Linköping Sweden Wallenberg Initiative Materials Science for Sustainability Linköping University Linköping Sweden Wallenberg AI Autonomous Systems and Software Program Linköping University Linköping Sweden

Additive manufacturing is an innovative production approach aimed at creating products that traditional techniques cannot produce with the desired quality and requirements. Throughout the additive manufacturing process, data is either used (such as materials properties, printer characteristics and settings) or generated (such as monitoring data during printing, slicing strategies setting parameters). However, managing such data with complex relationships remains a significant challenge in both research and industry in the additive manufacturing field. To address this issue, we developed a modular ontology that can be used as the basis for a framework that supports decision-making systems, facilitate semanticsaware data management, and enhance the understanding and optimization of additive manufacturing processes. In this paper we focus on one of the state-of-the-art additive manufacturing approaches, i.e., powder bed fusion. To show the use and the feasibility of our approach, we created a knowledge graph for an actual additive manufacturing experiment based on our ontology, and show how queries relevant to domain experts can be answered using this knowledge graph. © 2024 CEUR-WS. All rights reserved.

关键词： Ontology

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Sintering-based lithography metal additive manufacturing of chiral mechanical metamaterials with a twist

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Procedia CIRP 2025年 132卷 104-109页

作者： Ruslan Melentiev Ahmed Wagih Bram van der Heijden Gilles Lubineau Carlos A. Grande Advanced Membranes & Porous Materials Center. King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia KAUST Catalysis Center. King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Mechanical Engineering Program Physical Sciences and Engineering Division King Abdullah University of Science and Technology (KAUST) Saudi Arabia Mechanics of Composites for Energy and Mobility Lab King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Chemical Engineering Program. Physical Science and Engineering Division King Abdullah University of Science and Technology

Metamaterials are a class of materials with extraordinary capabilities derived from their engineered structure. In 2017, Frenzel et al. (science 358, 2017) conceptualized “three-dimensional mechanical metamaterials with a twist,” which convert linear deformation into rotational motion—a mechanical response that surpasses the bounds of Cauchy continuum mechanics. However, the lack of suitable manufacturing technologies for producing metallic twist metamaterials has precluded their experimental validation and potential applications to date. Herein, 316L-stainless-steel twist metamaterials are fabricated at various scales using an emerging sintering-based technology—lithography metal manufacturing (LMM) —and their mechanical responses are tested using stereo digital image correlation. Results provide the first empirical evidence of compression-induced rotation in steel twist metamaterials and highlight their sensitivity to manufacturing defects. Download: Download video (753KB) Download: Download video (2MB) Download: Download video (4MB)

关键词： Additive manufacturing sintering stainless steel metamaterials mechanical properties

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