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Stacking, strain, and twist in 2D materials quantified by 3D electron diffraction

Physical Review materials 2019年第6期3卷 064003-064003页

作者： Suk Hyun Sung Noah Schnitzer Lola Brown Jiwoong Park Robert Hovden Department of Materials Science and Engineering University of Michigan Ann Arbor Michigan 48109 USA Intel Electronics Kiryat Gat 82109 Israel Department of Chemistry University of Chicago Chicago Illinois 60637 USA Institute for Molecular Engineering University of Chicago Chicago Illinois 60637 USA James Franck Institute University of Chicago Chicago Illinois 60637 USA Applied Physics Program University of Michigan Ann Arbor Michigan 48109 USA

The field of two-dimensional (2D) materials has expanded to multilayered systems in which electronic, optical, and mechanical properties change—often dramatically—with stacking order, thickness, twist, and interlayer spacing. For transition metal dichalcogenides (TMDs), bond coordination within a single van der Waals layer changes the out-of-plane symmetry that can cause metal-insulator transitions or emergent quantum behavior. Discerning these structural order parameters is often difficult using real-space measurements; however, we show that 2D materials have distinct, conspicuous three-dimensional (3D) structure in reciprocal space described by nearly infinite oscillating Bragg rods. Combining electron diffraction and specimen tilt we probe Bragg rods in all three dimensions to identify multilayer structure with subangstrom precision across several 2D materials—including TMDs (MoS2, TaSe2, TaS2) and multilayer graphene. We demonstrate quantitative determination of key structural parameters such as surface roughness, inter- and intralayer spacings, stacking order, and interlayer twist using a rudimentary transmission electron microscope. We accurately characterize the full interlayer stacking order of multilayer graphene (1, 2, 6, 12 layers) as well the intralayer structure of MoS2 and extract a chalcogen-chalcogen layer spacing of 3.07±0.11 Å. Furthermore, we demonstrate quick identification of multilayer rhombohedral graphene.

关键词： 2-dimensional systems Graphene Honeycomb lattice Transition metal dichalcogenides Electron diffraction Electron microscopy Symmetries Transmission electron microscopy

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Theoretical and Experimental studies on Characterisation and Collection of Particulate Matter in Single-Wire, Single-Stage Electrostatic Precipitator with Square Cross-Section

SSRN

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SSRN 2024年

作者： Kumar, Aiswarya A. Nawale, Prashant Rohidas Mayya, Y.S. Sahu, Manoranjan Aerosol and Nanoparticle Technology Laboratory Environmental Science and Engineering Department Indian Institute of Technology Bombay Mumbai400076 India Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai400076 India Centre for Machine Intelligence and Data Science Indian Institute of Technology Bombay Mumbai400076 India Chemical Engineering Department Indian Institute of Technology Bombay Mumbai400076 India

Electrostatic precipitation (ESP) is a technology widely used to remove particulate matter (PM) from industrial gas streams. To adopt the same for varying scales as well as for different clean air delivery applications, there exists a requirement for the development of comprehensive, readily adaptable, reasonably good, comparable, rigorous, step-by-step analytical theory and experimental validation of same for design of modular units of ESP. In this regard, current study conducted theoretical and experimental studies to investigate corona characterisation and PM collection efficiency in a modular unit of a single-wire, single-stage, wire-plate ESP with square cross-sectional geometry. The theory integrated the corona discharge with particle transport while the experimental study was conducted using a laboratory scale ESP. Best agreement between I-V characteristics of theory and experiment was obtained while adjusting inception electric field to 12.35´105 Vm-1 as well as the ion diffusion coefficient value to 0.0647´10-4 m2s-1. Relative error for local minimum efficiency between theory as well as experiment for three tested flow rates 30 LPM, 50 LPM and 100 LPM were 5.37%, 1.36%, 14.58% and was 1.36%, 7.52% and 6.23% for three potentials 9 kV, 11 kV as we all as 13 kV respectively. As accuracy and reliability of present model are verified in terms of collecting efficiency at different operating conditions, present model can facilitate the design and scale-up of ESPs for indoor PM control with high collection efficiency. The study also illustrated a sample calculation on the applicability of this filter-less technology for air cleaning in an indoor environment. © 2024, The Authors. All rights reserved.

关键词： Electrostatic precipitators

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Emission energy barriers of scandate surfaces with adsorbed Ba and Ba-O using Density Functional Theory

Emission energy barriers of scandate surfaces with adsorbed ...

引用

IEEE International Vacuum Electronics Conference

作者： Ryan M. Jacobs Dane Morgan John H. Booske Materials Science Program University of Wisconsin-Madison 1415 Engineering Dr. Madison WI USA 53706

ISBN: (纸本)9781467359764

Density functional theory was used to calculate the surface electron emission barriers for the stable (011) and (111) surfaces of bixbyite Sc_20_3 in the presence of adsorbed Ba and Ba-O. A low surface barrier of 1.21 eV for a defected BaO monolayer on Sc_2O_3 (011) was found to be thermodynamically stable. This result provides a straightforward explanation of low effective work function measurements obtained for scandate cathodes.

关键词： surface barrier work function density functional theory scandium oxide scandate cathode

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A Wireless, Multi-Channel Printed Capacitive Strain Gauge System for Structural Health Monitoring

A Wireless, Multi-Channel Printed Capacitive Strain Gauge Sy...

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IEEE SENSORS

作者： Kshama L. Ranganatha Kaelee Novich Timothy Phero Kiyo T. Fujimoto Doug Litteken Dave Estrada Brian J. Jaques Benjamin C. Johnson Boise State University Boise ID Micron School of Materials Science and Engineering Boise State University Boise ID Center for Advanced Energy Studies Idaho Falls ID USA NASA Johnson Space Center Houston TX USA

Structural health monitoring of soft structural textiles plays a key role within the space industry to ensure the safety and integrity of space habitats, parachutes, and decelerator systems. Strain monitoring could be an effective means to evaluate structural integrity, but conventional monitoring systems are not suitable because they are intended for large, rigid structures. To overcome the limitations of rigid sensors, we recently proposed using printed capacitive strain gauges (CSGs) on flexible substrates to monitor the structural health of soft structure materials. Here, we present a strategy and implementation of a wireless, multi-channel readout system for distributed monitoring of soft structural textiles with printed CSGs. The system is comprised of localized sensor motes and a wireless Bluetooth hub. The sensor mote employs a relaxation oscillator frontend to convert capacitance to frequency with a high dynamic range using only three interface wires per mote. The mote’s high dynamic range ensures compatibility with various gauge designs and accommodates significant process variation associated with printed gauges. Each hub enables users to read 8 channels of data wirelessly at a sampling rate of 100Hz and can be scaled to higher channel counts through the use of additional hubs. The sensor motes and wireless hub are miniaturized to accommodate flexible substrates, such as a Kevlar strap. The system is tested and exhibits excellent linearity and dynamic range.

关键词： Wireless communication Wireless sensor networks Space technology Buildings Dynamic range Strain measurement Capacitive sensors

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Modified Metal−Organic Frameworks for Electrochemical Applications

Small Structures

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Small Structures 2022年第5期3卷

作者： Chen, Kefan Wang, Xiao-Li Hu, Wenhui Kong, Qingquan Pang, Huan Xu, Qiang School of Chemistry and Chemical Engineering Yangzhou University Jiangsu Yangzhou 225009 China Institute for Advanced Study Chengdu University Sichuan Chengdu 610106 China Department of Materials Science and Engineering SUSTech Academy for Advanced Interdisciplinary Studies and Guangdong-Hong Kong-Macao Joint Laboratory for hotonic-Thermal-Electrical Energy Materials and Devices Southern University of Science and Technology (SUSTech) Guangdong Shenzhen 518055 China

Metal−organic frameworks (MOFs) are neo-type porous materials synthesized via organic ligands and metal ions, which have drawn much attention due to their unparalleled advantages such as high specific surface area, large and clear pore structures, and uniformly distributed active sites. In these years, modified MOFs are regarded as kinds of materials with excellent electrochemical properties, that overcome poor conductivity and stability of original MOFs and narrow the gap between the basic science of MOFs and their future applications. At the same time, it also provides an opportunity to elaborate the synergistic effect of the synthesis strategy of modified MOFs on the performance. This review focuses on the synthesis, structure characterization, and electrochemical adhibition of modified MOFs and discusses the challenges and application prospects of modified MOFs in energy storage and conversion. © 2022 Wiley-VCH GmbH.

关键词： electrocatalysis electrochemical energy storage modified metal−organic frameworks

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Hazard at weather scale for extreme rainfall forecast reduces uncertainty

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Water Security 2021年 14卷

作者： Tripathy, Shrabani S. Karmakar, Subhankar Ghosh, Subimal Interdisciplinary Program in Climate Studies Indian Institute of Technology Bombay Mumbai 400076 India Environemntal Science and Engineering Department Indian Institute of Technology Bombay Mumbai 400076 India Department of Civil Engineering Indian Institute of Technology Bombay Mumbai 400076 India

Globally increasing intensity and frequency of extreme rainfall events demand reliable early warning systems. Despite significant improvements in the skills of weather models, the state-of-art extreme rainfall forecasts, at a sufficient lead time, still suffer from high biases, high uncertainties, low hit rates, and high false alarms. Bias correction methods often improve the performances of the models, but still, the skills remain moderate. Here, we propose a new methodology to forecast extreme rainfall events, in terms of hazard, instead of rainfall amount. At a weather scale, we define ‘hazard’ as the probability of occurrence of an extreme rainfall event, given a forecasted rainfall for a day with sufficient lead time. The conditional probability is obtained from the past observed data and the hindcast. The method is applied to India with observations from the India Meteorological Department (IMD) and hindcasts from the Global Ensemble Forecast System (GEFS) Reforecast Version 2 for 1985–2015. Extreme days at a grid level are defined as the days with observed rainfall exceeding the 95th percentile. Accordingly, we calculate the hazard for all the lead days till 15 days. For most of the extremes in each grid, the model can predict an extreme showing a high hazard value greater than 0.6 from lead day 7. This high hit rate may give the stakeholders adequate time to plan mitigation strategies. Comparing the proposed method with traditional methods, we find a significant improvement in terms of hit rate and the uncertainty across the ensembles. © 2021 Elsevier B.V.

关键词： Extreme rainfall Hazard Probabilistic forecast Weather forecast

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Elucidating Dynamic Conductive State Changes in Amorphous Lithium Lanthanum Titanate for Resistive Switching Devices

arXiv

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arXiv 2023年

作者： Shimizu, Ryosuke Cheng, Diyi Zhu, Guomin Han, Bing Marchese, Thomas S. Burger, Randall Xu, Mingjie Pan, Xiaoqing Zhang, Minghao Meng, Ying Shirley Department of NanoEngineering University of California San Diego La Jolla CA United States Materials Science and Engineering Program University of California San Diego La Jolla CA United States Pritzker school of Molecular Engineering University of Chicago ChicagoIL60637 United States Irvine Materials Research Institute University of California Irvine IrvineCA92697 United States

Exploration of novel resistive switching materials attracts attention to replace conventional Si-based transistor and to achieve neuromorphic computing that can surpass the limit of the current Von-Neumann computing for the time of Internet of Things (IoT). materials priorly used to serve as an electrode or electrolyte in batteries have demonstrated metal-insulator transitions upon an external electrical biasing due to resulting compositional change. This property is desirable for future resistive switching devices. Amorphous lithium lanthanum titanate (a-LLTO) was originally developed as a solid-state electrolyte with relatively high lithium ionic conductivity (~10-3 S/cm) and low electronic conductivity (~10-10 S/cm) among oxide-type solid electrolytes. However, it has been suggested that electric conductivity of a-LLTO changes depending on oxygen content. In this work, the investigation of switching behavior of a-LLTO sandwiched by nickel electrodes was conducted by employing a range of voltage sweep techniques, ultimately establishing a stable and optimal operating condition within the voltage window of -3.5 V to 3.5 V. This voltage range effectively balances the desirable trait of a substantial resistance change by three orders of magnitude with the imperative avoidance of LLTO decomposition. This switching behavior is also confirmed at nanodevice of Ni/LLTO/Ni through in-situ biasing inside focused-ion beam/scanning electron microscope (FIB-SEM). Experiment and computation with different LLTO composition shows that LLTO has two distinct conductivity states due to Ti reduction. The distribution of these two states is discussed using simplified binary model, implying the conductive filament growth during low resistance state. Consequently, our study deepens understanding of LLTO electronic properties and encourages the interdisciplinary application of battery materials for resistive switching devices. © 2023, CC BY.

关键词： Electric conductivity

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Evolution of magnetism in the magnetic topological semimetal NdSbxTe2−x+δ

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Physical Review B 2024年第18期109卷 184429-184429页

作者： Santosh Karki Chhetri Rabindra Basnet Jian Wang Krishna Pandey Gokul Acharya Md Rafique Un Nabi Dinesh Upreti Josh Sakon Mansour Mortazavi Jin Hu Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Physics University of Arkansas at Pine Bluff Pine Bluff Arkansas 71603 USA Department of Chemistry and Biochemistry Wichita State University Wichita Kansas 67260 USA Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Biochemistry University of Arkansas Fayetteville Arkansas 72701 USA

Magnetic topological semimetals LnSbTe (Ln=lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Recently, varying Sb-Te composition has been found to effectively control the electronic and magnetic states in LnSbxTe2−x. With this motivation, we report the evolution of magnetic properties with Sb-Te substitution in NdSbxTe2−x+δ, (0≤x≤1). Our work reveals the interesting nonmonotonic change in magnetic ordering temperature with varying composition stoichiometry. In addition, reducing the Sb content x drives the reorientation of moments from in-plane (ab-plane) to out-of-plane (c-axis) direction that results in the distinct magnetic structures for two end compounds NdTe2 (x=0) and NdSbTe (x=1). Furthermore, the moment orientation in NdSbxTe2−x+δ is also found to be strongly tunable upon application of a weak magnetic field, leading to rich magnetic phases depending on the composition stoichiometry, temperature, and magnetic field. Such strong tuning of magnetism in this material establishes it as a promising platform for investigating tunable topological states and correlated topological physics.

关键词： Charge density waves Magnetic phase transitions Spin reorientation transition

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Graphene calorimetric single-photon detector

arXiv

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arXiv 2024年

作者： Huang, Bevin Arnault, Ethan G. Jung, Woochan Fried, Caleb Russell, B. Jordan Watanabe, Kenji Taniguchi, Takashi Henriksen, Erik A. Englund, Dirk Lee, Gil-Ho Fong, Kin Chung Intelligence Community Postdoctoral Research Fellowship Program Massachusetts Institute of Technology CambridgeMA02139 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Pohang University of Science and Technology Pohang790-784 Korea Republic of Department of Physics Washington University in St. Louis St. LouisMO United States Research Center for Electronic and Optical Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan RTX BBN Technologies Quantum Engineering and Computing Group CambridgeMA02138 United States

Single photon detectors (SPDs) [1, 2] are essential technology in quantum science, quantum network, biology, and advanced imaging [3-5]. To detect the small quantum of energy carried in a photon, conventional SPDs rely on energy excitation across either a semiconductor bandgap or superconducting gap. While the energy gap suppresses the false-positive error, it also sets an energy scale that can limit the detection efficiency of lower energy photons and spectral bandwidth of the SPD [6-8]. Here, we demonstrate an orthogonal approach to detect single near-infrared photons using graphene calorimeters [9-13]. By exploiting the extremely low heat capacity of the pseudo-relativistic electrons in graphene near its charge neutrality point [14], we observe an electron temperature rise up to ∼2 K using a hybrid Josephson junction. In this proof-of-principle experiment, we achieve an intrinsic quantum efficiency of 87% (75%) with dark count © 2024, CC BY.

关键词： Particle beams

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End-to-end symmetry preserving inter-atomic potential energy model for finite and extended systems 18

End-to-end symmetry preserving inter-atomic potential energy...

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Proceedings of the 32nd International Conference on Neural Information Processing Systems

作者： Linfeng Zhang Jiequn Han Han Wang Wissam A. Saidi Roberto Car E. Weinan Program in Applied and Computational Mathematics Princeton University Institute of Applied Physics and Computational Mathematics China and CAEP Software Center for High Performance Numerical Simulation China Department of Mechanical Engineering and Materials Science University of Pittsburgh Program in Applied and Computational Mathematics Princeton University and Department of Chemistry and Department of Physics Princeton University and Princeton Institute for the Science and Technology of Materials Princeton University Program in Applied and Computational Mathematics Princeton University and Department of Mathematics Princeton University and Beijing Institute of Big Data Research China

Machine learning models are changing the paradigm of molecular modeling, which is a fundamental tool for material science, chemistry, and computational biology. Of particular interest is the inter-atomic potential energy surface (PES). Here we develop Deep Potential - Smooth Edition (DeepPot-SE), an end-to-end machine learning-based PES model, which is able to efficiently represent the PES of a wide variety of systems with the accuracy of ab initio quantum mechanics models. By construction, DeepPot-SE is extensive and continuously differentiable, scales linearly with system size, and preserves all the natural symmetries of the system. Further, we show that DeepPot-SE describes finite and extended systems including organic molecules, metals, semiconductors, and insulators with high fidelity.

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