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Novel Optical materials and Applications, NOMA 2020

作者： Li, Jingang Zheng, Yuebing Materials Science and Engineering Program and Texas Materials Institute University of Texas at Austin AustinTX78712 United States Department of Mechanical Engineering University of Texas at Austin AustinTX78712 United States

We report an all-optical approach to build colloids into active chiral nanostructures on a solid substrate, where the chiroptical response can be tailored on-demand. © 2020 OSA - The Optical Society. All rights r... 详细信息

ISBN: (纸本)9781943580798

关键词： Substrates

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Weak ferromagnetism in perovskite oxides

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Physical Review B 2020年第10期102卷 104420-104420页

作者： J.-S. Zhou L. G. Marshall Z.-Y. Li X. Li J.-M. He Materials Science and Engineering Program Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA

Weak ferromagnetism has been widely found in antiferromagnetic systems, including the technically important orthorhombic perovskites RFeO3 (R=rareearth) owing to spin canting associated with crystal symmetry. Antisymmetric exchange interaction (AEI) and single-ion anisotropy (SIA) are the essential mechanisms responsible for the development of noncollinear structures in antiferromagnetic systems. AEI and SIA share the same structural restriction to facilitate the spin canting. While both AEI and SIA originate from the spin-orbit coupling effect, they have sharply different dependences on the local structure. Consideration of the structural dependence of a canted spin motivates us to revisit the orthoferrite family. The spin canting along the c axis measured on precisely oriented crystals increases monotonically from LaFeO3 to LuFeO3. Based on Moriya's model, AEI is sensitive to the octahedral-site distortion in the perovskite structure. However, the site distortion does not exhibit a monotonic change with the rare-earth substitution. Instead, a linear relationship has been found in both the octahedral rotation and the spin canting angle versus the rare-earth ionic radius, which indicates that SIA plays a significant role leading the spin canting in orthoferrites.

关键词： Dzyaloshinskii-Moriya interaction Ferromagnetism Magnetic order Ferrites Perovskites

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Structural distortions in rare-earth transition-metal oxide perovskites under high pressure

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Physical Review B 2020年第22期101卷 224104-224104页

作者： J.-S. Zhou Materials Science and Engineering Program Mechanical Engineering University of Texas at Austin Austin Texas 78712 USA

Owing to their structural complexity and wide range of possible chemical combinations, perovskite oxides exhibit many technically important physical properties. Pressure is a thermodynamic parameter which is useful for tuning physical properties; however, the response of the complex crystal structure to high pressure has not been thoroughly studied and rationalized. This study focuses on in situ high-pressure x-ray diffraction of the orthorhombic perovskite oxides A3+B3+O3, commonly found for the rare-earth transition-metal oxides of the RMO3 formula. Each of the four families of RMO3 (M=Ti, Cr, Mn, Fe) perovskites in this study all crystallize in the same orthorhombic perovskite structure with the Pbnm space group. The lanthanide contraction in these materials leads to varying degrees of orthorhombic distortions that are primarily associated with octahedral site rotations. The pressure-induced change of the lattice parameters demonstrates an evolution from a suppression to an enlargement of the orthorhombic distortion for substitution of the rare-earth element from R=La to Lu in RMO3 perovskites. This unusual crossover of the lattice parameters’ dependence on pressure contradict the results from first-principles calculation but can be rationalized by the intrinsic distortion of the perovskite structure.

关键词： Pressure effects Structural properties Perovskites Transition metal oxides X-ray diffraction

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BEAST DB: Grand-Canonical Database of Electrocatalyst Properties

arXiv

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arXiv 2024年

作者： Tezak, Cooper Clary, Jacob Gerits, Sophie Quinton, Joshua Rich, Benjamin Singstock, Nicholas Alherz, Abdulaziz Aubry, Taylor Clark, Struan Hurst, Rachel Ben, Mauro Del Sutton, Christopher Sundararaman, Ravishankar Musgrave, Charles Vigil-Fowler, Derek Department of Chemical and Biological Engineering University of Colorado Boulder BoulderCO80309 United States Materials Chemical and Computational Science Directorate National Renewable Energy Laboratory GoldenCO80401 United States Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute TroyNY12180 United States Department of Chemistry University of Colorado Boulder BoulderCO80309 United States Department of Mechanical Engineering University of Colorado Boulder BoulderCO80309 United States Department of Chemical Engineering College of Engineering and Petroleum Kuwait University Safat13060 Kuwait Applied Mathematics & Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Chemistry and Biochemistry University of South Carolina ColumbiaSC29208 United States Department of Materials Science and Engineering Rensselaer Polytechnic Institute TroyNY12180 United States Materials Science and Engineering Program University of Colorado Boulder BoulderCO80309 United States Renewable and Sustainable Energy Institute University of Colorado Boulder BoulderCO80309 United States Department of Chemical Engineering University of Utah Salt Lake CityUT84112 United States

We present BEAST DB, an open-source database comprised of ab initio electrochemical data computed using grand-canonical density functional theory in implicit solvent at consistent calculation parameters. The database contains over 20,000 surface calculations and covers a broad set of heterogenous catalyst materials and electrochemical reactions. Calculations were performed at self-consistent fixed potential as well as constant charge to facilitate comparisons to the computational hydrogen electrode. This article presents common use cases of the database to rationalize trends in catalyst activity, screen catalyst material spaces, understand elementary mechanistic steps, analyze electronic structure, and train machine learning models to predict higher fidelity properties. Users can interact graphically with the database by querying for individual calculations to gain granular understanding of reaction steps or by querying for an entire reaction pathway on a given material using an interactive reaction pathway tool. BEAST DB will be periodically updated, with planned future updates to include advanced electronic structure data, surface speciation studies, and greater reaction coverage. Copyright © 2024, The Authors. All rights reserved.

关键词： Database systems

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Femtosecond Laser Ferroelectric Domains Reversal in Monodomain Calcium Barium Niobate Crystal

Femtosecond Laser Ferroelectric Domains Reversal in Monodoma...

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Laser science, LS 2021 - Part of Frontiers in Optics, FiO 2021

作者： Mazur, Leszek Mateusz Liu, Shan Chen, Xin Krolikowski, Wieslaw Sheng, Yan Advanced Materials Engineering and Modelling Group Faculty of Chemistry Wroclaw University of Science and Technology Wyb. Wyspianskiego 27 Wroclaw50-370 Poland Science Program Texas A&M University at Qatar Doha Qatar Laser Physics Centre Research School of Physics The Australian National University CanberraACT2601 Australia School of Physics and Optoelectronic Engineering Xidian University Xian710071 China

Femtosecond pulses are used for the first time to invert spontaneous polarization in the monodomain calcium barium niobate crystal. The resulting domain patterns allow transverse SHG without the nonlinear noise encoun... 详细信息

ISBN: (纸本)9781557528209

关键词： Femtosecond lasers

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Toward Perfect Surfaces of Transition Metal Dichalcogenides with Ion Bombardment and Annealing Treatment

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ACS Applied materials and Interfaces 2023年第12期15卷 16153-16161页

作者： Chen, Wan-Hsin Kawakami, Naoya Hsueh, Jing-Wen Kuo, Lai-Hsiang Chen, Jiun-Yu Liao, Ting-Wei Kuo, Chia-Nung Lue, Chin-Shan Lai, Yu-Ling Hsu, Yao-Jane Lien, Der-Hsien Hu, Chenming Chou, Jyh-Pin Luo, Meng-Fan Lin, Chun-Liang Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Physics National Central University Jhongli320 Taiwan Department of Physics National Cheng Kung University Tainan701 Taiwan Taiwan Consortium of Emergent Crystalline Materials National Science and Technology Council Taipei106 Taiwan Program on Key Materials Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan701 Taiwan Nanoscience Group National Synchrotron Radiation Research Center Hsinchu300 Taiwan Institute of Electronic Engineering National Yang Ming Chiao Tung University Hsinchu300 Taiwan International College of Semiconductor Technology National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of Physics National Changhua University of Education Changhua500 Taiwan

Layered transition metal dichalcogenides (TMDs) are two-dimensional materials exhibiting a variety of unique features with great potential for electronic and optoelectronic applications. The performance of devices fabricated with mono or few-layer TMD materials, nevertheless, is significantly affected by surface defects in the TMD materials. Recent efforts have been focused on delicate control of growth conditions to reduce the defect density, whereas the preparation of a defect-free surface remains challenging. Here, we show a counterintuitive approach to decrease surface defects on layered TMDs: a two-step process including Ar ion bombardment and subsequent annealing. With this approach, the defects, mainly Te vacancies, on the as-cleaved PtTe2 and PdTe2 surfaces were decreased by more than 99%, giving a defect density 10 cm-2, which cannot be achieved solely with annealing. We also attempt to propose a mechanism behind the processes. © 2023 American Chemical Society.

关键词： Scanning tunneling microscopy

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Photonic Metacrystal: Design and Experimental Results

Photonic Metacrystal: Design and Experimental Results

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CLEO: science and Innovations, S and I 2022

作者： Hu, S. Khater, M. Kratschmer, E. Engelmann, S. Arnold, K.P. Green, W.M.J. Weiss, S.M. Department of Electrical and Computer Engineering Vanderbilt University NashvilleTN37235 United States IBM T J Watson Center 1101 Kitchawan Road Yorktown HeightsNY10598 United States INanoBio Inc 1600 Adams Drive Menlo ParkCA94025 United States Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37235 United States

ISBN: (纸本)9781557528209

Going beyond the limited design freedoms of traditional photonic crystals, we experimentally show how photonic metacrystals exploit the inclusion of subwavelength dielectric scatterers in the unit cell to deterministically modify k-space and real space profiles. © Optica Publishing Group 2022, © 2022 The Authors.

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Poly (L-leucine) modified carbon paste electrode as an electrochemical sensor for the detection of paracetamol in presence of folic acid

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materials science for Energy Technologies 2020年 3卷 626-632页

作者： Naik, T.S. Sunil Kumar Swamy, B.E. Kumara Ramamurthy, Praveen C. Chetankumar, K. Department of P. G. Studies and Research in Industrial Chemistry Kuvempu University Jnana Sahyadri Shankaraghatta -577451 ShivamogaKarnataka India Department of Materials Engineering Indian Institute of Science Bangalore India

Here, L-leucine based electrochemical sensor was designed for the simultaneous analysis of paracetamol (PA) and folic acid (FA). Electropolymerization of L-leucine was carried out on the surface of the carbon paste electrode (CPE). The electrochemical deeds of the biomolecules were explored through cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at the fabricated sensor. The invented poly (L-leucine) modified carbon paste electrode (PLCN-MCPE) showed very good interaction with the analyte molecules which results in the significant determination of PA and FA in terms of sensitivity and selectivity. The electrochemical reaction mechanism between the surface of the developed sensor and the analytes was carried out in terms of effects of scan rate, concentration, and the electrode process was found to be adsorption-controlled. The kinetics such as the number of electron transfer (n) and the heterogeneous rate constant (ko) were defined for PA and FA at MCPE. The lower limit of detection for PA and FA were assessed to be 0.44 and 2.4 µM correspondingly. As well, the availability of the sensor in real-world sample analysis was also investigated with satisfactory results. © 2020

关键词： Electrochemical sensors

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Voting Technique for Islanding Detection in Microgrid Using Superimposed Angle Variations

Voting Technique for Islanding Detection in Microgrid Using ...

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Sustainable Energy and Future Electric Transportation (SEFET), International Conference on

作者： Harikrishna Muda Energy and Environment Program Natural Science Engineering National Institute of Advanced Studies IISc Campus Bangalore India

ISBN: (数字)9781728156811

ISBN: (纸本)9781728156828

The detection of islanding events in a microgrid is a problematic issue. In this paper, four angle variations of superimposed sequence components are derived, and a new technique is proposed using the highest aggregate votes. Space vector transform is applied to decompose positive sequences and negative sequences from power signals. From the pre-state and post-state information, mathematical relationships of superimposed components are generated, and angle variation in between the superimposed component and pre-event component of each sequence is computed. This technique identifies the islanding state, even under perfectly power match conditions without the threshold setting, and hence overcomes the non-detection zone (NDZ) problem. Also, the non-islanding states such as the variable fault resistance, single-pole tripping, recloser operation, non-linear loads, and reconnection of the DEU are addressed. The proposed technique is verified using the thirteen bus microgrid simulation model in a real-time digital environment. The proposed technique is found to be fast and accurate on the change in source capacity, location, and type of DEU.

关键词： Transportation Microgrids Transforms Real-time systems Time factors Standards Load modeling

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Polyacrylamide hydrogel containing rice husk ash as internal curing agent in mortar/concrete

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Journal of Molecular Liquids 2025年 423卷

作者： de Almeida, Edson Araujo Kruger, Fábio Rodrigo Valderrama, Patrícia da Silva Gonzalez, Regiane Muniz, Edvani Curti Chemistry Postgraduation Program Chemistry Department State University of Maringá – UEM Paraná Maringá87020-90 Brazil Civil Engineering Department Federal University of Technology – Paraná – UTFPR-CM Paraná Campo Mourão87301-899 Brazil Chemistry Department Federal University of Technology – Paraná – UTFPR-CM Paraná Campo Mourão87301-899 Brazil Food Postgraduation Program Federal University of Technology – Paraná – UTFPR-CM PR Campo Mourão87301-899 Brazil Materials Science and Engineering Postgraduation Program Federal University of Technology – Paraná – UTFPR-LD PR Londrina86036-370 Brazil Chemistry Postgraduation Program Chemistry Department Federal University of Piauí – UFPI Piauí Teresina64049-550 Brazil

Internal curing is a process based on the addition of materials that work as water reservoirs in cementitious media. Their function is to minimize the effect of water lost through evaporation and self-desiccation that occurs during curing. Hydrogels are polymeric materials that have the ability of absorbing and retaining water and releasing it in a gradual and sustained way. In this work, polyacrylamide hydrogel containing rice husk ash (PAAm/RHA) was synthesised and applied in mortar and concrete formulations. The aim was to study the influence of this material on the hydration process and on the final properties of such cementitious materials. The results indicated that the addition of as prepared composite hydrogel improved the mechanical strength and reduced shrinkage in the mortar in 23%;however, its application in concrete led to a reduction of 7.1% in the mechanical strength. Despite this, it can be postulated that the developed hydrogel acts satisfactorily for internal curing in cementitious materials. To the best of our knowledge, it is the first time that hydrogel formulation uses rice husk ash (RHA) and crosslinked polyacrylamide to be used as curing agent for mortars and concrete. Beyond the technological use of composite hydrogel as curing agent, the methodology is also interesting because rice husk ash, as by-product from rice agro-industries, was used. So, it should be seen also as a contribution for environment. © 2025 Elsevier B.V.

关键词： Mortar

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