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SSRN 2024年

作者： Wiklund, Urban Hassila, Carl-Johan Malmelöv, Andreas Andersson, Carl Fisk, Martin Lundbäck, Andreas Hektor, Johan Applied Materials Science Uppsala University UppsalaSE-751 03 Sweden Department of Engineering Sciences and Mathematics Luleå University of Technology LuleåSE-971 87 Sweden Materials Science and Applied Mathematics Malmö University MalmöSE-205 06 Sweden Division of Solid Mechanics Lund University P.O. Box 118 LundSE-221 00 Sweden

The presence of residual stresses in produced parts is a well-recognizedphenomenon. These residual stresses not only elevate the risk of crack formation but also imposelimitations on in-service performance. Moreover, it can distort printed parts if released, or inthe worst case even cause a build to fail due to collision with the powder scrape. This studyintroduces a thermo-mechanical finite element model designed to predict the impact of variousscanning strategies. The investigation focuses on the deformation and the residual stresses oftwo geometries manufactured by laser-based powder bed fusion (PBF-LB). To account for relaxationeffects during the process, a mechanism-based material model has been implemented andused. Additionally, a purely mechanical model, based on the inherent strain method, has beencalibrated to account for different scanning strategies. To assess the predicted residual stresses,high-energy synchrotron measurements have been used to obtain values for comparison. Thepredictions of the models are evaluated, and their accuracy is discussed in terms of the physicalaspects of the PBF-LB process. Both the thermo-mechanical models and the inherent strainmethod capture the trend of experimentally measured residual stress fields. While deformationsare adequately captured, there is an overall underprediction of their magnitude. © 2024, The Authors. All rights reserved.

关键词： Residual stresses

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Tuning photoresponse of graphene-black phosphorus heterostructure by electrostatic gating and photo-induced doping

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Chinese Chemical Letters 2022年第1期33卷 368-373页

作者： Yanpeng Liu Ming Yang Junpeng Lu Ying Liu Hongwei Liu Erwen Zhang Wei Fu Junyong Wang Zhenliang Hu Jun Yin Goki Eda Shijie Wang Jiabao Yi Ajayan Vinu Kian Ping Loh Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Applied Physics The Hong Kong Polytechnic UniversityHong KongChina School of Physics Southeast UniversityNanjing 211189China College of Jincheng Nanjing University of Aeronautics and AstronauticsNanjing 211156China School of Physics and Technology Nanjing Normal UniversityNanjing 210023China Department of Chemistry National University of SingaporeSingapore 117543Singapore Institute of Materials Research and Engineering Agency for ScienceTechnology and Research(A*STAR)Innovis 138634Singapore Global Innovative Centre for Advanced Nanomaterials College of EngineeringScience and EnvironmentThe University of NewcastleNewcastle NSW 2308Australia

Metal-semiconductor diodes constructed from two-dimensional(2D)van der Waals heterostructures show excellent gate electrostatics and a large built-in electric field at the tunnel junction,which can be exploited to make highly sensitive *** we demonstrate a metal-semiconductor photodiode constructed by the monolayer graphene(Gr)on a few-layer black phosphorus(BP).Due to the presence of a built-in potential barrier(~0.09±0.03 eV)at the Gr-BP interface,the photoresponsivity of the Gr-BP device is enhanced by a factor of 672%,and the external quantum efficiency(EQE)increases to648%from 84%of the bare *** gating allows the BP channel to be switched between p-type and n-type *** further demonstrate that excitation laser power can be used to control the current polarity of the Gr-BP device due to photon-induced *** versatility of the Gr-BP junctions in terms of electrostatic bias-induced or light-induced switching of current polarity is potentially useful for making dynamically reconfigurable digital circuits.

关键词： Black phosphorous Graphene Heterostructure Gate-tunable Photodetector Photoinverter

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A deformation mismatch strategy enables over 120% stretchability of encapsulated serpentine silicon strips for stretchable electronics

FlexMat

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FlexMat 2024年第2期1卷 150-159页

作者： Yihao Shi Bingchang Zhang Jianzhong Zhao Jiahao Qin Ke Bai Jia Yu Xiaohong Zhang Institute of Functional Nano & Soft Materials (FUNSOM) Jiangsu Key Laboratory of Advanced Negative Carbon Technologies Soochow University Suzhou China School of Optoelectronic Science and Engineering Key Laboratory of Advanced Optical Manufacturing Technologies of Jiangsu Province Key Laboratory of Modern Optical Technologies of Education Ministry of China Soochow University Suzhou China Applied Mechanics Laboratory Department of Engineering Mechanics Tsinghua University Beijing China Laboratory of Flexible Electronics Technology Tsinghua University Beijing China Bingchang Zhang Jianzhong Zhao and Xiaohong Zhang. Suzhou Industrial Park Monash Research Institute of Science and Technology Monash University Suzhou China Department of Materials Science and Engineering Monash University Clayton Victoria Australia

It is significant to develop stretchable electronics based on silicon materials for practical applications. Although various stretchable silicon structures have been reported, electronic systems based on them exhibit limited stretchability due to the constraints between them and polymer substrates. Here, an innovative strategy of deformation mismatch is proposed to break the constraints between silicon structures and polymers and effectively reduce the strain concentration in silicon structures. As a result, encapsulated serpentine silicon strips (S-Si strips) achieve unprecedented stretchability, exceeding 120%. The encapsulated S-Si strip also exhibits remarkable mechanical stability and durability, enduring 100 000 cycles of 100% stretch without fracture. The effect of key parameters, including the central angle, thickness, and width of the S-Si strip, on the deformation mismatch is revealed through combing experiments and theoretical analysis, which will guide the rational implementation of the deformation mismatch strategy. Electrical testing showcases the strain-insensitive nature and good electrical stability of encapsulated S-Si strips, benefiting practical applications. This work provides a new paradigm of silicon materials with excellent stretchability and will facilitate the development of stretchable electronics.

关键词： deformation mismatch encapsulated serpentine silicon strips stretchable electronics stretchable silicon structures

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Layer-dependent optically induced spin polarization in InSe

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Physical Review B 2023年第11期107卷 115304-115304页

作者： Jovan Nelson Teodor K. Stanev Dmitry Lebedev Trevor LaMountain J. Tyler Gish Hongfei Zeng Hyeondeok Shin Olle Heinonen Kenji Watanabe Takashi Taniguchi Mark C. Hersam Nathaniel P. Stern Applied Physics Program Northwestern University Evanston Illinois 60208 USA Department of Physics and Astronomy Northwestern University Evanston Illinois 60208 USA Department of Material Science and Engineering Northwestern University Evanston Illinois 60208 USA Computational Science Division Argonne National Laboratory Lemont Illinois 60439 USA Material Science Division Argonne National Laboratory Lemont Illinois 60439 USA Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba 305-0044 Japan International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba 305-0044 Japan Department of Chemistry Northwestern University Evanston Illinois 60208 USA Department of Electrical Engineering and Computer Science Northwestern University Evanston Illinois 60208 USA

Optical control of spin in semiconductors has been pioneered using nanostructures of III-V and II-VI semiconductors, but the emergence of two-dimensional van der Waals materials offers an alternative low-dimensional platform for spintronic phenomena. Indium selenide (InSe), a group-III monochalcogenide van der Waals material, has shown promise for optoelectronics due to its high electron mobility, tunable direct band gap, and quantum transport. In addition to these confirmed properties, there are predictions of spin-dependent optical selection rules, suggesting the potential for all-optical excitation and control of spin in a two-dimensional layered material. Despite these predictions, layer-dependent optical spin phenomena in InSe have yet to be explored. Here, we present measurements of layer-dependent optical spin dynamics in few-layer and bulk InSe. Polarized photoluminescence reveals layer-dependent optical orientation of spin, thereby demonstrating the optical selection rules in few-layer InSe. Spin dynamics are also studied in many-layer InSe using time-resolved Kerr rotation spectroscopy. By applying out-of-plane and in-plane static magnetic fields for polarized emission measurements and Kerr measurements, respectively, the g factor for InSe was extracted. Further investigations are done by calculating precession values using a k·p model, which is supported by ab initio density functional theory. Comparison of predicted precession rates with experimental measurements highlights the importance of excitonic effects in InSe for understanding spin dynamics. Optical orientation of spin is an important prerequisite for optospintronic phenomena and devices, and these first demonstrations of layer-dependent optical excitation of spins in InSe lay the foundation for combining layer-dependent spin properties with advantageous electronic properties found in this material.

关键词： Magneto-optics Spin dynamics Chalcogenides Layered semiconductors Van der Waals systems Density functional theory Kerr effect Photoluminescence k dot p method

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Revealing the high-frequency attenuation mechanism of polyurea-matrix composites

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Acta Mechanica Sinica 2020年第1期36卷 130-142页

作者： J.Cheng Z.L.Liu C.C.Luo T.Li Z.J.Li Y.Kang Z.Zhuang Applied Mechanics Laboratory School of Aerospace EngineeringTsinghua UniversityBeijing100084China Key Laboratory of Advanced Materials of Ministry of Education Department of Chemical EngineeringTsinghua UniversityBeijing100084China School of Materials Science and Engineering Tsinghua UniversityBeijing100084China

In this paper,a method for analyzing the high-frequency attenuation property of polyurea-matrix composites is developed by combining experimental,computational and theoretical ***,the ultrasonic experimental platform is established by solving the difficulties of high-frequency ultrasonic testing as high-frequency signal distortion,insufficient driving voltage and sampling rate failure,to study the dynamic mechanical properties(1-5 MHz)of pure polyurea and polyurea-matrix ***,the influences of composite parameters including the size and volume fraction of inclusions on wave attenuation performance under different frequencies are obtained and further verified by numerical ***,the contribution of inclusions to the wave attenuation performance is also theoretically *** is found that the increase of inclusion volume fraction and inclusion diameter will increase the attenuation coefficient of the *** the attenuation of composites with the inclusions of a 150-μm diameter and 30%as volume fraction can be 82%higher than pure *** amplifying attenuation effect of inclusions is mainly attributed to the scattering effect,which is verified by comparing numerical and theoretical results.

关键词： Polyurea Viscoelastic Dynamic mechanical properties Ultrasound

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Increased light-emission efficiency in disordered InGaN through the correlated reduction of recombination rates

arXiv

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arXiv 2023年

作者： Pant, Nick Kioupakis, Emmanouil Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Materials Science & Engineering University of Michigan Ann ArborMI48109 United States

Experiments have shown that the light-emission efficiency of indium gallium nitride (InGaN) light-emitting diodes improves with increasing indium concentration. It is widely thought that compositional fluctuations due to indium incorporation suppress diffusion of carriers to non-radiative centers, thus leading to defect-insensitive emission. However, recent experiments have challenged this hypothesis by revealing unexpectedly long diffusion lengths at room temperature. Here, we demonstrate an alternative mechanism involving the correlated reduction in radiative and nonradiative recombination rates that explains the increase in light-emission efficiency of InGaN with increasing indium concentration, without invoking the suppression of carrier diffusion. Our analysis challenges the notion that carrier localization gives rise to defect tolerance in InGaN. Copyright © 2023, The Authors. All rights reserved.

关键词： III-V semiconductors

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Learning from 2D: machine learning of 3D effective properties of heterogeneous materials based on 2D microstructure sections

arXiv

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arXiv 2023年

作者： Hu, Guangyu Latypov, Marat I. Department of Materials Science and Engineering University of Arizona TucsonAZ85721 United States Graduate Interdisciplinary Program in Applied Mathematics University of Arizona TucsonAZ85721 United States

Microstructure–property relationships are key to effective design of structural materials for advanced applications. Advances in computational methods enabled modeling microstructure-sensitive properties using 3D models (e.g., finite elements) based on microstructure representative volumes. 3D microstructure data required as input to these models are typically obtained from either 3D characterization experiments or digital reconstruction based on statistics from 2D microstructure images. In this work, we present machine learning (ML) approaches to modeling effective properties of heterogeneous materials directly from 2D microstructure sections. To this end, we consider statistical learning models based on spatial correlations and convolutional neural networks as two distinct ML strategies. In both strategies, models are trained on a dataset of synthetically generated 3D microstructures and their properties obtained from micromechanical 3D simulations. Upon training, the models predict properties from 2D microstructure sections. The advantage of the presented models is that they only need 2D sections, whose experimental acquisition is more accessible compared to 3D characterization. Furthermore, the present models do not require digital reconstruction of 3D microstructures. © 2023, CC BY.

关键词： Microstructure

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Large effective magnetic fields from chiral phonons in rare-earth halides

arXiv

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arXiv 2023年

作者： Luo, Jiaming Lin, Tong Zhang, Junjie Chen, Xiaotong Blackert, Elizabeth R. Xu, Rui Yakobson, Boris I. Zhu, Hanyu Department of Materials Science and Nano Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Rice University HoustonTX77005 United States

Time-reversal symmetry (TRS) is pivotal for materials’ optical, magnetic, topological, and transport properties. Chiral phonons, characterized by atoms rotating unidirectionally around their equilibrium positions, generate dynamic lattice structures that break TRS. Here we report that coherent chiral phonons, driven by circularly polarized terahertz light pulses, can polarize the paramagnetic spins in CeF3 like a quasi-static magnetic field on the order of 1 Tesla. Through time-resolved Faraday rotation and Kerr ellipticity, we found the transient magnetization is only excited by pulses resonant with phonons, proportional to the angular momentum of the phonons, and growing with magnetic susceptibility at cryogenic temperatures, as expected from the spin-phonon coupling model. The time-dependent effective magnetic field quantitatively agrees with that calculated from phonon dynamics. Our results may open a new route to directly investigate mode-specific spin-phonon interaction in ultrafast magnetism, energy-efficient spintronics, and non-equilibrium phases of matter with broken TRS. Copyright © 2023, The Authors. All rights reserved.

关键词： Phonons

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Bioplastic reinforced with parthenocarpic date palm fibers:Characterization and microorganisms involved in degradation

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Food Bioscience 2023年第1期51卷 1202-1211页

作者： Hammadi Hamza Imen Bettaieb Ameni Benltoufa Achraf Ghorbal Hela Ben Ahmed Walid Elfalleh Arid and Oases Cropping Laboratory Arid Area InstituteMedenine4119Tunisia Energy WaterEnvironment and Process Laboratory(LR18ES35)National Engineering School of GabesUniversity of GabesGabes6072Tunisia Research Unit Advanced Materials Applied MechanicsInnovative Processes and EnvironmentUR22ES04Higher Institute of Applied Sciences and Technology of Gabes(ISSATG)University of GabesGabes6072Tunisia Laboratory of Plant Soil and Environment Interactions LR21ES01 Department of BiologyFaculty of Science of Tunis2092 TunisUniversity of Tunis EL ManarTunis1068Tunisia

The environment suffers more and more from the accumulation of plastics made by petrochemical rows,which are *** is why this study aims to develop bio-based films by incorporating fibers concentrate of parthenocarpic date(FCPD)as easily available *** FCPD based film showed enhanced thickness,water solubility,phenol content and antioxidant ***,the transparency was reduced which enhanced the film opacity by the addition of *** electronic microscopy(SEM)showed homogeneity between fibers and the constituents of the *** addition of FCPD did not change the FTIR peaks in comparison with starch-based *** hydroxyl index value and water contact angle showed that the hydrophilicity increases with the film FCPD *** addition,the FCPDs have enhanced the microbial biodegradation of the developed films as showed by *** PCR using specific primers for nine target microbial groups showed that fungi were the predominant agent of the *** bacteria,realtime PCR showed thatβ-Proteobacteria,Acidobacteria,Bacteriodetes andα-Proteobacteria groups were involved in film biodegradation.

关键词： Parthenocarpic date Fibers Bioplastic Biodegradation SEM qPCR

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Precipitation-strengthened micromechanical behaviors of magnesium alloy under cyclic loading

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Journal of Magnesium and Alloys 2024年

作者： Liu, Chuhao Xie, Di Gao, Yanfei Zhang, Xiaodan Zhong, Shengyi Wang, Huamiao An, Ke Liaw, Peter K. Peng, Yinghong State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China Department of Materials Science and Engineering The University of Tennessee KnoxvilleTN37996 United States School of mechanical engineering and automation Fuzhou University Fujian 350116 China School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200249 China SJTU Paris Elite Institute of Technology Shanghai Jiao Tong University Shanghai200240 China Neutron Scattering Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Shanghai Frontier Science Center of Mechanoinformatics Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering Science Shanghai University Shanghai200072 China

The microscopic-deformation mechanisms of an extruded magnesium alloy with and without precipitates [Guinier-Preston (GP) zones] subjected to cyclic deformation were investigated by in-situ neutron-diffraction (ND) measurements and crystal-plasticity modeling. The relationship between the macroscopic-cyclic-deformation behavior and the microscopic responses (particularly twinning and detwinning) at the grain level was established. The general deformation-mechanism evolution in the solution-state (ST) sample was similar to that in the peak-aged-state (PA) sample over fatigue cycles. Both samples plastically deformed by extension twinning during compression, and by a sequential process of detwinning and dislocation motion under reverse tension. The main difference is that in the PA sample, the presence of precipitating particles constrains the twinning/detwinning behaviors, which leads to an increase in the participation of dislocation slip in the plastic deformation and then induces a strengthening effect during cyclic loading. Based on the combination of the previous in-situ ND results and crystal-plasticity model, our work provides a comprehensive analysis of the interaction between the precipitation strengthening and twinning/detwinning mechanism under the whole multi-cycle cyclic loading and their effect on the macro- and micro-mechanical behavior of the precipitate-strengthened magnesium alloys. © 2024

关键词： Magnesium alloys

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