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arXiv 2025年

作者： Li, Xuefeng Pant, Nick Rahman, Sheikh Ifatur Armitage, Rob Rajan, Siddharth Kioupakis, Emmanouil Feezell, Daniel University of New Mexico AlbuquerqueNM87106 United States Department of Materials Science & Engineering University of Michigan Ann ArborMI48109 United States Applied Physics Program University of Michigan Ann ArborMI48109 United States Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Lumileds LLC San JoseCA95131 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States

We investigate the impact of quantum well (QW) thickness on efficiency loss in c-plane InGaN/GaN LEDs using a small-signal electroluminescence (SSEL) technique. Multiple mechanisms related to efficiency loss are independently examined, including injection efficiency, carrier density vs. current density relationship, phase space filling (PSF), quantum confined stark effect (QCSE), and Coulomb enhancement. An optimal QW thickness of around 2.7 nm in these InGaN/GaN LEDs was determined for quantum wells having constant In composition. Despite better control of deep-level defects and lower carrier density at a given current density, LEDs with thin QWs still suffer from an imbalance of enhancement effects on the radiative and intrinsic Auger-Meitner recombination coefficients. The imbalance of enhancement effects results in a decline in internal quantum efficiency (IQE) and radiative efficiency with decreasing QW thickness at low current density in LEDs with QW thicknesses below 2.7 nm. We also investigate how LED modulation bandwidth varies with quantum well thickness, identifying the key trends and their implications for device performance. Copyright © 2025, The Authors. All rights reserved.

关键词： Semiconductor quantum wells

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Defect-driven relaxation of nanostructured Cu examined by in situ heating high-energy synchrotron X-ray microbeam diffraction

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Journal of Alloys and Compounds 2025年 1028卷

作者： Lee, Isshu Bhatta, Laxman Xu, Donghua Blankenburg, Malte Lienert, Ulrich Liss, Klaus-Dieter Kawasaki, Megumi Materials Science Program Oregon State University CorvallisOR97331 United States School of Mechanical Industrial and Manufacturing Engineering Oregon State University CorvallisOR97331 United States Hamburg22607 Germany University of Tennessee Oak Ridge Innovation Institute KnoxvilleTN37996 United States

Bulk nanostructured metals introduced by severe plastic deformation contain an excess of lattice defects. A nanostructured copper (Cu) processed by a high-pressure torsion technique was examined during in situ heating to investigate microstructural relaxation and quantify the evolution of microstructural parameters using high-energy synchrotron microbeam X-ray diffraction. While general microstructural relaxations, such as recovery, recrystallization, and subsequent grain growth, were observed, the key microstructural parameters, including grain size, microstrain, dislocation density, and thermal expansion coefficient, and their changes at critical temperatures were uniquely described and quantified through diffraction data. Based on this analysis, the stored energies driving thermally activated microstructural changes were estimated for individual defect types — grain boundaries, dislocations, and vacancies — that are expected to significantly influence the relaxation behavior of nanostructured Cu. This study demonstrates the effectiveness of diffraction characterization techniques for gaining a comprehensive understanding of the thermal stability of bulk nanostructured materials. © 2025 Elsevier B.V.

关键词： Dislocations (crystals)

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High-Performance Silicon Anodes Enabled by Multifunctional Ultrafine Silica Nanoparticle-Embedded Carbon Coatings for Lithium-Ion Batteries

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Advanced Energy materials 2025年第0期

作者： Sun, Zhefei Yin, Quanzhi Zhou, Shenghui Chen, Haoyu Wen, Sifan Yang, Huiping Wu, Xiaoyu Pan, Jianhai Han, Jiajia Yang, Hui Zhuang, Zilong Feng, Shijie Zhang, Li Peng, Dong-Liang Zhang, Qiaobao State Key Laboratory of Physical Chemistry of Solid Surfaces College of Materials Xiamen University Xiamen361005 China State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical Engineering Tan Kah Kee Innovation Laboratory Collaborative Innovation Center of Chemistry for Energy Materials Xiamen University Fujian Xiamen361005 China State Key Laboratory of Material Processing and Die & Mould Technology Department of Mechanics School of Aerospace Engineering Huazhong University of Science and Technology Hubei Wuhan430074 China Department of Mechanical Engineering University of Wisconsin-Madison MadisonWI53706 United States Materials Science and Engineering Program University of California San Diego La JollaCA92093 United States Longmen Laboratory Henan Luoyang471023 China

Silicon (Si) holds immense promise as viable anode for next-generation high-energy-density Li-ion batteries (LIBs). However, its poor ionic/electronic conductivity and significant volumetric changes during cycling lead to rapidly deteriorated LIB performance. Here, a novel multifunctional coating featuring ultrafine SiO2 nanoparticles (2-C) to resolve these challenges is proposed. This unique uSiO2-C coating provides high-efficient electron and ion transport pathways, while also improves interfacial stability and mitigates volume changes during cycling, thereby enhancing the conductivity and structural integrity of Si@uSiO2-C, as corroborated by extensive experimental and computational studies. In addition, the abundant interfaces in uSiO2-C coating facilitate Li+ transport and the evenly distributed ultrafine SiO2 nanoparticles impart high electrochemical reactivity and mechanical robustness. Consequently, the Si@uSiO2-C anode achieves a high reversible capacity of 2093 mAh g−1 at 0.2 A g−1, with a high initial Coulombic efficiency of 88.3%, superior rate capability and durability (1000 cycles, 928 mAh g−1 at 1.0 A g−1, 75% capacity retention). Full cells paired with commercial LiFePO4 cathodes demonstrate high cyclability, maintaining 80% capacity retention over 500 cycles at 4 C. This work highlights the vital role of multifunctional coating in promoting the electrochemical performance of Si-based anodes for high-performance LIBs. © 2025 Wiley-VCH GmbH.

关键词： SiO2 nanoparticles

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SF6 Plasma Surface Modification of Flax Fibers for Improved Adhesion in Polypropylene Composites

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Fibers and Polymers 2025年第6期26卷 2569-2579页

作者： Veiga, Anderson Thiago Vasconcelos da Silva, Yuri Ferreira Cavalcante, Rafael Cordeiro Simão, Renata Antoun Metallurgical and Materials Engineering Program COPPE Federal University of Rio de Janeiro Av. Horácio Macedo 2030 F-213 RJ Rio de Janeiro21941-599 Brazil Department of Wood Science Faculty of Forestry The University of British Columbia 2424 Main Mall VancouverBCV6T 1Z4 Canada Université Paris-Saclay SFR Condorcet FR CNRS 3417 3 Rue Des Rouges Terres Pomacle51110 France Fraunhofer Institute for Machine Tools and Forming Technology IWU Theodor-Körner-Allee 6 Saxony Zittau02763 Germany

Flax fibers have attracted growing interest in the automotive industry as an eco-friendly reinforcement for polymer composites. However, their limited interfacial compatibility with hydrophobic matrices is detrimental to adhesion, a key factor in the composite mechanical behavior. To address this issue, this study investigates the surface modification of flax fibers using sulfur hexafluoride (SF6) plasma. The proposed treatment promotes fiber surface hydrophobization while preserving their bulk properties. The effect of SF6 plasma treatments on flax fiber adhesion to polypropylene (PP) blends containing post-consumer material is thoroughly examined. The analysis, conducted using scanning electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and infrared spectroscopy, reveals that the plasma treatment induces the etching of amorphous substances present in the fibers, including amorphous cellulose, hemicelluloses, and lignin. Plasma etching in combination with fluorination significantly enhances the adhesion of flax fibers to the PP blend matrix. Notably, the treated fibers exhibit improvements in tensile strength (9%) and elastic modulus (25%) compared to untreated fibers. These findings highlight the potential of SF6 plasmas as an effective pretreatment method for natural fiber composite reinforcements. © The Author(s), under exclusive licence to the Korean Fiber Society 2025.

关键词： Sulfur hexafluoride

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CREASE-2D Analysis of Small Angle X-ray Scattering Data from Supramolecular Dipeptide Systems

arXiv

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arXiv 2025年

作者： Gupta, Nitant Akepati, Sri V.V.R. Bianco, Simona Shah, Jay Adams, Dave J. Jayaraman, Arthi Department of Chemical and Biomolecular Engineering University of Delaware NewarkDE19716 United States Data Science Program University of Delaware NewarkDE19716 United States School of Chemistry University of Glasgow GlasgowG12 8QQ United Kingdom Department of Materials Science and Engineering University of Delaware NewarkDE19716 United States

In this paper, we extend a recently developed machine-learning (ML) based CREASE-2D method to analyze the entire two-dimensional (2D) scattering pattern obtained from small angle X-ray scattering measurements of supramolecular dipeptide micellar systems. Traditional analysis of such scattering data would involve use of approximate or incorrect analytical models to fit to azimuthally-averaged 1D scattering patterns that can miss the anisotropic arrangements. Analysis of the 2D scattering profiles of such micellar solutions using CREASE-2D allows us to understand both isotropic and anisotropic structural arrangements that are present in these systems of assembled dipeptides in water and in the presence of added solvents/salts. CREASE-2D outputs distributions of relevant structural features including ones that cannot be identified with existing analytical models (e.g., assembled tubes’ cross-sectional eccentricity, tortuosity, orientational order). The representative three-dimensional (3D) real-space structures for the optimized values of these structural features further facilitate visualization of the structures. Through this detailed interpretation of these 2D SAXS profiles we are able to characterize the shapes of the assembled tube structures as a function of dipeptide chemistry, solution conditions with varying salts and solvents, and relative concentrations of all components. This paper demonstrates how CREASE-2D analysis of entire SAXS profiles can provide an unprecedented level of understanding of structural arrangements which has not been possible through traditional analytical model fits to the 1D SAXS data. © 2025, CC BY-NC-SA.

关键词： X ray scattering

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Can air carbon arc gouging sensitize stabilized or low-carbon austenitic stainless steel?

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International Journal of Pressure Vessels and Piping 2025年 217卷

作者： de Bribean Guerra, Arthur Campesan, Gabriel Roberto Bolfarini, Claudemiro Koga, Guilherme Yuuki Federal University of São Carlos Department of Materials Science and Engineering Rod. Washington Luís SP São CarlosCEP 13565–905 Brazil Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luís SP São CarlosCEP 13565–905 Brazil Rod. Washington Luís SP São CarlosCEP 13565–905 Brazil

This paper challenges the widespread skepticism surrounding the use of air carbon arc gouging (ACAG) in repair welding for critical applications in stainless steels, such as oil and gas assets, by evaluating its effects on the electrochemical properties of AISI 316L and AISI 321 austenitic stainless steels. This investigation examines the degree of sensitization and intergranular corrosion susceptibility in a simulated repair scenario. The experimental setup involved creating a gouged groove (6–7 mm depth) adjacent to the heat-affected zone (HAZ) using air carbon arc gouging (ACAG), followed by rewelding via submerged arc welding (SAW). Welded joints were analyzed under three surface preparation conditions after gouging: i) no cleaning, ii) brushing, and iii) rectifying. Electrochemical evaluation was conducted using the double loop potentiokinetic reactivation (DL-EPR) technique in accordance with ISO 12732:2017, while susceptibility to intergranular corrosion was assessed using ASTM A262-15, Practice A, oxalic acid etching tests. The results debunk the prevailing assumption that ACAG inevitably compromises the corrosion resistance of stainless steels. They demonstrate that, even without post-process cleaning, the procedure does not increase sensitization or susceptibility to intergranular attack. These findings validate ACAG as a viable, efficient, and cost-effective method for repair welding in low-carbon or stabilized austenitic stainless steels, simulating field conditions. This includes demanding industries such as oil and gas, where it ensures effective defect removal and full weld penetration while preserving asset integrity and resistance to localized corrosion. © 2025 Elsevier Ltd

关键词： Austenitic stainless steel

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HP40Nb reformer tube exposed to 950 °C – Machine learning informed microstructure evolution and multi-scale mechanical properties

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International Journal of Pressure Vessels and Piping 2025年 216卷

作者： Khan, Adnan Shunmugasamy, Vasanth C. Abuhelaiqa, Mousa Hamer, Wouter J. Laycock, Nicholas J. Mansoor, Bilal Department of Materials Science and Engineering Texas A&M University College StationTX United States Mechanical Engineering Program Texas A&M University at Qatar Doha Qatar Qatar Shell Research and Technology Center QSTP Doha Qatar Shell Global Solutions International B.V. Grasweg 31 Amsterdam1031 HW Netherlands

Austenitic stainless steel tubes extensively employed in energy sector, endure extreme service temperatures over long period of time and are susceptible to creep damage. This study investigates microstructural evolution and mechanical properties of HP40Nb (25Cr35Ni1Nb) steel exposed to 950 °C for up to 1600h, with specimens retrieved at 200h intervals. Advanced multi-scale characterization methods, including scanning electron microscopy, energy dispersive spectroscopy, and micro- and nanoindentation were utilized to analyze transformation of precipitates and resulting impact on mechanical properties. Microstructural changes (precipitate evolution, transformation and coarsening) were quantified using Machine Learning based algorithm and correlated with the mechanical properties. The as-cast microstructure comprised two primary intergranular Cr- and Nb-rich carbides in austenitic matrix. Post 200h exposure at 950 °C, secondary intragranular Cr-rich pepper carbide was observed in the austenite matrix. Following this, segregation of Si around Cr-rich precipitates occurred resulting in dark phases. At 800h, Si migrated to NbC resulting in transformation of NbC to Ni-Nb Silicide phase (G-phase). Transformation of NbC to G-phase and coarsening of the primary Cr-rich carbides was observed towards end of study at 1600h. The microstructural changes resulted in microcracks owing to precipitate transformation, coarsening and thermal coefficient mismatch. It was identified that both Nb and Cr precipitates are susceptible to microcracks post 800h at 950 °C. The study offers improved understanding of microstructural changes occurring in austenitic stainless steels used as reformer tubes during exposure to elevated service temperature. © 2025

关键词： Coarsening

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Phase Transitions of the CU6Sn5 Phase Under Electric Currents

Phase Transitions of the CU6Sn5 Phase Under Electric Current...

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International Conference on Electronics Packaging (ICEP)

作者： Shubhayan Mukherjee Yu-Chen Liu Shih-Kang Lin Department of Materials Science and Engineering National Cheng Kung University Tainan Taiwan Hierarchical Green-Energy Materials (Hi-GEM) Research Centre National Cheng Kung University Tainan Taiwan Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan Taiwan Department of Mechanical Engineering National Cheng Kung University Tainan Taiwan

ISBN: (数字)9784991191190

ISBN: (纸本)9798331514747

The performance and reliability of interfacial regions in electronic solder joints are critical for the durability of lead-free solder systems. The intermetallic compound $\text{Cu}_{6}\text{Sn}_{5}$ , which forms at the interface between Sn-based solders and Cu substrates, exists in two crystal structures: the low-temperature monoclinic phase $(\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5})$ and the high-temperature hexagonal phase $(\eta-\text{Cu}_{6}\text{Sn}_{5})$ . Although the thermal behavior of these phases is well-documented, the effects of electric current on the stability and mechanical properties of $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ remain less understood. This study investigates the impact of electric current on the microstructural evolution of $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ through high-resolution transmission electron microscopy (HR-TEM) following the synchrotron radiation-based X-ray diffraction (SR-XRD). Single-phase $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ samples were subjected to a current density of 1.5 x 10 3 A/cm 2 for 5 hours. Microstructural observations from HR-TEM, following SR-XRD, reveal significant insights into the behavior of monoclinic $\eta^{\prime}-\text{Cu}_{6}\text{Sn}_{5}$ under electric current stressing. These findings offer insights into the relationship between electric current and phase stability in interfacial compounds, which could enhance the reliability of solder joints in advanced electronic systems.

关键词： X-ray scattering Synchrotrons High-resolution transmission electron microscopy materials reliability X-ray diffraction Stability analysis Compounds Current Soldering Thermal stability

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Intermetallic Compound Formation and Growth Behavior Between Ruthenium and Tin System

Intermetallic Compound Formation and Growth Behavior Between...

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International Conference on Electronics Packaging (ICEP)

作者： Hsiu-mei Yang Tzu-hsuan Huang Yu-hsuan Lin Min-cian Chen Shih-kang Lin Department of Materials Science and Engineering National Cheng Kung University Tainan Taiwan Program on Semiconductor Packaging and Testing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan Taiwan Taiwan Semiconductor Manufacturing Company Limited Hsinchu Taiwan

ISBN: (数字)9784991191190

ISBN: (纸本)9798331514747

This study investigates the liquid/solid reflow process under a vacuum environment of 1 Pa at reflow temperatures of 300°C for different reaction times. The research finds that at the Sn/Ru interface, during 300°C reflow for 24 hours, the RU 3 Sn 7 intermetallic compound was formed. As the reflow time increases, the IMC thickness increases. This study provides a fundamental understanding of the interfacial reactions between Sn and Ru. The mechanisms of the interfacial reactions and the growth kinetics of the intermetallic compounds (IMC) will be revealed through phase diagrams, thermodynamics, and kinetic analysis.

关键词： Thermodynamics Ruthenium Tin Atoms Kinetic theory Intermetallic Compounds Microstructure Substrates Electronics packaging

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Change in Magnetic Order in NiPS3 Single Crystals Induced by a Molecular Intercalation

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Chemistry of materials 2025年第10期37卷 3594-3607页

作者： Chakraborty, Nirman Harchol, Adi Arnold, Beatriz Costa Sharma, Kusha Prabhu Gaonkar, Diksha Abu-Hariri, Azhar Yadav, Rajesh Kumar Dawod, Muhamed Eyal, Anna Amouyal, Yaron Brumme, Thomas Heine, Thomas Naveh, Doron Lifshitz, Efrat Schulich Faculty of Chemistry Solid State Institute Russel Berrie Nanotechnology Institute Grand Program for Energy and the Helen Diller Quantum Center Technion-Israel Institute of Technology Haifa3200003 Israel Helmholtz-Zentrum Dresden-Rossendorf Bautzner Landstr. 400 Dresden01328 Germany Center for Advanced Systems Understanding CASUS Untermarkt 20 Gorlitz02826 Germany Faculty of Engineering Bar-Ilan University Ramat-Gan5290002 Israel Institute of Nanotechnology and Advanced Materials Bar-Ilan University Ramat-Gan5290002 Israel Department of Materials Science and Engineering Technion-Israel Institute of Technology Haifa3200003 Israel Department of Physics Technion Haifa3200003 Israel Department of Theoretical Chemistry Technische Universität Dresden Bergstrasse 66 Dresden01069 Germany Yonsei University and ibs-cnm Seoul120-749 Korea Republic of

Intercalation is a robust method for tuning the physical properties of a vast number of van der Waals (vdW) materials. However, the prospects of using intercalation to modify magnetism in van der Waals (vdW) systems and the associated mechanisms have not been adequately studied. In this work, we modulated magnetic order in XY antiferromagnet NiPS3 single crystals by introducing pyridine molecules into the vdW’s gap under different thermal conditions. X-ray diffraction measurements indicated pronounced changes in the lattice parameter β, while magnetization measurements at in-plane and out-of-plane configurations exposed reversal trends in the crystals’ Néel temperatures through intercalation/deintercalation processes. The changes in magnetic ordering were also supported by three-dimensional thermal diffusivity experiments. The preferred orientation of the pyridine dipoles within the vdW gaps was deciphered via polarized Raman spectroscopy. The results highlighted the relationship between the preferential alignment of the intercalants, thermal transport, and crystallographic disorder, along with the modulation of anisotropy in the magnetic order. DFT + U calculations indicated that the varying interlayer exchange interactions, regulated by intercalants, were responsible for modulating samples’ magnetic ordering. The study uncovers the possible merit of intercalation for manipulating spin orientations in spin electronics and advanced quantum devices. © 2025 American Chemical Society.

关键词： Magnetization reversal

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