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Microstructure and properties of as-cast Zr-2.5Nb-1X(X=Ru,Mo,Ta and Si) alloys for biomedical application

Rare Metals 2023年第10期42卷 3497-3509页

作者： Xi-Nu Tan Fei-Tao Li Yu-Shun Liu Ri-Sheng Qiu Qing Liu Electron Microscopy Center College of Materials Science and EngineeringChongqing UniversityChongqing400044China International Joint Laboratory for Light Alloys(MOE) College of Materials Science and EngineeringChongqing UniversityChongqing400044China TU Ilmenau Chair Materials for Electrical Engineering and ElectronicsInstitute of Materials Science and Engineering and Institute of Micro-and Nanotechnologies MacroNanoIlmenau98693Germany Department of Mechanical Engineering University of ManitobaWinnipegMBR3T 5V6Canada Key Laboratory for Light-Weight Materials Nanjing Tech UniversityNanjing210009China

The micro structure and properties of as-cast Zr-2.5Nb-1X(X=Ru,Mo,Ta and Si) alloy are screened to explore novel biomedical zirconium alloys for magnetic resonance *** micro structure and phase transformation were characterized using X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM).Hardness test,magnetic detection and electrochemical corrosion measurements are taken to present *** results show that all alloys consist of α-Zr,β-Zr and ω-Zr.α-Zr and β-Zr mainly exist in the form of parallel and intersecting plates,and nanoscale ω-Zr is dispersed in β-Zr ***,blocky ω-Zr with needle-like α-Zr is only found in plate-free blocks of Zr-2.5Nb-1Mo/Ru *** orientation relationship(OR) between α-Zr and ω-Zr follows [1120]_α//[1101]_ω and(0001)_α//([1011]_ω 011)_ω.Combining this OR with the OR between β-Zr and ω-Zr,the transformation relationship between β-Zr/ω-Zr and α-Zr is also ***-2.5Nb-1Ru alloy with high corrosion potential(-0.500 V),low corrosion rate(0.949 μm·year^(-1)) and low magnetic susceptibility(92×10^(-6)) shows great potential to be a novel biomedical implant with magnetic resonance imaging *** on the experimental results,the possible relationship among alloying elements,micro structure and properties has been established in these Zr-2.5Nb-1X alloys.

关键词： Zirconium alloy Microstructure Phase transformation Electrochemical corrosion Magnetic susceptibility

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Design and Optimization of Featherweight, Ultra-Thin, Flexible PET/CNF/PU Multilayered Sandwich Structure for Absorption-Dominant EMI Shielding

Design and Optimization of Featherweight, Ultra-Thin, Flexib...

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2024 IEEE Microwaves, Antennas, and Propagation Conference, MAPCON 2024

作者： Tahalyani, Jitendra Akhtar, M. Jaleel Kar, Kamal K. Materials Science Programme IIT Kanpur India Department of Electrical Engineering IIT Kanpur India

ISBN: (纸本)9798350379693

In the present work, thin, lightweight, and flexible multi-layer sandwich structure (FMSS) nanocomposite is designed and developed for next-generation EMI shielding which can be used in complex environments and conformal surfaces. Such type of FMSS nanocomposite is fabricated by encapsulating the carbon nanofiber (CNF) between the polyethylene terephthalate (PET) and polyurethane (PU). FMSS has tri-layered structure which work as an absorber-reflector-absorber. The 2 wt% CNF (FMSS2) displays both enhancement in the conductivity and shielding effectiveness (SET) in the X-band. The maximum SET of -24.80 dB is observed for FMSS2 at just 0.15 mm thickness. The micrographs and electrical conductivity of the fabricated FMSS are explored further for the absorption dominating mechanism for EMI shielding. The stacked layers of FMSS2 (0.3 mm thick) display the maximum SET of -32.61 dB, showing high resistance towards two hours of water sonication, bending horizontally/vertically, and 1000 mechanical bending cycles. The CST simulation was performed in at 8.2-12.4 GHz using the materials microwave properties and SET is verified numerically with the experimental values. The fabricated FMSS are flexible, lightweight, thin and showing advancement in the SET values can be used in conformal electronic packaging and coating in civil, defense, and aerospace applications. © 2024 IEEE.

关键词： Sandwich structures

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To suppress thermomigration of Cu–Sn intermetallic compounds in flip-chip solder joints

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Journal of materials Research and Technology 2023年 24卷 7910-7924页

作者： Huang, Yan-Rong Tran, Dinh-Phuc Hsu, Po-Ning Yang, Shih-Chi Gusak, A.M. Tu, K.N. Chen, Chih Department of Materials Science and Engineering National Chiao Tung University Hsinchu30010 Taiwan Department of Materials Science and Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Centre of Excellence for Nanophotonics Advanced Materials and Novel Crystal Growth-Based Technologies Ensemble3 Warsaw Poland Department of Materials Science and Engineering City University of Hong Kong Hong Kong Department of Electrical Engineering City University of Hong Kong Hong Kong

We report here an approach to inhibit Cu–Sn intermetallic compounds (IMCs) in flip chip solder joints under thermal-gradient annealing. We reflowed two types of solders joints, Cu/SnAg/Cu and Cu/SnAg/Ni, in an oven (isothermal) and on a hot plate (with thermal-gradient) at 260 °C. During the isothermal reflow, the IMC growth rates in the top and bottom sides of the solder joint were ∼4.0 × 10−2 and 8.9 × 10−2 μm/min, respectively. However, the IMC growth rate increased to 7.8 × 10−1, 7.9 × 10−1, and 8.9 × 10−1 μm/min in the cold ends with low, medium, and high thermal gradients, respectively. Yet, the IMC thickness on the hot ends remained almost unchanged. These results indicate that the thermal gradient has facilitated the Cu–Sn IMC formation in the cold ends. But, when a Ni film was sandwiched at the cold end, the IMC growth rates in the cold end were reduced to ∼9.7 × 10−2, 1.4 × 10−1, and 1.5 × 10−1 μm/min with low, medium, and high thermal gradients, respectively, indicating that the thermomigration of IMCs was retarded by the Ni. It is speculated that the Ni layer transformed the IMCs on the hot end into stable (Cu,Ni)6Sn5 ternary IMCs, and thus the thermomigration of Cu was suppressed. A kinetic model is also proposed to address the competitive reactions of Cu-molten solder joints. © 2023 The Author(s)

关键词： Intermetallics

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Enhanced methanol production from photothermal CO_(2) reduction via multilevel interface design

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Nano Research 2025年第2期18卷 235-241页

作者： Hongmin Wang Bo Shang Chungseok Choi Sungho Jeon Yuanzuo Gao Tyler Wang Nia J.Harmon Mengxia Liu Eric A.Stach Hailiang Wang Department of Chemistry Yale UniversityNew HavenCT 06520USA Energy Sciences Institute Yale UniversityWest HavenCT 06516USA School of Materials Science and Engineering Southeast UniversityNanjing 211189China Current address:SKKU Advanced Institute of Nanotechnology and Department of Nanoengineering Sungkyunkwan UniversitySuwon 16419Republic of Korea Department of Materials Science and Engineering University of PennsylvaniaPhiladelphiaPA 19104USA Department of Physics Yale UniversityNew HavenCT 06511USA Department of Electrical Engineering Yale UniversityNew HavenCT 06511USA

Photothermal CO_(2) hydrogenation is a promising route to produce methanol as a sustainable liquid solar ***,most existing catalysts require a combination of solar irradiation and additional heat input to achieve a satisfactory reaction *** the few that can be driven solely by light,their reaction rates are one order of magnitude *** develop a photothermal catalyst with multilevel interfaces that achieves improvedmethanol production from photothermal CO_(2) hydrogenation without external *** catalyst features a layered structure comprising Cu/ZnO/Al_(2)O_(3)(CZA)covered by oxidized carbon black(oCB),where the oCB/CZA interface promotes efficient heat generation and transfer,and the Cu/oxide interface contributes to high catalytic *** a mild pressure of 8 bar,our oCB/CZA catalyst shows a methanol selectivity of 64.7%with a superior production rate of 4.91 mmol-geza-1-h-1,at least one order of magnitude higher than other photothermal catalysts solely driven by *** work demonstrates a photothermal catalyst design strategy for liquid solar fuel production.

关键词： photothermal catalysis CO_(2)hydrogenation methanol production solar fuel multilevel interface Cu/ZnO/Al_(2)O_(3)(CZA)catalyst

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Intermittent oxidation kinetics and metal/oxide interfacial undulation

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Physical Review B 2024年第8期110卷 085402-085402页

作者： Dongxiang Wu Xianhu Sun Judith C. Yang Guangwen Zhou Department of Mechanical Engineering & Materials Science and Engineering Program Department of Chemical and Petroleum Engineering

The phenomenon of oxygen adsorption induced surface restructuring is widespread across various metal-oxygen systems, yet its impact on initiating bulk oxide formation remains largely unexplored. Through in situ atomic-resolution electron microscopy observations of surface oxidation of Cu(110) and Cu85Au15(110), we unveil intermittent oxide-film growth modulated by oxygen-induced surface restructuring. This modulation is evidenced by repeated pinning of the Cu2O growth front at isolated Cu columns of the c(6×2)-O reconstruction, owing to required long-range diffusion of Cu and O atoms to the Cu2O growth front. We reveal that Cu vacancies, generated at the Cu2O growth front, are injected into the Cu2O/Cu interface, inducing hill and valley undulation of the Cu2O film. In contrast, atomic vacancies produced during the Cu85Au15(110) oxidation preferentially migrate into interfaces between Au-rich and Au-poor regions in the bulk, resulting in a flat and adherent Cu2O film. These findings demonstrate the critical role of oxygen-induced surface restructuring in modulating oxide film growth kinetics and the manipulability of the fate of injected vacancies by alloying, thereby offering insights applicable to a broader range of metal-oxygen systems for fine-tuning oxidation kinetics and enhancing oxide/metal interfacial adhesion.

关键词： Surface & interfacial phenomena Surface reconstruction Surface growth Density functional theory Transmission electron microscopy

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A Multi-bit ECRAM-Based Analog Neuromorphic System with High-Precision Current Readout Achieving 97.3% Inference Accuracy

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IEEE Transactions on Biomedical Circuits and Systems 2024年第3期19卷 590-604页

作者： Um, Minseong Kang, Minil Eom, Kyeongho Kwak, Hyunjeong Noh, Kyungmi Lee, Jimin Son, Jeonghoon Kwon, Jiseok Kim, Seyoung Lee, Hyung-Min Korea University School of Electrical Engineering Seoul02841 Korea Republic of Korea University Department of Semiconductor System Engineering Seoul02841 Korea Republic of Pohang University of Science and Technology Department of Materials Science and Engineering Pohang37673 Korea Republic of The Catholic University of Korea School of Information Communications and Electronic Engineering Bucheon14662 Korea Republic of

This article proposes an analog neuromorphic system that enhances symmetry, linearity, and endurance by using a high-precision current readout circuit for multi-bit nonvolatile electro-chemical random-access memory (ECRAM). For on-chip training and inference, the system uses activation modules and matrix processing units to manage analog update/read paths and perform precise output sensing with feedback-based current scaling on the ECRAM array. The 250nm CMOS neuromorphic chip was tested with a 32 x 32 ECRAM synaptic array, achieving linear and symmetric updates and accurate read operations. The proposed circuit system updates the 32 x 32 ECRAM across 100 levels, maintaining consistent synaptic weights, and operates with an output error rate of up to 2.59% per column. It consumes 5.9 mW of power excluding the ECRAM array and achieves 97.3% inference accuracy on the MNIST dataset, close to the software-confirmed 97.78%, with only the final layer (64 x 10) mapped to the ECRAM. © 2007-2012 IEEE.

关键词： CMOS integrated circuits

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Topological magnonic properties of an antiferromagnetic chain

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Physical Review B 2024年第14期110卷 144448页

作者： Topojit Debnath Shri Hari Soundararaj Sohee Kwon Alexander A. Balandin Roger K. Lake Laboratory for Terahertz & Terascale Electronics (LATTE) Department of Electrical and Computer Engineering Materials Science and Engineering Department of Materials Science and Engineering

The magnonic excitations of a dimerized, one-dimensional, antiferromagnetic chain can be trivial or topological depending on the signs and magnitudes of the alternating exchange couplings and the anisotropy. The topological phase that occurs when the signs of the two different exchange couplings alternate is qualitatively different from that of the Su-Schrieffer-Heeger model. A material that may exhibit these properties is the quasi-one-dimensional material MoI3 that consists of dimerized chains weakly coupled to adjacent chains. The magnetic ground state and its excitations are analyzed both analytically and numerically using exchange and anisotropy parameters extracted from density functional theory calculations.

关键词： First-principles calculations Magnetic anisotropy Magnetic coupling Magnetic interactions Magnetic order Magnetic phase transitions Magnetic texture Magnetism Magnons Topological phase transition 1-dimensional spin chains Antiferromagnets Classical spin chains Density functional calculations Heisenberg model Holstein-Primakoff method Linear spin wave theory Quantum spin chains

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Variable Temperature Hot Casting Study of 2D Perovskite Thin Films

Variable Temperature Hot Casting Study of 2D Perovskite Thin...

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2024 IEEE MetroCon, MetroCon 2024

作者： Mather, Thomas Aryal, Sujan Kaul, Anupama B. University of North Texas Department of Electrical Engineering DentonTX76207 United States University of North Texas Department of Electrical Engineering Department of Materials Science and Engineering DentonTX76207 United States

ISBN: (纸本)9798331507640

Three-dimensional perovskites (3DP) have soared to the forefront of modern thin-film solar cell technology owing to their remarkable optoelectronic properties. These properties allow the creation of devices with power conversion efficiencies exceeding 27% steadily approaching the Shockley-Quesser limit. Despite these positive characteristics, 3DP are often inadequate and degrade when subjected to environmental conditions such as changes in temperature, moisture levels, or even sunlight itself. Ruddlesden-Popper phase two-dimensional perovskite (2DP) films are a direct counterpart to 3D perovskites and have shown great stability when compared to 3DP. However, 2DP-based devices tend to suffer from problems attributed to inherent poor charge transport characteristics caused by organic cations which act like spacers between the conductive inorganic layers. To improve charge transport we can improve the morphology of the 2DP, ideally making the film near single-crystalline quality. Near single crystal perovskites have a strongly preferential out-of-plane alignment with respect to contacts in planar devices facilitating improved charge transport. In this article, we report on how changes in temperature, specifically during fabrication, can affect the crystallography of 2DP. To examine film morphology after production, both optical and SEM images were taken of each fabricated device showing uniform films as well as unique amorphous structures. Photoluminescent spectroscopy (PL) was performed for each annealing temperature illustrating a red shift with increasing temperatures. I/V measurements were also taken to monitor the charge transport characteristics of each respective film with current levels in the nA range. An increase in current is noted from 100 to 145 degrees Celsius before dropping down at higher temperatures. Lastly, solar cells were fabricated with 2DP absorber layers hot casted at various temperatures with the peak PCE at around 2%. © 2024 IEEE.

关键词： Amorphous films

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A strategy for enhancing luminescence thermometry via Ta^(5+)-triggered K_(0.5)Na_(0.5)NbO_(3):Er^(3+)transparent ceramics

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Journal of Materiomics 2024年第5期10卷 984-994页

作者： Quan Zhang Zetian Yang Mingyuan Wang Yang Liu Shuangying Lei Laihui Luo Dirk Poelman Key Laboratory of MEMS of Ministry of Education School of Electrical Science and EngineeringSoutheast UniversityNanjing210096China LumiLab Department of Solid StateSciencesGhent UniversityKrijgslaan 281-S1GhentB-9000Belgium School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing210094China Department of Microelectronic Science and Engineering Ningbo UniversityNingbo315211China

Luminescence thermometry is a reliable approach for remote thermal sensing,and extensive studies have been devoted to designing a luminescence thermometer with heightened thermal ***,we report a promising luminescence thermometric material,Ta^(5+)-substituted K_(0.5)Na_(0.5)NbO_(3):0.003Er^(3+)transparent ferroelectric *** temperature sensing sensitivity is significantly improved by adjusting the concentration of Ta^(5+)in the ***,utilizing the fluorescence intensity ratio from the 2H_(11/2) and 4S_(3/2) thermally coupled states of Er^(3+)as a detecting signal within the temperature range of 273–543 K,an optimal maximum absolute sensitivity of 0.0058 K–1 and relative sensitivity of 0.0158 K–1 are achieved for K_(0.5)Na_(0.5)NbO_(3):0.65Ta^(5+)/0.003Er^(3+).Simultaneously,as the concentration of Ta5+increase,a unique evolution of structural phase transitions is observed from orthorhombic to tetragonal and then to *** is accompanied by an improvement in luminescence temperature sensing properties,and the best sensitivity is demonstrated in the cubic-phase ***,a huge change in infrared luminescence properties as a function of temperature is found around the structure transition temperature of the *** results indicate a promising potential for achieving highly sensitive thermometry or monitoring phase structure transitions through luminescence thermometry behavior in the K_(0.5)Na_(0.5)NbO_(3) host.

关键词： Transparent ceramics Temperature sensing Phase transition Upconversion emission

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Theory of mechanical exfoliation of van der Waals bonded layered materials

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Physical Review materials 2024年第6期8卷 064003-064003页

作者： Haoye Sun Ozan Sahin Ali Javey Joel W. Ager D. C. Chrzan Department of Materials Science and Engineering Department of Electrical Engineering and Computer Sciences Materials Sciences Division

A theoretical framework for analyzing the mechanical exfoliation of 2D materials at finite temperature is introduced. As an example, this framework, based on transition-state theory and calculation of the reaction pathway, is applied to the mechanical exfoliation of multilayer MoS2. The theory predicts that altering the bonding of the top layer to the bulk through straining or twisting and slowly exfoliating at low temperatures will enhance the yield of the monolayer material.

关键词： Adhesion

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