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STRUCTURE AND DIELECTRIC PROPERTIES OF BI-DOPED (BA, SR)TIO3 THIN FILMS FABRICATED BY SOL-GEL METHOD

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STRUCTURE AND DIELECTRIC PROPERTIES OF BI-DOPED (BA, SR)TIO3...

FERROELECTRIC PROPERTIES OF PB(ZR,TI)O3 HETEROLAYERED THIN FILMS FOR FRAM APPLICATION

第8届国际材联电子材料国际研讨会

作者： Kyoung-TaeKim Chang-ⅡKim sung-gap lee School of Electrical Electronic Engineering Chungang University 221 Huksuk-Dong Dongiak-Gu Seoul 156-756 Korea Department of Electronics Electrical Engineering Seonam University Namwon Chonbuk 590-170 South Korea

The structure and dielectric properties of Bi-doped barium strontium titanate (BST) thin film were studied. Pure and Bi doped BaTiTiO thin films were fabricated by sol-gel method through alkoxide-based precursors on Pt/Ti/SiO/Si substrates. The structure and morphology of the films were analyzed by x-ray diffraction, atomic force microscope, and scanning electron microscope. The Bi doping

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FERROELECTRIC PROPERTIES OF PB(ZR,TI)O3 HETEROLAYERED THIN F...

Effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on tensile and bending properties of high-Al-containing Mg alloys

第8届国际材联电子材料国际研讨会

作者： sung-gap lee Kyoung-TaeKim Chang-ⅡKim Department of Electronics Electrical Engineering Seonam University Namwon Chonbuk 590-170 South Korea School of Electrical Electronic Engineering Chungang University 221 Huksuk-Dong Dongjak-Gu Seoul 156-756 Korea

Ferroelectric Pb(Zr, Ti)O (PZT) heterolayered thin films were fabricatied by the alkoxide-based sol-gel method. PZT(20/80) and PZT(80/20) stock solutions were made and alternately spin-coated on the Pt/Ti/SiO/Si substrate. Each layer was dried at 300℃for 30min and sintered at 650℃for 1h. The coating and heating procedure was repeated several times to form heterolayered films. All PZT heterolayered films show

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Journal of Magnesium and Alloys 2024年第2期12卷 779-793页

作者： Sumi Jo Gyo Myeong lee Jong Un lee Young Min Kim sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Department of Magnesium Korea Institute of Materials ScienceChangwon 51508Republic of Korea

This study investigates the effect of characteristics and distribution of Mg_(17)Al_(12)precipitates on the uniaxial tensile and three-point bending properties of extruded Mg alloys containing high Al *** extruded Mg–9Al–1Zn–0.3Mn(AZ91)alloy contains lamellar-structured Mg_(17)Al_(12)discontinuous precipitates along the grain boundaries,which are formed via static precipitation during natural air *** extruded Mg–11Al–1Zn–0.3Mn(AZ111)alloy contains spherical Mg_(17)Al_(12)precipitates at the grain boundaries and inside the grains,which are formed via dynamic precipitation during *** to inhomogeneous distribution of precipitates,the AZ111 alloy consists of two different precipitate regions:precipitate-rich region with numerous precipitates and finer grains and precipitate-scarce region with a few precipitates and coarser *** AZ111 alloy exhibits a higher tensile strength than the AZ91 alloy because its smaller grain size and more abundant precipitates result in stronger grain-boundary hardening and precipitation hardening effects,***,the tensile elongation of the AZ111 alloy is lower than that of the AZ91 alloy because the weak cohesion between the dynamic precipitates and the matrix facilitates the crack initiation and *** bending,a macrocrack initiates on the outer surface of bending specimen in both *** AZ111 alloy exhibits higher bending yield strength and lower failure bending strain than the AZ91 *** bending specimens of the AZ91 alloy have similar bending formability,whereas those of the AZ111 alloy exhibit considerable differences in bending formability and crack propagation behavior,depending on the distribution and number density of precipitates in the *** bending specimens of the AZ111 alloy,it is found that the failure bending strain(ε_(f,bending))is inversely proportional to the area fraction of precipitates in the outer zone of bending specimen(A_(ppt)),with a relation

关键词： Mg–Al alloy Extrusion Bending Precipitation Microstructure

Enhanced prediction of anisotropic deformation behavior using machine learning with data augmentation

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Journal of Magnesium and Alloys 2024年第1期12卷 186-196页

作者： Sujeong Byun Jinyeong Yu Seho Cheon Seong Ho lee sung Hyuk Park Taekyung lee School of Mechanical Engineering Pusan National UniversityBusan 46241South Korea School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566South Korea

Mg alloys possess an inherent plastic anisotropy owing to the selective activation of deformation mechanisms depending on the loading *** characteristic results in a diverse range of flow curves that vary with a deformation *** study proposes a novel approach for accurately predicting an anisotropic deformation behavior of wrought Mg alloys using machine learning(ML)with data *** developed model combines four key strategies from data science:learning the entire flow curves,generative adversarial networks(GAN),algorithm-driven hyperparameter tuning,and gated recurrent unit(GRU)*** proposed model,namely GAN-aided GRU,was extensively evaluated for various predictive scenarios,such as interpolation,extrapolation,and a limited dataset *** model exhibited significant predictability and improved generalizability for estimating the anisotropic compressive behavior of ZK60 Mg alloys under 11 annealing conditions and for three loading *** GAN-aided GRU results were superior to those of previous ML models and constitutive *** superior performance was attributed to hyperparameter optimization,GAN-based data augmentation,and the inherent predictivity of the GRU for *** a first attempt to employ ML techniques other than artificial neural networks,this study proposes a novel perspective on predicting the anisotropic deformation behaviors of wrought Mg alloys.

关键词： Plastic anisotropy Compression Annealing Machine learning Data augmentation

Comparison of commercial silicon-based anode materials for the design of a high-energy lithium-ion battery

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Nano Research 2024年第6期17卷 5270-5277页

作者： Minhong Choi Eunhan lee Jaekyung sung Namhyung Kim Minseong Ko Division of Convergence Materials Engineering Pukyong National UniversityBusan 48547Republic of Korea Department of Materials Engineering and Convergence Technology Gyeongsang National University501 Jinju-daeroJinju 52828Republic of Korea Department of Materials System Engineering Pukyong National UniversityBusan 48547Republic of Korea

Silicon(Si)is considered a potential alternative anode for next-generation Li-ion batteries owing to its high theoretical capacity and ***,the commercial use of Si anodes is hindered by their large volume expansion(~300%).Numerous efforts have been made to address this *** these efforts,Si-graphite co-utilization has attracted attention as a reasonable alternative for high-energy anodes.A comparative study of representative commercial Si-based materials,such as Si nanoparticles,Si suboxides,and Si−Graphite composites(SiGC),was conducted to characterize their overall performance in high-energy lithium-ion battery(LIB)design by incorporating conventional ***-Si was found to exhibit poor electrochemical performance,with severe volume expansion during *** suboxide provided excellent cycling stability in a full-cell evaluation with stable volume variation after 50 cycles,but had a large irreversible capacity and remarkable volume expansion during the first *** displayed a good initial Coulombic efficiency and the lowest volume change in the first cycle owing to the uniformly distributed nano-Si layer on graphite;however,its long-term cycling stability was relatively *** complement each disadvantage of Si suboxide and SiGC,a new combination of these Si-based anodes was suggested and a reasonable improvement in overall battery performance was successfully achieved.

关键词： silicon-based anode high-energy comparison lithium ion battery blended electrode

Strengthening mechanisms analysis and tailoring of bimodal grain structures for enhanced strength in CoCrFeMnNi high-entropy alloys

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Rare Metals 2024年第8期43卷 3893-3903页

作者： Jaesoung lee Seulgi Kim Taehyun Kwon Young II Kim Suyeon Kim sung Ho Song Bin lee Dongju lee Department of Urban Energyand Environmental EngineeringChungbuk National UniversityCheongju 28644Republic of Korea Division of Advanced Materials Engineering Kongju National UniversityChungnam 330-717Republic of Korea Department of Advanced Materials Engineering for Information and Electronics Integrated-Education Institute for Frontier Science and Technology(BK21 Four)Kyung Hee UniversityYongin17104Republic of Korea

The CoCrFeMnNi high-entropy alloys(HEAs)with a(face-centered cubic) FCC structure has garnered considerable attention for its exceptional ductility and strain hardening ***,its yield strength is insufficient for structural *** this study,strengthening mechanisms in these HEAs were investigated to gain insight into the mechanical properties according to alloy powder ***,we present a novel approach to achieve both high strength and high ductility through the creation of a bimodal structure consisting of both coarse and fine grains via gas atomization and spark plasma sintering processes.A bimodally structured HEA prepared with a mass ratio of 2:8 between coarse particles(75-106 μm) and fine particles(≤25 μm)yielded optimal results,with a strength of 491.95 MPa and elongation of 19.64%.This strength value represents an~41% increase compared with the sample that displayed a fine single microstructure(347.08 MPa for yield strength).The strength enhancement was attributed to the prevention of plastic deformation initiation from the fine particles during *** innovative approach to the creation of HEAs with bimodal structures shows promise for various applications,such as structural components that require a combination of high strength and high ductility.

关键词： High-entropy alloys CrCoFeMoNi Bimodal Gas atomization Mechanical properties

Ionizing terahertz waves with 260 MV/cm from scalable optical rectification

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Light(Science & Applications) 2024年第6期13卷 1075-1087页

作者： Hyeongmun Kim Chul Kang Dogeun Jang Yulan Roh Sang Hwa lee Joong Wook lee Jae Hee sung Seong Ku lee Ki-Yong Kim Advanced Photonics Research Institute GISTGwangju61005Korea Department of Physics and Optoelectronics Convergence Research Center Chonnam National UniversityGwangju61186Korea Pohang Accelerator Laboratory POSTECHPohang37673Korea Center for Relativistic Laser Science Institute for Basic ScienceGwangju61005Korea Institute for Research in Electronics and Applied Physics Department of PhysicsUniversity of MarylandCollege ParkMaryland20742USA

Terahertz(THz)waves,known as non-ionizing radiation owing to their low photon energies,can actually ionize atoms and molecules when a sufficiently large number of THz photons are concentrated in time and ***,we demonstrate the generation of ionizing,multicycle,15-THz waves emitted from large-area lithium niobate crystals via phase-matched optical rectification of 150-terawatt laser pulses.A complete characterization of the generated THz waves in energy,pulse duration,and focal spot size shows that the field strength can reach up to 260 megavolts per *** particular,a single-shot THz interferometer is employed to measure the THz pulse duration and spectrum with complementary numerical *** intense THz pulses are irradiated onto various solid targets to demonstrate THz-induced tunneling ionization and plasma *** study also discusses the potential of nonperturbative THz-driven ionization in gases,which will open up new opportunities,including nonlinear and relativistic THz physics in plasma.

关键词： optical interferometer matched

Intelligent reflecting surface for sum rate enhancement in MIMO systems

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Digital Communications and Networks 2024年第1期10卷 94-100页

作者： Chan-Yeob Park Ji-sung Jung Yeong-Rong lee Beom-Sik Shin Hyoung-Kyu Song Department of Information and Communication Engineering Sejong UniversitySeoulGwangjin-guGunja-dong 98Republic of Korea Department of Convergence Engineering for Intelligent Drone Sejong University SeoulGwangjin-guGunja-dong 98Republic of Korea

The research for the Intelligent Reflecting Surface(IRS)which has the advantages of cost and energy efficiency has been *** capacity can be effectively increased by appropriately setting the phase value of IRS elements according to the channel ***,the problem of obtaining an appropriate phase value of IRs is difficult to solve due to the non-convex *** paper proposes an iterative algorithm for the alternating optimal solution in the Single User Multiple-Input-Multiple-Output(SU-MIMO)*** proposed iterative algorithm finds an alternating optimal solution that is the phase value of IRS one by *** results show that the proposed method has better performance than that of the randomized IRS *** number of iterations for maximizing the performance of the proposed algorithm depends on the channel state between the IRS and the receiver.

关键词： Intelligent reflecting surface MIMO Sum rate

Enhancement of vertical phase separation in sequentially deposited organic photovoltaics through the independent processing of additives

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Journal of Energy Chemistry 2024年第7期94卷 768-777页

作者： Damin lee Changwoo Park Gayoung Ham Young Yong Kim sung-Nam Kwon Junyeong lee sungjin Jo Seok-In Na Hyojung Cha Department of Hydrogen and Renewable Energy Kyungpook National UniversityDaegu 41566Republic of Korea Department of Energy Convergence and Climate Change Kyungpook National UniversityDaegu 41566Republic of Korea Pohang Accelerator Laboratory(PAL) Pohang University of Science and Technology(POSTECH)PohangGyeongbuk 37673Republic of Korea Department of Flexible and Printable Electronics Jeonbuk National UniversityJeonju-siJeollabuk-do 54896Republic of Korea School of Energy Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

Herein,the impact of the independent control of processing additives on vertical phase separation in sequentially deposited (SD) organic photovoltaics (OPVs) and its subsequent effects on charge carrier kinetics at the electron donor-acceptor interface are *** film morphology exhibits notable variations,significantly depending on the layer to which 1,8-diiodooctane (DIO) was *** incidence wide-angle X-ray scattering analysis reveals distinctly separated donor/acceptor phases and vertical crystallinity details in SD ***-of-flight secondary ion mass spectrometry analysis is employed to obtain component distributions in diverse vertical phase structures of SD films depending on additive *** addition,nanosecond transient absorption spectroscopy shows that DIO control significantly affects the dynamics of separated charges in SD *** SD OPVs,DIO appears to act through distinct mechanisms with minimal restriction,depending on the applied *** study emphasizes the significance of morphological optimization in improving device performance and underscores the importance of independent additive control in the advancement of OPV technology.

关键词： Sequential deposition Vertical phase separation Charge dynamics Organic photovoltaics Nonfullerene acceptors