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Reducing anisotropy of rhombohedral Bi-rich phase for high-performance Ag-alloyed Sn–Bi low-temperature solders

Journal of materials Research and Technology 2024年 30卷 16-24页

作者： Yang, Chih-han Liu, Yu-chen Nishikawa, Hiroshi Lin, Shih-kang Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka567-0047 Japan Research Center National Cheng Kung University Tainan70101 Taiwan Program on Smart and Sustainable Manufacturing Academy of Innovative Semiconductor and Sustainable Manufacturing National Cheng Kung University Tainan70101 Taiwan Core Facility Center National Cheng Kung University Tainan70101 Taiwan

The rhombohedral structure is with anisotropic properties, leading to brittle mechanical properties. However, it is one of the major constituent phases, the (Bi) phase, in the Sn–Bi-based low-temperature solders, which is demanding in the electronic industry for reducing the soldering temperature and alleviating the warpage in high-density fine-pitch electronic packaging. Herein, we proposed a high-performance Ag-alloyed Sn–Bi (SBA) low-temperature solder by reducing the fraction and, more importantly, the anisotropy of the (Bi) phase. We found that the (Bi) phase exhibited considerable solubility for Ag and Sn, even after thermal aging, without any nanoprecipitates as confirmed with both CALPHAD-type thermodynamic modeling and high-resolution TEM. The solution effects of Ag and Sn in the (Bi) phase is elaborated based on in situ nano-indentation, EPMA compositional analyses, EBSD characterizations, and ab initio calculations. The presence of Ag and Sn in the (Bi) phases resulted in both solid solution hardening and softening effects, depending on the Schmid factor of the grain. As a result, in (Bi) polycrystals, alloying could effectively mitigate the anisotropic mechanical properties of the (Bi) phase and facilitated a more uniform dispersion of forces exerted among (Bi) grains in all orientations. Consequently, the designed SBA solder exhibited superior mechanical properties, e.g., an ultimate tensile strength (UTS) of 55 MPa, elongation of 46%, and toughness of 20.6 × 106 J/m3 at a strain rate of 0.0005 s−1. This understanding opens the door for enhanced rhombohedral phase in alloy design for various applications. © 2024 The Authors

关键词： Anisotropy

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Development of Flexible Sendust Composite Sheets with Enhanced Magnetic Permeability for Microwave Absorbers and Antennas

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IEEE Transactions on Magnetics 2025年

作者： Whalen, Matthew P. Plouff, David T. Shevchenko, Nicholas B. Mirotznik, Mark Xiao, John Q. University of Delaware Quantum Science and Engineering Program NewarkDE19716 United States University of Delaware Department of Physics and Astronomy NewarkDE19716 United States University of Delaware Center for Composite Materials NewarkDE19716 United States University of Delaware Department of Electrical and Computer Engineering NewarkDE19716 United States

The demand for high-frequency soft magnetic composites with elevated permeability and flexibility is growing for applications in microwave absorbers and magnetodielectric antennas. However, balancing high permeability with mechanical flexibility remains challenging. This study presents flexible Sendust (FeSiAl) composite sheets, fabricated with a hot-pressing technique that aligns flakes within an acrylic rubber and epoxy resin matrix. The alignment significantly enhances relative permeability at high frequencies, achieving single-layer film properties of μr' = 14.8 and μr"= 20.4 at 1 GHz, alongside high saturation magnetization (118 eμg) and high hesitivity (44.7 kΩ m-1), outperforming commonly used materials such as NiZn ferrite. Our method supports customizable thickness without sacrificing permeability, establishing a versatile platform for advanced conformal microwave absorber and antenna applications. © 2025 IEEE.

关键词： Saturation magnetization

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Evolution of magnetism in the magnetic topological semimetal NdSbxTe2−x+δ

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Physical Review B 2024年第18期109卷 184429-184429页

作者： Santosh Karki Chhetri Rabindra Basnet Jian Wang Krishna Pandey Gokul Acharya Md Rafique Un Nabi Dinesh Upreti Josh Sakon Mansour Mortazavi Jin Hu Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Physics University of Arkansas at Pine Bluff Pine Bluff Arkansas 71603 USA Department of Chemistry and Biochemistry Wichita State University Wichita Kansas 67260 USA Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Biochemistry University of Arkansas Fayetteville Arkansas 72701 USA

Magnetic topological semimetals LnSbTe (Ln=lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Recently, varying Sb-Te composition has been found to effectively control the electronic and magnetic states in LnSbxTe2−x. With this motivation, we report the evolution of magnetic properties with Sb-Te substitution in NdSbxTe2−x+δ, (0≤x≤1). Our work reveals the interesting nonmonotonic change in magnetic ordering temperature with varying composition stoichiometry. In addition, reducing the Sb content x drives the reorientation of moments from in-plane (ab-plane) to out-of-plane (c-axis) direction that results in the distinct magnetic structures for two end compounds NdTe2 (x=0) and NdSbTe (x=1). Furthermore, the moment orientation in NdSbxTe2−x+δ is also found to be strongly tunable upon application of a weak magnetic field, leading to rich magnetic phases depending on the composition stoichiometry, temperature, and magnetic field. Such strong tuning of magnetism in this material establishes it as a promising platform for investigating tunable topological states and correlated topological physics.

关键词： Charge density waves Magnetic phase transitions Spin reorientation transition

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Packing fraction related transport in disordered quantum dot arrays

arXiv

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arXiv 2024年

作者： Eshraghi, K. Natani, S. Bandaru, P. Program in Materials Science University of California La Jolla San DiegoCA92093 United States Department of Mechanical Engineering University of California La Jolla San DiegoCA92093 United States

Models to describe electrical conduction in quantum dot (QD) constituted films often overlook the effects of geometric disorder. We address related issues by examining the influence of the QD packing fraction (PF) on the charge transport and transmission in QD arrays. Using transfer matrix based algorithms and Monte Carlo simulations, we quantify the transmission across disordered QD assemblies. Our results indicate a critical packing fraction (PFc) of ∼ 0.64, marking a transition from a non-conducting to a conducting state, aligning well with experimental observations and analytical predictions. This study enhances the understanding of transport in QD arrays, with implications for designing efficient electronic devices based on disordered nanoscale systems. © 2024, CC BY-NC-SA.

关键词： Semiconductor quantum dots

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Development of Flame Retardant Stearic Acid Doped Graphite Powder and Magnesium Hydroxide Nanoparticles, Material for Thermal Energy Storage Applications 21

Development of Flame Retardant Stearic Acid Doped Graphite P...

引用

21st International Union of materials Research Societies International Conference in Asia, IUMRS-ICA 2021

作者： Han, Kyaw Thet Lhosupasirirat, Siraprapa Srikhirin, Pongsid Houngkamhang, Nongluck Srikhirin, Toemsak Materials Science and Engineering Program School of Materials Science and Innovation Faculty of Science Mahidol University Bangkok10400 Thailand Ramkhamhaeng University Bangkok Thailand College of Nanotechnology King Mongkut's Institute of Technology Ladkrabang Bangkok10520 Thailand Research Network of NANOTEC Mahidol University National Nanotechnology Center Thailand Department of Physics Faculty of Science Mahidol University 272 Rama VI Road Ratchathewi District Bangkok10400 Thailand

Nano-enhanced organic phase change material (PCM) composite consists of stearic acid (SA, act as the thermal storage media), graphite powder(GP, function as thermal conductor), and magnesium hydroxide nanoparticles(nMH), micro-sized (MMH), function as the flame retarder), were formulated and investigated for their thermophysical properties and flammability. The flame-retardant properties of nano-enhanced composite PCM were evaluated by using the burning test. Phase change temperature, phase change latent heat, and thermal conductivity were obtained by the T-history method. To reduce the flammability, 5wt% of MH with 0.8µm and 200nm were added to PCMs. 1wt% of GP improved thermal conductivity of stearic acid from 0.245 to 0.4887 W/mk, and doping of flame-retardant nanoparticles to PCM showed the reduction of flammability and slightly effecting on latent heat of PCM. nMH were found to work better for stearic acid flammability than MMH, where combustion time of 0.1g pure stearic acid(SA) was decreased from 41s to 17s and 23s. For nano-sized(SA/nMH) and micron-sized(SA/MMH)composites, the latent heat of pure PCM dropped from 171.26 to 124.85KJ/kg, but micron-sized addition negatively affects latent heat values by reducing from 171.26 to 88.87 KJ/kg. The results confirmed that nMH/GP/SA composite could reduce flammability without showing a negative impact on storage capacity. © Published under licence by IOP Publishing Ltd.

关键词： Phase change materials

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Compositionally Complex Perovskite Oxides as a New Class of Li-Ion Solid Electrolytes

arXiv

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arXiv 2022年

作者： Ko, Shu-Ting Lee, Tom Qi, Ji Zhang, Dawei Peng, Wei-Tao Wang, Xin Tsai, Wei-Che Sun, Shikai Wang, Zhaokun Bowman, William J. Ong, Shyue Ping Pan, Xiaoqing Luo, Jian Materials Science and Engineering Program University of California San Diego La Jolla CA United States Department of Materials Science and Engineering University of California at Irvine IrvineCA United States Department of NanoEngineering University of California San Diego La Jolla CA United States Department of Physics and Astronomy University of California at Irvine IrvineCA United States Irvine Materials Research Institute University of California at Irvine IrvineCA United States

Compositionally complex ceramics (CCCs), including high-entropy ceramics (HECs) as a subclass, offer new opportunities of materials discovery beyond the traditional methodology of searching new stoichiometric compounds. Herein, we establish new strategies of tailoring CCCs via a seamless combination of (1) non-equimolar compositional designs and (2) controlling microstructures and interfaces. Using oxide solid electrolytes for all-solid-state batteries as an exemplar, we validate these new strategies via discovering a new class of compositionally complex perovskite oxides (CCPOs) to show the possibility of improving ionic conductivities beyond the limit of conventional doping. As an example (amongst the 28 CCPOs examined), we demonstrate that the ionic conductivity can be improved by >60% in (Li0.375Sr0.4375)(Ta0.375Nb0.375Zr0.125Hf0.125)O3-δ, in comparison with the state-of-art (Li0.375Sr0.4375)(Ta0.75Zr0.25)O3-δ (LSTZ) baseline, via maintaining comparable electrochemical stability. Furthermore, the ionic conductivity can be improved by another >70% via grain boundary (GB) engineering, achieving >270% of the LSTZ baseline. This work suggests transformative new strategies for designing and tailoring HECs and CCCs, thereby opening a new window for discovering materials for energy storage and many other applications. © 2022, CC BY.

关键词： Solid electrolytes

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Three-dimensional construction of hyperuniform, nonhyperuniform, and antihyperuniform disordered heterogeneous materials and their transport properties via spectral density functions

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Physical Review E 2025年第3期111卷 035310-035310页

作者： Wenlong Shi Yang Jiao Salvatore Torquato Materials Science and Engineering Arizona State University Tempe Arizona 85287 USA Department of Physics Arizona State University Tempe Arizona 85287 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Princeton Institute of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

Rigorous theories connecting physical properties of a heterogeneous material to its microstructure offer a promising avenue to guide the computational material design and optimization. The spectral density function χ̃V(k), which can be obtained experimentally from scattering data, enables accurate determination of various transport and wave propagation characteristics, including the time-dependent diffusion spreadability S(t) and effective dynamic dielectric constant εe for electromagnetic wave propagation. Moreover, χ̃V(k) determines rigorous upper bounds on the fluid permeability K. Given the importance of χ̃V(k), we present here an efficient Fourier-space based computational framework to construct three-dimensional (3D) statistically isotropic two-phase heterogeneous materials corresponding to targeted spectral density functions. In particular, we employ a variety of analytical functional forms for χ̃V(k) that satisfy all known necessary conditions to construct disordered stealthy hyperuniform, standard hyperuniform, nonhyperuniform, and antihyperuniform two-phase heterogeneous material systems at varying phase volume fractions. We show that by tuning the correlations in the system across length scales via the targeted functions, one can generate a rich spectrum of distinct structures within each of the above classes of materials. Importantly, we present the first realization of antihyperuniform two-phase heterogeneous materials in 3D, which are characterized by autocovariance function χV(r) with a power-law tail, resulting in microstructures that contain clusters of dramatically different sizes and morphologies. We also determine the diffusion spreadability S(t) and estimate the fluid permeability K associated with all of the constructed materials directly from the corresponding spectral densities. Although it is well established that the long-time asymptotic scaling behavior of S(t) only depends on the functional form of χ̃V(k), with the stealthy hyperuniform a

关键词： Spectral density

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Thermal-Protective and Oxygen-Resistant Nanocoating Using Silica-Nanocomposites for Laser Thinning of Polymorphic Molybdenum Ditellurides

SSRN

引用

SSRN 2023年

作者： Heo, Soyoung Kim, Seulbi Lee, Seung Yeon Yang, Heejun Park, Ji Hun Cho, Suyeon Division of Chemical Engineering and Materials Science Graduate Program in System Health Science and Engineering Ewha Womans University Seoul03760 Korea Republic of Department of Science Education Ewha Womans University Seoul03760 Korea Republic of Daejeon34141 Korea Republic of

Laser irradiation has been investigated as a method of fabricating atomically-thin crystals from layered two-dimensional (2D) materials with precise thickness control. However, during laser irradiation, inevitable structural changes can occur in the 2D materials due to the high thermal energy, altering their physical and chemical properties and introducing disorder, which has hindered the study and use of the intrinsic properties of atomically-thin materials. In this study, we report a laser thinning method using a new coating material, a layered silica-based nanocomposite (SNC), that preserves the pristine crystal structure of a polymorphic 2D material, MoTe2, down to an atomically thin geometry. The nano-porous coating of layered silica-based nanocomposite (SNC) was robust against thermal heating and behaved as a good thermal-protective and oxygen-resistant material in the laser thinning process. Therefore, the SNC-coated MoTe2 flakes were successfully thinned down to atomically-thin geometry, while preserving their 2H structure. Accordingly, our SNC coating of 2D materials is a promising way to engineer the phase and geometry of polymorphic 2D materials, enabling versatile applications in various optoelectronic, spintronic, and electronic devices. © 2023, The Authors. All rights reserved.

关键词： Coatings

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Solidification, A-Al Morphologies, Tensile Properties and Plc of Low-Sc Modified Al-Mg Alloys

SSRN

引用

SSRN 2023年

作者： Nunes, Anderson Thadeu Lisboa de Gouveia, Guilherme Spinelli, José Eduardo Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565905 Brazil Department of Materials Engineering Federal University of São Carlos – UFSCar SP São Carlos13565905 Brazil

Al alloys are very attractive in engineering applications that require a combination of low density and mechanical strength, such as in aeronautical and aerospace industry devices. Therefore, the search for alloys with higher specific strength is justified from environmental and economic points of view. This work aims to study the influence of cooling rates on the phase morphology and tensile properties of ternary Al-Mg-Sc alloys, whose composition covers the spectrum of low-Sc Al-Mg-Sc alloys. The ternary Al-3, -5, and -10wt.% Mg-0.1wt.% Sc alloys were processed by transient directional solidification. This process induces a wide range of cooling rates which causes the formation of a microstructural variety along the longitudinal cooling direction and, consequently, different tensile properties. Several characterization methods were employed, including: thermal analysis, x-ray diffraction (XRD) structural analysis, SEM-EDS, optical microscopy, CALPHAD, tensile tests, and fractography. Two major findings should be noted after fully characterizing the microstructures, the formed phases, and the tensile properties. Solidification evolution revealed that more Mg added resulted in higher solidification rates due to higher fluidity with more Mg. Furthermore, cell growth was mapped in the three alloy compositions while competing with dendrites. Second, although the Al-10 wt.% Mg-Sc alloy had more Mg in solid solution and slightly higher Portevin–Le Chatelier (PLC) severity, the Al-5 wt.% Mg-Sc alloy showed superior tensile strength due to the predominance of cells and thinner primary dendrites trunks forming its microstructure. © 2023, The Authors. All rights reserved.

关键词： Aluminum alloys

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Recent advance in synthesis and application of heteroatom zeolites

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Chinese Chemical Letters 2021年第1期32卷 328-338页

作者： Tingting Pang Xuanyu Yang Chenyi Yuan Ahmed A.Elzatahry Abdulaziz Alghamdi Xing He Xiaowei Cheng Yonghui Deng School of Materials Science and Engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of Chemistry Shanghai Key Laboratory of Molecular Catalysis and Innovative MaterialsFudan UniversityShanghai 200433China Materials Science and Technology Program College of Arts and SciencesQatar UniversityP.O.Box 2713DohaQatar Department of Chemistry College of ScienceKing Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia State Key Lab of Transducer Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China

Incorporation of heteroatoms into the framewo rk of zeolites has become a significant strategy to improve their performance in catalysis and adsorption,because the obtained heteroatom zeolites exhibit quite different properties from the conventional aluminosilicate zeolites in aspects of surface acidity,pore structures,particle size and so *** this review,the progress on the heteroatom zeolites including their synthesis and application is ***,the recent advance on the design and synthesis of different heteroatom zeolites is *** emphasis is placed on the introduction and comparison of three typical methods,including the direct synthesis,post synthesis and improved direct synthesis,for the traditional heteroatom zeolites(such as TS-1,Sn-MFI,Sn-β) and newly-reported heteroatom zeolites(such as W-MFI,Mo-MFI).According to their intrinsic characteristics,the application of heteroatom zeolites in diverse fields,such as production of fine chemicals,air pollution control and biomass conversion is then ***,the challenges and perspective on the future development of heteroatom zeolites in low-cost preparation and practical application are proposed.

关键词： Heteroatom zeolite Incorporation Tetrahedral coordination Research status Synthesis Application Prospective

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