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arXiv 2022年

作者： Sullivan, Sean E. Lee, Hwijong Weathers, Annie Shi, Li Materials Science and Engineering Program The University of Texas at Austin AustinTX78712 United States Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States

Heavy metal (HM)/magnet bilayers host many magnetoresistances (MR) and spin caloritronic effects. Here we show that the spin Peltier effect and electron-phonon scattering produce much larger unidirectional MR of an HM on a magnetic insulator than existing theories that neglect the interplay between MR and spin caloritronic effects. By accounting for local nonequilibrium in both the magnon chemical potential and temperature, our analytical model attributes the observed frequency dependence of the spin Peltier MR and the spin Seebeck effect to the reduction of the thermal penetration depth, which approaches the 1-μm scale magnon spin diffusion length at high frequencies. © 2022, CC BY.

关键词： Heavy metals

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Advanced Under-Rails Fiber-Optic Sensor for Detection of Rolling Stock and Axles in Tram Transport

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IEEE Transactions on Instrumentation and Measurement 2025年 74卷

作者： Fajkus, Marcel Jargus, Jan Nedoma, Jan Kepak, Stanislav Krizan, Daniel Cubik, Jakub Krenzelok, Tomas Leal, Arnaldo Marques, Carlos VSB—Technical University of Ostrava Faculty of Electrical Engineering and Computer Science Department of Telecommunications Ostrava708 00 Czech Republic Prodin a.s. Pardubice530 02 Czech Republic Graduate Program in Electrical Engineering Federal University of Espirito Santo Vitoria29075-910 Brazil University of Aveiro CICECO—Aveiro Institute of Materials Physics Department Aveiro3810-193 Portugal VSB—Technical University of Ostrava Department of Physics Ostrava708 00 Czech Republic

This article describes the implementation of an advanced fiber-optic intensity sensor for the comprehensive detection of axles and bogies of rail vehicles in tram transport. The sensor uses the principle of optical fiber bending, where the intensity of transmitted light is modulated due to mechanical stress on the fiber caused by the passage of a tram and the subsequent reversible deformation of the rail. The innovative design of the sensor allows for its easy installation under the rail foot, between the rail and the sleeper, replacing conventional anti-vibration pads, and includes specially designed deformable elements which the optical fiber bends and modulates the transmitted light intensity. During long-term testing (11 months in various weather conditions) conducted in the real tram depot (Ostrava, Czech Republic), 20602 tram passages were secured and analyzed. The sensor demonstrated success in detecting bogies, achieving 100% accuracy with no false positives (FPs) or false negatives (FNs). Axle detection showed an average success rate of 86.1%, with variability among different tram types up to 97.8%. The signal modulation was also subjected to detailed analysis, revealing differences in responses between various tram types, which can be attributed to differences in bogie construction and vehicle weight. Due to its electromagnetic immunity, the implemented fiber-optic sensor offers the potential for more reliable detection and broad application possibilities, including track occupancy monitoring, speed measurement, or determining the direction of travel on single-track lines. With slight optimization, the sensor could also be used to weigh rail vehicles or as an axle counter in railway or light rail transport. © 1963-2012 IEEE.

关键词： Bogies (railroad rolling stock)

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Novel Biosynthesis of Spherical Tungsten Trioxide Nanoparticles for Sustainable Photocatalytic Application

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Applied Organometallic Chemistry 2025年第6期39卷

作者： Parveen, Nazish Alnahdi, Kholoud M. Alsharif, Shada A. Ansari, Sajid Ali Ansari, Mohd Zahid Umar, Ahmad Awada, Chawki Al-Dosari, Haya Abdullah Department of Chemistry College of Science King Faisal University Saudi Arabia Al-Hasa Saudi Arabia Department of Physics Faculty of Science University of Tabuk Tabuk Saudi Arabia University College of Umluj University of Tabuk Tabuk Saudi Arabia Department of Physics College of Science King Faisal University Al-Ahsa Hofuf Saudi Arabia Chemical Engineering Program Texas A&M University at Qatar Doha Qatar Najran University Najran Saudi Arabia STEM Pioneers Training Lab Najran University Najran Saudi Arabia Department of Materials Science and Engineering The Ohio State University ColumbusOH United States

We developed a novel method for synthesizing tungsten trioxide nanoparticles, utilizing orange juice as a sustainable and economical catalyst. This innovative approach eliminates the need for expensive metals and harsh chemicals. The natural components of orange juice, particularly ascorbic acid and citric acid, play a crucial role in the formation and stabilization of these nanoparticles. We thoroughly tested the synthesized nanoparticles using a suite of analytical techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The results were compelling. When exposed to UV light, the nanoparticles were able to degrade approximately 95% of the model pollutant, methyl orange, demonstrating a rapid and efficient performance. Without the presence of these nanoparticles, the degradation of the pollutant was minimal. This confirms the effectiveness of the tungsten trioxide nanoparticles as a potent and environmentally friendly solution for pollutant degradation in various applications. This method not only offers a green alternative to traditional nanoparticle synthesis but also highlights the potential of using common natural resources in advanced environmental applications. © 2025 John Wiley & Sons Ltd.

关键词： Fourier transform infrared spectroscopy

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Giant long-range dipole-dipole interactions in a plasmonic lattice

Giant long-range dipole-dipole interactions in a plasmonic l...

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Frontiers in Optics + Laser science 2021, FiO+LS 2021 - Part of Frontiers in Optics, FiO 2021

作者： Boddeti, Ashwin K. Guan, Jun Sentz, Tyler Juarez, Xitali Newman, Ward Cortes, Cristian Odom, Teri W. Jacob, Zubin School of Electrical and Computer Engineering Birck Nanotechnology Center Purdue University West LafayetteIN47907 United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Intel Corporation BeavertonOR97007 United States Center for Nanoscale Materials Argonne National Laboratory LemontIL60439 United States Graduate Program in Applied Physics Department of Materials Science and Engineering Department of Chemistry Northwestern University EvanstonIL60208 United States

We observe long-range dipole-dipole interactions in a plasmonic lattice. Fluorescence lifetime measurements show density-dependent non-exponential decay dynamics over 800nm mean nearest-neighbour separation distances ... 详细信息

ISBN: (纸本)9781557528209

关键词： Plasmonics

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Measuring Minority Carrier Diffusion Length Using High-Injection Scanning Photocurrent Microscopy

arXiv

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arXiv 2024年

作者： Lian, Xiujun Gao, Hanwei Department of Physics Florida State University TallahasseeFL32306 United States Materials Science and Engineering Program Florida State University TallahasseeFL32306 United States Condensed Matter Science National High Magnetic Field Laboratory TallahasseeFL32310 United States

Scanning photocurrent microscopy (SPCM) has been widely used for characterizing charge transport properties, in particular, the minority carrier diffusion length of semiconductors. However, studying lightly doped or intrinsic semiconductors using SPCM remained challenging. Methods used in previous work required low levels of optical injection, which could not be fulfilled easily in semiconductors with lower carrier concentration. In this work, using finite-element simulation, we show that the minority diffusion length can also be quantified under high optical excitation. Not only being applicable both doped and intrinsic semiconductors, the method also lifted the restriction of implementing a Schottky contact in testing devices-a condition assumed to be necessary in previous studies. The results significantly expanded the versatility of SPCM in studying a broad spectrum of semiconducting materials with unprecedented flexibility in experimental conditions. Copyright © 2024, The Authors. All rights reserved.

关键词： Carrier concentration

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A robust bendable IrO_x thin film via mild alkaline solution process for neuron stimulating electrodes

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Surfaces and Interfaces 2024年 44卷

作者： Tso, Kuang-Chih Chan, Tzu-Ying Yu, Tsung-Chun Tao, Yu-Jen Chu, Chao-Yi Chen, San-Yuan Lee, Jyh-Fu Ohta, Jun Chen, Po-Chun Wu, Pu-Wei Graduate Program of Accelerator Light Source National Yang Ming Chiao Tung University Hsinchu 300 Taiwan Division of Materials Science Graduate School of Science and Technology Nara Institute of Science Technology Nara Ikoma Takayama 8916-5 Japan Department of Materials Science and Engineering National Yang Ming Chiao Tung University Hsinchu 300 Taiwan Institute of Materials Science and Engineering National Taipei University of Technology Taipei 106 Taiwan National Synchrotron Radiation Research Center Hsinchu 300 Taiwan

We demonstrate a unique chemical formula to deposit hydrous iridium oxide thin film on a platinum-coated polyimide substrate. In a mild alkaline solution, the iridium (III) precursor undergoes the ligand exchange and hydrolysis reaction to become the iridium (III) dimers that are physically adsorbed on the substrate for subsequent heterogeneous condensation and growth of amorphous hydrous iridium oxide thin film. Both UV–Vis and X-ray absorption spectroscopy (XAS) are employed to determine the reaction steps involved. The chemical nature and crystallinity of the hydrous iridium oxide thin film are investigated by XAS, X-ray photon spectroscopy, and X-ray diffraction. The hydrous iridium oxide thin film reveals an impressive normalized charge storage capacity (CSC) of 0.3 mC/cm²-nm and a low impedance (80.5 Ω) at 1k Hz. In addition, in bending test of 3,000 cycles, the hydrous iridium oxide thin film retains 91.2 % of its initial normalized CSC without any physical crack and delamination. The cell viability test suggests negligible bio-toxicity. Our results provide a solid evidence of fabricating a robust flexible electrode for neural interfaces for potential use in implantable electronic devices. © 2023 Elsevier B.V.

关键词： Bio-electrode Flexible substrate Implantable electronic devices Iridium dimers Iridium oxide Polyimide

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Reliable operation of Cr2O3:Mg/β-Ga2O3 p-n heterojunction diodes at 600◦C

arXiv

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arXiv 2024年

作者： Callahan, William A. Egbo, Kingsley Lee, Cheng-Wei Ginley, David O'Hayre, Ryan Zakutayev, Andriy Materials Science Center National Renewable Energy Laboratory GoldenCO80401 United States Advanced Energy Systems Graduate Program Colorado School of Mines GoldenCO80401 United States Department of Metallurgical and Materials Engineering Colorado School of Mines GoldenCO80401 United States

β-Ga2O3-based semiconductor heterojunctions have recently demonstrated improved performance at high voltages and elevated temperatures and are thus promising for applications in power electronic devices and harsh-environment sensors. However, the long-term reliability of these ultra-wide band gap (UWBG) semiconductor devices remains barely addressed and may be strongly influenced by chemical reactions at the p-n heterojunction interface. Here, we experimentally demonstrate operation and evaluate the reliability of Cr2O3:Mg/β-Ga2O3 p-n heterojunction diodes at during extended operation at 600◦C, as well as after 30 repeated cycles between 25-550◦C. The calculated pO3-temperature phase stability diagram of the Ga-Cr-O material system predicts that Ga2O3 and Cr2O3 should remain thermodynamically stable in contact with each other over a wide range of oxygen pressures and operating temperatures. The fabricated Cr2O3:Mg/β-Ga2O3 p-n heterojunction diodes show room-temperature on/off ratios >104 at ±5V and a breakdown voltage (VBr) of -390V. The leakage current increases with increasing temperature up to 600◦C, which is attributed to Poole-Frenkel emission with a trap barrier height of 0.19 eV. Over the course of a 140-hour thermal soak at 600◦C, both the device turn-on voltage and on-state resistance increase from 1.08V and 5.34 mΩ-cm2 to 1.59V and 7.1 mΩ-cm2 respectively. This increase is attributed to the accumulation of Mg and MgO at the Cr2O3/Ga2O3 interface as observed from TOF-SIMS analysis. These findings inform future design strategies of UWBG semiconductor devices for harsh environment operation and underscore the need for further reliability assessments for β-Ga2O3 based devices. © 2024, CC BY.

关键词： Gallium compounds

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Design, Fabrication, and Characterization of 1-3 Piezoelectric Composite Air-Coupled Ultrasonic Transducers with Micro-Membrane Filter Matching Layer

SSRN

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SSRN 2024年

作者： Wang, Chuanmin Gao, Huayun Zhou, Xinyi Ma, Weigang Tan, Hua Samart, Chanatip Salamon, David Yan, Chunze Zhang, Haibo School of Materials Science and Engineering State Key Laboratory of Material Processing and Die & Mould Technology Huazhong University of Science and Technology Wuhan430074 China Engineering Research Center of Ceramic Materials for Additive Manufacturing Ministry of Education Wuhan430074 China Guangdong HUST Industrial Technology Research Institute Dongguan523808 China Department of Chemistry Faculty of Science and Technology Thammasat University Pathumthani12120 Thailand Central European Institute of Technology Brno University of Technology Brno Czech Republic Faculty of Chemical Engineering Industrial University of Ho Chi Minh City Ho Chi Minh City71420 Viet Nam

Air-coupled ultrasonic transducers are widely used in various fields of nondestructive material characterization. This paper presents the fabrication and performance characterization of 1-3 piezoelectric composite air-coupled ultrasonic transducers operating at frequencies ranging from 400 kHz to 600 kHz. The transducers are fabricated using a dice-and-fill method with PZT-5 as the active material. A double-layer matching strategy is employed, utilizing hollow glass microsphere filled epoxy resin as the first matching and bonding layer. Additionally, micro-membrane filters with different pore sizes are used as the second matching layer. Thermoplastic adhesive TPU is utilized to bind the micro-membrane filter and the first matching layer. Due to the low acoustic impedance of the hollow glass microsphere filled epoxy resin and micro-membrane filter, acoustic impedance mismatch is reduced. Finite element simulation is used to determine the optimal ceramic volume fraction and ceramic pillar height of the 1-3 piezoelectric composites. When the pore size of the micro-membrane filter is 0.8 μm, the transducer achieves the lowest two-way insertion loss of -56.86 dB and the highest -6 dB bandwidth of 15.6 %, making it feasible for pulse-echo mode applications. © 2024, The Authors. All rights reserved.

关键词： Acoustic impedance

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Analytical Maximum Energy Product (BH)_max Model for Rare-Earth-Free Magnets: Core-Shell Nanostructure

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IEEE Transactions on Magnetics 2025年

作者： Hong, Yang-Ki Bae, Seok Park, Jihoon Choi, Minyeong Lee, Won-Cheol Yeo, Chang-Dong Wahed, Md Abdul Lee, Kisuk Yim-Choi, Haein Lee, Woo-Young Department of Electrical and Computer Engineering Materials Science Ph.D. Program The University of Alabama Tuscaloosa 35487 AL United States LG Innotek R&D Division Seoul South Korea Korea Institute of Materials Science Gyeongsangnam-Do Changwon South Korea Hyundai Motors Company R&D Division Namyang Gyeonggi-Do South Korea RF Development Team S.LSI Samsung Electronics Gyeonggi-Do Hwaseong 18448 South Korea Texas Tech University Department of Mechanical Engineering 79409 TX United States Ulsan National Institute of Science and Technology Department of Materials Science and Engineering Gyeongsangnam-Do Ulsan South Korea SookMyung Women’s University Department of Applied Physics Seoul South Korea Yonsei University Department of Materials Science and Engineering Seoul South Korea

This paper presents an analytical model for the maximum energy product ((BH)max) in core-shell structured magnetic exchange-coupled nanomagnets. The model was validated by comparing its results to the (BH)max from cor... 详细信息

This paper presents an analytical model for the maximum energy product ((BH)_max) in core-shell structured magnetic exchange-coupled nanomagnets. The model was validated by comparing its results to the (BH)_max from core-shell magnets reported in the literature. This approach can serve as a universal model for designing core-shell magnets that achieve the desired (BH)_max. The (BH)_max was determined under two distinct nucleation field (H_N) conditions: H_N ≤ M_r/2 and H_N ≥ M_r/2, where M_r is the remanent magnetization. Additionally, two different values of magnetic hysteresis loop squareness (SQ = M_r/M_S) were used: 1.0 and 0.7. The soft magnetic shell’s remanent magnetic flux density (B_r) ranged from 0.7 to 2.2 T, while the core diameter (D_h) varied between 50 and 250 nm in this (BH)_max model. The LTP (low-temperature phase) MnBi-core/soft-shell nanomagnet can achieve a (BH)_max of 40 MGOe at a B_r of 1.6 T, with a shell thickness (δ_S) of 40 nm, a D_h of 250 nm, and a volume fraction of the hard-core (f_h) of 0.43. The (BH)_max of the hexaferrite (SrFe₁₂O₁₉)/soft-shell (1.9 T) nanomagnet can be improved from 5.8 (single hexaferrite phase) to 20 MGOe. This approach achieves the desired (BH)_max of the rare-earth-free permanent magnet, thereby tackling issues related to rare-earth mineral security and unstable supply chains. © 1965-2012 IEEE.

关键词： core-shell nanomagnet magnetic exchange coupling maximum energy product

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Rejuvenating Mullite-Zirconia Composites from Investment-Casting Shell Waste and Investigation of Their Physicochemical and Theoretical Radiation Shielding Properties

SSRN

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SSRN 2023年

作者： Avcıoğlu, Celal Avcıoğlu, Suna Bekheet, Maged F. Artır, Recep Technische Universität Berlin Faculty III Process Sciences Institute of Material Science and Technology Fachgebiet Keramische Werkstoffe Advanced Ceramic Materials Straße des 17. Juni 135 Berlin10623 Germany Usak University Scientific Research Projects Coordinatorship Usak64000 Turkey Yıldız Technical University Faculty of Chemistry and Metallurgy Department of Metallurgical and Materials Engineering Davutpaşa Campus Istanbul34210 Turkey Marmara University Faculty of Engineering Department of Metallurgical and Materials Engineering Istanbul34722 Turkey Department of Analysis and Evaluation

The growing global production of high-precision metal products via investment casting increases the amount of ceramic shell wastes (CW) being produced. The disposal of CW causes significant environmental issues, including water and soil pollution. Although the exact chemical composition of the CW varies by the production facility, it is mainly composed of different amounts of mullite, zircon, and silica. This article assesses the feasibility of CW as a raw material in producing high-performance mullite-zirconia ceramics. In this regard, we prepared a mixture containing CW, Al2O3, and MgO and then sintered at 1500, 1550, and 1600 °C with 4h soaking time. Alumina is added to consume the free silica from CW to yield mullite, and MgO is added to obtain proper microstructure development as well as to promote zircon dissociation. The results showed that increasing sintering temperature promotes densification and enhances mechanical properties. The mullite-zirconia composite sintered at 1600 °C presented promising results, with considerable flexural and compressive strength values of 190.18 and 227.93 MPa, respectively, which are comparable to or even better than the mullite ceramics prepared from most other waste materials. Furthermore, the total atomic cross-sections, mass attenuation coefficients, linear attenuation coefficients, mean free paths, half-value layers, energy absorption buildup factors, exposure buildup factors, effective atomic numbers, effective electron densities computed using the EpiXS software, and the neutron removal cross-sections investigated using the PhyX/PSD software. Then the results were compared with the other commonly used radiation shielding materials. © 2023, The Authors. All rights reserved.

关键词： Aluminum oxide

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