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Experimental evidence of crystal-field, Zeeman-splitting, and spin-phonon excitations in the quantum supersolid Na2BaCo(PO4)2

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Physical Review B 2025年第15期111卷 155129-155129页

作者： Ghulam Hussain Jianbo Zhang Man Zhang Lalit Yadav Yang Ding Changcheng Zheng Sara Haravifard Xiawa Wang Division of Natural and Applied Sciences Duke Kunshan University Kunshan Jiangsu 215316 China Center for High-Pressure Science and Technology Advanced Research Beijing 100094 China Department of Physics Duke University Durham North Carolina 27708 USA Department of Mechanical Engineering and Materials Science Duke University Durham North Carolina 27708 USA

Drawing inspiration from the recent breakthroughs in the Na2BaCo(PO4)2 quantum magnet, renowned for its spin supersolidity phase and its potential for solid-state cooling applications, our study delves into the interplay among lattice, spin, and orbital degrees of freedom within this compound. Using temperature-, field-, and pressure-dependent Raman scattering techniques, we present experimental evidence revealing crystal-electric-field (CEF) excitations, alongside the interplay of CEF-phonon interactions. We performed density functional theory calculations for the phonon frequencies and compared them with the experimentally observed modes. In addition, our experiments elucidated electronic transitions from j1/2 to j3/2 and from j1/2 to j5/2, with energy levels closely aligned with theoretical predictions based on point-charge models. Moreover, the application of a magnetic field and pressure revealed Zeeman splittings characterized by Landé-g factors as well as the CEF-phonon resonances. The anomalous shift in the coupled peak at low temperatures originated from the hybridization of CEF and phonon excitations due to their close energy proximity and shared symmetry. These findings constitute a significant step towards unraveling the fundamental properties of this exotic quantum material for future research in fundamental physics or engineering application.

关键词： Degrees of freedom (mechanics)

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Nanoindentation creep of supercrystalline nanocomposites

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materials and Design 2023年第1期231卷

作者： Yan, Cong Bor, Büsra Plunkett, Alexander Domènech, Berta Maier-Kiener, Verena Giuntini, Diletta Department of Mechanical Engineering Eindhoven University of Technology Netherlands Institute of Advanced Ceramics Hamburg University of Technology Germany ams-OSRAM International GmbH ams OSRAM Group Germany Department of Materials Science Montanuniversität Leoben Austria

Supercrystalline nanocomposites (SCNCs) are inorganic-organic hybrid materials with a unique periodic nanostructure, and thus they have been gaining growing attention for their intriguing functional properties and parallelisms with hierarchical biomaterials. Their mechanical behavior remains, however, poorly understood, even though its understanding and control are important to allow SCNCs’ implementation into devices. An important aspect that has not been tackled yet is their time-dependent deformation behavior, which is nevertheless expected to play an important role in materials containing such a distribution of organic phase. Hereby, we report on the creep of ceramic-organic SCNCs with varying degrees of organic crosslinking, as assessed via nanoindentation. Creep strains and their partial recoverability are observed, hinting at the co-presence of viscoelasticity and viscoplasticity, and a clear effect of crosslinking in decreasing the overall material deformability emerges. We rationalize our experimental observations with the analysis of stress exponent and activation volume, resulting in a power-law breakdown behavior and governing deformation mechanisms occurring at the organic sub-nm interfaces scale, as rearrangement of organic ligands. The set of results is reinforced by the evaluation of the strain rate sensitivity via strain rate jump tests, and the assessment of the effect of oscillations during continuous stiffness measurement mode. © 2023 The Author(s)

关键词： Nanocomposites

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Hydrogen Powered Fuel Cell Systems - A Review

Hydrogen Powered Fuel Cell Systems - A Review

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IEEE International Conference on Emerging & Sustainable Technologies for Power & ICT in a Developing Society (NIGERCON)

作者： Sunday A. Afolalu Temitayo S. Ogedengbe Moses E. Emetere Stella I. Monye Monye N. Snow Dept. of Mechanical and Mechatronics Engineering Department Afe Babalola University Ado-Ekiti Nigeria Dept. of Mechanical Science University Johannesburg South Africa Dept. of Mechanical Engineering Department Nile University of Nigeria Abuja Dept. of Physics Program. Bowen University Iwo Osun State Nigeria Dept. of Information Communication Technology University of Delta Agbor Delta State Nigeria

ISBN: (数字)9798331542559

ISBN: (纸本)9798331542566

The urgent need for sustainable energy sources has fuelled research into alternative power generation technologies. Among these, hydrogen fuel cells have emerged as promising candidates due to their high energy efficiency and zero-emission profile. This study presents a review on hydrogen energy and fuel cell. The design principles for fuel cells, hydrogen production methods, hydrogen storage technologies and the integration of fuel cells into power systems have been discussed. The review concludes with a discussion on technological advances in fuel cell materials and environmental impacts/sustainability of hydrogen fuel cells.

关键词： Renewable energy sources Humanities Hydrogen storage Reviews Hydrogen Fuel cells Production Power systems Sustainable development Power generation

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Gradient Design with Low-Tortuosity Overcoming Kinetic Limitations in High-Loading Solid-State Cathodes

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Angewandte Chemie 2025年

作者： Guangzeng Cheng Jinping Yu Yonghui Wang Zhengyu Ju Yue Zhu Weiqian Tian Jingwei Chen Huanlei Wang Jingyi Wu Guihua Yu School of Materials Science and Engineering Ocean University of China Qingdao 266404 China Materials Science and Engineering Program and Walker Department of Mechanical Engineering The University of Texas at Austin Austin Texas 78712 USA

The extensive commercialization of practical solid-state batteries (SSBs) necessitates the development of high-loading solid-state cathodes with fast charging capability. However, electrochemical kinetics are severely delayed in thick cathodes due to tortuous ion transport pathways and slow solid-solid ion diffusion, which limit the achievable capacity of SSBs at high current densities. In this work, we propose a conductivity gradient cathode with low-tortuosity to enable facile ion transport and counterbalance ion concentration gradient, thereby overcoming the kinetic limitations and achieving fast charging capabilities in thick cathodes. The LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathodes deliver a room-temperature (RT) capacities of 147 and 110 mAh g −1 at 5 C and 10 C, respectively, and meanwhile achieve a RT areal capacity of 3.3 mAh cm −2 at 3 C, enabling SSBs simultaneously high energy and power densities. The universality of this strategy is demonstrated in LiFePO 4 cathodes, providing a novel solution for fast charging and large-scale application of high-loading SSBs.

关键词： solid-state battery composite cathode high-loading gradient low-tortuosity

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First-Principles and Cluster Expansion Study of the Effect of Magnetism on Short-Range Order in Fe-Ni-Cr Austenitic Stainless Steels

SSRN

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SSRN 2024年

作者： Su, Tianyu Blankenau, Brian J. Kim, Namhoon Krogstad, Jessica A. Ertekin, Elif Department of Materials Science and Engineering University of Illinois at Urbana-Champaign 1304 W. Green Street UrbanaIL61801 United States Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 W. Green Street UrbanaIL61801 United States Materials Research Laboratory University of Illinois at Urbana-Champaign 104 South Goodwin Avenue UrbanaIL61801 United States Frederick Seitz Materials Research Laboratory

Short-range order (SRO) alters the mechanical properties of technologically relevant structuralmaterials such as medium/high entropy alloys and austenitic stainless steels. In thisstudy, we present a generalized spin cluster expansion (CE) model and show that magnetism is a primary factor influencing the level of SRO present in austenitic Fe-Ni-Cr alloys. The spin CE consists of a chemical cluster expansion combined with an Ising model for Fe-Ni-Cr alloys. It explicitly accounts for local magnetic exchange interactions, thereby capturing the effects of finite temperature magnetism on SRO. Model parameters are obtained by fitting to a first-principles data set comprising both chemically and magnetically diverse FCC configurations. The magnitude of the magnetic exchange interactions are found to be comparable to the chemical interactions. Compared to a conventional implicit magnetism CE built from only magnetic ground state configurations, the spin CE shows improved performance on several experimental benchmarks over a broad spectrum of compositions, particularly at higher temperatures due to the explicit treatment of magnetic disorder. We find that SRO is strongly influenced by alloy Cr content, since Cr atoms prefer to align antiferromagnetically with nearest neighbors but become magnetically frustrated with increasing Cr concentration. We predict that increasing the Cr concentration in typical austenitic stainless steels promotes the formation of SRO and increases order-disorder transition temperatures. This study underscores the significance of considering magnetic interactions explicitly when exploring the thermodynamic properties of complex transition metal alloys. It also highlights guidelines for customizing SRO through adjustments of alloy composition. © 2024, The Authors. All rights reserved.

关键词： Ground state

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Vibration Energy Harvesting: A Review on Trends, Challenges & Future Direction

Vibration Energy Harvesting: A Review on Trends, Challenges ...

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IEEE International Conference on Emerging & Sustainable Technologies for Power & ICT in a Developing Society (NIGERCON)

作者： Sunday A. Afolalu Temitayo S. Ogedengbe Moses E. Emetere Stella I. Monye Monye N. Snow Dept. of Mechanical and Mechatronics Engineering Department Afe Babalola University Ado-Ekiti Nigeria Dept. of Mechanical Science University Johannesburg South Africa Dept. of Mechanical Engineering Department Nile University of Nigeria Abuja Dept. of Physics Program Bowen University Iwo Osun State Nigeria Dept. of Information Communication Technology University of Delta Agbor Delta State Nigeria

ISBN: (数字)9798331542559

ISBN: (纸本)9798331542566

The worldwide need for sustainable energy solutions has continued to attract the attention of researchers. One vital means for such provision is the harvesting of energy using various methods. This study therefore reviews the recent trends in energy harvesting. Methods such as vibration energy harvesting as well as electrostatic energy harvesting and their applications have been thoroughly discussed. The study also reviewed the challenges with this energy harvesting methods and finally concludes with the future directions of this topic. It is believed that the generation of energy if greatly boosted will drive the economy of any state and ultimately result in wealth generation for the economy.

关键词： Vibrations Humanities Electric potential Reviews Developing countries Market research Energy harvesting Electrostatics

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A Computationally Derived Technique for the Precision Placement of Heterogeneous Nanoscale Species on a Single Substrate 17

A Computationally Derived Technique for the Precision Placem...

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17th Annual Conference on Foundations of Nanoscience: Self-Assembled Architectures and Devices, FNANO 2020

作者： Deluca, Marcello Gopinath, Ashwin Arva, Gaurav Department of Mechanical Engineering and Materials Science Duke University United States Department of Mechanical Engineering Massachusetts Institute of Technology United States

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Synergy Between Excluded Volume Effect with Co-embedded Microparticles and Chemical Doping in Carbon Nanotube Network-based Composites to Enhance Thermoelectric Power Factor

arXiv

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arXiv 2023年

作者： Akinboye, Oluwasegun Isaac Zhang, Yu Kondapalli, Vamsi Krishna Reddy Olivan, Lars Alexander Raut, Nilesh Jackson, Mark Oluwaseun, Adekoya White, Ryan Shanov, Vesselin Bahk, Je-Hyeong Department of Mechanical and Materials Engineering University of Cincinnati CincinnatiOH45221 United States Department of Electrical Engineering and Computer Science University of Cincinnati CincinnatiOH45221 United States Department of Chemical and Environmental Engineering University of Cincinnati OH45221 United States Department of Chemistry University of Cincinnati OH45221 United States

There is a growing momentum in recent thermoelectric materials research for flexible materials which enhance power output and efficiency at human wearable temperatures. In our previous work, we established the method to improve thermoelectric properties with co-embedding microparticles in carbon nanotube (CNT) network-based composites. In this work, we investigate the synergy of excluded volume effect by silica microparticles with CNT doping toward the enhancement of thermoelectric power factor. We find that the power factor can be enhanced to 28.46 μW/mK2 when the CNT is doped with 0.5 μg/ml of 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) before co-embedding silica microparticles within the carbon nanotube-based composite. We also fabricated and demonstrated flexible wearable thermoelectric devices made of the developed composites that exhibits a power output of 0.025 μW/cm2 at a temperature differential of only 4 K. © 2023, CC BY-NC-SA.

关键词： Thermoelectric equipment

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Three-dimensional cobalt-nitrogen-co doped carbon shells encapsulated NiFe-LDH as an advanced sensing platform for real-time electrochemical analysis of rutin

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Journal of Environmental Chemical engineering 2024年第2期12卷

作者： Elayappan, Vijayakumar Thirumalraj, Balamurugan Alagumalai, Krishnapandi Chen, Shen-Ming Palanivel, Umadevi Murugadoss, Vignesh Noh, Hyun Sung Kim, Younghoon Sun, Min Kyu Lee, Haigun Department of Materials Science and Engineering Korea University Seoul02841 Korea Republic of Department of Mechanical and Nuclear Engineering Khalifa University of Science and Technology Abu Dhabi127788 United Arab Emirates Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei106 Taiwan Department of Physics Sogang University Seoul04107 Korea Republic of Membrane and Separation Technology Division CSIR-Central Glass and Ceramic Research Institute 196 Raja S.C. Mullick Road Kolkata700 032 India School of Chemical Engineering Yeungnam University Gyeongsan38541 Korea Republic of

In this work, we designed a metal-organic framework (MOF) derived cobalt nanoparticles encapsulated nitrogen-rich carbon with nickel iron-layered double hydroxide (Co-NC@NiFe-LDH) for real time electrochemical analysis of the antioxidant flavonoid-rutin (RUT). The prepared composite was examined by various analytical techniques, cyclic voltammetry, and differential pulse voltammetry. A glassy carbon electrode (GCE) modified with Co-NC@NiFe-LDH (Co-NC@NiFe-LDH/GCE) exhibited superior response for RUT along with excellent reproducibility, sensitivity, and selectivity which is attributed to the synergistic effects between the Co-NC and NiFe-LDH, and enable excellent electron transfer across the electrode-electrolyte interface. The Co-NC@NiFe-LDH/GCE responds linearly to RUT concentrations of 0.01 − 20.10 µM and 20.10 − 267.31 µM, with a limit of detection (LOD) and higher sensitivity of 5 nM and 11.898 µA µM–1 cm−2, respectively. These exceptional features of Co-NC@NiFe-LDH arise from its significant active sites, substantial surface area, and excellent electrolyte accessibility. The Co-NC@NiFe-LDH/GCE offers improved stability, with the initial oxidation peak current decreasing by ≤ 5% over 25 days of air exposure. The sensor demonstrated substantial recovery levels of 96.99 − 98.70%, 96.15 − 99.76%, and 97.86 − 99.74% for real-time analyses of serum, urine, and medicinal samples. This study paves the way for advanced sensing platforms in biomedicine and clinical applications, capitalizing on nanohybrid design. © 2024 Elsevier Ltd

关键词： Metal nanoparticles

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Towards Autonomous Experimentation: Bayesian Optimization over Problem Formulation Space for Accelerated Alloy Development

arXiv

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arXiv 2025年

作者： Khatamsaz, Danial Wagner, Joseph Vela, Brent Arróyave, Raymundo Allaire, Douglas L. Department of Materials Science and Engineering Texas A&M University College StationTX77843 United States J. Mike Walker’66 Department of Mechanical Engineering Texas A&M University College StationTX77843 United States Wm Michael Barnes’64 Department of Industrial and Systems Engineering Texas A&M University College StationTX77843 United States

Accelerated discovery in materials science demands autonomous systems capable of dynamically formulating and solving design problems. In this work, we introduce a novel framework that leverages Bayesian optimization over a problem formulation space to identify optimal design formulations in line with decision-maker preferences. By mapping various design scenarios to a multi-attribute utility function, our approach enables the system to balance conflicting objectives—such as ductility, yield strength, density, and solidification range—without requiring an exact problem definition at the outset. We demonstrate the efficacy of our method through an in silico case study on a Mo-Nb-Ti-V-W alloy system targeted for gas turbine engine blade applications. The framework converges on a"sweet spot" that satisfies critical performance thresholds, illustrating that integrating problem formulation discovery into the autonomous design loop can significantly streamline the experimental process. Future work will incorporate human feedback to further enhance the adaptability of the system in real-world experimental settings. © 2025, CC BY.

关键词： Titanium alloys

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