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Preparation, microstructure and high-temperature lubrication properties of CoCrFeNiMn/Ba0.25Sr0.75SO4 high-entropy composites

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Ceramics International 2025年第17期51卷 23620-23634页

作者： Wang, Wenxiang Qiu, Pengfei Zhang, Xinghua Niu, Muye Cheng, Jun Department of Materials Science and Engineering Jiangsu University of Science and Technology Zhenjiang212003 China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Science Lanzhou730000 China

Current research in high-temperature tribology reveals that the CoCrFeNiMn high-entropy alloy exhibits suboptimal wear resistance under elevated temperature conditions. To improve its high-temperature tribological properties, CoCrFeNiMn-(5–10) wt.% Ba0.25Sr0.75SO4 self-lubricating composites were prepared in the present work by vacuum hot press sintering technique. The focus was on the effect of Ba0.25Sr0.75SO4 distribution on microstructure and the high temperature tribological mechanisms of the alloy. The self-lubricating composites consist of FCC phase, σ phase and lubricating phase Ba0.25Sr0.75SO4. The composite is also accompanied by the generation of nanotwins. The pure alloy exhibits high compressive strength and strain, reaching 1692 MPa and 43.9 %, respectively. The addition of lubricant Ba0.25Sr0.75SO4 promoted stress concentration and crack extension, which reduced the mechanical properties of the composites. The fracture mechanism shifted from ductile fracture to brittle fracture. 10 wt% Ba0.25Sr0.75SO4 composite exhibited optimal friction reduction and wear resistance at 800 °C. The friction coefficient and wear rate were reduced by approximately 50 % compared to the pure alloy without lubricant. Worn surface analysis reveals that the formation of lubrication film of Ba0.25Sr0.75SO4 and the appearance of oxides with high ionic potential Ni2O3, MnO2 play a good lubrication role at 800 °C. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Compressive strength

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Hyperdeterminants and composite fermion states in fractional Chern insulators

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Physical Review B 2024年第24期109卷 245125-245125页

作者： Xiaodong Hu Di Xiao Ying Ran Department of Physics Department of Materials Science and Engineering

Fractional Chern insulators (FCI) were proposed theoretically about a decade ago. These exotic states of matter are fractional quantum Hall states realized when a nearly flat Chern band is partially filled, even in the absence of an external magnetic field. Recently, exciting experimental signatures of such states have been reported in twisted MoTe2 bilayer systems. Motivated by these experimental and theoretical progresses, in this paper, we develop a projective construction for the composite fermion states (either the Jain's sequence or the composite Fermi liquid) in a partially filled Chern band with Chern number C=±1, which is capable of capturing the microscopics, e.g., symmetry fractionalization patterns and magnetoroton excitations. On the mean-field level, the ground states' and excited states' composite fermion wave functions are found self-consistently in an enlarged Hilbert space. Beyond the mean field, these wave functions can be projected back to the physical Hilbert space to construct the electronic wave functions, allowing direct comparison with FCI states from exact diagonalization on finite lattices. We find that the projected electronic wave function corresponds to the combinatorial hyperdeterminant of a tensor. When applied to the traditional Galilean invariant Landau level context, the present construction exactly reproduces Jain's composite fermion wave functions. We apply this projective construction to the twisted bilayer MoTe2 system. Experimentally relevant properties are computed, such as the magnetoroton band structures and quantum numbers.

关键词： Composite fermions Flat bands Fractional quantum Hall effect Landau levels Quantum anomalous Hall effect Quasiparticles & collective excitations Topological order Strongly correlated systems Twisted heterostructures Exact diagonalization Hartree-Fock methods Mean field theory Projective symmetries

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Electrical transport crossover and large magnetoresistance in selenium deficient van der Waals HfSe2−x (0≤x≤0.2)

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Physical Review materials 2024年第5期8卷 054006-054006页

作者： Wenhao Liu Yangzi Zheng Aswin Lakshmi Narayanan Kondusamy David L. Scherm Anton V. Malko Bing Lv Department of Physics Department of Materials Science and Engineering

Transition-metal dichalcogenides (TMDs) have received much attention in the past decade not only due to the new fundamental physics, but also due to the emergent applications in these materials. Currently chalcogenide deficiencies in TMDs are commonly believed either during the high-temperature growth procedure or in the nanofabrication process resulting in significant changes of their reported physical properties in the literature. Here, we perform a systematic study involving pristine stochiometric HfSe2, Se-deficient HfSe1.9, and HfSe1.8. Stochiometric HfSe2 transport results show semiconducting behavior with a gap of 1.1eV. Annealing HfSe2 under high vacuum at room temperature causes the Se loss resulting in HfSe1.9, which shows unconventionally large magnetoresistivity following the extended Kohler rule at low temperatures below 50 K. Moreover, a clear electrical resistivity crossover, mimicking the metal-insulator transition, is observed in the HfSe1.9 single crystal. Further increasing the degree of deficiency in HfSe1.8 results in complete metallic electrical transport at all temperatures down to 2 K. Such a drastic difference in the transport behaviors of stoichiometric and Se-deficient HfSe2 further emphasizes the defect control and engineering could be an effective method that could be used to tailor the electronic structure of 2D materials, potentially unlock new states of matter, or even discover new materials.

关键词： Electrical conductivity Growth

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Topological magnetoelectric response in ferromagnetic axion insulators

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National science Review 2024年第2期11卷 8-14页

作者： Yuhao Wan Jiayu Li Qihang Liu Department of Physics and Shenzhen Institute for Quantum Science and Engineering(SIQSE) Southern University of Science and Technology Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices Southern University of Science and Technology Guangdong Provincial Key Laboratory for Computational Science and Material Design Southern University of Science and Technology

The topological magnetoelectric effect （TME） is a hallmark response of the topological field theory,which provides a paradigm shift in the study of emergent topological ***,its direct observation is yet to be realized due to the demanding magnetic configuration required to gap all surface ***,we theoretically propose that axion insulators with a simple ferromagnetic configuration,such as the MnBi2Te4/（Bi2Te3）nfamily,provide an ideal playground to realize the *** the designed triangular prism geometry,all the surface states are magnetically *** a vertical electric field,the surface Hall currents give rise to a nearly half-quantized orbital moment,accompanied by a gapless chiral hinge mode circulating in ***,the orbital magnetization from the two topological origins can be easily distinguished by reversing the electric *** work paves the way for direct observation of the TME in realistic axion-insulator materials.

关键词： topological magnetoelectric effect axion insulator magnetic topological materials

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Accurate design of a novel high-performance 11-pole triple-mode dielectric resonator BPF with fully controllable multiple transmission zeros for mobile communication base stations

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science China(Information sciences) 2025年第2期68卷 387-388页

作者： Fan LIU Zhewang MA Masataka OHIRA Dongchun QIAO Guosheng PU Masaru ICHIKAWA Hunan Provincial Key Laboratory of Flexible Electronic Materials Genome Engineering School of Physics and Electronic SciencesChangsha University of Science and Technology Graduate School of Science and Engineering Saitama University Faculty of Science and Engineering Department of Electronics Doshisha University Huawei Technologies Japan K.K.

High performance dielectric resonator(DR) bandpass filters(BPFs) are critical components in modern RF/microwave front-end systems due to their many distinctive advantages like low loss, small size, light weight, and temperature-stable properties. In recent years, the rapid development of various wireless communication techniques is demanding much more critical specifications for microwave BPFs with better performance but further reduced loss, size, and *** a prospective approach to meet these stringent requirements, BPFs using triple-mode DRs are attracting much attention from both academia and industry [1–5].

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Polar materials for photocatalytic applications:A critical review

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Interdisciplinary materials 2024年第4期3卷 530-564页

作者： Xiaoqing Liu Yu Zhang Cong Wang Lei Shen Department of Mechanical Engineering National University of SingaporeSingaporeSingapore School of Physics Harbin Institute of TechnologyHarbinPR China School of Materials Science and Engineering Engineering Research Center of Optoelectronic Functional MaterialsMinistry of EducationChangchun University of Science and TechnologyChangchunPR China

The critical challenges of the energy crisis and environmental degradation promote innovative approaches for energy ***-based photocatalytic technology,which transforms solar energy into chemical energy,emerges as a promising ***,the practical application of this technology faces several challenges,such as the rapid recombination of photogenerated electrons and holes,significantly limiting photocatalytic *** this review,we provide a detailed discussion,an insightful perspective,and a critical evaluation of recent advances,challenges,and opportunities in the field of photocatalysis using polar *** present a comprehensive examination of the photocatalytic mechanisms,activity,and diverse applications of photocatalysts based on polar *** also briefly discuss the engineering design of polar photocatalysis in experiments and its scalability in the *** review outlines future trends and potential breakthroughs in the photocatalytic field using polar materials,projecting their transformative impact on environmental chemistry and energy engineering.

关键词： 2D Janus structures ferroelectric materials heterostructures photocatalysts polar materials

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Chevrel phase: A review of its crystal structure and electrochemical properties

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Progress in Natural science:materials International 2023年第1期33卷 8-15页

作者： Meng Liu Guocheng Lv Tianming Liu Hao Liu Lingchang Kong Lintao Tian Wenxiu Rao Yuxin Li Libing Liao Juchen Guo Engineering Research Center of Ministry of Education for Geological Carbon Storage and Low Carbon Utilization of Resources Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes National Laboratory of Mineral Materials School of Materials Science and Technology China University of Geosciences(Beijing) School of Science China University of Geosciences Materials Science and Engineering Program University of California-Riverside Department of Chemical and Environmental Engineering University of California – Riverside

Chevrel phase compounds have attracted increasing attention as electrochemical energy storage materials and electro-catalysts. Benefiting from their unique crystal structure, Chevrel phase compounds can not only function as the host structures for reversible intercalation of a broad range of cations, but also exhibit high catalytic activity in electrochemical reduction reactions. Here we provide an overview of recent progress in the development of Chevrel phase materials including new understanding of structural features, synthetic methods, and electrochemical properties. A brief conclusion and perspectives on the future development of Chevrel phase materials are also provided.

关键词： Chevrel phase Electrochemical properties Energy storage Electro-catalysis

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D-band center coordination modulated enzyme-like activity in Fe-Cu dual-metal single-atom nanozymes

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Nano Research 2024年第7期17卷 5872-5883页

作者： Ling Liu Shaofang Zhang Guo Li Yadong Zhe Jiamin Liu Xinxu Zhang Jiahao Wei Xin Sun Yonghui Li Xiao-Dong Zhang Tianjin Key Laboratory of Brain Science and Neural Engineering Academy of Medical Engineering and Translational MedicineTianjin UniversityTianjin 300072China Department of Physics and Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology School of SciencesTianjin UniversityTianjin 300350China

After explorations in a diversity of single-atom nanozymes(SAzymes),developing dual-centered SAzymes becomes a promising approach for superior catalytic *** confusing mechanisms including atomic coordination,spatial configuration,and metal–metal atom interaction hinder the development and design of ***,a dual-centered Fe-Cu-N_(x)SAzyme exhibits excellent peroxidase(POD)-and catalase(CAT)-like activities with d-band center(ε_(d))coordination of Fe and Cu in multiple reaction stages,which plays a critical role in the adsorption of H_(2)O_(2)molecule and H_(2)O and O_(2)***,the dband center coordination,which can be represented byε_(d)(Fe)–ε_(d)(Cu)shifts,leads to the competition between one-side and bilateral adsorption,which determines the favorable reaction path with lower energy *** on experimental statistics,simulated formation energies,and reaction barriers,3 configurations,Fe-Cu-N6-I,Fe-Cu-N_(8)-II,and Fe-Cu-N_(8)-III,are modeled and ***,configuration-dependent catalytic selectivity and the competition between one-side and bilateral adsorption can be unveiled by d-band center coordination paradigm *** simulations suggest that the unsymmetrical charge distribution over the three Fe-Cu configurations could tune the adsorption strength compared with the counterparts FeN_(4)and CuN_(4).The present work provides a potential route for optimizing enzyme-like catalysis by designing the dual-or even triple-metal SAzymes,which demonstrates the large space to modulate the metal atomic configuration and interaction.

关键词： single-atom catalysis Fe-Cu dual-metal d-band center coordination enzyme mimicking competitive adsorption mechanisms

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Controllable synthesis of one-dimensional silicon nanostructures based on the dual effects of electro-deoxidation and the Kirkendall effect

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Nano Research 2024年第9期17卷 7814-7823页

作者： Jianxin Tu Shuo Yu Kui Hao Le Sun Ruicheng Bai Fangzhou Zhang Aijun Li Hong Liu Institute of Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200444China Department of Applied Physics The Hong Kong Polytechnic UniversityKowloon 999077Hong KongChina Shaoxing institute of technology Shanghai UniversityShanghai 200444China

In this study,we successfully synthesized silicon nanotubes(Si-NTs)and silicon nanowires(Si-NWs)in a controllable manner using a catalyst-and template-free method through the direct electrolysis of SiO_(2)in a molten CaCl_(2)-CaO system,while also proposing a novel formation mechanism for ***-NWs are formed through electro-deoxidation when the cell voltage is within the range of CaO decomposition voltage and SiO_(2)decomposition *** subsequently adjusting the voltage to a value between the decomposition potentials of CaCl_(2)and CaO,in-situ electro-deoxidation of CaO takes place on the surface of the synthesized Si-NWs,leading to the formation of a Ca *** formation of Ca-Si diffusion couple leads to the creation of vacancies within the Si-NWs,as the outward diffusion rate of Si exceeds the inward diffusion rate of *** differential diffusion rates between Si and Ca in a diffusion couple exhibit an analogy to the Kirkendall *** vacancies gradually accumulate and merge,forming large voids,which ultimately result in the formation of hollow *** a subsequent dealloying process,the removal of the embedded calcium leads to the formation of *** the application of a carbon coating,the Si-NTs@C composite showcases a high initial discharge capacity of 3211 mAh·g^(-1)at 1.5 A·g^(-1)and exhibits exceptional long-term cycling stability,maintaining a capacity of 977 mAh·g^(-1)after 2000 cycles at 3.0 A·g^(-1).

关键词： silicon nanotubes silicon nanowires lithium-ion battery Kirkendall effect

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Atmospheric clearing of solid-particle debris using femtosecond filaments

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Physical Review Applied 2024年第1期22卷 014075-014075页

作者： Kyle S. Latty Kyle C. Hartig Nuclear Engineering Program Department of Materials Science and Engineering

Through nonlinear self-focusing, femtosecond pulses can propagate several kilometers beyond diffraction limits, forming an ionization channel in air known as a laser filaments. It has been demonstrated that in the wake of the filament, aerosols can be effectively cleared to improve the transmission of subsequent laser pulses or secondary light sources, pertinent to applications in atmospheric sensing. However, the current understanding of aerosol clearing is founded on interactions with droplets to simulate fogs and clouds and thus does not extend to solid particles or atmospheric debris. Using optical trapping, we isolate both graphite and silica microparticles and directly measure the subsequent displacement caused by the filament using time-resolved shadowgraphy. The shock wave from the filament is demonstrated to propel particles away from the filament, directly contributing to atmospheric debris clearing. Particles exposed to the laser light in either the intense filament core or the surrounding energy reservoir are axially displaced along the beam path. It is found that the optomechanical properties of the particle largely influence the axial displacement induced by laser exposure through mechanisms such as radiation pressure, mass ejection from ablation or optical damage, and particle deagglomeration.

关键词： Atmospheric science Light-matter interaction Microparticles Self-focusing Shock waves & discontinuities in plasma Aerosols Femtosecond laser irradiation Optical tweezers

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