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Improvement in hydrogen storage performance of Mg by mechanical grinding with molten salt etching Ti3C2Clx

Progress in Natural Science:Materials International 2023年第2期33卷 211-224页

作者： Shuaicheng Hu Lijun Lv Guo Yang Wei Liu Hong Miao Honghui Cheng Xingbo Han Zifeng Lin School of Mechanical Engineering Yang Zhou University Shanghai Institute of Applied Physics Chinese Academy of Sciences College of Materials Science and Engineering Sichuan University

Mg-based materials are currently a hot research topic as hydrogen storage materials due to their considerable theoretical hydrogen storage capacity. However, the kinetic performance of hydrogen absorption and desorption of Mg is too slow and requires high temperature, which seriously hinders the application of this material. MXene is a new type of two-dimensional material with significant role in improving thermodynamics and kinetics. In this experiment, a two-dimensional layered MXene containing Cl functional group was prepared by molten salt etching using the Ti-containing MAX phase as the raw material. Then different ratios of Ti3C2Clxwere uniformly dispersed onto the surface of Mg by high energy ball milling. The samples were characterized by hydrogen absorption and desorption kinetics, SEM, XRD, XPS, and DSC to investigate the effect of Ti3C2Clxon the hydrogen absorption and desorption performance of Mg. The onset hydrogen absorption temperature can be reduced to room temperature and the hydrogen release temperature is reduced by 200°C by doping Ti3C2Clx. And there is also 5.4 wt% hydrogen storage in the isothermal hydrogen absorption test at 400°C. The results of DSC demonstrate that the Eaof Mg+15 wt% Ti3C2Clxwas reduced by 12.6% compared to pristine Mg. The ΔH is almost invariable. The results of XPS show that the presence of multivalent Ti promotes electron transfer and thus improves the conversion between Mg2+/Mg and H-/H. This study provides a guideline for further improving the hydrogen absorption and desorption performance of Mg-based hydrogen storage materials.

关键词： Hydrogen storage materials Molten salt synthesis Catalyst doping MXene Mg

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Towards end-to-end structure determination from x-ray diffraction data using deep learning

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npj Computational Materials 2024年第1期10卷 1048-1059页

作者： Gabe Guo Judah Goldfeder Ling Lan Aniv Ray Albert Hanming Yang Boyuan Chen Simon J.L.Billinge Hod Lipson Department of Computer Science Columbia UniversityNew YorkNY10027USA Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY10027USA Department of Mechanical Engineering and Materials Science Duke UniversityDurhamNC27708USA Department of Mechanical Engineering Columbia UniversityNew YorkNY10027USA

Powder crystallography is the experimental science of determining the structure of molecules provided in crystalline-powder form,by analyzing their x-ray diffraction(XRD)*** many materials are readily available as crystalline powder,powder crystallography is of growing usefulness to many ***,powder crystallography does not have an analytically known solution,and therefore the structural inference typically involves a laborious process of iterative design,structural refinement,and domain knowledge of skilled experts.A key obstacle to fully automating the inference process computationally has been formulating the problem in an end-to-end quantitative form that is suitable for machine learning,while capturing the ambiguities around molecule orientation,symmetries,and reconstruction *** we present an ML approach for structure determination from powder diffraction *** works by estimating the electron density in a unit cell using a variational coordinate-based deep neural *** demonstrate the approach on computed powder x-ray diffraction(PXRD),along with partial chemical composition information,as *** evaluated on theoretically simulated data for the cubic and trigonal crystal systems,the system achieves up to 93.4%average similarity(as measured by structural similarity index)with the ground truth on unseen materials,both with known and partially-known chemical composition information,showing great promise for successful structure solution even from degraded and incomplete input *** approach does not presuppose a crystalline structure and the approach are readily extended to other situations such as nanomaterials and textured samples,paving the way to reconstruction of yet unresolved nanostructures.

关键词： structure powder crystalline

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Quasi-two dimensional Ruddlesden−Popper halide perovskites for laser applications

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Frontiers of physics 2024年第2期19卷 53-71页

作者： Kun Chen Qianpeng Zhang Yin Liang Jiepeng Song Chun Li Shi Chen Fang Li Qing Zhang School of Mechanical and Electrical Engineering Wuhan Institute of TechnologyWuhan 430205China School of Materials Science and Engineering Peking UniversityBeijing 100871China Institute of Applied Physics and Materials Engineering Macao UniversityMacao 999078China

Quasi-two-dimensional(2D)Ruddlesden‒Popper(RP)halide perovskites,as a kind of emerged two-dimensional layered materials,have recently achieved great attentions in lasing materials field owing to their large exciton binding energy,high emission yield,large optical gain,and wide-range tuning of optical *** review will introduce research progresses of RP halide perovskites for lasing applications in aspects of materials,photophysics,and devices with emphasis on emission and lasing properties tailored by the molecular composition and *** materials,structures and fabrications are introduced in the first ***,the optical transitions and amplified spontaneous emission properties are discussed from the aspects of electronic structure,exciton,gain dynamics,and interface ***,the research progresses on lasing devices are summarized and several types of lasers including VCSEL,DFB lasers,microlasers,random lasers,plasmonic lasers,and polariton lasers are *** last,the challenges and perspectives would be provided.

关键词： two-dimensional materials metal halide perovskite Ruddlesden−Popper halide perovskites lasing emission

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Review on the effect of isomorphic replacement on the structure and application performance of typical clay minerals

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Progress in Natural Science:Materials International 2024年第2期34卷 251-262页

作者： Ritong Huang Limei Wu Xiaolong Wang Ning Tang Lili Gao Aiqin Wang Yushen Lu School of Materials Science and Engineering Shenyang Jianzhu University School of Mechanical Engineering Shenyang Jianzhu University Key Laboratory of Clay Mineral Applied Research of Gansu Province Center of Eco-material and Green Chemistry Lanzhou Institute of Chemical Physics Chinese Academy of Sciences

Clay minerals represent a class of hydrated phyllosilicates making up the fine-grained portions of rocks, sediments, and soils. Due to the advantages of abundant reserves, low prices, and wide applications, the development and utilization of clay minerals have received increasing attention in recent years. Isomorphic replacement is a common phenomenon in clay minerals, which is one of the main causes of changes in mineral chemical composition and physical and chemical properties. This article briefly describes the crystal structure of several clay minerals such as montmorillonite, vermiculite, palygorskite, kaolinite, and halloysite. It summarized the research status of the effect of isomorphic replacement on their structure and application performance. The research results can provide theoretical basis for the structural research and efficient resource utilization of clay minerals.

关键词： Clay minerals Crystal structure Isomorphism Application performance

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Six-and five-coordinated Cr^(3+)in Ga_(2)GeO_(5) invokes tunable broadband near-infrared emission toward night-vision applications

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Rare Metals 2023年第11期42卷 3787-3796页

作者： Chao-Yue Peng Bo Wang Li-Fang Yuan Kai-Ge Hu Geng Chen Hao-Yi Wu Yi-Hua Hu Ya-Hong Jin School of Physics and Optoelectronic Engineering Guangdong University of TechnologyGuangzhou510006China School of Applied Physics and Materials Wuyi UniversityJiangmen529020China School of Electronics and Communications Guangdong Mechanical&Electrical PolytechnicGuangzhou510515China

Broadband near-infrared(NIR)light sources play a critical role in widespread applications such as advanced spectroscopy analysis and nondestructive *** of the most promising techniques is the fabrication of broadband NIR phosphor-converted light emitting diode(pc-LED).However,the purposeful design of a tunable ultra-broadband NIR-emitting phosphor in a single host is still a *** this work,Ga_(2)GeO_(5) with two sites of six-coordinated[Ga1O_(6)]and five-coordinated[Ga2O_(5)]is chosen to host Cr^(3+),successfully producing tunable broadband NIR luminescence(680-1350 nm).It can be tuned largely from 828 to 970 nm with the full-width at half maximum(FWHM)varied from 208 to 258 nm just by simply adjusting the Cr^(3+)-doping *** tailoring of the Cr^(3+)NIR spectral emission is ascertained to the site occupation preference and *** encapsulation of a prototype of NIR pc-LED with an output power of 29.5mW@390 mA is conducted for the implementation of night-vision *** work provides a novel broadband NIR phosphor by Cr^(3+)-doping in both the sixand five-coordination field,meanwhile,further demonstrating the feasibility of discovering new host material with more than one crystallographic site for Cr^(3+)to trigger tunable broadband NIR emission.

关键词： Cr^(3+) Near-infrared(NIR)emission Broadband Phosphor Night-vision

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Taut-line buzzers with periodic forcing

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Physical Review applied 2024年第1期22卷 014012-014012页

作者： Jesse M. Hanlan Douglas J. Durian Department of Physics and Astronomy Department of Mechanical Engineering and Applied Mechanics

The time-dependent forcing and work per cycle required to drive sinusoidal spinning of a taut-line buzzer is analytically derived, both on and off resonance, from the nonlinear equation of motion. To test predictions, a model experimental system is constructed and characterized in terms of contraction versus twist angle and damped oscillations. The predicted force profile is then approximately implemented by hand. Nearly sinusoidal motion is observed and the energy injection per cycle needed to maintain steady-state oscillations is found to agree with theory. Additional force profiles are implemented, one in an attempt to maximize nonsinusoidal response and one to minimize operator effort. With the latter, an aluminum disk of radius 5 cm and height 0.95 cm was spun at a peak speed of over 11 000 revolutions per minute for 15 min. The corresponding hand-powered centrifuge system would require 1.5 times more force, twice the power, and triple the time in order to run 90 times more samples than the prior state of the art.

关键词： Applications of soft matter Classical mechanics Energy harvesting devices Twist deformation Viscosity

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Experimental demonstration of coupled learning in elastic networks

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Physical Review applied 2024年第2期22卷 024053页

作者： Lauren E. Altman Menachem Stern Andrea J. Liu Douglas J. Durian Department of Physics & Astronomy Department of Mechanical Engineering and Applied Mechanics

Coupled learning is a contrastive local learning scheme for tuning the properties of individual elements within a network to achieve desired functionality of the system. It takes advantage of physics both to learn using local rules and to “compute” the output response to input data, thus enabling the system to perform decentralized computation without the need for a processor or external memory. We present three proof-of-concept mechanical networks of increasing complexity, and demonstrate how they can learn tasks such as self-symmetrization and node allostery via iterative tuning of individual spring rest lengths. These mechanical networks could feasibly be scaled and automated to solve increasingly complex tasks, hinting at a new class of smart metamaterials.

关键词： Applications of soft matter Elastic forces Learning Robustness Artificial neural networks mechanical metamaterials Smart materials Deep learning

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Quasiparticle and excitonic properties of monolayer 1T′ WTe2 within many-body perturbation theory

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Physical Review B 2024年第7期110卷 075133-075133页

作者： Jinyuan Wu Bowen Hou Wenxin Li Yu He Diana Y. Qiu Department of Mechanical Engineering and Materials Science Department of Applied Physics

In the monolayer limit, 1T′ WTe2 is a two-dimensional topological insulator exhibiting the quantum spin Hall effect and is believed to host an excitonic insulator ground state. However, theoretical analysis of this system is complicated by the difficulty of obtaining descriptions of the single-quasiparticle band structure consistent with experimental measurement within conventional first-principles techniques. Previous band-structure calculations using the Perdew-Burke-Ernzerhof functional and a one-shot GW approximation result in a semimetallic band structure, while calculations with hybrid functionals appear to open a band gap. Here, we demonstrate that self-consistently updating wave functions within a static GW approximation (static COHSEX) can reproduce the insulating band structure experimentally observed by angle-resolved photoemission spectroscopy without resorting to mechanisms beyond the quasiparticle picture. Finally, a finite-momentum Bethe-Salpeter equation calculation on top of self-consistent GW results in negative exciton excitation energies, leaving open the possibility of excitonic instability in 1T′ monolayer WTe2.

关键词： 2-dimensional systems Transition metal dichalcogenides Bethe-Salpeter equation Density functional calculations GW method

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Hydrodynamics of molecular rotors in lipid membranes

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Physical Review Fluids 2025年第4期10卷 L041101-L041101页

作者： Vinny Chandran Suja Naomi Oppenheimer Howard A. Stone School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA School of Physics and Astronomy and the Center for Physics and Chemistry of Living Systems Tel Aviv University Tel Aviv 6997801 Israel Department of Mechanical and Aerospace Engineering Princeton University Princeton New Jersey 08544 USA

Molecular rotors form twisted conformations upon photoexcitation, with their fluorescence relaxation time serving as a measure of viscosity. They have been used to assess membrane viscosities but yield higher values compared to other methods. Here, we show that the rotor's relaxation time is influenced by a combination of membrane viscosity and interleaflet friction. We present a theory for the relaxation time and obtain a correction factor that accounts for the discrepancy. If the membrane's viscosity is known, molecular rotors may enable the extraction of the elusive interleaflet friction.

关键词： Viscosity

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High-Quality van der Waals Epitaxial CsPbBr_(3)Film Grown on Monolayer Graphene Covered TiO_(2)for High-Performance Solar Cells

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Energy & Environmental Materials 2024年第4期7卷 239-246页

作者： Zhaorui Wen Chao Liang Shengwen Li Gang Wang Bingchen He Hao Gu Junpeng Xie Hui Pan Zhenhuang Su Xingyu Gao Guo Hong Shi Chen Institute of Applied Physics and Materials Engineering University of MacaoMacao 999078China MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter State Key Laboratory for Mechanical Behavior of MaterialsSchool of PhysicsXi’an Jiaotong UniversityXi’an 710049China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China Department of Materials Science and Engineering&Center of Super-Diamond and Advanced Films City University of Hong KongHong Kong 999077China

Two-dimensional materials have been widely used to tune the growth and energy-level alignment of ***,their incomplete passivation and chaotic usage amounts are not conducive to the preparation of highquality perovskite ***,we succeeded in obtaining higher-quality CsPbBr_(3)films by introducing large-area monolayer graphene as a stable physical overlay on top of TiO_(2)*** from the inert and atomic smooth graphene surface,the CsPbBr_(3)film grown on top by the van der Waal epitaxy has higher crystallinity,improved(100)orientation,and an average domain size of up to 1.22μ***,a strong downward band bending is observed at the graphene/perovskite interface,improving the electron extraction to the electron transport layers(ETL).As a result,perovskite film grown on graphene has lower photoluminescence(PL)intensity,shorter carrier lifetime,and fewer ***,a photovoltaic device based on epitaxy CsPbBr_(3)film is fabricated,exhibiting power conversion efficiency(PCE)of up to 10.64%and stability over 2000 h in the air.

关键词： all-inorganic perovskite solar cells buried interface modification monolayer graphene van der Waals epitaxial growth

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