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An ultrahigh fatigue resistant liquid crystal elastomer-based material enabled by liquid metal

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Science China materials 2022年第6期65卷 1679-1686页

作者： Hai-Feng Lu Zhen-Zhou Nie Hari Krishna Bisoyi Meng Wang Shuai Huang Xu-Man Chen Zhi-Yang Liu Hong Yang Institute of Advanced Materials School of Chemistry and Chemical EngineeringState Key Laboratory of BioelectronicsSoutheast UniversityNanjing 211189China Institute for Science and Applications of Molecular Ferroelectrics Key Laboratory of the Ministry of Education for Advanced Catalysis MaterialsZhejiang Normal UniversityJinhua 321004China Advanced Materials and Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State UniversityKentOH 44242USA

The low crosslink density characteristic of liquid crystal elastomer(LCE)materials causes poor fatigue resistance performance,which has seriously plagued their prospects in industrial *** we report that the introduction of 5 wt%liquid metal nanodroplets(average diameter:ca.195 nm)into the LCE network can dramatically reinforce the corresponding composite’s mechanical properties,in particular ultrahigh fatigue resistance,capable of bearing unprecedented 10,000 tensile cycles within a large range of strain amplitude up to 70%and 2000 times of continuous actuating ***,this liquid metal-incorporated LCE composite material exhibits large actuation stroke(maximum actuation strain:55%),high actuation stress(blocking stress:1.13 MPa),fully reversible thermal/photo-actuation functions,and self-healing ability at moderate temperatures,which qualifies the composite material for high-load actuators.

关键词： liquid crystal elastomer liquid metal fatigue resistance actuation

Chiral, Topological, and Knotted Colloids in Liquid Crystals

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arXiv 2024年

作者： Yuan, Ye Smalyukh, Ivan I. Hiroshima University Hiroshima Higashi-Hiroshima739-8526 Japan Department of Physics Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program Soft Materials Research Center University of Colorado BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado BoulderCO80309 United States

The geometric shape, symmetry, and topology of colloidal particles often allow for controlling colloidal phase behavior and physical properties of these soft matter systems. In liquid crystalline dispersions, colloidal particles with low symmetry and nontrivial topology of surface confinement are of particular interest, including surfaces shaped as handlebodies, spirals, knots, multi-component links, and so on. These types of colloidal surfaces induce topologically nontrivial three-dimensional director field configurations and topological defects. Director switching by electric fields, laser tweezing of defects, and local photo-thermal melting of the liquid crystal host medium promote transformations among many stable and metastable particle-induced director configurations that can be revealed by means of direct label-free three-dimensional nonlinear optical imaging. The interplay between topologies of colloidal surfaces, director fields, and defects is found to show a number of unexpected features, such as knotting and linking of line defects, often uniquely arising from the nonpolar nature of the nematic director field. This review article highlights fascinating examples of new physical behavior arising from the interplay of nematic molecular order and both chiral symmetry and topology of colloidal inclusions within the nematic host. Furthermore, the article concludes with a brief discussion of how these findings may lay the groundwork for new types of topology-dictated self-assembly in soft condensed matter leading to novel mesostructured composite materials, as well as for experimental insights into the pure-math aspects of low-dimensional topology. © 2024, CC BY.

关键词： Crystal symmetry

Designing the pressure-dependent shear modulus using tessellated granular metamaterials

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Physical Review E 2023年第3期108卷 034901-034901页

作者： Jerry Zhang Dong Wang Weiwei Jin Annie Xia Nidhi Pashine Rebecca Kramer-Bottiglio Mark D. Shattuck Corey S. O'Hern Department of Mechanical Engineering & Materials Science Yale University New Haven Connecticut 06520 USA Benjamin Levich Institute and Physics Department The City College of New York New York New York 10031 USA Department of Physics Yale University New Haven Connecticut 06520 USA Department of Applied Physics Yale University New Haven Connecticut 06520 USA Integrated Graduate Program in Physical and Engineering Biology Yale University New Haven Connecticut 06520 USA

Jammed packings of granular materials display complex mechanical response. For example, the ensemble-averaged shear modulus 〈G〉 increases as a power law in pressure p for static packings of soft spherical particles that can rearrange during compression. We seek to design granular materials with shear moduli that can either increase or decrease with pressure without particle rearrangements even in the large-system limit. To do this, we construct tessellated granular metamaterials by joining multiple particle-filled cells together. We focus on cells that contain a small number of bidisperse disks in two dimensions. We first study the mechanical properties of individual disk-filled cells with three types of boundaries: periodic boundary conditions (PBC), fixed-length walls (FXW), and flexible walls (FLW). Hypostatic jammed packings are found for cells with FLW, but not in cells with PBC and FXW, and they are stabilized by quartic modes of the dynamical matrix. The shear modulus of a single cell depends linearly on p. We find that the slope of the shear modulus with pressure λc<0 for all packings in single cells with PBC where the number of particles per cell N≥6. In contrast, single cells with FXW and FLW can possess λc>0, as well as λc<0, for N≤16. We show that we can force the mechanical properties of multicell granular metamaterials to possess those of single cells by constraining the end points of the outer walls and enforcing an affine shear response. These studies demonstrate that tessellated granular metamaterials provide a platform for the design of soft materials with specified mechanical properties.

关键词： Jamming Granular solids Mechanical metamaterials

Development of a novel quality control indicator for coffee roasting based on the digitalization of smell by a portable electronic nose

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Development of a novel quality control indicator for coffee ...

International Joint Conference on Computer Science and Software engineering (JCSSE)

作者： Varanya Somaudon Pathapee Sakuldee Teerakiat Kerdcharoen Faculty of Science Materials Science and Engineering Program Mahidol University Bangkok Thailand School of Science Material Engineering Mae Fah Luang University Chiang rai Thailand Department of Physics Faculty of Science Mahidol University Bangkok Thailand

Northern Thailand is home to several Arabica coffee-growing regions, including Mae-kampong, Teentok, Mae-lord, and Monngo Valleys, whose coffees are featured throughout this study. These coffees have distinct aromas and flavors due to their varied cultivation locations, which are influenced by unique climatic conditions. The purpose of this paper is to comprehend the aroma of coffees brought from various locations and roasted under the same conditions. Our lab-made electronic nose (e-nose) was used to digitalize and analyze the smell of coffee. In order to monitor the coffee scent throughout roasting and assess how similar the aromas of coffee samples taken from various locations are to one another, principal component analysis and hierarchical cluster analysis were used. It was found that our e-nose system is an effective tool for determining the geo-location of the coffee origin as well as for quality control of coffee production.

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Emergent Magnetic Phases and Piezomagnetic Effects in MnxNi1−xF2 Thin Film Alloys

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arXiv 2023年

作者： Van Haren, Ryan Hald, Nessa Lederman, David Department of Physics University of California Santa Cruz Santa CruzCA95064 United States Materials Science and Engineering Program School for Engineering of Energy Matter and Transport Arizona State University TempeAZ85287 United States

The effect of random competing single-ion anisotropies in antiferromagnets was studied using epitaxial MnxNi1−xF2 antiferromagnetic thin film alloys grown via molecular beam epitaxy. The crystal structure of this material is tetragonal for all values of x, and the Mn sites have a magnetic easy axis single-ion anisotropy while the Ni sites have an easy plane anisotropy perpendicular to the Mn easy axis. Crystallographic and magnetization measurements demonstrated that the thin film alloys were homogeneously mixed and did not phase-separate into their constituent parts. Pure MnF2 thin films epitaxially grown on MgF2 exhibited compressive strain along all three crystallographic axes which resulted in piezomagnetic effects. The piezomagnetism disappeared if the film was grown on a (MnNi)F2 graded buffer layer. A mean-field theory fit to the transition temperature as a function of the Mn concentration x, which takes into account piezomagnetic effects, gave a magnetic exchange constant between Mn and Ni ions of JMnNi = 0.305±0.003 meV. Mean-field theory calculations also predicted the existence of an oblique antiferromagnetic phase in the MnxNi1−xF2 alloy which agreed with the experimental data. A magnetic phase diagram for MnxNi1−xF2 thin film alloys was constructed and showed evidence for the existence of two unique magnetic phases, in addition to the ordinary antiferromagnetic and paramagnetic phases: an oblique antiferromagnetic phase, and an emergent magnetic phase proposed to be either a magnetic glassy phase or a helical phase. The phase diagram is quantitatively different from that of FexNi1−xF2 because of the much larger single-ion anisotropy of Fe2+ compared to Mn2+ © 2023, CC BY.

关键词： Ions

Distinct Composition-Dependent Topological Hall Effect in Mn2-xZnxSb

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arXiv 2024年

作者： Nabi, Md Rafique Un Li, Yue te Velthuis, Suzanne G.E. Chhetri, Santosh Karki Upreti, Dinesh Basnet, Rabindra Acharya, Gokul Phatak, Charudatta Hu, Jin Department of Physics University of Arkansas FayettevilleAR72701 United States MonArk NSF Quantum Foundry University of Arkansas FayettevilleAR72701 United States Materials Science Division Argonne National Laboratory LemontIL60439 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Department of Chemistry áPhysics University of Arkansas at Pine Bluff Pine BluffAR71603 United States Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States

Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect, a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn2-xZnxSb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high-Zn (χ>0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low-Zn (χ © 2024, CC BY-NC-SA.

关键词： Manganese compounds

HADOKEN: An Open-Source Software Package for Predicting Electron Confinement Effects in Various Nanowire Geometries and Configurations

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arXiv 2022年

作者： Wong, Bryan M. Chevalier, Cameron Department of Chemical & Environment Engineering Materials Science & Engineering Program Department of Physics & Astronomy Department of Chemistry University of California-Riverside RiversideCA92521 United States

We present an open-source software package, HADOKEN (High-level Algorithms to Design, Optimize, and Keep Electrons in Nanowires), for predicting electron confinement/localization effects in nanowires with various geometries, arbitrary number of concentric shell layers, doping densities, and external boundary conditions. The HADOKEN code is written in the MATLAB programming environments to aid in its readability and general accessibility to both users and practitioners. We provide several examples and outputs on a variety of different nanowire geometries, boundary conditions, and doping densities to demonstrate the capabilities of the HADOKEN software package. As such, the use of this predictive and versatile tool by both experimentalists and theorists could lead to further advances in both understanding and tailoring electron confinement effects in these nanosystems. © 2022, CC BY.

关键词： Poisson equation

Ultrafast measurements of the interfacial spin Seebeck effect in Au and rare-earth iron-garnet bilayers

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Physical Review materials 2021年第7期5卷 074401-074401页

作者： Víctor H. Ortiz Michael J. Gomez Yawen Liu Mohammed Aldosary Jing Shi Richard B. Wilson Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside California 92521 USA Department of Physics and Astronomy Program University of California Riverside California 92521 USA

We investigate picosecond spin currents across Au/iron-garnet interfaces in response to ultrafast laser heating of the electrons in the Au film. In the picoseconds after optical heating, interfacial spin currents occur due to an interfacial temperature difference between electrons in the metal and magnons in the insulator. We report measurements of this interfacial longitudinal spin Seebeck effect between Au and rare-earth iron-garnet insulators, i.e., RE3Fe5O12, where RE is Y, Eu, Tb, Tm. By systematically varying the rare-earth element, we modify the total magnetic moment of the iron garnet. We use time-domain thermoreflectance measurements to characterize the thermal response of the bilayer to ultrafast optical heating. We use time-resolved magneto-optic Kerr effect measurements of the Au layer to measure the time evolution of spin accumulation in the Au film. Replacing Y with other rare earths enhances the electron-magnon conductance Ge−m at the Au iron-garnet interface by as much as a factor of 3. The electron-magnon conductance does not follow the trend of either the total magnetization of the iron garnet or the magnetic moment of the rare earth.

关键词： Magneto-optical Kerr effect Magnons Spin Seebeck effect Spin polarization Ultrafast magnetic effects

Interfacial thermal transport in spin caloritronic material systems

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Physical Review materials 2021年第11期5卷 114403-114403页

作者： Frank Angeles Qiyang Sun Victor H. Ortiz Jing Shi Chen Li Richard B. Wilson Department of Mechanical Engineering and Materials Science and Engineering Program University of CaliforniaRiverside California 92521 USA Department of Physics and Astronomy Program University of California Riverside California 92521 USA

Interfaces often govern the thermal performance of nanoscale devices and nanostructured materials. As a result, accurate knowledge of thermal interface conductance is necessary to model the temperature response of nanoscale devices or nanostructured materials to heating. Here, we report the thermal boundary conductance between metals and insulators that are commonly used in spin-caloritronic experiments. We use time-domain thermoreflectance to measure the interface conductance between metals such as Au, Pt, Ta, Cu, and Al with garnet and oxide substrates, e.g., NiO, yttrium iron garnet (YIG), thulium iron garnet (TmIG), Cr2O3, and sapphire. We find that, at room temperature, the interface conductance in these types of material systems range from 50 to 300MWm−2K−1. We also measure the interface conductance between Pt and YIG at temperatures between 80 and 350 K. At room temperature, the interface conductance of Pt/YIG is 170MWm−2K−1 and the Kapitza length is ∼40 nm. A Kapitza length of 40 nm means that, in the presence of a steady-state heat current, the temperature drop at the Pt/YIG interface is equal to the temperature drop across a 40-nm-thick layer of YIG. At 80 K, the interface conductance of Pt/YIG is 60MWm−2K−1, corresponding to a Kapitza length of ∼300 nm.

关键词： Thermal conductivity