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arXiv 2023年

作者： Biswas, Abhijit Alvarez, Gustavo A. Li, Tao Christiansen-Salameh, Joyce Jeong, Eugene Puthirath, Anand B. Iyengar, Sathvik Ajay Li, Chenxi Gray, Tia Zhang, Xiang Pieshkov, Tymofii S. Kannan, Harikishan Elkins, Jacob Vajtai, Robert Birdwell, A. Glen Neupane, Mahesh R. Garratt, Elias J. Pate, Bradford B. Ivanov, Tony G. Zhao, Yuji Tian, Zhiting Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States DEVCOM Army Research Laboratory RF Devices and Circuits AdelphiMD20783 United States Naval Research Laboratory Chemistry Division WashingtonDC20375 United States

Heterostructures based on ultrawide-bandgap (UWBG) semiconductors (bandgap >4.0 eV), such as boron nitride (BN) and diamond, hold significant importance for the development of high-power electronics in the next generation. However, achieving in-situ hetero-epitaxy of BN/diamond or vice versa remains exceptionally challenging due to the complex growth kinetics involved. In this study, we have grown BN thin film on (100) single crystal diamonds using pulsed laser deposition and investigated its structural, magnetic, optical, and thermal properties. The structural analyses confirmed the growth of BN films, which exhibited diamagnetic behavior at room temperature. Notably, the film demonstrated anisotropic refractive index characteristics within the visible-to-near-infrared wavelength range. The room temperature cross-plane thermal conductivity of BN is 1.53 (± 0.77) W/mK, while the thermal conductance of the BN/diamond interface is 20 (± 2) MW/m2K. These findings have significant implications for a range of device applications based on UWBG BN/diamond heterostructures. © 2023, CC BY.

关键词： Diamonds

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Charge and Energy Transfer Dynamics of Hybridized Exciton-Polaritons in 2D Halide Perovskites

arXiv

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arXiv 2023年

作者： Anantharaman, Surendra B. Lynch, Jason Stevens, Christopher E. Munley, Christopher Li, Chentao Hou, Jin Zhang, Hao Torma, Andrew Darlington, Thomas Coen, Francis Li, Kevin Majumdar, Arka Schuck, P. James Mohite, Aditya Harutyunyan, Hayk Hendrickson, Joshua R. Jariwala, Deep Department of Electrical and Systems Engineering University of Pennsylvania PhiladelphiaPA19104 United States KBR Inc. BeavercreekOH45431 United States Air Force Research Laboratory Sensors Directorate Wright-Patterson Air Force Base OH45433 United States Department of Physics University of Washington SeattleWA98195 United States Department of Physics Emory University AtlantaGA30322 United States Department of Chemical and Biomolecular Engineering Rice University HoustonTX77005 United States Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Applied Physics Program Smalley‐Curl Institute Rice University HoustonTX77005 United States Department of Mechanical Engineering Columbia University New YorkNY10027 United States Department of Electrical and Computer Engineering University of Washington SeattleWA98195 United States

Excitons, bound electron-hole pairs, in Two-Dimensional Hybrid Organic Inorganic Perovskites (2D HOIPs) are capable of forming hybrid light-matter states known as exciton-polaritons (E-Ps) when the excitonic medium is confined in an optical cavity. In the case of 2D HOIPs, they can self-hybridize into E-Ps at specific thicknesses of the HOIP crystals that form a resonant optical cavity with the excitons. However, the fundamental properties of these self-hybridized E-Ps in 2D HOIPs, including their role in ultrafast energy and/or charge transfer at interfaces, remain unclear. Here, we demonstrate that > 0.5 µm thick 2D HOIP crystals on Au substrates are capable of supporting multiple-orders of self-hybridized E-P modes. These E-Ps have high Q factors (> 100) and modulate the optical dispersion for the crystal to enhance sub-gap absorption and emission. Through varying excitation energy and ultrafast measurements, we also confirm energy transfer from higher energy upper E-Ps to lower energy, lower E-Ps. Finally, we also demonstrate that E-Ps are capable of charge transport and transfer at interfaces. Our findings provide new insights into charge and energy transfer in E-Ps opening new opportunities towards their manipulation for polaritonic devices. © 2023, CC BY.

关键词： Charge transfer

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Foam Concrete with Mineral Additives: From Microstructure to mechanical/Physical Properties, Workability and Durability

Open Ceramics

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Open Ceramics 2025年

作者： Compaore Alassane Toure Kicoun Jean-Yves N’Zy Desmond Edem Primus Klenam Abdallah Sarroney Merenga Tabiri Kwayie Asumadu John David Obayemi Nima Rahbar Charles Migwi Winston Oluwole Soboyejo Department of Physics Kenyatta University P.O. Box 43844 Nairobi Kenya Department of Civil Engineering Worcester Polytechnic Institute 100 Institute Road Worcester MA 01609 USA Department of Mechanical Engineering Program in Materials Science and Engineering Worcester Polytechnic Institute Worcester Massachusetts USA Academic Development Unit and School of Chemical and Metallurgical Engineering University of the Witwatersrand Johannesburg South Africa Department of Mechanical Engineering College of Engineering State University of New York (SUNY) Polytechnic Institute Utica New York USA

This paper explores foam concretes produced from cement, sand, water, foaming agents and secondary cementitious materials (SCMs). We examine the effects of these constituents on the microstructure, mechanical/physical properties, workability, and the durability of foam concrete. The contributions of SCMs are assessed based on their pozzolanic activity. Various SCMs, through their pozzolanic reactivity, contribute significantly to pore refinement, matrix densification, and the enhancement of mechanical strength, thermal conductivity and durability characteristics, including resistance to water ingress, chloride penetration, and sulfate attack of foam concrete mixes. While the SCMs incorporation leads to improved strength, it may also increase brittleness, which can be balanced with the addition of fibers. Furthermore, the workability is greatly affected by the incorporation of SCMs, which often have a negative effect on reducing it. The paper highlights the opportunities to use metakaolin as an SCM for the optimization of foam concrete mechanical, durability and thermal properties.

关键词： foam concrete microstructure thermal conductivity mineral admixtures compressive strength

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Breaking mechanical Holography in Combinatorial Metamaterials

arXiv

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arXiv 2024年

作者： Sirote-Katz, Chaviva Palti, Ofri Spiro, Naomi Kálmán, Tamás Shokef, Yair Department of Biomedical Engineering Tel Aviv University Tel Aviv69978 Israel The Future Scientists Center Alpha Program Tel Aviv Youth University Tel Aviv69978 Israel University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Mathematics Institute of Science Tokyo H-214 2-12-1 Ookayama Tokyo Meguro-ku152-8551 Japan Hiroshima University Higashi-Hiroshima Hiroshima739-8526 Japan School of Mechanical Engineering Tel Aviv University Tel Aviv69978 Israel Center for Computational Molecular and Materials Science Tel Aviv University Tel Aviv69978 Israel Center for Physics and Chemistry of Living Systems Tel Aviv University Tel Aviv69978 Israel

Combinatorial mechanical metamaterials are made of anisotropic, flexible blocks, such that multiple metamaterials may be constructed using a single block type, and the system’s response strongly depends on the mutual orientations of the blocks within the lattice. We study a family of possible block types for the square, honeycomb, and cubic lattices. Blocks that are centrally symmetric induce holographic order, such that mechanical compatibility (meaning that blocks do not impede each other’s motion) implies bulk-boundary coupling. With them, one can design a compatible metamaterial that will deform in any desired texture only on part of its boundary. With blocks that break holographic order, we demonstrate how to design the deformation texture on the entire boundary. Correspondingly, the number of compatible holographic metamaterials scales exponentially with the boundary, while in non-holographic cases we show that it scales exponentially with the bulk. © 2024, CC BY.

关键词： Holography

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Structure of amorphous aluminosilicates obtained from mineral transformation: Potential path for partial remediation of alkaline bauxite residues

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Environmental Advances 2021年 6卷

作者： Bollinger, David L. Erickson, Jessica Stone-Weiss, Nicholas Lere-Adams, Arumala Josiah Karcher, Sam Akin, Idil Deniz McCloy, John S. Materials Science and Engineering Program Washington State University Pullman 99164 WA United States School of Mechanical and Materials Engineering Washington State University Pullman 99164 WA United States Department of Civil and Environmental Engineering Washington State University Pullman 99164 WA United States

Highly alkaline wastes known as bauxite residue are the abundant byproducts of refining bauxite into alumina through the Bayer process, and worldwide estimates of these bauxite residue stockpiles exceed 3 billion tons, with hundreds of millions of tons produced annually. Bauxite residue utilization and remediation are significantly complicated by the presence of recalcitrant minerals that buffer pH, such as sodalite and cancrinite, commonly referred to as desilication products (DSP) in the alumina industry. In this work, a mixture of sodalite (∼52 wt%) and cancrinite (∼30 wt%) was produced using similar conditions to those encountered in some alumina refineries using the Bayer process. These synthetic minerals were then transformed to hydrated aluminosilicates using a simple, low temperature aqueous process. The transformed products were then characterized with X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance, and electron microscopy. Results suggest that a hypothesized conversion to 2:1-type clay minerals was not achieved, but that the materials were ∼79 wt% X-ray amorphous, resembling protoclay-like materials, with silicate network structures and primarily 4-coordinated Al atoms. This was confirmed by independent synthesis and structural comparison with amorphous aluminosilicates based on allophane and imogolite. Water vapor sorption behavior was similar for the synthesized allophane and the converted DSP minerals;∼0.3 g/g sorbed water content. The current process produces highly amorphous aluminosilicate gels with hydraulic properties similar to silica-rich allophane, which have the potential to aid in the remediation of bauxite residue storage facilities. © 2021 The Authors

关键词： Allophane Bauxite Cancrinite Imogolite Protoclays Sodalite

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Tailoring the Microstructure of a Cu-0.7cr-0.07zr Alloy Submitted to Ecap at Cryogenic Temperature for Improved Thermal Stability

SSRN

引用

SSRN 2022年

作者： Oliveira, Pedro H.F. Magalhães, Danielle Cristina Camilo Unti, Luiz Fernando K. Cintho, O.M. Kliauga, Andrea M. Sordi, Vitor Luiz Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luís km 235 São Carlos SP CEP 13565-905 Brazil Federal University of São Carlos Department of Materials Engineering Rod. Washington Luís km 235 São Carlos SP CEP 13565-905 Brazil Department of Mechanical Engineering Aeronautics Institute of Technology Praça Marechal Eduardo Gomes 50 SP São José dos CamposCEP 12228-900 Brazil Department of Materials Engineering State University of Ponta Grossa Av. General Carlos Cavalcanti PR Ponta GrossaCEP 84030-900 Brazil

Severe Plastic Deformation (SPD) routes, such as Equal Channel Angular Pressing (ECAP), are capable of producing ultrafine-grained (UFG) materials with outstanding mechanical properties. Although grain refinement and the increase in mechanical processing could be enhanced through ECAP processing at cryogenic temperatures, this route presents the drawback of microstructural instability, which is responsible for reversing the gain in mechanical properties and microstructural refinement when the material is stored at room temperature or submitted to relatively high temperatures. Aiming to design severely deformed and stable microstructures, this study investigated pure copper (Cu) and a commercial ITER-grade Cu-0.7Cr-0.07Zr alloy submitted to ECAP at 298 and 123 K followed by annealing heat treatments. ECAP processing introduced a high density of dislocations and vacancy concentration in the materials assessed. Pure Cu showed poor microstructural stability when long-term stored at room temperature after ECAP processing at cryogenic temperatures, and when submitted to annealing post-ECAP processing. In contrast, the Cu-0.7Cr-0.07Zr alloy submitted to cryo-ECAP showed outstanding thermal stability even when submitted to annealing at 673 K for 120 min. For this alloy, the fine Cr-rich precipitates were responsible for preventing static recovery and preserving a grain size of ~6.6 μm and an area fraction of recrystallized grains of 6.2%. Finally, it was possible to pave the way for the design of refined and stable microstructures after cryo-SPD processing. © 2022, The Authors. All rights reserved.

关键词： Equal channel angular pressing

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MOF-derived spinel NiMn2O4/CoMn2O4 heterojunction and its application in a high-performance photocatalyst and supercapacitor

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Journal of Environmental Chemical engineering 2023年第5期11卷

作者： Lee, Kuen-Chan Hsiao, Yu-Sheng Sung, Ming-Yen Chen, Yi-Lun Wu, Nian-Jheng Huang, Jen-Hsien Cho, Er-Chieh Weng, Huei Chu Hsu, Shih-Chieh Department of Science Education National Taipei University of Education No. 134 Section 2 Heping E. Road Da-an District Taipei City106 Taiwan Ph.D. Program in Medical Neuroscience College of Medical Science and Technology Taipei Medical University 250 Wuxing Street Taipei City110 Taiwan Department of Materials Science and Engineering National Taiwan University of Science and Technology No. 43 Section 4 Keelung Road Da-an District Taipei10607 Taiwan Department of Clinical Pharmacy School of Pharmacy College of Pharmacy Taipei Medical University 250 Wuxing Street Taipei City110 Taiwan Université Paris-Saclay CNRS Institut des Sciences Moléculaires d′Orsay Orsay91405 France Department of Green Material Technology Green Technology Research Institute CPC Corporation No. 2 Zuonan Rd. Nanzi District Kaohsiung City81126 Taiwan Department of Mechanical Engineering Chung Yuan Christian University No. 200 Chungpei Rd Chungli District Taoyuan City32023 Taiwan Department of Chemical and Materials Engineering Tamkang University No. 151 Yingzhuan Road Tamsui District New Taipei City25137 Taiwan

Metal oxide heterojunctions have attracted considerable attention in photocatalyst and supercapacitor applications. In this study, NiMn2O4/CoMn2O4 (NMO/CMO) heterojunctions were synthesized using ternary metal-organic frameworks (MOFs) as precursors. After calcination at 500 °C, the as-prepared NMO/CMO composite maintains the porous sheet-like morphology of the ternary MOF, exhibiting a highly porous structure. The heterostructured NMO/CMO composite demonstrates enhanced photocatalytic performance compared with pure NMO and CMO. This enhancement may be attributed to the well-aligned energy levels at the NMO/CMO interface, which effectively reduces charge recombination and facilitates the efficient transport of photogenerated carriers. In addition, the NMO/CMO heterojunction exhibits enhanced supercapacitor performance owing to the increased number of active redox sites and reduced charge transfer resistance. When tested at 3 A/g, the NMO/CMO composite displays a higher capacitance (756.4 F/g) than pure NMO (579.6 F/g) and CMO (519.6 F/g) and remarkable rate capability, maintaining a capacitance of 639 F/g even at 10 A/g. Notably, asymmetric supercapacitors fabricated using NMO/CMO and activated carbon can achieve an energy density of 32.18 W h/kg at 750 W/kg and superior cycling life, retaining 92.1% of its initial capacitance after 3000 cycles. © 2023 Elsevier Ltd

关键词： Heterojunctions

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Stability and electronic properties of edges of SnS2

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Physical Review B 2020年第15期102卷 155306-155306页

作者： Tao Yan Pratap M. Rao N. Aaron Deskins Materials Science and Engineering program Worcester Polytechnic Institute Worcester Massachusetts 01609 USA Department of Mechanical Engineering Worcester Polytechnic Institute Worcester Massachusetts 01609 USA Department of Chemical Engineering Worcester Polytechnic Institute Worcester Massachusetts 01609 USA

Because of its two-dimensional structure and semiconducting properties, tin disulfide (SnS2) is of interest for many applications, such as photocatalysis, photovoltaics, sensing, and electronics. While the atomic and electronic structure of bulk and monolayer SnS2 have been studied, much less is known about the edges of layers. Such edges could have a major influence on the performance of SnS2. This paper reports on density functional theory (DFT) simulations of the atomic and electronic structure of the edges of SnS2. We modeled several different edge terminations at various S coverages and orientations, as well as performed thermodynamic analysis of edge terminations. Our results show that edges with 0% and 50% S atoms are most stable and that higher S coverage are unstable. We directly link edge stability with environmental temperature and pressure, which will guide the experimental synthesis of SnS2 materials. We found all the edges to be semiconducting, unlike other metal chalcogenides, and that the band gap energy decreased with increasing S coverage. Semiconducting edges could lead to lower charge recombination rates and better photocatalytic performance. Our calculations also show that edges may have direct or indirect band gaps, depending on the edge termination. Finally, we examined the reactivity of edges through hydrogen dissociation and found edges to be more reactive than basal planes. Our work provides important details on the nature of SnS2 edges and how these edges influence the electrical and chemical features of SnS2.

关键词： Dichalcogenides Surfaces Density functional theory

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Tailoring high precision polynomial architected material constitutive responses via inverse design

arXiv

引用

arXiv 2023年

作者： MacNider, Brianna Frankel, Ian Qian, Kai Pozos, Alan Santos, Aketzali Kim, H. Alicia Boechler, Nicholas Department of Mechanical and Aerospace Engineering University of California 9500 Gilman Drive La Jolla San DiegoCA92093 United States Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas Instituto Politécnico Nacional Mexico City Mexico Escuela Superior de Ingeniería Mecánica y Eléctrica Unidad Culhuacan Instituto Politécnico Nacional Mexico City Mexico Department of Structural Engineering University of California San Diego 9500 Gilman Drive San DiegoCA92093 United States Program in Materials Science and Engineering University of California San Diego 9500 Gilman Drive San DiegoCA92093 United States

The design of specified nonlinear mechanical responses into a structure or material is a highly sought after capability, which would have a significant impact in areas such as wave tailoring in metamaterials, impact mitigation, soft robotics, and biomedicine. Here, we present a topology optimization approach to design structures for desired polynomial nonlinear behavior, wherein we formulate the problem in such a way as to decouple the nonlinear response from the stiffness. We show results across qualitatively different polynomial behaviors while achieving a high degree of precision, creating a path toward analytically tractable nonlinear dynamical systems. The approach enables access to previously difficult to design for, or hitherto unachieved, nonlinear behavior via optimized structures, which can furthermore be incorporated as unit cells of designer materials with tailored nonlinear properties. Copyright © 2023, The Authors. All rights reserved.

关键词： Polynomials

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Local and global measures of the shear moduli of jammed disk packings

arXiv

引用

arXiv 2023年

作者： Zhang, Shiyun Jin, Weiwei Wang, Dong Xu, Ding Zhang, Jerry Shattuck, Mark D. O’Hern, Corey S. Department of Physics University of Science and Technology of China Anhui Hefei230026 China Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States

Strain-controlled isotropic compression gives rise to jammed packings of repulsive, frictionless disks with either positive or negative global shear moduli. We carry out computational studies to understand the contributions of the negative shear moduli to the mechanical response of jammed disk packings. We first decompose the ensemble-averaged, global shear modulus as hGi = (1 − F−)hG+i + F−hG−i, where F− is the fraction of jammed packings with negative shear moduli and hG+i and hG−i are the average values from packings with positive and negative moduli, respectively. We show that hG+i and h|G−|i obey different power-law scaling relations above and below pN2 ∼ 1. For pN2 > 1, both hG+iN and h|G−|iN ∼ (pN2)β, where β ∼ 0.5 for repulsive linear spring interactions. Despite this, hGiN ∼ (pN2)β0 with β0 & 0.5 due to the contributions from packings with negative shear moduli. We show further that the probability distribution of global shear moduli P(G) collapses at fixed pN2 and different values of p and N. We calculate analytically that P(G) is a Gamma distribution in the pN2 1 limit. As pN2 increases, the skewness of P(G) decreases and P(G) becomes a skew-normal distribution with negative skewness in the pN2 1 limit. We also partition jammed disk packings into subsystems using Delanunay triangulation of the disk centers to calculate local shear moduli. We show that the local shear moduli defined from groups of adjacent triangles can be negative even when G > 0. The spatial correlation function of local shear moduli C(~r) displays weak correlations for pn2sub −2, where nsub is the number of particles within each subsystem. However, C(~r) begins to develop long-ranged spatial correlations with four-fold angular symmetry for pn2sub & 10−2 © 2023, CC BY-NC-ND.

关键词： Elastic moduli

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