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Entanglement kinetics in polymer melts are chemically specific

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arXiv 2024年

作者： Dolata, Benjamin E. Galvani Cunha, Marco A. O’Connor, Thomas Hopkins, Austin Olmsted, Peter D. Department of Physics Institute for Soft Matter Synthesis & Metrology Georgetown University 3700 O St NW WashingtonDC20007 United States Department of Physics & Astronomy University of Pennsylvania PhiladelphiaPA19104 United States Department of Materials Science and Engineering Carnegie-Mellon University PittsburghPA15213 United States Department of Physics University of California Santa Barbara Santa BarbaraCA93106 United States Materials Science and Engineering Division National Institute of Standards and Technology GaithersburgMD20899 United States

We investigate the universality of entanglement kinetics in polymer melts. We compare predictions of a recently developed constitutive equation for disentanglement to molecular dynamics simulations of both united-atom polyethylene and Kremer-Grest models for polymers in shear and extensional flow. We confirm that entanglements recover on the retraction timescale, rather than the reptation timescale. We find that the convective constraint release parameter β is independent of molecular weight, but that it increases with the ratio of Kuhn length bK to packing length p as β ∼ (bK/p)α, with an exponent α = 1.9, which may suggest that disentanglement rate correlates with an increase in the tube diameter. These results may help shed light on which polymers are more likely to undergo shear banding. © 2024, CC BY.

关键词： Polymer melts

Tuning the Casimir-Lifshitz force with gapped metals

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Physical Review B 2023年第16期108卷 165306-165306页

作者： M. Boström M. R. Khan H. R. Gopidi I. Brevik Y. Li C. Persson O. I. Malyi Centre of Excellence ENSEMBLE3 Sp. z o. o. Wolczynska Str. 133 01-919 Warsaw Poland Department of Energy and Process Engineering Norwegian University of Science and Technology NO-7491 Trondheim Norway Department of Physics Nanchang University Nanchang 330031 China Institute of Space Science and Technology Nanchang University Nanchang 330031 China Centre for Materials Science and Nanotechnology Department of Physics University of Oslo P. O. Box 1048 Blindern NO-0316 Oslo Norway Department of Materials Science and Engineering KTH Royal Institute of Technology SE-100 44 Stockholm Sweden

The Casimir-Lifshitz interaction, a long-range force that arises between solids and molecules due to quantum fluctuations in electromagnetic fields, has been widely studied in solid-state physics. The degree of polarization in this interaction is influenced by the dielectric properties of the materials involved, which in turn are determined by factors such as band-to-band transitions, free carrier contributions, phonon contributions, and exciton contributions. Gapped metals, a new class of materials with unique electronic structures, offer the potential to manipulate dielectric properties and, consequently, the Casimir-Lifshitz interaction. In this study, we theoretically investigate the finite temperature Casimir-Lifshitz interaction in La3Te4-based gapped metal systems with varying off-stoichiometry levels. We demonstrate that off-stoichiometric effects in gapped metals can be used to control the magnitude and, in some cases, even the sign of Casimir-Lifshitz interactions. We predict measurable corrections due to stoichiometry on the predicted Casimir force between a La3Te4 surface and a gold sphere, attached to an atomic force microscopy tip.

关键词： Casimir effect Casimir effect & related phenomena Defects Dielectric properties

Theoretical lower limit of coercive field in ferroelectric hafnia

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arXiv 2024年

作者： Yang, Jiyuan Wu, Jing Li, Jingxuan Zhou, Chao Sun, Yang Chen, Zuhuang Liu, Shi Department of Physics School of Science Westlake University Zhejiang Hangzhou310024 China State Key Laboratory of Advanced Welding Joining of Materials and Structures School of Materials Science and Engineering Harbin Institute of Technology Shenzhen518055 China Department of Physics Xiamen University Xiamen361005 China Institute of Natural Sciences Westlake Institute for Advanced Study Zhejiang Hangzhou310024 China

The high coercive field (Εc) of hafnia-based ferroelectrics presents a major obstacle to their applications. The ferroelectric switching mechanisms in hafnia that dictate Εc, especially those related to domain nucleation in the Nucleation-Limited-Switching (NLS) model and domain wall motion in the Kolmogorov-Avrami-Ishibas (KAI) model, have remained elusive. We develop a deep-learning-assisted multiscale approach, incorporating atomistic insights into the critical nucleus, to predict both NLS- and KAI-type coercive fields. The theoretical NLS-type Εc values agree with previous experimental results as well as our own measurements and also exhibit the correct thickness scaling for films between 3 and 20 nm. Combined theoretical and experimental investigations reveal that the giant Εc in hafnia-based ferroelectrics arises from the ultra-thin geometry, which confines switching to the NLS mechanism. We predict that the theoretical lower limit for KAI-type Εc is 0.1 MV/cm arsing from mobile domain walls. The activation of KAI-type switching to achieve lower Εc is supported by our experimental demonstration of a low coercive field of 1 MV/cm in a 60 nm ferroelectric (HfO2)n/(ZrO2)n (n = 3 unit cells) superlattices. These findings establish a comprehensive framework for understanding ferroelectric switching in hafnia and highlight the potential of geometry and domain-wall engineering to achieve low-Εc devices. © 2024, CC BY.

关键词： Nucleation

Perovskite/Metal (Bi 0.5Na 0.5TiO 3-BaTiO 3/Ag) Lead-Free Composite Ceramics Featuring Enhanced Depolarization Temperature

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SSRN

SSRN 2023年

作者： Luo, Huajie Tang, Shiyu Sun, Zheng Zhang, Yueyun Yao, Yonghao Zheng, Huashan Yang, Jikun Ren, Yang Tang, Mingxue Huang, Houbing Liu, Hui Hinterstein, Manuel Chen, Jun Beijing Advanced Innovation Center for Materials Genome Engineering Department of Physical Chemistry University of Science and Technology Beijing Beijing100083 China School of Materials Science and Engineering Beijing Institute of Technology Beijing100081 China Condensed Matter Science and Technology Institute School of Instrumentation Science and Engineering Harbin Institute of Technology Harbin150080 China Department of Physics City University of Hong Kong Kowloon 518057 Hong Kong School of Materials Science and Engineering Beijing University of Science and Technology China Institute of Applied Materials Ceramic Materials and Technologies Karlsruhe Institute of Technology Karlsruhe76131 Germany

The thermal stability of Bi0.5Na0.5TiO3-based piezoelectrics is one of the most critical metrics for practical applications. Finite element method (FEM) calculations estimate that incorporating Ag into the perovskite 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 (BNT-6BT) matrix will generate increased tensile stress during the cooling process from sintering temperatures due to the large mismatch in the thermal expansion coefficient. Thus, we propose a strategy to improve the depolarization temperature (Td) by introducing Ag into the representative BNT-6BT and forming perovskite/metal (BNT-6BT/100xAg) composite ceramics. The Td is improved to 145 °C without the degradation of piezoelectric response, which is approximately 45 °C higher than the prototype BNT-6BT. Comparative experiments demonstrate that the increase in Td stems from the synergistic effect of residual thermal stress, colossal grain size (above 200 μm), and oxygen vacancies. The present study provides an effective method to improve the thermal stability of BNT-based ceramics and can be also extended to other systems. © 2023, The Authors. All rights reserved.

关键词： Perovskite

Corrigendum to “Structural, dielectric, electric and magnetic properties of magnesium substituted lithium nanoferrites” [Ceram. Int. 49 (2023) 31114–31123]

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Ceramics International 2023年第22期49卷 35700-35701页

作者： Mohd. Hashim D. Ravvinder Nayak Ateeq Ahmed Shalendra Kumar Sagar E. Shirsath Mukhlis M. Ismail S.K. Sharma Muntasir Ali Alayasreh Ravi Kumar D. Ravinder R.B. Jotania Sher Singh Meena Khalid Mujasam Batoo Department of Applied Physics Aligarh Muslim University Aligarh 202002 India T.S. Model School & College Gaddipally 508201 India Department of Materials Science and Engineering Chosun University Gwangju 61452 Republic of Korea Department of Physics School of Engineering University of Petroleum & Energy Studies Dehradun 248007 India School of Materials Science and Engineering University of New South Wales Sydney NSW 2052 Australia Department of Applied Science University of Technology-Iraq Iraq Nan Chand Anglo Sanskrit College of Meerut India Department of Physics Mutah University Jordan Department of Material Science and Engineering National Institute of Technology Hamirpur 177005 HP India Department of Physics Osmania University Hyderabad India Department of Physics Electronics and Space Science University School of Sciences Gujarat University Ahmedabad 380 009 India Solid State Physics Division Bhabha Atomic Research Centre Mumbai 400 085 India Collage of Science King Saud University P.O. Box-2455 Riyadh 11451 Saudi Arabia

Quantification of electronic asymmetry: chirality and axiality in solids

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arXiv 2024年

作者： Miki, Tatsuya Ikeda, Hiroaki Suzuki, Michi-To Hoshino, Shintaro Department of Physics Saitama University Saitama Sakura338-8570 Japan Department of Physics Ritsumeikan University Shiga Kusatsu525-8577 Japan Department of Materials Science Graduate School of Engineering Osaka Metropolitan University Osaka Sakai599-8531 Japan Center for Spintronics Research Network Graduate School of Engineering Science Osaka University Osaka Toyonaka560-8531 Japan

Chiral and axial materials offer platforms for intriguing phenomena, such as cross-correlated responses and chirality-induced spin selectivity. However, quantifying the properties of such materials has generally been considered challenging. Here, we demonstrate that the spatial distribution of the electron chirality, represented by Ψ†γ5Ψ with the four-component Dirac field Ψ, characterizes the chirality and axiality of materials. Furthermore, we reveal that spin-derived electric polarization can serve as an effective indicator of material polarity. We present quantitative evaluations of electron chirality distribution and spin-derived electric polarization based on first-principles calculations. Additionally, we propose that electron chirality can be directly observed via circular dichroism in photoemission spectroscopy, which measures the difference between right- and left-handed circularly polarized light. Electron chirality and spin-derived electric polarization provide a new framework for quantifying chirality, axiality, and polarity in asymmetric materials, paving the way for the exploration of novel functional materials. Copyright © 2024, The Authors. All rights reserved.

关键词： Dichroism

Dirac bilinears in condensed matter physics: Relativistic correction for observables and conjugate electromagnetic fields

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arXiv 2024年

作者： Hoshino, Shintaro Miki, Tatsuya Suzuki, Michi-To Ikeda, Hiroaki Department of Physics Saitama University Saitama Sakura338-8570 Japan Department of Materials Science Graduate School of Engineering Osaka Metropolitan University Osaka Sakai599-8531 Japan Department of Physics Ritsumeikan University Shiga Kusatsu525-8577 Japan Center for Spintronics Research Network Graduate School of Engineering Science Osaka University Osaka Toyonaka560-8531 Japan

Inspired by recent developments in electron chirality, we reconsider some microscopic physical quantities that have been overlooked or have received little attention in condensed matter physics, based on the non-relativistic limit of the Dirac bilinears in relativistic quantum theory. We identify the expression of physical quantities defined by the four-component Dirac field in terms of the two-component Schrödinger field, which is usually used in condensed matter physics, and clarify its conjugate electromagnetic field. This consideration bridges the fields of condensed matter physics, quantum chemistry, and particle physics, and paves the way to electromagnetic control of matter. Our findings provide a means of ab initio quantification of material characters such as chirality and axiality that are unique to low-symmetry materials, and stimulate the systematic search for useful, new functionalities. © 2024, CC BY-NC-SA.

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Toward batch synthesis of high-quality graphene by cold-wall chemical vapor deposition approach

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Nano Research 2022年第11期15卷 9683-9688页

作者： Kaicheng Jia Ziteng Ma Wendong Wang Yongliang Wen Huanxin Li Yeshu Zhu Jiawei Yang Yuqing Song Jiaxin Shao Xiaoting Liu Qi Lu Yixuan Zhao Jianbo Yin Luzhao Sun Hailin Peng Jincan Zhang Li Lin Zhongfan Liu Center for Nanochemistry Beijing Science and Engineering Center for NanocarbonsBeijing National Laboratory for Molecular ScienceCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Beijing Graphene Institute Beijing 100095China School of Physics and Astronomy University of ManchesterManchester M139PLUK State Key Laboratory for Chemo/Biosensing and Chemometrics College of Chemistry and Chemical EngineeringHunan UniversityChangsha 410082China Department of Engineering University of CambridgeCambridge CB30FAUK Academy for Advanced Interdisciplinary Studies Peking UniversityBeijing 100871China Key Laboratory of Opto-Electronics Technology Ministry of EducationCollege of Electronic Science and TechnologyFaculty of Information TechnologyBeijing University of TechnologyBeijing 100024China State Key Laboratory of Heavy Oil Processing College of ScienceChina University of PetroleumBeijing 102249China School of Materials Science and Engineering Peking UniversityBeijing 100871China

Chemical vapor deposition(CVD)has emerged as a promising approach for the controlled growth of graphene films with appealing scalability,controllability,and ***,the synthesis of high-quality graphene films still suffers from low production capacity and high energy consumption in the conventional hot-wall CVD *** contrast,owing to the different heating mode,cold-wall CVD(CW-CVD)system exhibits promising potential for the industrial-scale production,but the quality of as-received graphene remains inferior with limited domain size and high defect ***,we demonstrated an efficient method for the batch synthesis of high-quality graphene films with millimeter-sized domains based on CW-CVD *** reduced defect density and improved properties,the as-received graphene was proven to be promising candidate material for electronics and anti-corrosion *** study provides a new insight into the quality improvement of graphene derived from CW-CVD system,and paves a new avenue for the industrial production of high-quality graphene films for potential commercial applications.

关键词： graphene cold-wall chemical vapor deposition(CVD) defects electrical performance

Search for potential K ion battery cathodes by first principles

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Journal of Energy Chemistry 2021年第3期30卷 377-385页

作者： Kaining Li Xiaofeng Fan David J.Singh WTZheng Key Laboratory of Automobile Materials(Jilin University) Ministry of Educationand College of Materials Science and EngineeringJilin UniversityChangchun 130012JilinChina Department of Physics and Astronomy University of MissouriColumbiaMO 65211-7010USA Department of Chemistry University of MissouriColumbiaMO 65211USA State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130012JilinChina

An important challenge facing K-ion batteries lies in exploring earth-abundant and safe cathode materials that can provide high capacity with high migration rate of K ***,we propose a simple and efficient method for searching potential K cathode materials with first principles *** screening is based on combinations of weight capacity,K ion occupation ratio,volume change per K,and valence *** this screening method we predicted a series of potential K ions cathodes with favorable electrochemical performance,such as K_(2)VPO_(4)CO_(3)-like structures with 1 D diffusion channels,3 D channel structures K_(2)CoSiO_(4),layered materials KCoO_(2),KCrO_(2),KVF_(4) and K_(5)V_(3)F_(14),and *** potential cathodes have small volume changes,suitable voltage,and high capacity,with small diffusion *** may be useful in K-ion batteries with high energy density and rate performance.

关键词： K ion battery Cathodes First principles calculations High capacity with high migration rate Diffusion barriers