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A Flexible Metamaterial Terahertz Perfect Absorber

IOP Conference Series: materials Science and Engineering 2017年第1期281卷

作者： X R Chen Y W Zheng L M Qin G C Wei Z P Qin N G Zhang K Liu S Z Li S X Wang School of Electronic and Electrical Engineering Wuhan Textile University Wuhan Hubei 430073 People's Republic of China State Key Laboratory for Hubei New Textile Materials and Advanced Processing Technology Wuhan Textile University Wuhan 430020 P. R. China

We designed a THz matematerial absorber using metallic wires (MWs) and split resonant rings (SRRs). This matematerial absorber exhibits perfect absorption which up to 96% at 4.03 THz and is capable of wrapped around o...

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Sub-solvus Cellular Recrystallization and P Phase Formation in a Single-Crystal Superalloy Containing Re

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Acta Metallurgica Sinica(English Letters) 2015年第1期28卷 72-76页

作者： Long-Chao Zhuo Ming Huang Ji-Chun Xiong Jia-Rong Li Jing Zhu The State Key Laboratory of New Ceramics and Fine Processing Laboratory of Advanced Materials (MOE) School of Materials Science and Engineering National Center for Electron Microscopy in Beijing Tsinghua University Science and Technology on Advanced High Temperature Structural Materials Laboratory Beijing Institute of Aeronautical Materials

Sub-solvus recrystallization behavior of a second-generation single-crystal superalloy has been studied by transmission electron microcopy and scanning transmission electron microcopy. Surface local stress facilitated cellular recrystallization accompanied with formation of twin structure and TCP phase of P during annealing at sub-solvus temperature of 1,100 °C. The precipitation of P phase is considered to be attributed to the coarsening of c0 phase in the recrystallized aggregates which lower the activation energy for atomic migration.

关键词： Nickel-based single-crystal superalloys Interfaces Recrystallization Twin boundary STEM

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Direct imaging of a zero-field target skyrmion and its polarity switch in a chiral magnetic nanodisk

arXiv

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arXiv 2017年

作者： Zheng, Fengshan Li, Hang Wang, Shasha Song, Dongsheng Jin, Chiming Wei, Wenshen Kovács, András Zang, Jiadong Tian, Mingliang Zhang, Yuheng Du, Haifeng Dunin-Borkowski, Rafal E. Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute Forschungszentrum Jülich Jülich52425 Germany Department of Physics University of New Hampshire DurhamNH03824 United States Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory Chinese Academy of Sciences and University of Science and Technology of China Hefei230026 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Jiangsu Province210093 China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and Engineering Tsinghua University Beijing100084 China

A target skyrmion is a flux-closed spin texture that has two-fold degeneracy and is promising as a binary state in next generation universal memories. Although its formation in nanopatterned chiral magnets has been predicted, its observation has remained challenging. Here, we use off-axis electron holography to record images of target skyrmions in a 160-nm-diameter nanodisk of the chiral magnet FeGe. We compare experimental measurements with numerical simulations, demonstrate switching between two stable degenerate target skyrmion ground states that have opposite polarities and rotation senses and discuss the observed switching mechanism. Copyright © 2017, The Authors. All rights reserved.

关键词： Magnets

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A Metamaterial with Dual-Band Perfect Terahertz Transmission

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IOP Conference Series: materials Science and Engineering 2017年第1期250卷

作者： Guochao Wei Yawei Zheng Xiran Chen Zhengpeng Qin Luman Qin Nangang Zhang Kan Liu Songzhan Li Shengxiang Wang School of Electronic and Electrical Engineering Wuhan Textile University Wuhan 430020 P. R. China Advanced Micro-Nano Textile Innovation Research Center Wuhan Textile University Wuhan 430020 P. R. China State Key Laboratory for Hubei New Textile Materials and Advanced Processing Technology Wuhan Textile University Wuhan 430020 P. R. China

In recent years, the electromagnetic metamaterial has been development rapidly. Meanwhile, its peculiar electromagnetic properties have been widely studied in the fields of electromagnetism and optics. Compared to conventional natural materials, metamaterials show some unusual phenomena, for example, negative refractive index. Because of their exotic properties, metamaterials have been found with many applications, such as perfect lens, cloaking, solar cells and so on. In this paper, we report a metamaterial with dual-band perfect transmission in terahertz range. By tailoring the periodicity of the unit cell, significantly high transmission can be obtained with the metamaterial. The simulation results show that significant transmission peaks at 3.56THz and 7.16THz with the magnitudes of 99.8% and 99.7%, respectively.

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A 3D-printed metamaterial with electromagnetically induced transmission

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IOP Conference Series: materials Science and Engineering 2017年第1期250卷

作者： Zhengpeng Qin Xiran Chen Yawei Zheng Guochao Wei Luman Qin Nangang Zhang Kan Liu Songzhan Li Shengxiang Wang School of Electronic and Electrical Engineering Wuhan Textile University Wuhan 430020 P. R. China Advanced Micro-Nano Textile Innovation Research Center Wuhan Textile University Wuhan 430020 P. R. China State Key Laboratory for Hubei New Textile Materials and Advanced Processing Technology Wuhan Textile University Wuhan 430020 P. R. China

Metamaterials have recently enabled coupling electromagnetic transparency due to interference effects in coupled sub-wavelength resonators. In this work, it presents a three dimensional (3D) metamaterial designed with hollow cube whose simulation shows electromagnetically induced transparency in GHz regime with polarization insensitive to the incident electromagnetic wave due to the ultra-sharp resonance line width as a result of interaction between the constituent meta-atoms. Influences of various parameters including incident angle and frequency have been investigated numerically in detail. The simulation shows significant transmission magnitude of 99.8% at ~12GHz.

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Author Correction: Concise N-doped Carbon Nanosheets/Vanadium Nitride Nanoparticles materials via Intercalative Polymerization for Supercapacitors

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Scientific reports 2018年第1期8卷 6428页

作者： Yongtao Tan Ying Liu Zhenghua Tang Zhe Wang Lingbin Kong Long Kang Zhen Liu Fen Ran State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of Technology Lanzhou 730050 P. R. China. School of Material Science and Engineering Lanzhou University of Technology Lanzhou 730050 Gansu P. R. China. Guangzhou Key Laboratory for Surface Chemistry of Energy Materials New Energy Research Institute School of Environment and Energy South China University of Technology Guangzhou Higher Education Mega Centre Guangzhou 510006 China. Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal South China University of Technology Guangzhou Higher Education Mega Centre Guangzhou 510006 China. Department of Chemistry Xavier University of Louisiana New Orleans LA 70125 USA. Department of Physics & Engineering Frostburg State University Frostburg MD 21532-2303 USA. zliu@frostburg.edu. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of Technology Lanzhou 730050 P. R. China. ranfen@***. School of Material Science and Engineering Lanzhou University of Technology Lanzhou 730050 Gansu P. R. China. ranfen@***.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

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Density functional theory investigation of oxygen interaction with boron-doped graphite

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Applied Surface Science 2016年 390卷 273-282页

作者： Juan Liu Chen Wang Tongxiang Liang Wensheng Lai State Key Lab of New Ceramic and Fine Processing Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China Advanced Material Laboratory School of Materials Science & Engineering Tsinghua University Beijing 100084 China

Boron inserted as impurity by substitution of carbon atoms in graphite is known to change (improve or deteriorate) oxidation resistance of nuclear graphite, but the reason for both catalytic and inhibiting oxidation is still uncertain. As a first step, this work is more specially devoted to the adsorption and diffusion of oxygen atoms on the surface and related to the problem of oxygen retention on the pure and boron-containing graphite surfaces. Adsorption energies and energy barriers associated to the diffusion for molecular oxygen recombination are calculated in the density functional theory framework. The existence of boron modifies the electronic structure of the surface, which results in an increase of the adsorption energy for O. However, low boron loading makes it easier for the recombination into molecular oxygen. For high boron concentration, it induces a better O retention capability in graphite because the presence of B-B bonds decreases recombination of the adsorbed oxygen atoms. A possible explanation for both catalytic and inhibiting effects of boron in graphite is proposed.

关键词： Density functional calculations Chemisorption Graphite Boron Oxygen

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Integrated Intercalation-Based and Interfacial Sodium Storage in Graphene-Wrapped Porous Li4Ti5O12 Nanofibers Composite Aerogel

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advanced Energy materials 2016年第13期6卷

作者： Chen, Chaoji Xu, Henghui Zhou, Tengfei Guo, Zaiping Chen, Lineng Yan, Mengyu Mai, Liqiang Hu, Pei Cheng, Shijie Huang, Yunhui Xie, Jia State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China State Key Laboratory of Materials Processing and Die and Mould Technology School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan430074 China School of Mechanical Materials and Mechatronics Engineering University of Wollongong North WollongongNSW Australia State Key Laboratory of Advanced Technology for Materials Synthesis and Processing WUT-Harvard Joint Nano Key Laboratory Wuhan University of Technology Wuhan430070 China Collaborative Innovation Center of Intelligent New Energy Vehicle Tongji University Shanghai201804 China

Sodium storage in both solid–liquid and solid–solid interfaces is expected to extend the horizon of sodium-ion batteries, leading to a new strategy for developing high-performance energy-storage materials. Here, a novel composite aerogel with porous Li4Ti5O12 (PLTO) nanofibers confined in a highly conductive 3D-interconnected graphene framework (G-PLTO) is designed and fabricated for Na storage. A high capacity of 195 mA h g−1 at 0.2 C and super-long cycle life up to 12 000 cycles are attained. Electrochemical analysis shows that the intercalation-based and interfacial Na storage behaviors take effect simultaneously in the G-PLTO composite aerogel. An integrated Na storage mechanism is proposed. This study ascribes the excellent performance to the unique structure, which not only offers short pathways for Na+ diffusion and conductive networks for electron transport, but also guarantees plenty of PLTO–electrolyte and PLTO–graphene interfacial sites for Na+ adsorption. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词： Storage (materials)

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A three-dimensional model of non-slipping stress corrosion cracking under low loads

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Procedia Structural Integrity 2016年 2卷 612-621页

作者： Zhu Longkui Li Zhengcao Qiao Lijie State Key Laboratory of New Ceramics & Fine Processing Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and Engineering Tsinghua University Beijing 100084 People’s Republic of China Corrosion and Protection Center Key Laboratory for environmental fracture of Ministry of Education School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100084 People’s Republic of China

Stress corrosion cracking (SCC) of 316L single-crystal austenitic stainless steel subjected to low loads (σ nom = 20-40 MPa) in a 45 % boiling MgCl 2 solution was studied using synchrotron X-ray computed tomography, finite element analysis and so on. Results show that there was no surface slip band around the nucleation sites and the tips of short cracks. Three-dimensional reconstruction of discontinuous zig-zag surface SCC crack indicates that the crack was continuous inside the specimen. The obtaining through two-surface trace analysis manifests, rather than {1 1 1} slip planes, the cracks extended along {1 0 0} planes with the lowest surface energy. It is considered that microcleavage and local dissolution synergistically led to the SCC advance, and microshear was also one of the primarily microscopic SCC mechanisms under the high load. The three-dimensional SCC model was created at the low stress level, where a main SCC crack grew along the MPD due to anodic dissolution, and a microdefect was formed on the crack front. When the microdefect enlarged to a critical size, secondary microcracks nucleated at the stress-concentrated microdefect shoulders. Then, the microcracks propagated to two sides of the MPD through anodic dissolution, microcleavage or mciroshear, resulting in the formation of the river-like fractography and the discontinuous surface SCC cracks with or without surface slipping.

关键词： Single-crystal stainless steel Stress corrosion cracking Three-dimensional model Slip band Discontinuous cracks

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Interaction of boron with graphite: A van der Waals density functional study

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Applied Surface Science 2016年 379卷 402-410页

作者： Juan Liu Chen Wang Tongxiang Liang Wensheng Lai Beijing Key Lab of Fine Ceramics Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China State Key Lab of New Ceramic and Fine Processing Tsinghua University Beijing 100084 China Advanced Material Laboratory School of Materials Science & Engineering Tsinghua University Beijing 100084 China

Boron doping has been widely investigated to improve oxidation resistance of graphite. In this work the interaction of boron with graphite is investigated by a van der Waals density-functional approach (vdW-DF). The traditional density-functional theory (DFT) is well accounted for the binding in boron-substituted graphite. However, to investigate the boron atom on graphite surface and the interstitial impurities require use of a description of graphite interlayer binding. Traditional DFT cannot describe the vdW physics, for instance, GGA calculations show no relevant binding between graphite sheets. LDA shows some binding, but they fail to provide an accurate account of vdW forces. In this paper, we compare the calculation results of graphite lattice constant and cohesive energy by several functionals, it shows that vdW-DF such as two optimized functionals optB88-vdW and optB86b-vdW give much improved results than traditional DFT. The vdW-DF approach is then applied to study the interaction of boron with graphite. Boron adsorption, substitution, and intercalation are discussed in terms of structural parameters and electronic structures. When adsorbing on graphite surface, boron behaves as π electron acceptor. The π electron approaches boron atom because of more electropositive of boron than carbon. For substitution situation, the hole introduced by boron mainly concentrates on boron and the nearest three carbon atoms. The B-doped graphite system with the hole has less ability to offer electrons to oxygen, ultimately resulted in the inhibition of carbon oxidation. For interstitial doping, vdW-DFs show more accurate formation energy than LDA. PBE functional cannot describe the interstitial boron in graphite reasonably because of the ignoring binding of graphite sheets. The investigation of electron structures of boron doped graphite will play an important role in understanding the oxidation mechanism in further study.

关键词： Graphite Boron van der Waals density functional Oxidation

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