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Exploration of iron-chalcogenide superconductors

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Chinese Physics B 2013年第8期22卷 63-74页

作者：董持衡王杭栋方明虎 Department of Physics Zhejiang University Department of Physics Hangzhou Normal University

Iron-chalcogenide compounds with Fese（Te, S） layers did not attract much attention until the discovery of high-Tc superconductivity （SC） in the iron-pnictide compounds at the begining of 2008. Compared with FeAs-based superconductors, iron-chalcogenide superconductors have aroused enormous enthusiasm to study the relationship between SC and magnetisms with several distinct features, such as different antiferromagnetic ground states with relatively large moments in the parents, indicating possibly different superconducting mechanisms, the existence of the excess Fe atoms or Fe vacancies in the crystal lattice. Another reason is that the large single crystals are easily grown for the iron-chalcogenide compounds. This review will focus on our exploration for the iron-chalcogenide superconductors and discussion on several issues, including the crystal structure, magnetic properties, superconductivity, and phase separation. Some of them reach a consensus but some important questions still remain to be answered.

关键词： Fe-based superconductors Fe（Te se S） compounds （T1 K Rb）Fexse2 compounds

Measurement of secondary Electron Energy Spectra of Polymethyl Methacrylate

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Chinese Physics Letters 2018年第4期35卷 108-112页

作者：翁明刘婉殷明王芳曹猛 Key Laboratory for Physical Electronics and Devices (Ministry of Education) Department of Electronic Science and Technology Xi'an Jiaotong University

We report on a novel and convenient method of measuring secondary electron spectra for insulators in a secondary electron yield measurement system with a planar grid analyzer configuration and a metal mesh probe. In this measurement, the planar grid is negatively biased to force some emitted secondary electrons to return to the sample surface and to neutralize charges accumulated on the sample during the previous beam irradiation. The surface potential of the sample is then measured by use of a metal mesh probe. The grid bias for neutralization corresponding to the zero surface potential is determined based on the linear relationship between the surface potential and the grid bias. Once the surface potential equals zero, the secondary electron spectra of polymethyl methacrylate（PMMA） are studied experimentally by measuring the -curve and then fitting it to Everhart＇s formula. The measurement results show that the peak energy and the full width at half maximum of the spectra are 4.26 eV and 14.06 eV, respectively.

关键词： se In Measurement of secondary Electron Energy Spectra of Polymethyl Methacrylate

Time-resolved terahertz spectroscopy of charge carrier dynamics in the chalcogenide glass As_(30)se_(30)Te_(40)[Invited]

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Photonics Research 2016年第3期4卷 22-28页

作者： Tianwu Wang Elena A.Romanova Nabil Abdel-Moneim David Furniss Anna Loth Zhuoqi Tang Angela seddon Trevor Benson Andrei Lavrinenko Peter Uhd Jepsen Department of Photonics Engineering (DTU Fotonik) Technical University of Denmark Saratov State University Department of Physics Faculty of Engineering University of Nottingham

Broadband(1.6–18 THz) terahertz time-domain spectroscopy(THz-TDS) and time-resolved terahertz spectroscopy(TRTS) were performed on a 54 μm thick chalcogenide glass(As_(30)se_(30)Te_(40)) sample with a two-color laser-induced air plasma THz system in transmission and reflection modes, respectively. Two absorption bands at 2–3 and 5–8 THz were observed. TRTS reveals an ultrafast relaxation process of the photoinduced carrier response, well described by a rate equation model with a finite concentration of mid-bandgap trap states for self-trapped excitons.The photoinduced conductivity can be well described by the Drude–Smith conductivity model with a carrier scattering time of 12–17 fs, and we observe significant carrier localization effects. A fast refractive index change was observed 100 fs before the conductivity reached its maximum, with 2 orders of magnitude larger amplitude than expected for the optically induced THz Kerr effect, indicating that free carriers are responsible for the transient index change.

关键词： Te Invited se Time-resolved terahertz spectroscopy of charge carrier dynamics in the chalcogenide glass As

Timing and Source of the Hermyingyi W-Sn Deposit in Southern Myanmar, se Asia: Evidence from Molybdenite Re-Os Age and Sulfur Isotopic Composition

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Journal of Earth Science 2019年第1期30卷 70-79页

作者： Hai Jiang Shao-Yong Jiang Wenqian Li Kuidong Zhao State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Faculty of Earth Resources Collaborative Innovation Center for Exploration of Strategic Mineral Resources China University of Geosciences Key Laboratory of Mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of Sciences

The Hermyingyi W-Sn deposit, situated in southern Myanmar, se Asia, is a typical quartz-vein type W-Sn deposit. The ore-bearing quartz veins are mainly hosted by the Hermyingyi monzogranite which intruded into the Carboniferous metasedimentary rocks of Mergui series. According to mineral assemblages and crosscutting relationships, four ore-forming stages are recognized:(1) silicate-oxide stage;(2) quartz-sulfide stage;(3) barren quartz vein stage;(4) supergene stage. Five molybdenite samples from the deposit yield Re-Os model ages ranging from 67.8±1.6 to 69.2±1.6 Ma(weighted mean age of 68.7±1.2 Ma), and a well-defined isochron age of 68.4±2.5 Ma(MSWD=0.18, 2σ). This Re-Os age is consistent with the previously published zircon U-Pb age of the Hermyingyi monzogranite(70.0±0.4 Ma)(MSWD=0.9, 2σ) within errors, which indicates a genetic link between the monzogranitic magmatism and W-Sn mineralization. The new high-precision geochronological data reveal that the granitic magmatism and associated W-Sn mineralization in southern Myanmar took place during the Late Cretaceous(70–68 Ma). The extremely low Re contents(22.9 ppb to 299 ppb) in molybdenite, coupled with sulfide δ^(34)S values in the range of +1.9‰ to +5.6‰ suggest that ore-forming metals were predominately sourced from the crustal-derived granitic magma.

关键词： Hermyingyi W-Sn deposit molybdenite Re-Os dating sulfur isotopes Myanmar se Asia

selenium metabolism in animals and humans

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Journal of Environmental Sciences 1996年第3期8卷 328-340页

作者： P.D.Whanger(Department of Agricultural Chemistry, Oregon University, Oregon 97331-7301, USA) Department of Agricultural Chemistry Oregon University Oregon 97331-7301 United States

The main purpose of this paper is to point out the differences in the metabolism of se between animals and humans. This is not to imply that the work with animals is not applicable to human because the use of animals in se research has greatly assisted in understanding se metabolism in human subjects. It is fair to conclude that until results are confirmed in humans it is risky to draw conclusions on se metabolism in human based solely on animal data. Although animals have provided some extremely useful information on metabolism of se,there is convincing evidence to indicate that some features of se metabolism are unique to human. A few examples were given to support this contention.

关键词： se metabolism animals human.

In situ atomic-scale observation of size-dependent (de) potassiation and reversible phase transformation in tetragonal Fese anodes

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InfoMat 2023年第1期5卷 161-171页

作者： Ran Cai Lixia Bao Wenqi Zhang Weiwei Xia Chunhao Sun Weikang Dong Xiaoxue Chang Ze Hua Ruiwen Shao Toshio Fukuda Zhefei Sun Haodong Liu Qiaobao Zhang Feng Xu Lixin Dong Beijing Advanced Innovation Center for Intelligent Robots and Systems School of Medical TechnologyBeijing Institute of TechnologyBeijingPeople's Republic of China Analysis&Testing Center Beijing Institute of TechnologyBeijingPeople's Republic of China Department of Biomedical Engineering City University of Hong KongHong KongPeople's Republic of China Shaanxi Materials Analysis and Research Center School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'anPeople's Republic of China School of Environmental and Safety Engineering North University of ChinaTaiyuanPeople's Republic of China Department of Materials Science and Engineering College of MaterialsXiamen UniversityXiamenFujianPeople's Republic of China Department of Nanoengineering University of California San DiegoLa JollaCaliforniaUSA seU-FEI Nano-Pico Center Key Laboratory of MEMS of Ministry of EducationSoutheast UniversityNanjingPeople's Republic of China

Potassium-ion batteries(PIBs)are considered promising alternatives to lithium-ion batteries owing to cost-effective potassium resources and a suitable redox potential of-2.93 V(vs.-3.04 V for Li+/Li).However,the exploration of appro-priate electrode materials with the correct size for reversibly accommodating large K+ions presents a significant challenge.In addition,the reaction mecha-nisms and origins of enhanced performance remain elusive.Here,tetragonal Fese nanoflakes of different sizes are designed to serve as an anode for PIBs,and their live and atomic-scale potassiation/depotassiation mechanisms are revealed for the first time through in situ high-resolution transmission electron micros-copy.We found that Fese undergoes two distinct structural evolutions,sequen-tially characterized by intercalation and conversion reactions,and the initial intercalation behavior is size-dependent.Apparent expansion induced by the intercalation of K+ions is observed in small-sized Fese nanoflakes,whereas unexpected cracks are formed along the direction of ionic diffusion in large-sized nanoflakes.The significant stress generation and crack extension originating from the combined effect of mechanical and electrochemical interactions are elucidated by geometric phase analysis and finite-element analysis.Despite the different intercalation behaviors,the formed products of Fe and K_(2)se after full potassiation can be converted back into the original Fese phase upon depotassiation.In particular,small-sized nanoflakes exhibit better cycling perfor-mance with well-maintained structural integrity.This article presents the first successful demonstration of atomic-scale visualization that can reveal size-dependent potassiation dynamics.Moreover,it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs.

关键词： elucidated by geometric phase analysis and finite-element analysis. Despite the different intercalation behaviors the formed products of Fe and K 2 se after full potassiation can be converted back into the original Fese phase upon depotassiation. In particular small-sized nanoflakes exhibit better cycling perfor- mance with well-maintained structural integrity. This article presents the first successful demonstration of atomic-scale visualization that can reveal size- dependent potassiation dynamics. Moreover it provides valuable guidelines for optimizing the dimensions of electrode materials for advanced PIBs. KEYWOR DS in situ transmission electron microscopy potassium-ion batteries potassium-ion storage mechanism size-dependent effects tetragonal Fese

Rapid seismic analysis methodology for in-service wind turbine towers

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Earthquake Engineering and Engineering Vibration 2015年第3期14卷 539-548页

作者： Dai Kaoshan Huang Yichao Gong Changqing Huang Zhenhua Ren Xiaosong State Key Laboratory of Disaster Reduction in Civil Engineering and College of Civil Engineering Tongji University State Key Lab of Power Transmission Equipment & System security and New Technology Chongqing University Department of Engineering Technology University of North Texas

The wind energy industry has been growing rapidly during the past decades.Along with this growth,engineering problems have gradually emerged in the wind power industry,including those related to the structural reliability of turbine towers.This study proposes a rapid seismic analysis methodology for existing wind turbine tower structures.The method is demonstrated and validated using a case study on a 1.5 MW tubular steel wind turbine tower.Three finite element(FE)models are developed first.Field tests are conducted to obtain the turbine tower’s vibrational characteristics.The tests include(1) remotely measuring the tower vibration frequencies using a long range laser Doppler Vibrometer and(2) monitoring the tower structural vibration by mounting accelerometers along the height of the tubular structure.In-situ measurements are used to validate and update the FE models of the wind turbine tower.With the updated FE model that represents the practical structural conditions,seismic analyses are performed to study the structural failure,which is defined by the steel yielding of the tubular tower.This research is anticipated to benefit the management of the increasing number of wind energy converters by providing an understanding of the seismic assessment of existing tubular steel wind turbine towers.

关键词： wind turbine tower fi eld testing laser sensing se

Early J_2 basalts in se China:Incipience of large-scale late Mesozoic magmatism

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Science China Earth Sciences 2006年第8期49卷 796-815页

作者： XIE Xin1, XU Xisheng1, ZOU Haibo2, JIANG Shaoyong1, ZHANG Ming3 & QIU Jiansheng1 1. State Key Laboratory of Mineral Deposit Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China 2. Department of Earth and Space Sciences, University of California at Los Angeles, Los Angeles, CA90095-1567, USA. 3. GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, N.S.W. 2109, Australia State Key Laboratory of Mineral Deposit Research Department of Earth Sciences Nanjing University Nanjing China Department of Earth and Space Sciences University of California at Los Angeles Los Angeles USA GEMOC ARC National Key Centre Department of Earth and Planetary Sciences Macquarie University Sydney Australia

Magmatism in se China was dormant during 204―180 Ma, but was reactivated in 180― 170 Ma (early J2), and then became more and more intensive towards the end of early Cretaceous. The small-scale early J2 magmatism is the incipience to long-term and large-scale magmatism in this region. A near east-west (EW) trend volcanic belt was distributed across south Hunan, south Jiangxi and southwest Fujian was formed during early J2 time. Along this belt from the inland toward the coast, the lithology of basalts changes from alkali into tholeiite, and the amount of erupted volcanic rocks and the proportions of rhyolites coexisting with the basalts increase. On the basis of geochemical char- acteristics of these basalts, we infer that the melting degree of source rocks and the extent of frac- tional crystallization and crustal contamination all increased whereas the depth of mantle source de- creased from the inland to the coast, which led to the variations of geological characteristics of the volcanic belt. In early J2, the western spreading Pacific plate began to subduct underneath se China continental block, reactivating near EW trend deep fault that was originally formed during the Indos- inian event. The stress of the western spreading Pacific plate and the extent of asthenosphere up- welling increased from the inland to the coast, which is consistent with the generation and evolution of early J2 basalts.

关键词： early J2 basalts, upwelling of asthenosphere, large-scale magmatism, se China, the Pacific plate.

Characteristics of Spontaneous Emission of Polarized Atoms in Metal-Dielectric Multiple Layer Structures

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Chinese Physics Letters 2007年第11期24卷 3137-3140页

作者：赵丽明顾本源周云松 Department of Physics Capital Normal University Beijing 100037 Institute of Physics Chinese Academy of Sciences PO Box 603 Beijing 100080

The spontaneous emission （se） progress of polarized atoms in a stratified structure of air-dielectric（DO）-metal（M） dielectric（D1）-air can be controlled effectively by changing the thickness of the D1 layer and rotating the polarized direction of atoms. It is found that the normalized se rate of atoms located inside the DO layer crucially depends on the atomic position and the thickness of the D1 layer. When the atom is located near the DO-M interface, the normalized atomic se rate as a function of the atomic position is abruptly onset for the thin D1 layer. However, with the increasing thickness of the D1 layer, the corresponding curve profile exhibits plateau and stays nearly unchanged. The substantial change of the se rate stems from the excitation of the surface plasmon polaritons in metal-dielectric interface, and the feature crucially depends on the thickness of D1 layer. If atoms are positioned near the DO-air interface, the substantial variation of the normalized se rate appears when rotating the polarized direction of atoms. These findings manifest that the atomic se processes can be flexibly controlled by altering the thickness of the dielectric layer D1 or rotating the orientation of the polarization of atoms.

关键词： se Metal-Dielectric Multiple