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Enhanced memristor performance via coupling effect of oxygen vacancy and ferroelectric polarization

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Journal of Materials Science & Technology 2024年第4期171卷 139-146页

作者： Zhi yun yue Zhi Dong zhang Zhan Jie wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

As a new type of nonvolatile memory,the resistive memristor has broad application prospects in in-formation storage and neural computing based on its excellent resistive switching(RS)*** present,it is still a great challenge to improve both ferroelectric polarization and leakage current to achieve a high RS on/offratio of ferroelectric ***,epitaxial Pb(Zr_(0.40)Ti_(0.60))O_(3)(PZT)thin films with low content Ca doping were deposited on the Nb:SrTiO_(3)substrate to prepare PCZT/NSTO het-erostructures and their RS behaviors were *** research findings show that compared with pure PZT film,the ferroelectric polarization of 1-mol%-Ca-doped PZT film is slightly improved,while the leak-age current is increased by three orders of ***,the RS on/offratio reaches 2.5×10^(5),about three orders of magnitude higher than pure PZT *** theoretical analysis reveals that the RS behavior of PCZT/NSTO heterostructures is controlled by the PCZT/NSTO interfacial barrier and the space charge-limited current *** results demonstrate that the ferroelectricity and electricity of ferroelectric thin films can be improved simultaneously by doping low-content Ca ions to increase the RS performance,which provides a good reference for the development of high-performance ferroelectric memristor devices.

关键词： Ferroelectric memristor Ca-doped PZT Ferroelectric polarization Oxygen vacancies Resistive switching

Detecting secondary spin with extreme mass ratio inspirals in scalar-tensor theory

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Chinese Physics C 2024年第9期48卷 210-224页

作者： hong guo Chao zhang yunqi Liu Rui-hong yue yun-Gui Gong Bin wang Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Escola de Engenharia de Lorena Universidade de São PauloLorenaSP 12602-810Brazil Shanghai Frontier Research Center for Gravitational Wave Detection Shanghai Jiao Tong UniversitySha nghai 200240 China 4 School of Aeronautics and AstronauticsShanghai Jiao Tong UniversityShanghai 200240China School of Physics Huazhong University of Science and TechnologyWuhan 430074China Department of Physics School of Physical Science and TechnologyNingbo UniversityNingbo 315211China

In this study,we investigate the detectability of the secondary spin in an extreme mass ratio inspiral(EMRI) system within a modified gravity model coupled with a scalar *** central black hole,which reduces to a Kerr one,is circularly spiralled by a scalar-charged spinning secondary body on the equatorial *** analysis reveals that the presence of the scalar field amplifies the secondary spin effect,allowing for a lower limit of the detectability and an improved resolution of the secondary spin when the scalar charge is sufficiently *** findings suggest that secondary spin detection is more feasible when the primary mass is not large,and TianQin is the optimal choice for detection.

关键词： Gravitational wave EMRI secondary spin scalar radiation

Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1557-1565页

作者： Jin-Xi zhang Kai-Di Xu qing-guo wang IEEE the State Key Laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China Institute of Artificial Intelligence and Future Networks Beijing Normal UniversityZhuhai 519087 Guangdong Key Laboratory of Artificial Intelligence and Multi-Modal Data Processing Beijing Normal University-Hong Kong Baptist University United International CollegeZhuhai 519087

The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this ***, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings.

关键词： Nonlinear systems output constraints prescribed performance reference tracking time delays

Vertically grown MoS_(2)nanosheets on graphene with defect-rich structure for efficient sodium storage

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Rare Metals 2024年第3期43卷 1062-1071页

作者： Ying wang Jia-Peng He Han-qing Pan qing-Peng wang Lei zhang Yong-Chang Liu qing-hong wang School of Chemistry&Materials Science Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional MaterialsJiangsu Normal UniversityXuzhou221116China Institute of Biopharmaceutical Research Liaocheng UniversityLiaocheng252059China Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyState Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing100083China Centre for Catalysis and Clean Energy Gold Coast CampusGriffith UniversityGold CoastQLD4222Australia

The synthesis of a perpendicular growth structure of MoS_(2)nanosheets on graphene for efficient sodium storage is challenging yet ideal due to the benefits of open ion diffusion channels and high electronic *** this study,we have successfully fabricated a novel structure of vertical MoS_(2)nanosheets on graphene,with ZnS nanoparticles serving as bonding points(MoS_(2)/ZnS/G),through a facile hydrothermal *** the synthesis process,Zn^(2+)not only acts as a landing site for the vertical growth of MoS_(2)nanosheets but also triggers the formation of a defect-rich structure in the final *** unique architecture of MoS_(2)/ZnS/G effectively combines the advantages of a vertically aligned geometry and a defectrich structure for energy *** resulting structure displays shortened transport paths for electrons/ions,enhanced conductivity,improved structural integrity,and an increased number of active sites for promising electrochemical *** expected,when used as anode for sodium-ion batteries,the as-synthesize d MoS_(2)/ZnS/G exhibits excellent rate capability(high capacity of 298 mAh·g^(-1)at 5 A·g^(-1))and good cycling stability(a capacity decay of 0.056%per cycle after 500 cycles at 1 A·g^(-1)).According to the kinetic investigations,the electrochemical process of the MoS_(2)/ZnS/G sample is primarily governe d by a pseudocapacitive behavior,which enhances the charge/discharge kinetics and allows the MoS_(2)/ZnS/G structure to remain intact during cycling.

关键词： MoS_(2) Perpendicular growth Graphene Sodium storage Electrochemical performance

Ti_(3)C_(2)T_(x)/SnO_(2)P–N heterostructure construction boosts room-temperature detecting formaldehyde

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Rare Metals 2024年第1期43卷 267-279页

作者： yue zhang Ming-yue wang Xiao-Guang San Yan-Bai Shen guo-Sheng wang Lei zhang Dan Meng College of Chemical Engineering Shenyang University of Chemical TechnologyShenyang 110142China Institute for Superconducting and Electronic Materials(ISEM) Australian Institute for Innovative Materials(AIIM)University ofWollongongWollongongNSW2500Australia College of Resources and Civil Engineering Northeastern UniversityShenyang 110819China

Formaldehyde is a common atmospheric pollutant produced in industrial production and daily ***,the traditional semiconductor formaldehyde gas sensor cannot work at room temperature,which limits its practical ***,developing high-performance gas sensors for rapidly and accurately detecting formaldehyde at room temperature is an important *** this study,Ti_(3)C_(2)Tx/SnO_(2)heterostructures were constructed,which could selectively detect formaldehyde at room temperature with a response value of 29.16%(10×10^(-6)).In addition,the sensor shows a remarkable theoretical detection limit of 5.09×10^(-9)and good longterm *** functional theory(DFT)simulations reveal that SnO_(2)nano spheres provide the majority of adsorption sites that strongly interact with ***,Ti_(3)C_(2)T_(x)acting as a conductive layer facilitates the transfer of charge carriers so that they show a sensing response to formaldehyde at room ***,the formation of p-n heterostructures between SnO_(2)and Ti_(3)C_(2)T_(x)boosts the Schottky barrier at the interface,which is the critical factor in enhancing the sensing properties by turning the Schottky barrier upon introducing formaldehyde *** perspective is expected to provide instructive guidance for utilizing MXene/metal oxide nanocomposites to improve the gas sensing performance at room temperature.

关键词： Ti_(3)C_(2)T_(x)/SnO_(2)nanocomposites p-n heterostructures Formaldehyde sensing Room temperature DFT calculations

Enhanced bright green luminescence from GdOF:Ho^(3+) up-conversion phosphor via Yb^(3+) doping

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Journal of Rare Earths 2024年第2期42卷 263-269,I0002页

作者： Linjun Qin yue guo Jing Xu Lixi wang Qitu zhang College of Materials Science and Engineering Nanjing Tech UniversityNanjing211816China

In this paper,a series of GdOF-based green phosphors doped with Ho^(3+) and Yb^(3+) ions was prepared by a simple co-precipitation *** crystal structure s and optical prope rties were investigated in *** intensity of the emission of GdOF:Yb^(3+),Ho^(3+) phosphors is enhanced by the effective energy transfer from Yb^(3+) to Ho^(3+),and the optimal luminescence is achieved with the Ho^(3+)doping amount of 0.1 mol%as well as Yb^(3+) doping amount of 5 mol%.Tunable UC emission of samples is achieved by adjusting the doping concentration of Ho^(3+) or Yb^(3+).The purity of the green UC emission is further improved by enhancing the excitation pumping *** addition,logarithmic functions of green,red and nearinfrared radiation intensities were calculated versus logarithmic function of pump power for further study.A possible UC luminescence mechanism between Yb^(3+) and Ho^(3+) is discussed based on powerdependent UC luminescence spectrum and decay *** results suggest that GdOF:Yb^(3+),Ho^(3+)phosphors with bright and high-purity green UC emission have potential applications in the fields of bioimaging,display and illumination.

关键词： Up-conversion GdOF Lanthanide ions Rare earths

Interfacial reaction between AZ91D magnesium alloy melt and mild steel under high temperature

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China Foundry 2024年第2期21卷 159-167页

作者： Jia-hong Dai Jian-yue zhang Bin Jiang Xiang-jun Xu Zhong-tao Jiang hong-mei Xie qing-shan Yang guo-qing zhang College of Materials Science and Engineering Yangtze Normal UniversityChongqing 408100China National Engineering Research Center for Magnesium Alloys College of Materials Science and EngineeringChongqing UniversityChongqing 400044China Chongqing Jiulongyuan High-tech Industry Group Co. Ltd.Chongqing 400080China Loncin Industry Co. Ltd.Chongqing 400080China Department of Materials Science and Engineering The Ohio State UniversityColumbusOH 43210USA Chongqing Key Laboratory of Materials Surface&Interface Science Chongqing University of Arts and SciencesChongqing 402160China School of Metallurgy and Material Engineering Chongqing University of Science and TechnologyChongqing 401331China

The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting ***,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is *** the present study,the interfacial reaction between molten AZ91D Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of AZ91D melt and mild ***,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and ***_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg *** is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction *** measuring the thickness of different layers,the growth constant was *** increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in AZ91D with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of AZ91D than holding time.

关键词： AZ91D mild steel interface reaction intermetallic growth kinetics

Theoretical study on the effect of H_(2)O on the formation mechanism of NO_(x) precursors during indole pyrolysis

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Frontiers of Chemical Science and Engineering 2024年第6期18卷 99-112页

作者： Ziqi wang Jun Shen Xuesong Liu Sha wang Shengxiang Deng Hai zhang yun guo School of Mechanical and Automotive Engineering Shanghai University of Engineering ScienceShanghai 201620China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

The incineration technology of kitchen waste is one of the effective technologies to achieve the resource utilization of municipal solid *** is an important stage of *** is a rich initial product in the pyrolysis process of kitchen waste,and the presence of H_(2)O has a significant impact on the decomposition of indole to form NO_(x) ***,this study uses density functional theory method to study the effect of H_(2)O on the thermal decomposition of indole to produce NH_(3),HNCO,and *** H_(2)O participates in the reaction,it can provide oxidative groups to generate a new product HNCO,which is different from the previous findings by indole pyrolysis without the presence of H_(2)***,this study theoretically proves that NH_(3) is easier to form than *** is consistent with the phenomenon that NH_(3) release is higher than HCN release in pyrolysis *** addition,compared with the individual pyrolysis of indole,the participation of H_(2)O reduces the energy barriers for the formation of NH_(3) and HCN during indole pyrolysis,thereby promoting the formation of NH_(3) and HCN.

关键词： indole pyrolysis H_(2)O NO_(x)precursors DFT

Switching,explosion,and chaos of multi-wavelength soliton states in ultrafast fiber lasers

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 82-90页

作者： Zhi-Zeng Si yue-yue wang Chao-qing Dai College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityLin’an 311300China

Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are *** this study,the switching and periodic soliton explosion processes of the multi-wavelength soliton state in a negative dispersion passively mode-locked fiber laser are *** generation of the multi-wavelength soliton state undergoes the process of noise,oscillation,and stable mode-locking,and the splitting and annihilation of solitons with different group velocities directly impact the generation and disappearance of three *** and negative dispersion lead to different group velocities of *** presence and displacement of solitons with different group velocities cause soliton collisions,which lead to soliton explosions.A soliton experiences relative phase oscillation,chaos,and oscillation,as well as convergence and separation before and after an *** an increase in parameters related to pump power,single-soliton oscillation,multi-wavelength solitons,and chaos are found in experiments and simulations,proving the relevance and reliability between simulation and experimental *** work promotes the dynamical study of multi-soliton collisions in nonlinear science and the development of chaos theory in multi-comb lasers.

关键词： multi-wavelength fiber laser soliton explosion chaos state switching real-time dynamics