bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational study on thermal stability of an AuCu249 alloy cluster on the atomic scale
Authors: Shao Chen-Wei  , Wang Zhen-Hua  , Li Yan-Nan  , Zhao Qian  , Zhang Lin  ,   School of Science, Northeastern University, Shenyang 110004, China;,   College of Science, Shenyang University of Technology, Shenyang 110178, China
Published: December 2020

Structural change of an AuCu intermetallic alloy cluster including 249 atoms during heating is studied by molecular dynamics simulation within the framework of embedded atom method. The analyses of pair-distribution function, atomic density function, and pair analysis technique show that the structural change of this cluster involves different stages from the outer part into the inner part owing to continuously interchanging positions among atoms at elevated temperature. During the change of the atom packing structure, gold atoms move from the inner part to the outer part of this cluster, whereas copper atoms move from the outer part into the inner part.
Experimental study on X-band repetitively oversized backward wave oscillator
Authors: Wu Yang  , Jin Xiao  , Ma Qiao-Sheng  , Li Zheng-Hong  , Ju Bing-Quan  , Su Chang  , Xu Zhou  , Tang Chuan-Xiang  ,   Department of Engineering Physics, Tsinghua University, Beijing 100084, China;,   Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

A new type of high power microwave device is developed based on bitron and backward wave oscillator. The device is composed of two parts: the modulation cavity and the extraction cavity (which is similar to slow wave structure). The modulation cavity acts as electron beam modulator and microwave reflector, which forms a microwave resonator in combination of the extraction cavity. The electron is modulated when it passes through the modulation cavity, and the high power microwave is generated when the modulated beam passes through the extraction cavity. An X-band high power microwave device is designed for a 20 GW accelerator, and the simulation results are frequency 8.25 GHz and output power 5.70 GW. Using superconducting magnet as guiding magnet, a microwave power of 5.20 GW at X-band (frequency (8.250.01)GHz) is obtained in single pulse mode. The radiation power is 5.06 GW when the repetition rate is 30 Hz, and the pulse length is 13.8 ns.
Three-dimensional particle-in-cell simulation studies on a new radial three-cavity coaxial virtual cathode oscillator
Authors: Yang Chao  , Liu Da-Gang  , Zhou Jun  , Liao Chen  , Peng Kai  , Liu Sheng-Gang  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

A new radial three-cavity structure of the coaxial virtual cathode oscillator is proposed and studied numerically in this paper. Using the radial three-cavity structure, the beam-wave conversion efficiency is enhanced by modulating the electric field in the beam-wave interaction area, while the resonator composed of the radial three-cavity configuration and the mesh anode helps restrain mode competition effectively . And then the coaxial extraction structure benefits the energy extraction, and it can also absorb the used electrons entering into the drifting tube. Therefore, this new kind of virtual cathode oscillator can achieve a high output power. With an electron beam of 50 kA at 400 kV, a peak power of about 6 GW is achieved by simulation at 4.5 GHz. The mean power reaches 3.1 GW and the beam-wave conversion efficiency is about 15%.
Investigation on focus and transport characteristics of high transmission rate sheet electron beam
Authors: Ruan Cun-Jun  , Wang Shu-Zhong  , Han Ying  , Li Qing-Sheng  ,   Key Laboratory of High Power Microwave Sources and Technologies, Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The investigation on focus and transport characteristics of sheet electron beam has been a key technique for the development of high-power microwave and millimeter-wave vacuum electronic devices. Compared with the period permanent magnetic system to transport the sheet electron beam, the uniform magnetic focusing system has many advantages, such as easily adjusting and matching the magnet with the beam, focusing the intensity electron beam, no cut off beam voltage restriction, etc. However, the Diocotron instability of the sheet electron beam in the uniform magnetic field can produce the distortion, deformation, vortex and oscillation to destroy the beam transportation. In this paper, the single-particle model and the cold-fluid model theory and calculation are used to indicate that if the electron optics system parameters of the sheet beam are designed more carefully, the magnitude of uniform magnetic field and the filling factor of the beam in transport tunnel are increased appropriately, the Diocotron instability can be reduced, even vanished completely to transport the sheet beam effectively in a long distance. To verify the above conclusion, the electron gun with the ellipse cathode and the electron optics system are designed and optimized with the three-dimensinal simulation software in detail. After the complex assembly and weld process with the small geometry and high precision, the W-band sheet electron beam tube is manufactured and tested. The sheet beam cross section of 10 mm0.7 mm is achieved experimentally with the one-dimensional compression and formation of electron gun. Also, with a beam voltage of 2080 kV, and beam current of 0.644.60 A,the experimental transmission rate of sheet beam electron tube manufactured is more than 95% with a drift length of 90 mm, which is higher than the periodic cusp magnetic field transport experiment result of 92% obtained recently.
Analysis and measurement for passive tag modulationperformance of backscatter link
Authors: Li Bing  , He Yi-Gang  , Hou Zhou-Guo  , She Kai  , Zuo Lei  ,   College of Electrical and Information Engineering, Hunan University, Changsha 410082, China
Published: December 2020

Optimal conditions for maximizing the effectively received power of reader receiver in passive ultra high frequency radio-frequency identification system are analyzed in this paper. The mismatched impendence affecting modulation index of tag backscatter link is discussed. Expressions of backscattered modulation indexes for calculating normalized effective received power of reader receiver, lower boundary of signal-to-noise ratio for demodulated output signal, and bit error rate are derived. Modulation indexes of backscatter link under different parameters are measured in open indoor environment. The measurement results show that the tag can be detected successfully when the modulation index of backscatter link is in a range from 5% to 10%.
Experiment and simulation of time lens using electro-opticphase modulation and cross phase modulation
Authors: Li Bo  , Tan Zhong-Wei  , Zhang Xiao-Xing  ,   Institute of Lightwave Technology, Beijing Jiaotong University, Beijing 100044, China
Published: December 2020

Temporal imaging is one of the important research issues of time lens. The theory of temporal imaging is investigated briefly. The experiment using electro-optic phase modulation to perform optical pulses compression is demonstrated. And the simulation and the discussion using electro-optic phase modulation and cross phase modulation to perform temporal imaging system are presented. The experimental results show that the temporal imaging system which consisits of time lens basing electro-optic phase modulation can effectively compress the optical pulses. However, the compression coefficient is restricted by the aperture of the time lens, and the resolution of the temporal imaging system is low. Further more, the simulation results and the analysis results indicate that the temporal imaging system which consists of time lens basing cross phase modulation has a bigger compression coefficient and a higher resolution. However, this temporal imaging system is difficult to realize.
Statistics property of polarized photon emission driven bya pair of pulses in single quantum dot
Authors: Gu Li-Shan  , Wang Dong-Sheng  , Peng Yong-Gang  , Zheng Yu-Ju  ,   Department of Physics, Changji University, Changji 831100, China;,   School of Physics, Shandong University, Jinan 250100, China
Published: December 2020

We study the properties of the x- and the y-polarized photons of the single quantum dot system driven by a pair of pulses using the generating function approach. Our results show that the quantum interference effects on the line shapes and the Mandels parameter Q of the x- and y-polarized photons and the linear and the nonlinear cross correlations are important.
Wavelet transform of odd- and even-binomial states
Authors: Song Jun  , Xu Ye-Jun  , Fan Hong-Yi  ,   Department of Material and Chemical Engineering, West Anhui University, Lu'an 237012, China;,   Department of Material Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

In the context of quantum mechanics the classical wavelet transform of a function f with the mother wavelet can be recast into a matrix element of the squeezing-displacing operator U(,s) as 〈|U(,s) |f〉. The technique of integral within an ordered product of operators is used to support this theory. Based on this, wavelet transforms are done for even- and odd-binomial states, and the corresponding numerical calculation leads to the spectrum of wavelet transform, which is helpful for recognizing the difference between even- and odd-states.
Mapping between multi-photon polarization state and single-photon spatial qudit and its applications
Authors: Lin Qing  ,   College of Information Science and Engineering, Huaqiao University, Xiamen 361021, China
Published: December 2020

Based on a special controlled-NOT gate, a multi-photon state encoded in polarizations of photons could be transformed into the corresponding single photon qudit encoded in spatial mode. It will make the processing on multi-photon change into the operation on a single-photon, if the inverse transformation from a single photon qudit back to a multi-photon state could be realized also. Associated with linear optical multi-port interferometer for single-photon unitary operation, the positive-operator value measurement and the universal unitary operation for multi-photon state are realized. This approach is more efficient than the previous one with decomposition into two-qubit gates in the circuit-based quantum computation, and it is feasible with using the current experimental technology.
Theoretical analysis of two-stage pumping technology for high power fiber lasers
Authors: Yang Wei-Qiang  , Hou Jing  , Song Rui  , Liu Ze-Jin  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The problems of direct pumping and two-stage pumping for high power fiber lasers are theoretically analyzed. The simulation results show that 1070 nm laser directly pumped by 975 nm laser provides a theoretical slope efficiency up to 80%. But it is hard to make the highest temperature of the fiber core reduce below 150 ℃ by forced water cooling when pump power is 10 kW. For the two-stage pumping technology, if the conventional cladding pumping technology is used the slope efficiency is less than 20% when a 1070 nm laser is pumped by a 1018 nm laser. With the pump power filling factor increasing from 0.0025 to 0.1, the slope efficiency can be raised from 18.5% to 80.9%, thus the total slope efficiency is raised from 15.5% to 68%. Two-stage pumping is inferior to direct pumping in terms of slope efficiency, but it has the obvious advantage of thermal management. How to raise the pump power filling factor to achieve high slope efficiency and good temperature characteristics at the same time is the key technology of the two-stage pumping.
Interactions of Laguerre-Gaussian solitons instrongly nonlocal nonlinear media
Authors: Zhang Xia-Ping  , Liu You-Wen  ,   Faculty of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China;,   Department of Physics, Nanjing Xiaozhuang University, Nanjing 210017, China
Published: December 2020

Based on the modified Snyder-Mitchell model, the optical fields that are produced by two collinear Laguerre-Gaussian solitons (LGS) in a strongly nonlocal nonlinear medium are studied. Various novel kinds of solitons on the profiles which depend on the model-index and the relative amplitude of LGS are shown. It is the phase vortices of the LGS that lead to the optical singularities. The many-ring soliton is produced first with the collinear component LGS. The optical field may rotate in propagation, and the angular velocity of the spiral soliton is given.
Theoretical and experimental studies on ultra-broad-bandwavelength tunableness by optical soliton mechanism
Authors: Zhu Qi-Hua  , Zhou Shou-Huan  , Zhao Lei  , Zeng Xiao-Ming  , Huang Zheng  , Zhou Kai-Nan  , Wang Xiao  , Huang Xiao-Jun  , Feng Guo-Ying  ,   School of Electronics and Information, Sichuan University, Chengdu 610064, China;,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

It is crucial but challengeable that the generation of optical exact by synchronized seed pulses both for the main amplifier chain and for the pump-laser chain of an optical parametric chirped pulse amplification system, which are tried to be developed by the soliton mechanism. Detailed numerical simulation of the soliton propagation mechanism are accomplished. So the evolutions of solitons in time-domain and frequency-domain as well as the reciprocity characteristic with other nonlinear effects are clarified. Experiments are carried out, for validating the method of using soliton mechanism to generate ultra-broad band tunable ultra-short laser pulses. Forming, breaking up and self-frequency shift of a soliton are observed. The favorable tunablenesses of the wavelength between the visible and the near-infrared regions are exhibited. All these experimental results are well consistent with the theoretical analyses.
Experimental determination of scattering matrix of fire smoke particles at 532 nm
Authors: Zhang Qi-Xing  , Li Yao-Dong  , Deng Xiao-Jiu  , Zhang Yong-Ming  ,   State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230027, China;,   College of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009, China
Published: December 2020

Based on polarization modulation and lock-in detection, an experimental apparatus is built to determine several important angular dependent scattering matrix elements at 532 nm. The apparatus is tested by water droplets through comparing measurement results with Mie calculations. Measurement results of scattering matrix elements and element ratios between smoke particles produced by smoldering cotton test fire and those produced from flaming n-heptane test fire are presented. We find that results of Mie calculations are able to describe the experimental data of smoldering cotton test fire smoke, which indicates that the particles generated by smoldering cotton test fire are mostly spherical in shape with considering the particle size relative to the wavelength. Using the optimization method, we estimate the refractive index (m=1.49+i0.01) and size distribution (lognormal distribution, g=2.335 and dg=0.17 m) of smoldering cotton test fire smoke. Contrarily, the experimental data of flaming n-heptane fire smoke cannot be described by Mie scattering, which is interpreted by the nonspherical, fractal aggregate morphology of the particulates.
Model of quench cooling and experimental analysis of cylindrical infrared chalcogenide glass
Authors: Song Bao-An  , Dai Shi-Xun  , Xu Tie-Feng  , Nie Qiu-Hua  , Shen Xiang  , Wang Xun-Si  , Lin Chang-Gui  ,   Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China
Published: December 2020

The tapping temperature and the cooling rate are the key parameters during the development process of chalcogenide glass. Based on the theory of heat conduction equation, a model for calculating the temperature distribution of cylindrical chalcogenide glass is established using the least square fitting method in this paper. The tapping temperature, the temperature distribution and the cooling rate are simulated by using the model. The simulation results are compared with experimental data. The results show that the glass temperature stays in a non-steady non-uniform distribution, the surface cooling is the fastest, and the temperature decreases exponentially with time when the glass is tapped off from the furnace; the temperature of glass rod from the center to the edge is approximately of parabola distribution; the crystallization is the most difficult when the glass is tapped off at 50100 ℃ higher than crystallization temperature and a surface heat exchange coefficient of 180 W m-2K-1. Under the guidance of the theoretical model the uniform and transparent chalcogenide glass with a diameter of 110 mm and height of 80 mm is obtained. The glass transmission spectrum range is 0.817 m. The 2 mm thick flat sheet has the average transmittance higher than 65% in a 812 m range.
Core-shape transitions in photonic crystal fiber
Authors: Sun Gui-Lin  , Chen Zi-Lun  , Xi Xiao-Ming  , Chen Hong-Wei  , Hou Jing  , Jiang Zong-Fu  ,   Department of Basic Sciences, Naval Aeronautics and Astronautics University, Yantai 264001, China;,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

The mode field and the translational efficiency are studied by the finite difference beam propagation method in an anamorphic photonic crystal fiber. Selective hole collapse is realized in laboratory and anamorphic fibers with circular to rectangular cores and small to large mode fields are made. The loss at wavelength 1550 nm is below 0.05 dB during each translation. The calculated and the experimental results are consistent with each other.
Symplectic symmetry feature of thermoacoustic network
Authors: Yang Zhi-Chun  , Wu Feng  , Guo Fang-Zhong  , Zhang Chun-Ping  ,   Graduate School, Naval University of Engineering, Wuhan 430033, China;,   School of Science, Wuhan Institute of Technology, Wuhan 430073, China;,   School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

Symplectic mathematics is introduced into the thermoacoustic network model. The transferring matrix of thermoacoustic system is analyzed, and the transferring matrix of working gas in isothermal fluid pipe of thermoacoustic system is a symplectic matrix. The transferring matrix of working gas in regenerator of thermoacoustic system is not a symplectic matrix, but it can be converted into a symplectic matrix by variable transformation. With variable transformation, the whole transferring matrix of thermoacoustic system can be represented by a symplectic matrix. The form of symplectic matrix is conducible to analyzing and calculating the thermoacoutic network model.
A type of new conserved quantity of Mei symmetry for Nielsen equations
Authors: Jia Li-Qun  , Sun Xian-Ting  , Zhang Mei-Ling  , Wang Xiao-Xiao  , Xie Yin-Li  ,   School of Science, Jiangnan University, Wuxi 214122, China;,   College of Electric and Information Engineering, Pingdingshan University, Pingdingshan 467002, China
Published: December 2020

A type of new conserved quantity of Mei symmetry of Nielsen equations for a holonomic system is studied. Under the infinitesimal transformation of groups, new structural equation and new conserved quantity of Mei symmetry of Nielsen equations for a holonomic system are obtained from the definition and the criterion of Mei symmetry of Nielsen equations. Finally, an example is given to illustrate the application of the results.
A two-lane cellular automaton traffic flow model with the influence of driving psychology
Authors: Hua Xue-Dong  , Wang Wei  , Wang Hao  ,   Key Laboratory of Transportation Planning and Management of Jiangsu Province, School of Transportation, Southeast University, Nanjing 210096, China
Published: December 2020

A two-lane cellular automaton model is developed to analyze the urban traffic flow with considering the influence of driving psychology. In order to show the different psychological characters of drivers when changing lane and braking, lane-changing choice probability and safety parameter are introduced. By computer simulation, the relationships among speed, density and traffic volume are given to show the influence of driving psychology on the traffic flow. The simulation results indicate that the lane-changing choice probability has little effect on the average speed, but it makes the variance of speed larger. And the safety parameter can increase the average speed and the traffic volume.
Magnetic shear effect on zonal flow generation in ion-temperature-gradient mode turbulence
Authors: Lu He-Lin  , Chen Zhong-Yong  , Li Yue-Xun  , Yang Kai  ,   Department of Physics, Yunnan Nationalities University, Kunming 650031, China;,   School of Physics and Electronic Information Technology, Yunnan Normal University, Kunming 650092, China
Published: December 2020

By decoupling the nonlinear fluid equations of ion-temperature-gradient (ITG) mode, the zonal flow-drift wave nonlinear dynamical equation including magnetic shear is derived. The role of magnetic shear for zonal flow generation by ITG mode turbulence is studied using a four-wave interaction model of modulational instability. Finally we can draw the conclusion that within a smaller range of k//, as |k//| increases, the growth rate of zonal flow is also increased.
Shock timing experiment in polystyrene target based on imaging velocity interferometer system for any reflector
Authors: Wang Feng  , Peng Xiao-Shi  , Liu Shen-Ye  , Jiang Xiao-Hua  , Ding Yong-Kun  ,   Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The shock timing experiment in ablator material wave, where the shock wave transferring and catching up are investigated, can be simulated with an inertial confinement fusion planar target. The photo ionization effect caused by the X-ray from Hohlraum target is explained. With the simulation data, the block effects of Au and Cu for shock wave are analyzed. The shock velocity and the transfer time of two-shock wave in CH material are compared by using two radiation sources. The shock signals of acceleration and deceleration are obtained after adding Au block layer with thickness 5 μm to the Al layer. The shock signals of acceleration, deceleration and reloading for two shock wave experiment are achieved after adding Au layer with thickness 2 μm and Cu layer with thickness 3 μm. The experimental data show that the two conditions should be satisfied in order to obtain the two shock signals. The first condition is that the difference in radiation between two steps source should be large, and the second condition is that the shield layer should be the combination of high impedance Au and low impedance Cu. These experimental results show the shock timing ability of "Shenguang-Ⅲ", and give the reference design for planar target in shock timing technique.
Simulation of protective effect of the buffer on the first mirror in HL-2A tokamak
Authors: Zheng Ling  , Zhao Qing  , Zhou Yan  ,   School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China;,   Southwestern Institute of Physics, Chengdu 610041, China
Published: December 2020

How to improve the protective effect of the first mirror is urgent for tokamaks at present. Buffer is one of the efficient methods to reduce the impurity redeposition on the first mirror. In order to study the protective effect of the buffer, the physical model of the particle redeposition on the first mirror is established with the Monte Carlo method on the basis of the parameters and experiments of the HL-2A tokamak. Particle redepositions on the first mirror are simulated under different conditions, including the cases without buffer and with cone buffer. The simulation results match well with the experimental results. The accuracy of the model is verified, and the simulation is efficient for providing theoretical basis for the protection of the first mirror.
Experimental study on emission spectra of air plasma induced by femtosecond laser pulses
Authors: Zhu Zhu-Qing  , Wang Xiao-Lei  ,   Key Laboratory of Optoelectronic Technology of Jiangsu Province, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210046, China;,   Key Laboratory of Optoelectronic Information Science and Technology of Ministry of Education, Institute of Modern Optics, Nankai University, Tianjin 300071, China
Published: December 2020

The emission spectra produced in ambient air with focused strong femtosecond laser pulses are studied experimentally. The results show the emission spectrum presents the short-wavelength continuum spectrum with stronger intensity(cutoff wavelength 340 nm) and long-wavelength line spectrum with less weak intensity(near 800 nm). A similar spectrum shape can be acquired with fixed pulse width 50 fs and adjustable laser pulse energy. When the pulse energy is 1 mJ and the pulse width increases from 50 fs to 1ps, the peak value of continuum spectrum located in 500 nm wavelength becomes strong and gradually presents the line spectrum characteristics.
Neutron diffraction study of aging process effect on phase structure of single crystal superalloy
Authors: 孙光爱  , 陈波  , 吴二冬  , 李武会  , 张功  , 汪小琳  , V. Ji  , T. Pirling  , D. Hughes  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China;,   National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;,   Institute of Orsay Molecular Chemistry and Materials, Université Paris-Sud 11, Paris 91405, France;,   Institute of Laue Langevin, Grenoble 38042, France
Published: December 2020

The neutron diffraction results obtained by oscillating and fixing during data collection show that the high ageing temperature is effective to eliminate dendrite crystals and the microstrain exists mainly in the ' phase. Based on the microstructure obtained by neutron diffraction and scanning electron microscope, the influence of ageing temperature and time on ' phase are evaluated. The unique misorientations among ' phase grains are observed from superlattice measurements. According to the neutron diffractions of different crystal planes, the crystal symmetry is slightly changed from cubic to quartet (a c) due mainly to the matrix phase and the experimental results also prove the strain deviation in difference orientations, thus providing the basis for the existence of driving force for the raft model. The calculation based on the superlattice diffraction shows that in the interfaces between the and ' phases exists a complex distortion: the mismatch varies from -0.1% to -0.3% and the mismatch value can be reduced by high temperature during the first ageing and long time during the second ageing.
Effects of thermal evaporation and electron beam evaporation on two-dimensional patterned Ag nanostructure during nanosphere lithography
Authors: Luo Yin-Yan  , Zhu Xian-Fang  ,   Department of Physics, Xiamen University, Xiamen 361005, China
Published: December 2020

In the process of fabricating two-dimensional Ag nano-arrays via nanosphere lithography, different deposition methods present different lattice point shapes of Ag nanostructure. Nano-triangles are produced by thermal evaporation whereas nano-rings are obtained by electron beam evaporation although they are both of hexagonal lattice. It is indicated that the sizes, the surface nanocurvature, the thermal and the kinetic energies of the particles deposited are key factors controlling the formation of the shape of Ag lattice point.
Long-range Finnis-Sinclair potential for Zn-Mg alloy
Authors: Wang Zhao-Ke  , Wu Yong-Quan  , Shen Tong  , Liu Yi-Hu  , Jiang Guo-Chang  ,   Key Laboratory of Modern Metallurgy and Materials Processing of Shanghai, Shanghai University, Shanghai 200072, China
Published: December 2020

A set of optimal long-range Finnis-Sinclair (F-S) potential parameters of single Mg are achieved by fitting the lattice energy, lattice constants, and elastic constants to experimental results. With the same method, the set of the F-S potential parameters of single Zn are obtained through the introduction of modifying factor to the repulsive term. Finally, the lattice energy and lattice constants of Mg21 Zn25, MgZn2 and Mg2Zn11 alloys are further fitted to achieve the F-S potential parameters of Zn-Mg based on the previous F-S potential parameters of Mg-Mg and Zn-Zn. After that, a series of molecular dynamics simulations of single Mg, Zn, and Mg21 Zn25, MgZn2, Mg2Zn11 alloys is performed at 300 K with the achieved F-S potential parameters, thereby proving the F-S potential parameters to be appropriate for the description of Zn-Mg alloys. The long-range F-S potential parameters of Zn and Zn, Mg and Mg, Zn and Mg are obtained.
Research on the conductivity of KAg4 I5-AgI composite
Authors: Gao Shao-Hua  , Wang Yu-Xia  , Wang Hong-Wei  , Yuan Shuai  ,   Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

KAg4I5(10%AgI) composite is prepared by the solid-state reaction method in the dark and dry conditions, and its structure, morphology, ion conductivity properties, and phase transition temperature are studied by X-ray diffraction, scanning electron microscope, impedance spectroscopy, differential scanning calorimetry and other analytical tools. The results show that when the two phases (AgI and KAg4I5 phases) in the composite are both fast ionic conductor phases, ionic conductivity of composite is higher than that of the single phase, and the heating and cooling of the conductivity curves form a hysteresis loop.During heating and cooling, AgI phase transition temperature lags 5 and 10 ℃ respectively.We use the interaction interface, the interface stress phase and Gouy-Chapman model to analyze the mechanism for the improved conductivity of this composite and phase transition temperature change when the two phases are both the fast ionic conductive.
Helicity effects on Rh adsorption behavior inside and outside the single-wall carbon nanotubes
Authors: Liu Sha  , Wu Feng-Min  , Teng Bo-Tao  , Yang Pei-Fang  ,   Institute of Condensed Matter Physics, Zhejiang Normal University, Jinhua 321004, China;,   College of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China
Published: December 2020

The curvature and the helicity of single-wall carbon nanotube (SWCNT) are the important factors which influence the adsorption behaviors of metal atoms inside and outside carbon tubes. However, it is difficult to investigate the separate effects of SWCNT helicity on the adsorption behaviors of metal atoms. In the present work, the armchair (6, 6), zigzag (10, 0), and chiral (8, 4) tubes with similar curvature are selected, then the Rh adsorption behaviors inside and outside the tubes are systematically investigated using the density functional theroy. Due to the different SWCNT helicities, the stable configurations of Rh atoms on tubes are different. The neighbor carbon atoms interacting with Rh atoms vary with tube helicity, therefore, the Rh adsorption energies for a similar configuration are also different. It indicates that the outer charge density of SWCNT is higher than the inner one. Different helicities lead to different charge density variations along the radial direction. Charge density difference shows that the orbital orientations of Rh adatom and the electrons obtained and lost are slightly different due to the different helicities. The bandstructure indicates that the doping band appears near the Fermi energy level. The (6, 6) tube with Rh adatom still exhibits metallicity. When Rh atoms are adsorbed inside the (10, 0) tube, the nanotube transforms from the semiconducting into the metallic one. However, the band gap reduces when Rh atoms adsorbed outside the tube. After the Rh adsorption, the (8, 4) tube band gap reduces.
Effects of Mn and N codoping on microstructure and performance of anatase TiO2
Authors: Zhang Xue-Jun  , Liu Qing-Ju  , Deng Shu-Guang  , Chen Juan  , Gao Pan  ,   Department of Physics and Electron Information Engineering, Hunan City University, Yiyang 413000, China;,   Key Laboratory of Nanomaterials and Nanotechnology of Yunnan Province, College of Physics Science and Technology, Yunnan University, Kunming 650091, China;,   Department of Information Engineering, Hunan Vocational and Technical College of Engineering, Changsha 410151, China
Published: December 2020

The effects of Mn and N codoping on the crystal structure, defect formation energy, electronic structure, optical property and redox ability of anatase TiO2 are investigated by first-principles calculations of plane-wave ultrasoft pseudopotential. The calculation results show that the octahedral dipole moment of anatase TiO2 increases due to its lattice distortion after Mn, N codoping, which is favorable for effective separation of photogenerated electron-hole pairs. Some impurity bands appear in the band gap, which leads to the red-shift of optical absorption edge and to the increase in coefficient of light absorption, thereby facilitating the enhancement of the photocatalytic efficiency. If the impurity band is not taken into account, the band edge redox potential of codoped TiO2 is only slightly changed compared with that of pure TiO2 . All of these results can explain the better photocatalytic performances of Mn, N codoped anatase TiO2 under visible-light irradiation.
First principles study of structural, electronic and elastic properties of Mg2 Si polymorphs
Authors: Yu Ben-Hai  , Liu Mo-Lin  , Chen Dong  ,   College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang 464000, China
Published: December 2020

The structural and the elastic properties of the Mg2Si polymorphs are calculated. The calculations are performed by using the plane-wave pseudo-potential method within the framework of first principles. The anti-fluorite structure, the anti-cotunnite structure and the Ni2In-type structure of Mg2Si can retain their mechanical stability in the pressure intervals 07 GPa,7.520.2 GPa and 21.940 GPa, separately. The relationships between pressure and the elastic moduli (elastic constant, bulk modulus, shear modulus, Youngs modulus, Poisson ratio and anisotropy factor) are discussed. The electron density distribution, the density of states, the bond length and the Mulliken population of these polymorphs are systemically investigated. Our results show that the anti-fluorite Mg2Si is a semiconductor and the other two polymorphs are metallic materials. The interaction between Mg 2p, 3s and Si 3p plays a dominant role in the stability of the Mg2Si polymorphs. The strongest interactions in the anti-fluorite Mg2Si and the Ni2In-type Mg2Si are Mg-Mg and Mg-Si interactions, respectively. Our results are concordant with the experimental data and the previous results.
Investigation on the dynamic conductance of mesoscopic system based on the self-consistent transport theory
Authors: Quan Jun  , T. C. Au Yeung  , Shao Le-Xi  ,   School of Physics Science and Technology, Zhanjiang Normal University, Zhanjiang 524048, China;,   School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore
Published: December 2020

According to the self-consistent electronic dynamic transport theory of mesoscopic system, we present the dynamic conductance of mesoscopic structure. As an application of this theory, we employ a coherent mesoscopic parallel-plate capacitor model in the present study. The results show that the dynamic conductance of system depends on the frequency of external field and Fermi energy of system, and is a complex with a finite imaginary part. For a smaller frequency, the conductance shows a similar feature to dc case, but with the increase of the frequency of external fields, substantial deviations between dc case and ac case are observed, the dynamic conductance of system presents a peak structure with Fermi energy varying. For a given Fermi energy, the dynamic conductance is oscillatory with frequency varying, moreover some negative imaginary parts of conductance are observed. The negative imaginary part implies the capacitive behavior, and positive imaginary part refers to the inductive behavior.
Effect of palladium adsorption on the electrical transport of semiconducting carbon nanotubes
Authors: Zhao Hua-Bo  , Wang Liang  , Zhang Zhao-Hui  ,   State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Published: December 2020

The metal Pd is deposited on semiconducting single-walled carbon nanotubes (SWNTs) by physical vapor deposition. The image of scanning electron microscopy shows that the Pd nanoparticles (10—30 nm) are formed on the carbon nanotubes. It is found by the conductive atomic force microscopy that with the increase of Pd nanoparticles, the semiconducting carbon nanotube is changed gradually into a metallic one. Furthermore, our density functional theory calculation demonstrates that with the Pd adsorption increasing the band gap of the SWNT becomes smaller, and eventually disappears, which is in good agreement with the experimental result.
Properties of MgB2 ultra-thin films grown by hybrid physical-chemical vapor deposition
Authors: Sun Xuan  , Huang Xu  , Wang Ya-Zhou  , Feng Qing-Rong  ,   State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Application Superconductivity Research Center, School of Physics, Peking University, Beijing 100871, China
Published: December 2020

We fabricate MgB2 ultra-thin films via hybrid physical-chemical vapor deposition technique. Under the same background pressure, the same H2 flow rate, by changing B2H6 flow rate and deposition time, we fabricate a series of ultra-thin films with thickness ranging from 5 nm to 80 nm. These films grow on SiC substrate, and are all c-axis epitaxial. We study the Volmer-Weber mode in the film formation. As the thickness increases, critical transition temperature Tc(0) also increases and the residual resistivity decreases. Especially, a very high Tc(0) 32.8 K for the 7.5 nm film, and Tc(0) 36.5 K, low residual resistivity (42 K) 17.7 cm, and extremely high critical current density Jc (0 T,4 K) 107 A/cm2, upper critical field Hc2(0) for 10 nm film are achieved. Moreover, by optimizing the H2 flow rate, we obtain relatively smooth surface of the 10 nm epitaxial film, with a root-mean-square roughness of 0.731 nm, which makes them well qualified for device applications.
Preparation and electric field driven magnetoelectric effect for multiferroic La2/3Sr1/3MnO3/BaTiO3 composite films
Authors: Li Ting-Xian  , Zhang Ming  , Wang Guang-Ming  , Guo Hong-Rui  , Li Kuo-She  , Yan Hui  ,   College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China;,   National Engineering Research Central for Rare Earth Materials, General Research Institute for Nonferrous Metals, Beijing 100088, China
Published: December 2020

Using pulsed laser deposition, multiferroic La2/3Sr1/3MnO3(LSMO)/BaTiO3(BTO) composite films are deposited on LaAlO3 (LAO)(001) substrate. X-ray diffraction results show that LSMO and BTO films exhibit only (001) orientation. Film smoothness is verified by their low root-mean-square surface roughness values as 1.4 nm from atomic force microscope study. The magnetic and the electric properties of these composite films are investigated. Furthermore, the variations of resistivity and metal-insulator transition temperature TMI of LSMO, induced by the external electric field, are studied. The resisitivity is reduced while the TMI is enhanced for hole accumulation state which is induced by negative electric field across BTO layer. In contrast, the resistivity is enhanced while the TMI is reduced for hole depletion state, which shows coupling between magnetic and electric order parameters, i.e., there is a magnetoelectric effect induced by electric field.
Design of a wide-band metamaterial absorber based on loaded magnetic resonators
Authors: Gu Chao  , Qu Shao-Bo  , Pei Zhi-Bin  , Xu Zhuo  , Bai Peng  , Peng Wei-Dong  , Lin Bao-Qin  ,   College of Science, Air Force Engineering University, Xi'an 710051, China;,   Key Laboratory of Electronics Ceramics and Devices of Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China;,   Research Center of Synthetic Electronic Information System and Electronic Countermeasure, Air Force Engineering University, Xi'an 710051, China
Published: December 2020

A wide-band, polarization-insensitive and wide-angle metamaterial absorber based on loaded magnetic resonator is proposed. A single unit cell of the absorber is comprised of a magnetic resonator loaded with lumped elements, a substrate and a back metal board. Simulated absorbances of the one-dimensional-array absorber under loading and unloading conditions indicate that compared with under the unloading condition, the one-dimensional absorber under the loading condition can realize a wide-band absorption. Simulated absorbances of the one-dimensional-array absorber with lossy and loss-free substrates indicate that the power loss in the absorber results from lumped resistances in magnetic resonators, and is insensitive to the loss of the substrate. Simulated absorbances of the one-dimensional-array absorber with different lumped resistances and capacitances indicate that there exist optimal values for lumped resistances and capacitances, where the absorbance is highest and the bandwidth is widest. Simulated absorbances of the two-dimensional-array absorber under different polarization angles and different incident angles indicate that the absorber is polarization-insensitive and angle-wide.
Design of a wide-band metamaterial absorber based on resistance films
Authors: Gu Chao  , Qu Shao-Bo  , Pei Zhi-Bin  , Xu Zhuo  , Lin Bao-Qin  , Zhou Hang  , Bai Peng  , Gu Wei  , Peng Wei-Dong  , Ma Hua  ,   College of Science, Air Force Engineering University, Xi'an 710051, China;,   Key Laboratory of Electronics Ceramics and Devices of Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, China;,   Research Center of Synthetic Electronic Information System and Electronic Countermeasure, Air Force Engineering University, Xi'an 710051, China;,   College of Engineering and Technology, Chengdu University of Technology, Leshan 614300, China
Published: December 2020

A wide-band, polarization-insensitive and wide-angle metamaterial absorber is presented, which is based on resistance films. A unit cell of the absorber consists of a hexagonal resistance film, a substrate and a metal backboard. Simulated reflectances and absorbances indicate that this absorber has a wide-band strong absorption for the incedent wave from 7.0 GHz to 27.5 GHz, indicating that electrocircuit resonances are more suited to realize a wide-band strong absorption than electromagnetic resonances. Simulated absorbances under different polarization angles and different incident angles show that this absorber is polarization-insensitive and angle-wide. Simulated influence of substrate and resistance film on the absorbance of the absorber indicates that there exist optimal values for the capacitance between the resistance film and the metal backboard and for the resistance of the resistance film, where electrocircuit resonances are strongest and the absorption band is widest.
Femtosecond photoinduced magnetization of terbium gallium garnet crystal
Authors: Jin Zuan-Ming  , Guo Fei-Yun  , Ma Hong  , Wang Li-Hua  , Ma Guo-Hong  , Chen Jian-Zhong  ,   Department of Physics, Shanghai University, Shanghai 200444, China;,   College of Chemistry and Chemistry Engineering, Fuzhou University, Fuzhou 350002, China
Published: December 2020

The photoinduced magnetization in magneto-optical crystal terbium gallium garnet (TGG) is investigated by time-resolved pump-probe spectroscopy. When the pump pulse is elliptically polarized, the rotation signal and the ellipticity signal of the probe pulse are observed at zero time delay, resulting from the optical Kerr effect and the inverse Faraday effect. The direction of the effective magnetic field is dominated by the helicity of the pump pulse, so the rotation signal and the ellipticity signal of the probe pulse can be triggered selectively by modifying the helicity of the pump pulse. The full widths at half maximum of the rotation signal and the ellipticity signal both can be as fast as about 500 fs, which indicates that TGG crystal is expected to be a candidate material of ultrafast all-optical magnetic switching.
Effect of spin-coating process on the performance of passive-matrix organic light-emitting display
Authors: Liu Nan-Liu  , Ai Na  , Hu Dian-Gang  , Yu Shu-Fu  , Peng Jun-Biao  , Cao Yong  , Wang Jian  ,   Institute of Polymer Optoelectronic Material and Devices, South China University of Technology, Guangzhou 510640, China
Published: December 2020

By improving the spin-coating process during the deposition of hole transport layer poly(3,4-ethylenedioxythiophene)-poly(styrene-sulfonate)(PEDOT:PSS), high efficient monochrome passive-matrix organic light-emitting display is fabricated. The PEDOT:PSS film is spin-coated with a two-step spin-coating process, in which the substrate is turned 180° during the spin-coating, forcing the piled-up materials to move reversely. By introducing the second spin-coating step, the film thickness difference between single and double lines significantly reduces, leading to a more uniform light emission and a larger fill factor for the 3.81 cm monochrome polymer light-emitting diode display. Green light-emitting display with a peak current efficiency of 17 cd/A is successfully fabricated, and the efficiency is improved by 40 percent compared with that made by traditional spin-coating method. A 3.81 cm 96×64 full color display with a current efficiency of 1.25 cd/A is also successfully made.
Effects of incident polarization and electric field coupling on the surface plasmon properties of square hollow Ag nanostructures
Authors: Li Shan  , Zhong Ming-Liang  , Zhang Li-Jie  , Xiong Zu-Hong  , Zhang Zhong-Yue  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China;,   Key Laboratory of Nanomaterials and Chemistry, Wenzhou University, Wenzhou 325027, China
Published: December 2020

Square hollow nanostructure can induce a large-area enhanced electric field at the main plasmon peak. Therefore, it can be used as a substrate for the surface enhanced Raman scattering. The effects of the incident polarization on the extinction spectrum and the electric field distribution of the square Ag nanostructure are studied by the discrete dipole approximation method. The results show that the plasmon peaks do not shift with the variation of incident polarization. However, the electric field distribution is strongly dependent on the direction of incident polarization. Additionally, the effect of the electric field coupling between adjacent square Ag nanostructures on the plasmon mode is also studied. It is found that the plasmon resonance can be tuned by varying the separation between adjacent squares. These results could be used to guide the preparation of such closed nanostructures for specific plasmonic applications.