bluuebunny/crossref_metadata_2025 huggingface dataset:
Torsion strain spectrum and its application to in phase transformation
Authors: Wu Xiao-Yi  , Xiong Xiao-Min  , Zhang Jin-Xiu  ,   State Key Laboratory of Optoelectronic Materials and Technologies, Department of Physics, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
Published: December 2020

Torsion strain spectrum refers to the variation of the torsion strain of a specimen with external field, such as temperature, electric and magnetic fields, which facilitates the research of its dynamic behavior. We demonstrate that a torsion strain spectrum can be achieved in a high accuracy by making use of the conventional inverted torsion pendulum. By measuring its torsion strain spectrum of ferroelectric relaxor PMN-32%PT, we verify that its tetragonal-cubic transformation belongs to a burst-type martensite transformation.
The nonlocal thermal equilibrium simulation of Z-pinch Al plasma radiation
Authors: Gao Qi  , Wu Ze-Qing  , Zhang Chuan-Fei  , Li Zheng-Hong  , Xu Rong-Kun  , Zu Xiao-Tao  ,   Institute of Nuclear Physics and Chemistry, Mianyang 621900, China;,   University of Electronic Science and Technology of China, Chengdu 610054, China;,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

In this article, the atomic structure and processes for Al are calculated in details by using the flexible atomic code. With these atomic parameters, the rate equations are established and resolved in order to obtain the level populations. The X ray radiation from Z-pinch Al plasma is then calculated. The experimental spectra are identified in details according to our theoretical results.
Structural analysis of FeTe alloy and its superconducting film preparation
Authors: Zhang Lu-Shan  , Yu Hong-Fei  , Guo Yong-Quan  ,   School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Published: December 2020

The vacuum sintered alloy with nominal composition of FeTe was analyzed using powder X-ray diffraction and refined with Rietveld method. It is shown that FeTe alloy crystallizes a tetragonal structure with space group of P/4nmm and its lattice constant is a = 3.8214(3)Å, c = 6.2875(3) Å, Z = 2. Fe at 2a and 2c positions and Te at 2c positions. FeTe films prepared by pulsed laser deposition showed superconducting transition with starting transition temperature Tc,onset of 13.2 K and Tc,0 of 9.8 K.
Quasi-exponentid relationship and amplification effects of surface component for NiAl compound
Authors: Zheng Hui  , Shen Liang  , Bai Bin  , Sun Bo  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China;,   National Key Laboratory for Surface Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621907, China
Published: December 2020

A detailed knowledge of the structure and composition of NiAl compound is essential for understanding its oxidation resistance and the fracture process. The atomic distribution, concentration and long range order parameters in interior and (110) surface layer of NiAl compound at 1273 K are calculated by the grand canonical Monte Carlo simulation method. We find a quasi-exponentid relationship between the component deviations from the stoichiometry in surface layer and interior of NiAl in Al-rich region. It is observed that the deviation of component from stoichiometry in surface layer is over 30 times greater than that in interior.
Microstructures of Mo/Si multilayer mirror after proton irradiation
Authors: Guan Qing-Feng  , Lü Peng  , Wang Xiao-Dong  , Wan Ming-Zhen  , Gu Qian-Qian  , Chen Bo  ,   State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics,Chinese Academy of Sciences, Changchun 130033, China;,   College of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

In this paper we characterize the microstructures of Mo/si multilager in space solar telescope induced by proton irradiation by transmission electron microscope (TEM). The optical performances of the Mo/Si multilayer mirror before and after proton irradiation are also determined. The experimental results show that some defect structures are introduced after proton irradiation. The Mo/Si periodic structure is destructed in some irradiation regions. The widths of Mo layer and Si layer significantly change and the Mo/Si interface is much rougher than before irradiation. Moreover, the obvious distortions of the Mo/Si interface and the formation of the small islands in Mo layer are also found. Furthermore, proton irradiation reduces the reflectivity of Mo/Si multilayer mirror. The dominante mechanism of optical degeneration of the Mo/Si multilayer induced by proton irradiation should be attributed to the formation of the defect structures.
Transition of contact behavior induced by interfacial adhesion
Authors: Duan Fang-Li  , Yang Ji-Ming  , Qiu He-Bing  , Wu Cong-Ying  ,   State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing 400030, China
Published: December 2020

Large-scale molecular dynamics simulations are performed to study the adhesive contact between a rigid spherical tip and an elastic flat substrate. We focus on he relations between the real contact area and the external load and between the repulsive force and attractive force on contact interface. The simulated results are consistent with the corresponding continuum contact theories, which are Hertz model, Ggeenwood-Williamson (or Persson) model and Maugis-Dugdale model according to surface roughness and interfacial adhesion. We show that there are same relations between the real contact area and the repulsive force for both non-adhesive and adhesive contact, which means that the effect of adhesion on contact behavior can be equivalent to that of a virtual load. We demonstrate that the attractive force on contact interface increases with the real contact area in a power-law function, with a power exponent larger than 1 for the atomic-scale smooth tip and with a power exponent smaller than 1 for the atomic-scale rough tip.
Electronic and optical properties of anatase and rutile TiO2:Nb
Authors: Zhang Rui-Shuo  , Liu Yong  , Teng Fan  , Song Chen-Lu  , Han Gao-Rong  ,   State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
Published: December 2020

First-principles calculations based on the density functional theory are used to study the crystal structure, electronic and optical properties of Nb doped anatase and rutile TiO2. The calculated results reveal that anatase TiO2:Nb has a smaller effective mass and carriers nearly twice lager than those of rutile TiO2:Nb under the same doping concentration. And anatase TiO2:Nb also exhibits a greater room-temperature ionization of donors. Besides, the calculated optical properties indicate that anatase TiO2:Nb has a more excellent transparency than rutile TiO2:Nb. All the results suggest that anatase TiO2:Nb is more applicable to transparent conductive oxides. The calculated results consist well with the available experimental results.
First principles study of the electronic structure and optical properties of Magnli phase titanium suboxides Ti8O15
Authors: Guan Dong-Bo  , Mao Jian  ,   College of Material Science and Engineering, Sichuan University, Chengdu 610064, China
Published: December 2020

The electronic structure and the optical properties of Magnli phase titanium suboxide Ti8O15 are studied by using the plane-wave ultrasoft pesudopotential method based on the density functional theory. The band structure reveals that the energy band gap of Ti8O15 is reduced a lot compared with that of anatase TiO2, which is due to the fact that O 2p, Ti 3p and Ti 3d of Ti8O15 shift toward the left compared with those of TiO2, and a new electron energy level formed by the redundant electrons of Ti 3d and Ti 3p of Ti8O15 due to the lack of oxygen atom in lattice. The results from DOS analysis show that electron distribution near the Fermi level of Ti8O15 is different from that of anatase TiO2, contribution of O 2p to Fermi level decreases and that of Ti 3d increases. Compared with anatase TiO2 which only has high ultraviolet light absorption, Ti8O15 has high light absorptivity both in ultraviolet spectrum and visible spectrum, because its narrow forbidden band width results in the red shift toward visible-light region. The light absorptivity calculated results are consistent with those from UV-vis diffuse absorption test results of anatase TiO2 and Magnli phase titanium suboxides.
First principles study of effects of the concentration of Ga/N highly doped p-type ZnO on electric conductivity performance and red shift
Authors: Hou Qing-Yu  , Ma Wen  , Ying Chun  ,   College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China;,   Material Science, Inner Mongolia University of Technology, Hohhot 010051, China
Published: December 2020

Based on first principles within the density-functional theory, using the plane-wave ultrasoft pseudopotential method, the models of unit cell pure ZnO and two highly Ga/N co-doped supercells of Zn0.9375Ga0.0625O0.9375N0.0625 and Zn0.875Ga0.125O0.75N0.25 with different doping concentrations are constructed, and the geometry optimizations for the three models are carried out. The total density of states and the band structures are also calculated. The calculation results show that at a higher doping concentration, when the co-doping concentration is more than a special value, the conductivity decreases with the increase of Ga/N co-doping concentration in ZnO, furthermore the red shift effect is more prominent which is consistent with the change trend of the experimental results.
Numerical algorithm for slave-boson mean field approach to the multi-band Hubbard model
Authors: Quan Ya-Min  , Liu Da-Yong  , Zou Liang-Jian  ,   Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

A numerical algorithm is proposed for multi-orbital slave-boson mean field approach through the integrating pattern search method, the generalized Lagrange multiplier method, and the Rosenbrock method. Since the crystal field splitting, inter-orbital hopping and realistic band structures can be considered, the proposed slave-boson mean field approach can be utilized to study realistic material. To validate our algorithm, the Mott transitions in twoorbital Hubbard models are studied with the elliptical density of states. The results are consistent with the reported ones available. Then we use this method to study the correlation effect on the three-orbital Hubbard model for NaxCoO2. It is shown that the six small Fermi surfaces constructed by the eg' orbital vanish in the intermediate Coulomb correlations. The physical reason is that the hole occupations of eg' orbital decrease with U increasing. All the calculated results verify the accuracy and the efficiency of our numerical algorithm.
First principles study of rare earth doped in ZnTe used for CdTe solar cell back contact layer
Authors: Xia Zhong-Qiu  , Li Rong-Ping  ,   Key Laboratory of Semiconductor Photovoltaic Technology at Universities of Inner Mongolia Autonomous Region, School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

In consideration of the preparation of CdS/CdTe solar cell back contact layer, the band structure and the density of states of undoped and (Y, Gd) doped in ZnTe were caculated from the plane wave ultra soft pseudo potential method based on density functional theory and generalized gradient approximation. We acquired the system total energy and lattice parameter. As a result, the structural stability improve after doping, the lattice match between ZnTe and CdTe are better when Y doped. (Y, Gd) doped make the ZnTe semiconductor degeneration. Compared with Gd, the electronic effective mass of ZnTe doped with Y are lighter. The carrier concentration order of magnitude in different doping system are same. We analysed the influence on ZnTe used for back contact layer when doped with (Y, Gd).
Doped with Ag and Zn effects on electronic structure and optical properties of CdS
Authors: Li Chun-Xia  , Dang Sui-Hu  ,   College of Physics and Electronic Engineering, Yangtze Normal University, Chongqing 408003, China
Published: December 2020

The geometry structure, electronic structure and optical properties of zinc bende CdS:M (M = Ag,Zn) were studied systemically using density functional theory based on first-principles ultrasoft pseudopotential method and GGA.The relationship between the distribution of the electronic states and their structures has been analyzed. The dielectric function and the complex refractive index function on doping CdS system have been obtained. The calculation results showed that the hole concentration of Ag-doped CdS is increased, enhanced the conductivity of the material. But the carrier concentration of Al-doped CdS was not changed; the optical band gap were narrowed for Ag-doping, Zn-doping CdS. The mechanism of luminescence has been explained in terms of an analysis of the dielectric function and the complex refractive index function.
Digital simulation for 3D reconstruction of coherent x-ray diffractive imaging
Authors: Zhou Guang-Zhao  , Wang Yu-Dan  , Ren Yu-Qi  , Chen Can  , Ye Lin-Lin  , Xiao Ti-Qiao  ,   Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In coherent x-ray diffractive imaging, the oversampled far-field diffraction pattern for phase retrieval iterative algorithm is used in order to reconstruct the information about the real space. The support constraint is one of the most important steps of the 3D phase retrieval process. Here we use a small nonperiodic 2D digital image as an object for studying the algorithm of pursuing support constraint automatically and noise correction for different types of noises in the diffraction pattern. We find an efficient method of noise correction while the traditional methods do not work well in the high noise condition. The result shows that this method can be used to reduce the effect effectively for the reconstruction. We also study the 3D reconstruction for the electron density distribution of Au nano-particles. We achieve a good reconstruction separately with and without noise effect in the diffraction pattern and we find that the signal-to-noise ratio should be bigger than 27 for successful 3D reconstruction.
Temporal evolution and controllable factors for self-deflection of screening photovoltaic solitons in LiNbO3 crystal
Authors: Li Wen-Hui  , Hu Man-Li  , Ma Zhi-Bo  , Zhong Lan-Xiang  , Wan Yun  ,   Department of Physics, Northwest University, Xi’an 710069, China;,   Institute of Information Science and Technology, Northwest University, Xi’an 710069, China
Published: December 2020

According to the band transport model theory, we establish the temporal evolution for dynamic equations concerning screening photovoltaic solitons in LiNbO3 crystal in this paper. By using the finite difference method, we find that there exist large self-deflection bright and dark screening photovoltaic solitons in LiNbO3 crystal, where the shape of the solitons becomes asymmetry ic with the increase of time. In addition, the absolute value of slope of the curve in deflection direction turns larger, while it tends to be smaller in the opposite direction as time increases. On the other hand, analysis shows that the factors related to the degree of self-deflection and deformation include acceptor concentration NA, dark radiation Id and applied electric field E0. When NA rises, the self-deflection degree and the deformation of bright soliton become smaller and the counterpart of dark soliton has opposite tendency while Id and E0 keep invariant. Moreover, for the bright and dark solitons, the space charge field induced in crystals is easier to reach saturation as Id diminishes and there is no saturation phenomenon in both cases when the ratio between center light intensity and dark radiation intensity is 10-1. With the E0 increases, the bright soliton self-deflection degree and deformation decrease, while the dark soliton self-deflection degree and deformation increase.
Analytical mechanics representations of a moving charged particle in a magnetic field with radiation friction
Authors: Ding Guang-Tao  ,   College of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
Published: December 2020

The anatylical mechanics representations of a charged particle moving in a uniform magnetic field with radiation friction are studied. First, by solving the inverse problem of Birkhoffian mechanics for the differential equations of motion the 4 Birkhoffian representations of the charged particle are obtained. Secondly, 4 Lagrangian representations in the state space and 4 Lagrangian representations in the configuration space are derived, and then 4 Hamiltonians are constructed. Lastly, 4 first integrals are obtained from the analytical mechanics representations of the moving particle, and the solutions of the equations of motion are presented.
Single electron transport in a cavity containing a two-level atom
Authors: Shi Hong-Yun  , Chen He-Sheng  ,   College of Physics Science and Technology, Yangzhou University, Yangzhou 225009, China
Published: December 2020

Quantum dot is a typical nano functional device, which has a very attractive prospect in biotechnology, semiconductor technology, quantum optics and other fields. In this paper, we construct a cavity containing a two-level atom to simulate a nano cavity coupling a two-level quantum dot, and study the electrical transmission in the cavity. We solve the transfer function of a single electron and obtain the formulas of transportation and reflection. By adjusting the intrinsic properties of the cavity and the atom and coupling between them, we study the transmission characteristics of a single electron in the cavity and understand the role of the two-level atom and the cavity in the electrical transport. The results can provide some theoretical support for quantum control of the electron transport in a nano device.
Geometric quantum phase for three-level mixed state
Authors: Rao Huang-Yun  , Liu Yi-Bao  , Jiang Yan-Yan  , Guo Li-Ping  , Wang Zi-Sheng  ,   School of Nuclear Engineering & Technology East China Institute of Technology, Fuzhou 344000, China;,   Department of Physics, Anqing Teachers College, Anqing 246011, China;,   School of Physics and Technology,Wuhan University, Wuhan 430072, China;,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China
Published: December 2020

By expanding the density matrix of the open system in terms of Gell-mann matrix in a three-level system, we parameterize coefficients of expansion by some azimuthal angles and find an identity mapping of the density matrices onto interior points of the unit Poincaré sphere. Thus, the relations between the points on the unit Poincaré sphere and wave functions are extended to connect the interior points in the sphere with the nonunit vector rays corresponding to an open system in complex Hilbert space. Thus,the geometric phases for the open system are proposed to be observed by the nonunit vector rays,where the geometric phase of the pure state is the limiting case of our definition. The results show that this geometric phase merely with duplicate three-dimensional Hilbert projection space geometry structure related, has nothing to do with the open system concrete evolution way; and it depends on population inversion and is a slippy and single-value curve of Bloch radius. Therefore, the mixed state of open system retains indeed a memory of its motion in the form of a geometric phase factor.
Bursting oscillations and the bifurcation mechanism in oxidation on platinum group metals
Authors: Li Xiang-Hong  , Bi Qin-Sheng  ,   Faculty of Science, Jiangsu University, Zhengjiang 212013, China;,   Department of Mathematics and Physics, Shijiazhuang Tiedao University, Shijiazhuang 050043, China
Published: December 2020

Applying the regression analysis to the measured data in CO oxidation on platinum group metals, a analytical theory model with different time scales is established in this paper. The stabilities of equilibria are discussed in detail, and different types of the solutions may bifurcate from the equilibria with the change of the parameters. With a certain parameter, the system can exhibit periodic oscillations via the saddle-node homoclinic orbit bifurcation, which can evolve into periodic bursting, owing to Hopf bifurcation of the fast subsystem. The bifurcation connecting the quiescent state and the repetitive spikes is presented to account for the occurrence of the Nk oscillations. Furthermore, the mechanism of sequence of the period-adding bifurcations is explored to reveal why the length of the sequences become longer with the variation of the parameters.
A 4-D chaos with fully qualified four-wing type
Authors: Yu Fei  , Wang Chun-Hua  , Yin Jin-Wen  , Xu Hao  ,   College of Information Science and Engineering, Hunan University, Changsha 410082, China
Published: December 2020

In this paper we propose a new simple four-dimensional (4D) chaotic system by introducing a nonlinear state feedback controller. There is a fully qualified four-wing type in all directions of the chaotic attractor. With a larger positive Lyapunov exponent, some interesting and complex dynamic behaviors are obtained. Basic dynamical properties of the four-wing attractor are studied by numerical and theoretical analyses, such as dissipativity equilibria, Poincaré map, spectrum map, continuous spectrum and chaotic behaviors. The sensitivities of system parameters to the chaotic behaviors are further explored by calculating, in detail, its Lyapunov exponent spectrum and bifurcation diagrams. Finally, an oscillator circuit is designed for implementation. The EWB observation results are in reasonable agreement with the numerical simulation results.
Parameter identification of map chaotic system with discrete variational method
Authors: Cao Xiao-Qun  , Zhang Wei-Min  , Song Jun-Qiang  , Zhu Xiao-Qian  , Zhao Jun  ,   School of Computer Science, National University of Defense Technology, Changsha 410073, China
Published: December 2020

In this paper a method is proposed to estimate the unknown parameters of nonlinear map based on the discrete variational principle, which can be applied to all map chaotic systems governed by the following equation: xk+1 = F(xk,). Numerical simulations on the well-known Logistic map and Henn map are conducted and all unknown parameters of the two discrete chaotic systems are identified respectively. Simulation results show that the discrete variational method is effective for parameter identification of the map chaotic system.
Experimental investigation of spectrum of strontium intercombination transition
Authors: Wang Ye-Bing  , Chen Jie  , Tian Xiao  , Gao Feng  , Chang Hong  ,   National Time Service Center, Chinese Academy of Sciences, Key Laboratory of Time and Frequency Primary Standards of Chinese Academy of Sciences, Xi’an 710600, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

We observe the fluorescence and the saturated fluorescence spectra of (5s2)1S0(5s5p)3P1 intercombination transition of thermal strontium atomic beam. Experimental investigation of 88Sr(5s2)1S0(5s5p)3P1 intercombination transition is performed on the different experimental conditions. Our study indicates that experimental parameters affect spectra largely, including temperature, intensity of laser and scanning frequency of laser. Intensity of spectrum is reciprocal of scanning frequency of laser due to long lifetime of (5s5p)3P1 state of Sr atom. Owing to Doppler broadening, transit broadening and other experimental factors, the linewidth of (5s2)1S0(5s5p)3P1 fluorescence spectrum is far more than its natural linewidth and proportional scanning frequency of laser.
Study on colorimetric properties of LED array sources for color vision application
Authors: Zhu Zhen-Min  , Qu Xin-Ghua  , Bi Chao  , Jia Guo-Xin  , Zhang fu-Min  ,   State Key Laboratory of Precision Measuring Technology and Instrument, Tianjin University, Tianjin 300072, China;,   School of Electrical and Electronic Engineering, East China Jiaotong University, Nanchang 33013, China
Published: December 2020

Color vision is based on a three-color colorimeter of colorimetric principle, and the colorimetric properties of illumination is the key factor for color imaging. Therefore based on the principle of colorimetry, in this paper we analyse and calculate the colorimetric properties of LED array sources for color vision application. By comparison with the standard D65 light source, the adjustment principle and range of correlated color temperature are studied for LED array sources. Chromaticity coordinates and relevant color temperature of white balance are also studied. The LED array source has a large range for adjusting the correlated color temperature and has a better ability of color display. Chromaticity coordinates and relevant color temperature of white balance R:G:B=254:237:90 are closer to those of the standard chromaticity. The ability of color reproduction reaches a better result of color reproduction. Therefore, the colorimetric properties of LED array sources are more appropriate for color vision application.
First-principles calculations for the mechanical properties of BC5
Authors: Li De-Hua  , Su Wen-Jin  , Zhu Xiao-Ling  ,   College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610066, China;,   College of Physics Science and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

We employ ab initio plane-wave pseudo potential density functional theory to calculate the equilibrium lattice parameters, elastic constants, anisotropies, Poisson's ratios, and the Cauchy violation under hydrostatic pressures of 060 GPa for BC5 with hexagonal P3m1 and tetragonal I4m2 structures. The results show that two structures are stable under high pressure and the incompressibility increases with pressure. In addition, the electron structures, the total and the partial densities of states are also calculated. BC5 is found to be metallic with band gap, unlike other B-C compounds. The material properties of BC5 are mainly determined by B 2p1 and C 2p2 electronic states together. All these show that BC5 is an unusual super hard material, and it may be a potential candidate for diamond at high temperature. The given density of states indicates the covalent hybridization between B and C atoms in this compound. The pressure slightly influences the density of states and the band gap, indicating stability under high pressure. We also find that pressure has no influence on the density of states near Fermi level and the band gap, except for slight shifts of the bands. It can be further inferred that BC5 will have good stability under high pressure.
Correlated Doppler optical coherence tomography
Authors: Huang Liang-Min  , Ding Zhi-Hua  , Hong Wei  , Wang Chuan  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

A new method based cross-correlation technique (CD-OCT) is proposed to acquire and analyse the information about flow velocity with low signal-to-noise ratio(SNR) in spectral-domain optical coherence tomography(SD-OCT). We theoretically study the procedure of this method, and analyse the correlation between the noises by computer simulation and experiment. The Doppler flow images reconstructed by CD-OCT are compared with those reconstructed by Joint spectral and time-domain optical coherence tomography (STD-OCT). The results demonstrate that CD-OCT can significantly improve the SNR, thus rendering it suitable for the flow measurement in low SNR.
Analysis of aerosol sources and optical properties based on backward trajectory method over SACOL
Authors: Li Xia  , Zhang Lei  ,   Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
Published: December 2020

Backward trajectories computed using the NOAA HYSPLIT model and global NOAA-NCEP/NCAR pressure level reanalysis data from November 2007 to October 2010, are used to trace air history and analyze the atmospheric transportation properties over SACOL. The cluster analysis has the advantage of providing highly disaggregated trajectory clusters, from which fifteen significant clusters arriving at the SACOL, which reflect the main feature of air mass trajectories, are obtained during this period. It is found that the air mass trajectories from Sichuan province and Chongqing account for 16% of all trajectories and have the biggest influence, those from local and Shanxi province have the second biggest influence, and those from the Eastern Europe and Bangladesh have the smallest influence. The Aerosol Optical Depth (AOD) at 870nm and ngstrm exponent acquired by a Multi-Filter Rotating Shadowband Radiometer (MFRSR) at SACOL are employed to analyze aerosol optical properties and particle characteristics under the control of different air mass sources. The maximum average AOD of 0.29 0.12 (mean standard deviation of mean) corresponds to the air mass originating from Taklimakan Desert, whereas the minimum average AOD is 0.14 0.02 from Bangladesh. According to ambient conditions of the studied site and the geographical conditions and moved track of air mass, the quantitative contributions of different sources to the three-year average AOD of 0.22 are investigated. The results show that the greatest contribution to the average AOD, accounting for almost 41.1%, came from local and regional sources, an additional important contribution from dust areas is about 28.4% of the average AOD, the contribution from the Central Asia source occupies 17.9%, that from Eastern Europe and Middle East is 12.6%.
A new type of bidirectional long distance optical fiber chaotic secure communication system
Authors: Liu Yu-Ran  , Wu Zheng-Mao  , Wu Jia-Gui  , Li Ping  , Xia Guang-Qiong  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China
Published: December 2020

Based on the chaotic synchronization of two response semiconductor lasers (RLs) under the injection from a common chaotic signal of a drive laser (DL), a new type of secure communication system, which allows bidirectional and long-distance information transmissions, is proposed. A corresponding theoretical model is established to study the bidirectional transmission performance, security performance and the system performance under different transmission distances. The results show that when two RLs receive chaotic light injected from a DL, the chaotic outputs of two RLs achieve a fairly good isochronal synchronization without any time delay, while there is a big difference between the signals of RLs and the signal of DL; the system owns high security level after having analyzed the various ways from which eavesdropper may obtain message; if the ordinary single mode optical fiber is used as a transmission channel, the Q factor of decoded message can reach more than 6 after a propagation over 50km; if the dispersion-shifted fiber is employed, the Q factor of decoded message can still reach more than 6 after a propagation over 200km.
Surface crystallization of amorphous fused silica during electron cyclotron resonance plasma etching
Authors: Wang Feng  , Wu Wei-Dong  , Jiang Xiao-Dong  , Tang Yong-Jian  ,   Centre of Laser Fusion Research of CAEP, Mianyang 621900, China;,   School of Science, Chongqing Jiaotong University, Chongqing 400074, China
Published: December 2020

After low pressure fluorine plasma ecthing and oxygen ion passivation, a crystallized layer composed of SiO2 nano-crystal grains is observed in an amorphous fused silica surface. The depth of crystallized layer is at least several hundreds nanometers. Fluorine and carbon ion are generated from Ar/CF4 by the method of electron cyclotron resonance (ECR). F ion breaks Si-O band of initial silica surface layer and releases O ion. Carbon ion combines with oxygen ion, and turns into CO2, and SiF4 is generated from fluorine and silicon. After initial surface layer is removed, unsaturated Si atom remains. Si dangling bond recombines with new O ion and then creates crystallized -cristobalite nano-crystal grains under a high temperature.
Super-resolution optical microscopic imaging method based on annular illumination with high numerical aperture
Authors: Zhi Shao-Tao  , Zhang Hai-Jun  , Zhang Dong-Xian  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

On the basis of narrow-band filtered annular light-cone illumination with high numerical aperture, a new far-field super-resolution optical microscopic imaging method is proposed, and its physical model is established. Using the scalar diffraction theory, the formula of diffraction intensity in the image plane is derived for annular light-cone illumination and imaging under different numerical apertures. The diffraction patterns are further simulated through the Matlab program, which demonstrates that such a method may significantly increase the microscopic imaging resolution. Experiments have been carried out on a self-build microscopic system, showing that a resolution can be achieved to be better than 150 nm under 450 nm light wavelength and 1.125-1.25 annular numerical apertures. The experimental results are in good agreement with the theoretical predictions, thus proving the feasibility of this microscopic imaging method.
Far-field divergent properties of linearly polarized Laguerre-Gauss beams
Authors: Zhou Guo-Quan  ,   School of Sciences, Zhejiang A & F University, Lin’an 311300, China
Published: December 2020

Based on the method of stationary phase and the theorem of the vectorial structure, the analytical expressions for the vectrorial terms, namely the TE and TM terms, of a linearly polarized Laguerre-Gauss beam are derived in the far-field. According to the far-field energy flux distributions of the TE and TM terms, the ratios of the powers of the TE and TM terms to the power of the Laguerre-Gauss beam are given. The analytical formulae of the far-field divergence angles of the Laguerre-Gauss beam and its TE and TM terms are presented, respectively. A relation among the far-field divergence angles of the TE term, the TM term, and the Laguerre-Gauss beam is also derived. The formulae obtained are applicable not only to the paraxial case, but also to the non-paraxial case. The dependences of the ratios of the powers of the TE and TM terms to the whole power onf-parameter and mode number are numerically examined. The effects of thef-parameter, the mode number, and the linearly polarized angle on the far-field divergence angle of the Laguerre-Gauss beam and its TE and TM terms are also analyzed. This research reveals the far-field divergent properties of the linearly polarized Laguerre-Gauss beam from the vectorial structure, and enriches the recognition of the propagation characteristics of the linearly polarized Laguerre-Gauss beam.
Direct simulation of melting solid particles sedimentation in a Newtonian fluid
Authors: Tong Zhi-Hui  , Liu Han-Tao  , Chang Jian-Zhong  , An Kang  ,   The Lab. of Energy & Environment and Computational Fluid Dynamic, North University of China, Taiyuan 030051, China
Published: December 2020

The influence on the motion of single solid particles in a Newtonian fluid by melting and convection is direcly simulated. The fluid motion is computed from the conservation laws. Density and viscosity change with fluid temperature, and the particle moves according to the equation of motion of a rigid body under the action of gravity and hydrodynamic forces arising from the motion of the fluid. In the process of melting, a distinctive morphology develops due to the different heat fluxes around the particle's surface, and the thermal gradient determines the melting rate. The phases are coupled by the fluid-particle mutual force , force moment and the boundary conditions. In our study, two different situations are carried out, which are sedimentation in isothermal fluid without thermal convection and melting; sedimentation with thermal convection and melting, two double particles are simulated separately. The results show that the vortex shedding arising by the natural convection, mass losing by melting and melting morphology change the sedimentation velocity and induce horizontal oscillation.
The influence of channel size on total dose irradiation and hot-carrier effects of sub-micro NMOSFET
Authors: Cui Jiang-Wei  , Yu Xue-Feng  , Ren Di-Yuan  , Lu Jian  ,   The Xinjiang Technical Institute of Physics & Chemistry, CAS, Urumqi 830011, China;,   Xinjiang Key Laboratory of Electric Information Materials and Devices, Urumuqi 830011, China;,   Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Total dose irradiation and the hot-carrier damages are two of the important factors for the application of sub-micro and even smaller MOS devices. Therefore, how to prevent the device from being damaged attracts much attention. Total dose irradiation and hot-carrier effects of sub-micro NMOSFET with various channel sizes are studied. Electronic parameters are measured and the results show that though the principles of damages are somewhat similar, the total dose irradiation and the damage behavior and their dependences on the width-to-length(W/L) ratio of channel size for these two effects are different. The most notable damage of radiation lies in the great increase of the off-state leakage current, and the damage increases withW/L reducing. While for hot-carrier effect, several parameters such as trans-conductance change a lot, except for the off-state leakage current. And the damage increases as channel length and channel width decrease. The different damage behaviors and different relations to channel size are attributed to the different location of charges induced. Therefore, different aspects should be considered when the device is hardened against these two effects.
Preparation of NiO transparent conductive film and its application in polymer solar cells
Authors: Xiao Zheng-Guo  , Zeng Xue-Song  , Guo Hao-Min  , Zhao Zhi-Fei  , Shi Tong-Fei  , Wang Yu-Qi  ,   Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences,Hefei 230031, China
Published: December 2020

NiO films are prepared with radio frequency magnetron sputtering. Ellipsometric experiment results show that NiO film is transparent for visible light,and its refractive index can be modified by changing Tsub and annealing temperature. Scanning electron microscopy and X-ray diffraction experiment results show that Tsub and annealing temperature can modify the morphology and crystal structure of NiO film which can further modify the conductivity of NiO. The optimized NiO film is used in polymer solar cell (PSC) as an anode blocking layer. The experimental results show that NiO is a better candidate than the PEDOT:PSS often used as an anode blocking layer for PSC. The power conversion efficiency of PSC with NiO reaches 2.26% which is three times as high as that with PEDOT:PSS.
Interfacial rheological study of silica nanoparticle monolayer by an indentation approach
Authors: Zang Du-Yang  , Zhang Yong-Jian  ,   Key Laboratory of Space Applied Physics and Chemistry of Ministry of Education, School of Science, Northwestern Polytechnical University, Xi’an 710129, China;,   State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

We propose a novel approach for the study of rheological properties of silica nanoparticle monolayers at the air-water interface. The layers are deformed by indenting and raising a titanium cone. The surface pressure variations in these down-up cycles are recorded and analysed. The oscillation amplitude of surface pressure d results from the tensile deformation of the particle layer. d and the relaxation time are strongly dependent on the adsorption energy of particles at the interface, thereby significantly changing the particle hydrophobicity. The results provide a deeper insight into the viscoelastic behaviour of particle layer, suggesting that the proposed method can be utilized for the rheological study of the layers of this kind.
Study of electronic structure and optical propertise of -AlON crystal
Authors: Pan Lei  , Lu Tie-Cheng  , Su Rui  , Wang Yue-Zhong  , Qi Jian-Qi  , Fu Jia  , Zhang Yi  , He Duan-Wei  ,   College of Physical Science and Technology, Sichuan University, Chengdu 610064, China;,   Key Laboratory of Radiation Physics and Technology of Ministry of Education, Sichuan University ,Chengdu 610064, China;,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
Published: December 2020

Based on the density function theory, the electronic structure, densities of states, and optical properties of -AlON are calculated by using the local density approximation and plane-wave pseudoptential method. The complex dielectric functions and the optical properties including refractive index, reflection spectra, absorption spectra of -AlON are analyzed in terms of calculated density of state. As shown by the theoretical calculation, the static dielectric function of -AlON is 1(0)=2.60, and the refractive index is n0=1.61, its absorptions in a range from IR to NUV and a UV range up to 20.23eV all approach to zero, showing the optical transparent behaviors . The calculated results are consistent with relevant experimental values, providing theoretical basis and reference for the application of the optical material to windows and domes.
Electrical properties of platinum doped armchair graphene nanoribbons
Authors: Xu Jun-Min  , Hu Xiao-Hui  , Sun Li-Tao  ,   SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
Published: December 2020

The platinum-doped graphene has been achieved in our previous experiments. To further study the effects of metal doping on the band structures of graphene, and provide theoretical guidance for the next step of the experiment, we analyze the electronic properties of armchair graphene nanoribbons (AGNRs) with platinum atoms doping in the divacancy positions using first principle calculation based on density functional theory. The results show that the band structures of AGNRs can be effectively tailored by controlling the doping position on ribbons. Edge position is the most stable position for platinum atom. The band gaps of edge doped AGNRs can be shown in three curves like that of pristine AGNRs. However, they degenerate into two curves at large width, inhibiting the vibration of band gaps to some extent. In addition, several narrow platinum-doped AGNRs with width index Na = 3p and 3p + 1 have impurity level(s) in the band gap, reducing the large band gap effectively. Furthermore, band characteristics of platinum doped AGNRs are not sensitive to doping concentration, thus reducing the challenge of experimental precision. Our results will promote the application of graphene nanoribbons in the field of nano-electronics.
Improvement in breakdown characteristics of 4H-SiC MESFET with a gate-drain surface epi-layer and optimization of the structure
Authors: Song Kun  , Chai Chang-Chun  , Yang Yin-Tang  , Zhang Xian-Jun  , Chen Bin  ,   Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of the Ministry of Education, School of Microelectronics, Xidian University, Xi’an 710071, China
Published: December 2020

A novel SiC MESFET structure with a p-type surface epi-layer is proposed and 4H-SiC MESFET models are presented which precisely describe the working mechanism of the device. Considering carrier velocity saturation, impact ionization and electric field modulation, the effect on distribution of electric field is analyzed. Also, the output current (Ids) and breakdown voltage (VB) dependences on the dimensions of the p-type epi-layer are studied based on abrupt junction approximation. The high electric field peak at the gate edge is suppressed by introducing a new electric field peak at the drain side, and the built-in field of p-n junction formed along channel surface further weakens the electric field peaks, leading to smoother distribution of electric field. By comparison with the conventional and the fieldplated MESFETs, it is shown that the proposed structure greatly improves the characteristic of SiC MESFET. In addition, the optimized dimensions are obtained and the results show that VB is greatly increased by 33% with Ids unchanged (less than 3%) when the thickness and the doping concentration of the surface epi-layer are chosen as 0.12 upm and 5 1015 cm-3, respectively.
Charging effects of SiO2 thin films under defocused electron beam irradiation
Authors: Li Wei-Qin  , Zhang Hai-Bo  , Lu Jun  ,   School of Automation and Information Engineering, Xi’an University of Technology, Xi’an 710048, China;,   Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Department of Electronic Science and Technology, Xi’an Jiaotong University, Xi’an 710049, China
Published: December 2020

Based on a three-dimensional self-consistent numerical model with consideration of electron scattering, trapping and transport, the charging effects due to low-energy defocused electron beam irradiation are simulated for a SiO2 thin film with a grounded conductive substrate. The results show that because of electron drift and diffusion, electrons can transit the electron scattering region, forming negative space charges. The space charge is, therefore, positive and negative within and outside the scattering region, respectively. Some electrons can flow to the conductive substrate, forming the leakage current, and the transient negative charging process tends to equilibrium as the leakage current increases. In comparison, the transient positive charging process approaches equilibrium with the number of returned electrons increasing due to the positive surface potential. In the equilibrium state, the surface potential of the film negatively charged decreases with film thickness and trap density increasing; it increases with electron mobility and dielectric constant. However, the equilibrium surface potential of the film positively charged varies slightly with film parameter.
Plasmonic properties of silver cross-shape nanostructure
Authors: Zhong Ming-Liang  , Li Shan  , Xiong Zu-Hong  , Zhang Zhong-Yue  ,   School of Physical Science and Technology, Southwest University, Chongqing 400715, China
Published: December 2020

The extinction spectra and the electric field distributions of the cross-shaped nanostructures are calculated by the discrete dipole approximation method. Compared with the individual nanorod, the cross-shape nanostructure can generate high local electric fields at the lateral surface. Because of the electric field couplings between adjacent protruding parts, much enhanced electric fields always occur at the lateral surface of the cross-shape nanostructure, with the incident polarization direction varied. In addition, the effects of the structural parameters of the cross-shape nanostructures on their plasmonic properties are also investigated. These results would guide the preparation of the cross-shape nanostructures for their applications in surface enhanced Raman scattering.