bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of an atomic Bose-Einstein condensate on the squeezing properties of V-type three-level atomic lasers
Authors: Li Ming  ,   Department of Mathematics and Physics, Guilin University of Technology, Guilin 541004,China
Published: December 2020

The Hamiltonian operator of a system of V-type three-level atomic Bose-Einstein condensation interacting with two-mode squeezed coherent light field is analyzed in terms of the lattice-liquid model. It is indicated that the contribution of the interaction between atoms to the Hamiltonian in the literature is irrational,so the Hamiltonian operator is improved and the squeezing properties of atomic laser coupled output from the system of V-type three-level atomic Bose-Einstein condensation interacting with two-mode squeezed coherent light field are studied. The results show that the interaction intensity of light-atoms in the Bose-Eimtein condenation has evident influence on the fluctuations of two quadrature components of the atomic laser.
Characteristics of deposition for neutral atoms in laser standing wave with different velocities
Authors: Zhang Wen-Tao  , Zhu Bao-Hua  , Xiong Xian-Ming  , Huang Jing  ,   (1)Division of Research Administration, Guizhou University for Nationalities, Guiyang 550000, China; (2)School of Electronic Engineering and Automation, Guilin University of Electronic Technology, Guilin 541004, China
Published: December 2020

The deposition patterns of neutral chromium atoms in a laser standing wave with different longitudinal and transverse velocities are discussed. The simulation results of atoms show that the full width at half maximum (FWHM) of a nanometer stripe is 1.49 nm and the contrast is 62.1 ∶1 when the ideal longitudinal velocity of chromimum atom is the most probable velocity 960 m/s, the FWHM of the stripe is 5.35nm and the contrast is 25.6 ∶1 when the longitudinal velocity of chromimum atom is half the most probable velocity. The simulation results of deposition with different transverse velocities are shown at the same time, the FWHM of the stripe is 4.18nm and the contrast is 20.9 ∶1, with the transverse velocity of chromimum atom being 0.25 m/s; the FWHM of the stripe is 58.4 nm and the contrast is 8.9 ∶1, with the transverse velocity of chromimum atom being 0.50 m/s.
Spectroscopic parameters and potential energy function of the ground state of TiO (X 3 Δr)
Authors: Wei Hong-Yuan  , Xiong Xiao-Ling  , Liu Guo-Ping  , Luo Shun-Zhong  ,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Based on the theory of atomic and molecular statics, the reasonable dissociation limit for the ground state of TiO is derived.The structural optimization and the frequence analysis for the ground state (X3Δr) of TiO molecule are performed using different density functional theory methods or MP2, MP4 methods with the different basis sets. By comparison with the above calculation results, the conclusion is obtained that the B3LYP method with 6-311+G basis set for O atom and 6-311+ +G** basis set for Ti atom is the most suitable for the geometric structure, vibrational frequence and dissociation energy calculation. The analytical potential energy curve for the ground state (X3Δr) of TiO molecule is scanned using the chosen method, and then fitted to the Murrell-Sortie function using least squares fitting. Finally the spectroscopic constants related to the analytical potential energy function are calculated. All calculation results are in good agreement with the experimental data.
A combinative triple-well optical trap for three-species cold atoms or molecules
Authors: Lu Jun-Fa  , Zhou Qi  , Yin Jian-Ping  , Ji Xian-Ming  ,   (1)Department of Physics, East China Institute of Technology, Fuzhou 344000, China; State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China; (2)School of Science, Nantong University, Nantong 226007, China; (3)State Key Laboratory of Precision Spectroscopy, Department of Physics, East China Normal University, Shanghai 200062, China
Published: December 2020

We propose a scheme to form a combinative triple-well optical trap for cold atoms or molecules in focus plane by using an optical system composed of a lens and a phase-type spatial light modulator (SLM) based on liquid crystal microdisplays illuminated by a plane light wave. The principle of forming a triple-well optical trap is analyzed and the characteristic parameters of optical potential are calculated. We also discuss the evolution between a tripe-well optical trap and a double-well one (or a single-well one). Additionally, the propotential applications of our triple-well trap and its novel optical lattices in four-wave mixing with matter waves, cold collision of three atomic species and so on, are explored.
External quantum efficiency of microcavity planar emitting devices
Authors: Ma Feng-Ying  , Su Jian-Po  , Guo Mao-Tian  , Chi Quan  , Chen Ming  , Yu Zhen-Fang  ,   School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China
Published: December 2020

The calculation models of the external quantum efficiency for the planar surface emitting devices are presented with considering their spatial distribution of radiance/luminance and relative spectral power distribution. These models can be applied to all kinds of planar surface emitting devices including OLEDs, VCSEL, MOLED, MCLED and planar THz emitting devices. Two planar emitting devices with and without cavity are fabricated with the structure of Glass /DBR /ITO /NPB /Alq ∶C545T /Alq /LiF /Al and Glass /ITO /NPB /Alq ∶C545T /Alq /LiF /Al. The external quantum efficiencies are calculated at different current densities using the corresponding model. The external quantum efficiency of the cavity device is close to 1.5% at a current density of 14 A/m2 and brightness of 100 cd/m2, and reaches 2% around 0.14 A/m2 and 2.2 cd/m2.
Theoretical research of Fernald forward integration method for aerosol backscatter coefficient inversion of airborne atmosphere detecting lidar
Authors: Liu Hou-Tong  , Chen Liang-Fu  , Su Lin  ,   (1)State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China; (2)State Key Laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University, Beijing 100101, China; Department of Applied Physics, Mathematical Physics Colle
Published: December 2020

Preliminary inversion results show that the Fernald forward integration method (FFIM) can be used to calculate aerosol backscatter coefficient from airborne atmosphere detecting lidar. But the corresponding theoretical explanations have not been found in relevant papers. In this paper,We use the simulated data based on the ground-based atmosphere detecting radar in Hefei lidar data on February 27, 2008, to quantitatively analyze the above inversion results obtained by the FFIM . Results show that there are three main reasons that the FFIM can be used to calculate aerosol backscatter coefficient when the altitude of lidar calibration points is about 10km. First, the inversion error cannot be infinite and negative results will not appear because the difference batween the denominator items in the Fernald forward integration equation is always greater than zero. Second, inversion error is no more than 0.006 when calibration error is 100%, which is 0.6 percent of the denominator value. Third, Molecule backscatter coefficient is dominant in the calibration item of the Fernald forward integration equation. Big fluctuation range of aerosol backscatter coefficient in the calibration points has little influence on the calibration item value. In general, the atmosphere structure that has a small density in the upper layer but a big density in the lowerlayer, and a high calibration position are two basic reasons for which the FFIM can be applied to the aerosol backscatter coefficient inversion through using airborne atmosphere detecting lidar data.
Nonlinear Faraday rotation in electromagnetically induce transparency medium
Authors: She Yan-Chao  , Zhang Wei-Xi  , Wang Deng-Long  ,   Department of Physics and Electronic Science, Tongren University, Tongren 554300, China;,   Department of Physics and Electronic Science, Tongren University, Tongren 554300, China; Department of Physics, Key Laboratory of Quantum Engineering and Micro-Nano Energy Technology of Education Bureau of Hunan Province, Xiangtan University, Xiangtan 411;,   Department of Physics, Key Laboratory of Quantum Engineering and Micro-Nano Energy Technology of Education Bureau of Hunan Province, Xiangtan University, Xiangtan 411105, China
Published: December 2020

By using multiple-scale methods, we study analytically the propagation properties of the weak linear polarization probe optical field in a cold lifetime-broadened five-level V type atomic system via electromagnetically induced transparency. It is shown that with the strength of the coupling field increasing, the absorption of the probe optical field decreases rapidly and the group velocity of the probe optical field increases quickly under the consideration of linear effect. However, the velocity is several orders of magnitude slower than the light speed in vacuum. Meanwhile, we find that for the same magnetic field the nonlinear Faraday rotation direction is opposite to linear Faraday rotation, and its rotation angle grows bigger than that of linear Faraday rotation. These results mean that the Faraday rotation of the electromagnetically induced transparency medium can be controlled by the nonlinear effect.
Enhanced stimulated Raman scattering of weak-gain mode C—H stretching vibration of benzene
Authors: Cao An-Yang  , Li Zhan-Long  , Li Zuo-Wei  , Sun Cheng-Lin  , Jiang Yong-Heng  ,   (1)College of Physics, Jilin University, Changchun 130021,China; (2)Department of Physics, Changchun University of Science and Technology, Changchun 130022,China; (3)State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012,China; (4)State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012,China; College of Physics, Jilin University, Changchun 130021,China
Published: December 2020

In the paper we report on the enhanced stimulated Raman scattering of the weak-gain mode of benzene. The stimulated Raman scattering of C—H stretching vibration of benzene is observed in liquid core optical fiber by mixing toluene. The result is explained by (toluene-benzene)+ and (toluene-toluene)+ dimmer of plasma
Design of high-index broken-ring-based all-solid photonic bandgap fibers
Authors: Li Yan-Feng  , Hu Xiao-Kun  , Wang Ai-Min  ,   (1)Institute of Quantum Electronics, School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China; (2)Ultrafast Laser Laboratory, College of Precision Instrument and Optoelectronics Engineering, Key Laboratory of Opto-electronic Information Science and Technology of Ministry of Education Tianjin University, Tianjin 300072, China
Published: December 2020

The design of all-solid photonic bandgap fibers based on a high-index broken ring is investigated, where the background material is silica and the broken ring consists of several individual high-index rods. Density of states maps and Bloch mode field distributions obtained by plane wave expansion method show that a high-order bandgap in such fibers can be engineered and broadened. The principle is that both the azimuthal and the radial orders of the LP modes of the high-index rods in the cladding can be controlled by the broken ring. It is demonstrated that the highest azimuthal order of the group of less affected LP modes is determined by the rod number and the bandgap width is largely affected by the rod size. The high-order bandgap can be used to design all-solid photonic bandgap fiber with broad transmission ranges of 488 nm and 944 nm for a center wavelength of 800 nm and 1550 nm, respectively, and the transmission window features the typical normal-zero-anomalous dispersion profile.
New complexity metric of chaotic pseudorandom sequences using fuzzy relationship entropy
Authors: Chen Xiao-Jun  , Li Zan  , Bai Bao-Ming  , Cai Jue-Ping  ,   (1)Schoole of Microelectronics,Xidian University, Xi’an 710071,China; (2)State Key Laboratory of Integrated Service Networks (ISN),Xidian University,Xi’an 710071,China
Published: December 2020

A new complexity metric to evaluate the unpredictability of the chaotic pseudorandom sequences based on the fuzzy relationship entropy (F-REn) is proposed in the view of maximal randomness of the sequences with arbitrary length. On this condition,two basic properties of F-REn are proved. Simulations and analysis results show that, the proposed F-REn works effectively to discern the changing complexities of the chaotic pseudorandom sequences, and compared with complexity metric based on the approximate entropy(ApEn) and symbolic dynamics approach , F-REn works have obvious advantages in the applicability of symbolic space, the sensitivity of vector dimension and the robustness of resolution parameter.
M-dimensional space-time error correction code theory for switch node based on omnidirectionalradiation of electromagnetic wave
Authors: Xie Ying-Hai  , Yang Wei  , Xu Chang-Long  ,   State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China; State Key Laboratory of Integrated Service Networks, Xidian University, Xi'an 710071, China
Published: December 2020

In wireless communication field, the omnidirectional radiation of electromagnetic wave in free space is always considered as a big shortcoming, nevertheless, it can be used to improve the performace of wireless communication system in network entironment. Here, we consider that M nodes use a switch node to exchang their information in a wireless network. Differert from the conventional method, the switch node will take the joint coding method for the M independent information, then transmit the same codeword to all M nodes simultaneously through the omnidirectional radiation. For the novel network code, the mathematical definition of the M -dimension space-time error correction code is proposed, and some theorems about its performance are proved to lay a foundation to construct good codebooks. The redundancy of time and space domain is added to the novel codebook at the same time, and the efficiency of the transmit power is improved, so we can design high-rate codebook with good error detection and correction capability. Moreover, the complexity of its decoding algorithm can be reduced, owing to the distributed data processing. Here, we emphasize that contrary to one’s intuition, our proposed codebook reveals that it is in general not correct to take the rate of codebook which has the error detection and correction capability to be less than 1.
Robust localization and identification method of moving sound sources based on worst-case performance optimization
Authors: Shi Jie  , Yang De-Sen  , Shi Sheng-Guo  ,   Science and Technology on Underwater Acoustic Laboratory, Harbin Engineering University, Harbin 150001, China
Published: December 2020

Based on the passive synthetic aperture principle, a new robust high-resolution focused array signal processing method of moving sound source localization and identification is proposed in this paper. By means of the integrated optimization, this method generates the coordinates of a virtual array and the data matrix through the vector maximum likelihood focused algorithm, then utilizes the sparse virtual array focused algorithm based on the worst-case performance optimization to obtain the robust high-resolution localization and recognition effects. The theory and the simulation analysis show that this method is applicable to the complex experimental situations such as non-uniform motion and tipsy array, and the focused spatial spectrum indicates the greater dynamic range, the sharper focused peak, and the stronger ability to suppress the fluctuations of the background noise. The higher robustness and better results of this proposed method are verified in the lake experiment. Under the same experimental condition, the dynamic range of high-resolution MVDR focused algorithm is only 3.5dB, however, it can reach 50 dB by the proposed method.
Theoretical and experimental study of femtosecond pulse laser heating on thin metal film
Authors: Ma Wei-Gang  , Wang Hai-Dong  , Zhang Xing  , Wang Wei  ,   (1)Institute of Microelectronics, Peking University, Beijing 100871, China; National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Beijing 100871, China; (2)Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
Published: December 2020

Ultrashort pulse laser heating is not only capable of resolving and observing the ultrafast interaction of energy carriers, i.e. electrons, phonons, but also widely applied to material processing, i.e., laser ablation. However, the previous theories, i.e., two-temperature model, parabolic one-step model, can be applied only to some limited segments. In this paper, according to the two-temperature model and Fourier’s law, a general theoretical model is presented for the description of the entire heat relaxation process after the thin metal film deposited on the substrate has been heated by the ultrashort pulse laser. Moreover, the heat conduction process is also experimentally studied by using the rear-pump front-probe transient thermoreflectance technique on Au/glass and Au/SiC at 300 K, and the theoretical prediction accords well with the experimental result, which illustrates the validity of the present theoretical model. Based on the good agreement between theoretical predictions and experimental data, the electron-phonon coupling factor of the thin gold film and thermal boundary conductance of the Au/glass and Au/SiC interfaces are extracted and the measured results are in good agrement with the previous reported values. The electron-phonon coupling factor is close to that of the bulk material and does not exhibit size effect. The thermal boundary conductance is greater than the prediction of diffuse mismatch model, and the reasons responsible for the discrepancies are electrons participating in the interfacial heat conduction, interfacial atom diffusion and inelastic scattering.
Magnetization mechanism of magnetized water
Authors: Ding Zhen-Rui  , Zhao Ya-Jun  , Chen Feng-Ling  , Chen Jin-Zhong  , Duan Shu-Xing  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

The physical properties of three different kinds of water under the action of an electromagnetic field and stirring are studied. The result shows that the surface tension coefficient, the viscosity and the density of water significantly change with magnetic induction intensity and magnetization time. This experimental law has also been reported in many other papers, but has not yet been explained. In the present paper, according to the molecular structure of water and characteristics of hydrogen bond, we further study the mechanism of magnetized water with the theories of thermology, electromagnetism and structural chemistry, and also investigate more extreme phenomena about surface tension coefficient, viscosity and density of magnetized water. It is found that the breaking of a large number of hydrogen bonds is due to the fact ther electrons states are affected by magnetic field or perturbation, and thus the interaction between electrons is influenced when the water solution is magnetized in a field of 200 mT above. As the formation conditions of hydrogen bond are easily satisfied, the breaking and the forming of the hydrogen bond of the liquid water coexiste at a certain temperature, and their occurence probabilities are alternated in magnitude in the magnetization process, resulting in more extreme phenomena. The change extent of physical quantity with random fluctuation depends on the strong or weak extent of the breaking and the forming of hydrogen bond.
Target patterns obtained by suddenly increasing applied voltage in dielectric barrier discharge
Authors: Dong Li-Fang  , Yue Han  , Fan Wei-Li  , Li Yuan-Yuan  , Yang Yu-Jie  , Xiao Hong  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China
Published: December 2020

Stable target patterns are produced by suddenly increasing the applied voltage in argon dielectric barrier discharge at atmospheric pressure for the first time. The stability and wavelength selection of target patterns obtained by gradually increasing applied voltage after suddenly increasing applied voltage and by directly suddenly increasing applied voltage are studied respectively. It is found that the target patterns obtained by gradually increasing applied voltage are unstable. There is mutual transformation between target pattern and spiral, in which the target pattern can only survive for several tens milliseconds. The target patterns obtained by directly suddenly increasing applied voltage are much more stable, which can survive for more than 5min. The wavelength selections of target patterns obtained by above two methods are studied. It is found that the wavelength of target patterns obtained by directly suddenly increasing applied voltage decreases more quickly as the applied voltage increases. The results show that the applied voltage increasing way in which the target patterns are obtained plays an important role in the stability and wavelength selection of target pattern.
Range and annealing behavior of Er ions implanted in SiC
Authors: Qin Xi-Feng  , Liang Yi  , Wang Feng-Xiang  , Li Shuang  , Fu Gang  , Ji Yan-Ju  ,   College of Science, Shandong Jianzhu University, Jinan 250101,China
Published: December 2020

Er ions with an energy range of 300—500 keV are implanted in 6H-SiC crystal samples separately. The values of mean projected range Rp and range straggling ΔRp of Er ions with a dose of 5×1015 cm-2 implanted in 6H-SiC crystal are measured by Rutherford backscattering technique. The measured data are compared with TRIM code prediction. It is seen that the experimental Rp values are in good agreement with theoretical values, but for ΔRp values there are bigger differences between the experimental data and the theoretical values. Research shows that the higher the implanting energy, the heavier the damage is. Perfect recrystallization of 6H-SiC is achieved by annealing at 1400 ℃, however it is accompanied by the segregation of Er ions to the surface.
Dispersing performance of KTP(011) crystal
Authors: Zhao Jia  , Cui Ming-Qi  , Zhao Yi-Dong  , Zhou Ke-Jin  , Zheng Lei  , Zhu Jie  , Sun Li-Juan  , Chen Kai  , Ma Chen-Yan  ,   (1)College of Mechanical Engineering, Beijing Technology and Business University, Beijing 100048, China; (2)Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

According to the requirements for the performance of analyzers in soft x-ray regime of synchrotron radiation, the qualities of various crystals often used in soft x-ray range are investigated. We find that crystals KTP (KTiOPO4)(011) crystal is an ideal one among large d-spacing crystals. We propose an experimental method to measure diffraction efficiencies of crystals with synchrotron radiation source. In particular, we find that the diffraction efficiency is closely related to the source emittance. The lattice constant and diffraction efficiencies of KTP(011)crystal are also presented in this paper.
Generalized planar fault energy of body-centered cubic Ta andits application to plastic deformation of mode Ⅱ crack tip
Authors: Mei Ji-Fa  , Li Jun-Wan  , Ni Yu-Shan  , Wang Hua-Tao  ,   Department of Mechanics and Engineering Science, Fudan University, Shanghai 200433, China
Published: December 2020

The generalized planar fault energy, including the generalized stacking fault (GSF) and the generalized twinning fault energy (GTF) of body-centered cubic metal Ta are investigated based on the embedded atom potential. The GSF of Ta, much different from that of fcc metal, reveals that no evident energy minimum is observed in the energy curve. This implies that only full dislocations are possibly emitted in the {112} slip plane. From the GTF it is predicted that the minimum thickness of a metastable twin is as large as four layers and the five-layer twin is more stable. The incipient twin Ta tends to grow thicker once it is created. To confirm the significance of the GSF and GTF in revealing incipient plasticity, quasicontinuum method is used to simulate the mode Ⅱ crack of single Ta crystal. The results show that deformation twin and full dislocation along direction in {112} plane are two co-existing mechanisms of crack tip plastic deformation. The initial four-layer twin quickly extends into five-layer and more-layer twins with further loading. A full dislocation is emitted into the front of the crack tip in {112} plane. These two plastic deformation mechanisms are well explained by the GTF and the GSF respectively.
Effect of annealing on microstructure and mechanical propertiesof AlTiN multilayer coatings
Authors: Luo Qing-Hong  , Lou Yan-Zhi  , Zhao Zhen-Ye  , Yang Hui-Sheng  ,   (1)Beijing Institute of Aeronautical Materials, Beijing 100095, China; (2)Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

The AlTiN composition multilayer coatings with a periodic change in nitrogen content are deposited on high speed steel (W18Cr4V) substrates with a medium-frequency reactive magnetron sputtering system and TiAl targets and by alternately changing nitrogen flux during deposition. These of coatings are annealed separately at temperatures of 600, 700 and 800 ℃ in vacuum for 5 hours. Their microstructures are studied by x-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy, while their mechanical behaviors and adhesion properties are investigated using nano-indenter, scratch test, and friction and wear instrument. The results show that the AlTiN composition multilayer coatings obtained by alternately changing nitrogen flux during deposition possess stable and good mechanical properties. After 800 ℃ vacuum annealing, the interface of AlTiN multilayer coating is still very clear. Annealing increases crystallization degree and grain size of AlTiN multilayer coating, but the crystallization degree of high nitrogen content layer is still higher than that of low nitrogen content layer. After vacuum annealing, the hardness of AlTiN multilayer coating reduceds. The hardness of AlTiN multilayer coating after 800 ℃ annealing is larger than after 600 ℃ annealing, but as the annealing temperature increases, wear resistance and anti-spalling performance of AlTiN multilayer coatings decrease dramatically.
Simulation of bubble growth process in pool boilingusing lattice Boltzmann method
Authors: Jiang Fang-Ming  , Liao Quan  , Zeng Jian-Bang  , Li Long-Jian  ,   Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education, Chongqing University, Chongqing 400030, China;,   Key Laboratory of Low-grade Energy Utilization Technologies and Systems of Ministry of Education, Chongqing University, Chongqing 400030, China; Key Laboratory of Renewalde Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou 510640, China;,   Key Laboratory of Renewalde Energy and Gas Hydrate, Chinese Academy of Sciences, Guangzhou 510640, China
Published: December 2020

In this paper, a new single-component lattice Boltzmann model, which is based on exact difference method and extended with an energy transfer equation to model heat transfer, is proposed to describe liquid-vapor phase transition process. The wettability of the heated wall is modeled by an interaction force between solid wall and fluid. This new model is validated through the simulation of water phase transition process. It is found that the simulation results are in good agreement with the experimental data. The surface tension of water, which is obtained from simulation results at different temperatures, is closed to experimental data. These results are in agree ment with those obtained from Laplace law. In order to demonstrate the availability of this model for dealing with phase transition and two-phase problems, the bubble growth process on a heated surface is simulated in pool boiling. It is found that the bubble departure diameter is proportional to g-0.5 and the release frequency scales with g0.75, where g is the gravitational acceleration. These results are in good agreement with those obtained from the empirical relationship and reference results. Finally, simulation results show no relationship between the bubble departure diameter and the static contact angle, but the bubble release frequency increases exponentially with the latter.
Effect of far field flow on the stability of thespherical crystal in undercooled melt
Authors: Cao Bin  , Lin Xin  , Huang Wei-Dong  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xian 710072, China
Published: December 2020

A model is developed to investigate the effects of far field flow on the solidification of a spherical particle from the melt, under the influence of thermal and solute flow. The stability of the spherical interface is studied and the growth rate of the interface perturbation is calculated. The perturbation to the maximum growth rate becomes larger when the spherical radius increases. The downwind side of the interface is more unstable than the upwind side. The effect of far field flow reduces the critical radius of the spherical crystal.
Shock-induced phase transformation in nanocrystalline iron
Authors: Ma Wen  , Zhu Wen-Jun  , Zhang Ya-Lin  , Jing Fu-Qian  ,   (1)Department of Physics, National University of Defense Technology, Changsha 410073, China; National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineeriag Plysies, Mianyang 621900, China; (2)Institute of Computer Application, China Academy of Engineeriag Plysies, Mianyang 621900, China; (3)National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineeriag Plysies, Mianyang 621900, China
Published: December 2020

The shock-induced phase transformation of nanocrystalline iron with different grain sizes is investigated by using molecular dynamic simulations. The critical shock stress for shock-induced phase transformation (from body-cubic centered α phase into hexagonal-close packed ε phase) of nanocrystalline irons is about 15 GPa. Under shock compression, the nanocrystalline irons first experience elastic deformation, then plastic deformation purely caused by grain boundaries, after that phase transformation nucleated mostly at the grain boundaries, and finally nucleation areas expanding into the entire samples. These processes can be reflected by the stress profile and the particle velocity profile, and also be distinguished by local atomic structures analyses in the corresponding areas. The microstructures of the shocked samples consist of grain boundary and hexagonal-closed packed new phase with the face-cubic centered atoms as the twin boundary. The grain size obviously influences the deformation of grain boundary and the microstructure after shock compression, and turns to change the profiles of stress or velocity. The mechanism is primarily analyzed.
Theoretical calculation of molar heat capacity at constant pressureof nanoparticle and nanocrystalline
Authors: Chen Hui-Min  , Liu En-Long  ,   (1)Materials Science and Engineering College, Henan University of Science and Technology, Luoyang 471003,China; (2)School of Materials Science and Engineering, Tongji University, Shanghai 200092, China
Published: December 2020

In this paper the theoretical calculation methods for CP(T) (molar heat capacity at constant pressure) values of nanoparticle and nanocrystalline are investigated. Theoretical formulas for calculating CP(T), Debye temperature and volume expansion coefficient of nanoparticle using melting point of nanoparticle are set up and the calculated values of CP(T) for copper nanoparticle are fairly consistent with the experimental ones. A relationship between Debye temperature and density of nanocrystalline is proposed, and Debye temperature can decrease with the reduction of nanocrystalline density. The calculated values of CP(T) of copper nanocrystalline are also quite consistent with the experimental ones. The bulk modulus of elasticity of nanocrystalline will drop off with the decrease of grain size of nanocrystalline, which should be taken into account when the CP(T) of nanocrystalline is calculated. The calculation methods proposed in this paper are feasible.
Liquid-like structure and self-diffusion channels on Al surfaces
Authors: Chen Gong-Bao  , Lu Wen-Jiang  , Tang Fu-Ling  , Xie Yong  ,   Key Laboratory of Advanced Non-ferrous Metal Materials of Gansu Province, Lanzhou University of Technology, Lanzhou 730050, China;,   Key Laboratory of Advanced Non-ferrous Metal Materials of Gansu Province, Lanzhou University of Technology, Lanzhou 730050, China; Key Laboratory of Non-ferrous Metal Alloys and Processing of Ministry of Education, School of Material Science and Engineeri;,   Key Laboratory of Non-ferrous Metal Alloys and Processing of Ministry of Education, School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China
Published: December 2020

Molecular dynamics simulation with embedded atom method potentials is performed to study the atomic structure and self-diffusion on three aluminum surfaces: (001), (110) and (111). Using mean-square displacement, structure ordering parameter, radial-distribution function and z-direction density, we find that their atoms on the first layer present obvious self-diffusion then change into liquid-like structure under melting points: Al(110) at 700±10 K, Al(001) at 860±10 K, and Al(111) at 930±10 K. In the liquid-like structure, self-diffusions always take place on the first layer of the original surface along the direction parallel rather than vertical to the surface: some of the diffusions occur on the outermost layer and more diffusions occur outside the original surface. The main diffusion channels of the three surfaces are different: along [001] on Al(110), [110] and [110] on Al(001), and [110], [101] and [011] on Al(111). No inter-layer diffusion takes place in liquid-like structure, which is different from in the liquid structure of melted surface.
Electronic structure and optical property of Boron adsorption on wurtzite ZnO(0001) surface
Authors: Zhang Yu-Fei  , Guo Zhi-You  , Cao Dong-Xing  ,   Institute of Optoelectronic Material and Technology, South China Normal University, Guangzhou 510631, China
Published: December 2020

The geometrical structure of clean ZnO(0001) surface and B/ZnO(0001) adsorption system are optimized by using the ultra-soft pseudopotential method of total-energy plane wave based on the density functional theory. Adsorption energy, band structure, density of states and optical properties are calculated and discussed in detail. The results reveal that the T4 site is the most stable adsorption site of ZnO(0001) surface. After a B atom is adsorbed on T4 site, the surface band gap narrows down and the surface state changes a lot, the n-type conduction characteristic is weakened. As for the optical properties, we can find that the absorbing ability of ZnO(0001) surface to ultraviolet light is obviously enhanced after the B atom has been adsorbed on the T4 site of ZnO(0001) surface.
Influence of pressure on structure and properties of Si-doped glow discharge polymer film
Authors: Yan Jian-Cheng  , Tang Yong-Jian  , Li Ping  , He Zhi-Bing  , Zhang Ying  ,   (1)Centre of Laser Fusion Research, China Academy of Engineering Physics, Mianyang 621900, China; (2)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; (3)Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; Centre of Laser Fusion Research, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

The Si-doped glow discharge polymer (Si-GDP) films are deposited by glow discharge polymerization technology at different pressures. The structure and the composition of eath Si-doped glow discharge polymer film are characterized by the Fourier transform infrared spectroscopy and x-ray photoelectron. Using ultraviolet/visible spectroscopy, the optical band gap is analyzed. The results show that the Si element exists mainly in the form of Si—C, Si—H, Si—O, Si—CH3. The relative content of Si—C decreases and then increases with the increase of pressure. It can be found that the ratio between C—C and C C decreases with the increase of pressure. As the pressure increases, the optical band-gap decreases and then increases.
Surface modification and the friction coefficient of tetrahedral amorphous carbon films bombarded by energetic N ion
Authors: Han Liang  , Chen Xian  , Yang Li  , Wang Yan-Wu  , Wang Xiao-Yan  , Zhao Yu-Qing  ,   (1)Key Laboratory for Physical Electronics and Devices of Ministry of Education,School of Electronic and Information Engineering,Xi’an Jiaotong University, Xi’an 710049, China; (2)Key Laboratory for Physical Electronics and Devices of Ministry of Education,School of Electronic and Information Engineering,Xi’an Jiaotong University, Xi’an 710049, China; School of Technical Physics, Xidian University, Xi’an 710071, China
Published: December 2020

The ta-C films with more than 80% sp3 fraction were deposited by FCVA technique, and then were bombarded by energetic N ion. The composition and structure of the ta-C films prior to and after the bombardment of energetic N ion is analyzed by x-ray photoelectron spectroscopy. The surface morphology is investigated by Atomic force microscopy .The result shows that the N concentration in the films slightly increase from 10% to 12% when N ion bombardment energy increases from 1000 eV to 2200 eV. The bombardment of energetic N ion induces the conversion of sp3 bond to sp2 bond. The CN bonds can be formed in the films after energetic N ion bombardment. Energetic N ion bombardment is implanted superficially. The RMS of the films decreases from 0.2 to 0.18 nm after the bombardment, and then increases again to 0.33 nm with the increment of the N ion energy. The friction test indicates that the minimum of friction coefficient is about 0.09 nm before ta-C film was bombarded by energetic N ion. The friction coefficient increased to about 0.16 nm after the bombardment of N ions. But the friction coefficient does not depend on the N ion energy.
Electronic structure of CuAlS2 doped with Mg and Zn
Authors: Wan Wen-Jian  , Yao Ruo-He  , Geng Kui-Wei  ,   School of Electronic and Information Engineering, South China University of Technology, Guangzhou 510640, China
Published: December 2020

Electronic structure of chalcopyrite-type CuAlS2 is analyzed from the band structure and the density of states. Compared with bulk CuAlS2, the effect of doping with Mg and Zn are investigated from the crystal structure, band structure, density of states and electron density difference. The results reveal that Mg and Zn substituting Al both increase the lattice constants and cell volume, yield acceptor states on the top of valence band, providing p-type conductance. CuAlS2 ∶Zn has a slightly larger ionization energy than CuAlS2 ∶Mg, while the former has lower total energy and its crystal structure is more stable.
Effect of exponential-doping structure on quantum yield of transmission-mode GaAs photocathodes
Authors: Zhang Yi-Jun  , Niu Jun  , Zhao Jing  , Zou Ji-Jun  , Chang Ben-Kang  ,   Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

The quantum yield formulas for exponential-doping and uniform-doping transmission-mode GaAs photocathodes are modified by adding a shortwave constraint factor to the photoelectron generation function in a one-dimensional continuity equation. Based on the modified transmission-mode quantum yield formulas, the experimental exponential-doping and uniform-doping transmission-mode quantum yield curves are respectively fitted, and the fitted curves are consistent well with the experimental curves. In addition, the fitted cathode performance parameters indicate that as compared with the uniform-doping photocathode, the exponential-doping photocathode can obtain a higher cathode performance because of the built-in electric field. The exponential-doping structure can effectively increase the quantum yield of transmission-mode photocathode.
Rectifying behavior and photovoltaic effect in La0.88 Te0.12 MnO3/Si heterostructure
Authors: Chen Peng  , Jin Ke-Xin  , Chen Chang-Le  , Tan Xing-Yi  ,   Shaanxi Key Laboratory of Condensed Matter Structures and Properties, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

The photovoltaic effect and the good rectifying behavior are observed in La0.88Te0.12MnO3(LTMO)/Si heterostructure fabricated by a pulsed laser deposition method. The photovoltage increases quickly to a maximum value at about 394 μs and then decreases gradually. The maximum photovoltage is about 13.7 mV at T = 80 K. The maximum photovoltage decreases with temperature increasing, which is attributed to the stronger thermal fluctuation. A nonlinear decrease of the maximum photovoltage in the photovoltages-temperature curve is observed, which is mainly caused by the change in the band structure of the LTMO layer due to the metal-insulator transition.
Bandgap energy tuning and photoelectrical properties of self-assembly quantum well structure in organic-inorganic hybrid perovskites
Authors: Zheng Ying-Ying  , Deng Hai-Tao  , Wan Jing  , Li Chao-Rong  ,   Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018, China
Published: December 2020

Organic-inorganic hybrid perovskite materials have excellent performance in optical, electrical and magnetic properties. The energy-band structure of the hybrid materials can be tuned at the molecular level. In this paper, thin films of hybrid perovskite (C6H13NH3)2(CH3NH3)n-1PbnI3n+1 (n=1, 2, 3, n is the number of two-dimensional inorganic-sheet) have been successfully prepared by a simple spin-coating method. The effects of the inorganic-sheet number (n) on the crystal structure, bandgap energy, exciton binding energy, photoluminescent emission and photocondunctive performance of the hybrid materials have been investigated systematically. With the increasing of inorganic-sheet number, the exciton absorption peak shows an obvious red shift, the bandgap becomes narrow, and the exciton binding energy decreases. Further, the exciton is separated into holes and electrons easily due to the expansion of the exciton Bohr radius and, moreover, the carrier mobilities are increased due to the increasing of inorganic-layer thickness. Consequently, the photocondunctivity of the films is greatly enhanced.
Simulation of optical performance of red top emitting organic light emitting devices based on phase-shift on reflection theory
Authors: Li Hui-Ying  , Duan Yu  ,   (1)College of Computer Science and Technology, Jilin University, Changchun 130012, China; (2)State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering Jilin University, Changchun 130012, China
Published: December 2020

In this paper, we study the phase shift of the reflection from a semitransparent electrode of a top-emitting organic light-emitting device (TOLED) which is able to adjust spectrum of TOLED. Based on the micro-cavity theory and the transfer matrix theory, a model is set up to simulate the red TOLED. The simulation results show that the modulation of the device is not only limited to organic layer thickness, but also related to the reflection phase shift. The phase shift of the reflection of top electrode is adjusted through changing the thickness of organic layer capped on the top electrode, thus the TOLED optical performance can be changed. This result provides a useful method of improving the performance of the device.
Effect of High-permeability FeCuNbSiB on magnetoelectric property of magnetostrictive/piezoelectric composite
Authors: Chen Lei  , Li Ping  , Wen Yu-Mei  , Wang Dong  ,   Key Laboratory for Optoelectronic Technology and Systems of Ministry of Education, College of Optoelectronic Engineering Chongqing University, Chongqing 400044, China
Published: December 2020

A brand-new magnetostrictive/piezoelectric laminated composite is presented using the giant magnetostrictive Terfenol-D, piezoelectric PZT and high-permeability FeCuNbSiB. Since the high-permeability FeCuNbSiB changes the effective magnetic field in the Terfenol-D and the deformed FeCuNbSiB applies a stress to the Terfenol-D in an external magnetic field, thus the saturation magnetostrictive coefficient of Terfenol-D is enhanced, resulting in a higher magnetoelectric voltage output for the composite. Based on the equivalent magnetic charge theory, the effect of the FeCuNbSiB on the effective magnetic field in the Terfenol-D is analyzed, and the magnetostrictive coefficient of Terfenol-D and the theoretical formula of low-frequency magnetoelectric voltage coefficient are derived based on the nonlinear constitutive model of magnetostrictive material and the equivalent circuit method. The analytical results accord with the experiments qualitatively, and the magnetoelectric voltage of the composite is 1.3 times as high as that of the Terfenol-D/PZT-8H (MP) composite. The experimental results indicate that the thickness of FeCuNbSiB has a great influence on magnetoelectric property. The magnetoelectric voltage coefficient increases nearly linearly with the increase of the thickness of FeCuNbSIB until 180μm.
Theory and calculation of magnetoelectric effect in longitudinally polarized and magnetized laminate materials
Authors: Luo Ying  , Bao Bing-Hao  ,   (1)Faculty of Science, Jiangsu University, Zhenjiang 212013, China; (2)Micro-Nano Science and Technology Research Center, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
Published: December 2020

Based on constituent equations of longitudinally polarized piezoelectric materials and magnetized magnetostrictive materials, and equation of motion of the magnetoelectric element, the expression to calculate the open circuit voltage of the piezoelectric material is presented. In view of the characteristics of high impedance for the piezoelectric materials, and considering the capacitance of the lead cable to transfer signal, as well as the capacitance and the internal resistance of the measuring instrument, a formula to calculate the actual magnetoelectric voltage is derived by using an equivalent circuit. Taking different materials parameters, we calculate the effect of parameter variation on magnetoelectric voltage. The results show that the influence of material parameters, cable capacitance and the input capacitance and resistance of the measuring instrument on the output voltage must be taken into account. Non-uniformly biased field will yield forces on the two ends of the magnetostrictive materials and the research result shows that the constant force produced by gradient bias magnetic field will generate stabilized voltage, which is unable to be measured by the oscilloscope.