bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomic-hydrogen Balmer line's abnormal broadening of argon and hydrogen plasma in hollow cathode
Authors: Luan Bo-Han  , Qiao Zeng-Xi  , Liu Peng  , Zhao Wei  , E Peng  , Yu Da-Ren  ,   Department of Electronic Engineering, Heilongjiang University, Harbin 150080, China;,   Department of Thermal Energy and Power Engineering, Harbin Institute of Technology, Harbin 150001, China;,   Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

In the study of new energy resource, hydrogen energy has become a green energy the same as solar energy and wind energy. Under the action of certain catalytic materials (such as Ar+), the hydrogen atom of fractional hydrogen plasma can transit from the ground state to the fractional principal quantum number energy levels lower than the ground level, meanwhile the energy is largely released. By the study of the law of Balmer line's abnormal broadening of atomic hydrogen in argon and hydrogen plasma, the possibility of hydrogen plasma reaction with such a large amount of releasing energy is discussed. The research is in two aspects: by using hollow cathode discharge tube, the existence of fast hydrogen is confirmed and the relationship between the abnormal broadening and the ratio of argon to hydrogen is found to be consistent with the feature of catalytic reaction; by the comparative approach and experiments of strengthening reaction of fractional hydrogen plasma, we have obtained the broader Balmer line's abnormal broadening (the half height broadening reaches 0.245 nm).
Opto-electronic properties of CdS nano particle/carbon nanotube composites
Authors: Li Zhen-Wu  ,   Heze University Jiang Zhen Electromechanical Engincering Institute, Heze 274015, China
Published: December 2020

Based on the outstanding optical properties of CdS and excellent electronic properties of single walled carbon nanotube (SWCNT), nano-CdS particle/SWCNT composite materials and nano-CdS/polyethyleneimine (PEI) functionalized SWCNT composite materials are prepared. Their optical and the electrical properties are investigated by using fluorescent light simulated sunlight. The results show that nano-CdS/SWCNT composite material displays a significant negative photo-conductivity phenomenon, while nano-CdS/PEI-SWCNT composite material displays a positive photo-conductivity phenomenon, which can be were explained by using electron-transfer theory. The optical and the electrical properties of two samples are unchanged in the case of large angle bending. Therefore, the nano-CdS/SWCNT composite materials in optical and electrical areas, especially in the emerging field of flexible opto-electronics have a good prospect.
Study of modeling for hetero-materiel gate fully depleted SSDOI MOSFET
Authors: Cao Lei  , Liu Hong-Xia  , Wang Guan-Yu  ,   Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

In this paper,we propose a new device structure called HMG SSDOI (hetero-materiel gate strained Si directly on insulator), which combines the advantages of strained-silicon and hetero-material gate technology. By solving 2D Poisson's equation, we present models of the surface potential, surface electric field and threshold voltage for the new structure. These models take into account the effects of the gate length, the work function and the energy band. ISE TCAD is also used to simulate the performance of new device structure. The comparison results of model calculation and mathematic simulation show that the new structure of HMG SSDOI can enhance the carrier transport efficiency and suppress short channel effect, drain induction barrier lower and hot carrier effect, which improves device performance greatly.
Polaron spin relaxation in a two-dimensional quantum dot
Authors: Wang Qi-Wen  , Hong Lan  ,   College of Physics and Electronic Information Inner Mongolia Hulunbei'er College, Haila'er 021008, China
Published: December 2020

We theoretically investigate the spin relaxation of polaron, which arises from the electron interactions with the longitudinal optical phonon between the sublevel Zeeman splitting of the polaron ground state by using the vibrational and the unitary transformation methods in a two-dimensional quantum dot, where the Rashba spin-orbital coupling is taken into account. In fact, this process occurs by means of the absorption (or emitting) of a deformation potential acoustic phonon (or a piezoelectric one). The relaxation rate dependences of the magnetic, the quantum dot radius, the lander parameter, the Rashba spin-orbital coupling parameter are studied under the conditions of the strong coupling limitation and the weak one.
A microstructure-based study on electromigration in Cu interconnects
Authors: Wu Zhen-Yu  , Yang Yin-Tang  , Chai Chang-Chun  , Liu Li  , Peng Jie  , Wei Jing-Tian  ,   Key Laboratory of Ministry of Education for Band-Gap Semiconductor Materials and Devices, School of Microelectronics,linebreak Xidian University, Xi'an 710071, China
Published: December 2020

A microstructure-based electromigration model of Cu interconnects is proposed. Mechanisms of scaling and critical length effects of Cu electromigration are studied by transmission electron microscopy and statistical failure analysis. The results show that the lifetime of electromigration is reduced with Cu grain size decreasing when the width of interconnect is scaled down. Electromigration failure is not observed when the interconnect length is smaller than the critical length due to insufficient vacancies for voiding the whole Cu grains. Some small grains are vacated at the cathode end when the interconnect length is larger than the critical length during the testing. The proportion of failures increases and the lifetime decreases with interconnect length increasing. The failure time is dependent mainly on Cu grain size, and the failure lifetime and failure proportion fluctuate with grain size varying when the interconnect length is beyond the diffusion length.
Effect of contact resistance on field emission from carbon nanotube
Authors: Lu Wen-Hui  , Zhang Shuai  ,   Department of Physics, Zhanjiang Normal College, Zhanjiang 524048, China;,   Science and technology office, Zhanjiang Normal College, Zhanjiang 524048, China
Published: December 2020

After accounting for a contact resistance between carbon nanotube (CNT) and substrate, the local electric filed of top of CNT were calculated by combining an improved floated sphere model and the Fowler-Nordheim theory for understand the effect of the contact resistance on field emission from CNT. It is found that the field emission current is limited and current saturation and nonlinear characteristics of the Fowler-Nordheim plots are produced by the contact resistance in region of high electric field. The origin can be attributed to the local electric filed of top of CNT remarkably debases as compared to without the contact resistance.
Solving method of solitary wave for (3+1) - dimensional burgers disturbed system
Authors: Xu Yong-Hong  , Yao Jing-Sun  , Mo Jia-Qi  ,   Department of Mathematics & Physics, Bengbu College, Bengbu 233030, China;,   Department of Mathematics, Anhui Normal University, Wuhu 241003, China
Published: December 2020

A class of higher-dimensional disturbed nonlinear Burgers system in physical model is studied. By using the modifying generalized variational iteration method, the corresponding iteration expansions are constructed. And the approximate solutions of the solitary wave by using the iteration method are obtained.
Experimental study of tungsten and tungsten alloy coating produced by cold gas dynamic spray and tungsten particles calculation and simulation
Authors: Zhang Xiao-Feng  , Ge Chang-Chun  , Li Yu-Jie  , Guo Shuang-Quan  , Liu Wei-Liang  ,   Institute of Nuclear Materials, University of Science and Technology Beijing (USTB), Beijing 100083, China;,   School of Materials Science & Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, China;,   School of Materials Science and Engineering, Southwest Jiaotong University (SWJTU), Chengdu 610031, China
Published: December 2020

Results of optical microscopy, scanning electron microscopy, AFM are presented for tungsten coating produced by low and high cold gas dynamic spraying, respectively. The critical velocity of tungsten powder was calculated, what is more, tungsten particles collision was also simulated by soft ANSYS/LS-DYNA. Cold gas dynamic spray (CGDS) is a rapidly developing coating technology, in which spray particle are deposited through plastic impact on substrate at high velocities at low temperature. In these experiments, the process produced a reasonably dense tungsten coating and tungsten alloy coating. This paper reports the effect of deposition parameters which including temperature, spraying distance, particle size, etc. on the structures formed.
Parameter modulation digital communication and its circuit implementation using fractional-order chaotic system via a single driving variable
Authors: Cao He-Fei  , Zhang Ruo-Xun  ,   College of Physics, Hebei Normal University, Shijiazhuang 050016, China;,   Department of Physics, Shijiazhuang College, Shijiazhuang 050035, China;,   College of Elementary Education, Xingtai University, Xingtai 054001, China
Published: December 2020

Based on the sliding mode variable structure control theory and the adaptive control technique, a single-state adaptive-feedback controller containing a novel fractional integral sliding surface is developed to synchronize a class of fractional-orderchaotic systems. According to the modulation-parameter principle, using single driving variable for a fractional order chaotic system, a kind of digital communication scheme is presented. The results of the circuit stimulation and the circuit experiment show that the information can be received and sent successfully, which demonstrates the feasibility and the effectiveness of the scheme.
Adaptive generalized synchronization between two different complex networks with time-varying delay coupling
Authors: Wang Jian-An  ,   School of Electronics Information Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China
Published: December 2020

This paper deals deals with the problem of generalized synchronization (GS) between two different complex networks with time-varying delay coupling. By designing a nonlinear adaptive controller, the GS between these two networks is achieved based on Barbalat's lemma. Furthermore, when the topological structures of two networks are fully unknown, the GS problem is also discussed. Numerical simulations are provided to demonstrate the effectiveness of the proposed methods.
New soliton solutions and soliton evolvements for the (3+1)-dimensional Burgers system
Authors: Jiang Li-Hong  , Ma Song-Hua  , Fang Jian-Ping  , Wu Hong-Yu  ,   College of Computer and Information Engineering, Li shui University, Lishui 323000, China;,   College of Mathematics and Physics, Lishui University, Lishui 323000, China
Published: December 2020

With the help of the symbolic computation system Maple and the improved projective method and variable separation method, a new family of solitory wave solutions for (3+1)-dimensional Burgers system is derived. Based on the derived solution, some novel soliton structures and soliton evolvements are investigated.
Numerical simulations of dynamic scaling behavior of the etching model on fractal substrates
Authors: Zhang Yong-Wei  , Tang Gang  , Han Kui  , Xun Zhi-Peng  , Xie Yu-Ying  , Li Yan  ,   Department of Physics, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

In order to investigate the effect of the structure of fractal substrates on dynamic scaling behavior of the surfaces, the etching model growing on the Sierpinski arrowhead and crab fractal substrates is simulated by means of Kinetic Monte Carlo (KMC). It is found that the etching model evolving on two kinds of fractal substrates can exhibit dynamic scaling behavior, and can still be described by the Family-Vicsek scaling relation. Although the Sierpinski arrowhead and crab fractal substrates have the same fractal dimension, the obvious different values of roughness exponent and dynamic exponent z, however, are obtained on these two substrates, and they neither of them satisfy the scaling relation +z=2, which is satisfied in the usual Euclid space. It can be seen from the results obtained here that the scaling exponents of the etching model growing on fractal substrate are determined by not only the fractal dimension but also the fractal structure.
Symmetry and conserved quantity of Lagrangians for nonholonomic variable mass system
Authors: Zhang Bin  , Fang Jian-Hui  , Zhang Ke-Jun  ,   College of Physics Science and Technology, China University of Petroleum (East China), Qingdao 266555, China
Published: December 2020

In this paper are study the symmetry of Lagrangians and the conserved quantities for a nonholonomic variable mass system. Firstly, the criterion of the symmetry of Lagrangians for a nonholonomic variable mass system is given. Secondly, the conditions under which there exist a conserved quantity and the form of the conserved quantity, are obtained. Finally, an example is given to illustrate the application of the results.
Soliton excitations of one-dimensional Bose-Hubbard model
Authors: Xie Yuan-Dong  ,   school of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China; Laboratory of Photonic Information Technology, South China Normal University, Guangzhou 510006, China
Published: December 2020

One-dimensional Bose-Hubbard model is studied in detail. Soliton solutions in infinite space is presented, The elliptic function wave solutions and its nenergy and effective mass are also found under the periodic boundary condition.
Mechanism of spatial super-resolution of time-reversed microwave system
Authors: Chen Ying-Ming  , Wang Bing-Zhong  , Ge Guang-Ding  ,   Institute of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

Time-reversed system with a sub-wavelength structure is one of the necessary conditions for the system to show spatial super-resolution characteristics. In the near field zone, Coulomb field predominates the transmission of signals. The resolution limit of Coulomb field is characterized only by the sizes and the spatial distribution of scatterers, which is useful for obtaining the super-resolution beyond the diffraction limit.
Selection of regularization parameters using an atmospheric retrievable index in a retrieval of atmospheric profile
Authors: He Ming-Yuan  , Du Hua-Dong  , Long Zhi-Yong  , Huang Si-Xun  ,   Institute of Meteorology, Chinese People’s Liberation Army University of Science and Technology, Nanjing 211101, China
Published: December 2020

Using an atmospheric retrievable index and The Nelder-Mead simplex method, a dynamic regularization parameter selection method for the retrieval of atmospheric profile with remote sensing data. And a series of test is carried out with four typical regional profiles. The results show that the ranges of the optimal regularization parameter for different profiles are small. And to improve computational efficiency in the actual retrieval process, the regularization parameter can be approximately taken as a constant. The results provide a valuable method of selecting the regularization parameters in the retrieval of atmospheric profiles using the remote sensing data.
Analysis of dynamic properties of a spatial flexible beam with large overall motion and nonlinear deformation in non-inertial reference frame
Authors: He Xing-Suo  , Yan Ye-Hao  , Deng Feng-Yan  ,   Department of Engineering Mechanics, Northwestern Polytechnical University, Xi’an 710072, China
Published: December 2020

In this paper, the dynamic properties of a spatial flexible beam with large overall motion and nonlinear deformation in non-inertial reference frame are investigated. The dynamic response of the present model is compared with those of zero-order approximate model and one-order coupling model. Then changing of dynamic stiffening terms due to the new coupling terms is discussed according to different models. At the same time, the effect of initial static deformation on the tip is considered to study the vibrant deformation of flexible beam. In addition, when the overall motion is free, the rigid-flexible coupling dynamic theory is extended to spatial structure from planar structure. The difference among zero-order approximate model, one-order coupling model and the present exact model is revealed by the frequency spectrum analysis method and concludes that the speed of overall motion is a vital cause for the difference among different models. And the dynamic stiffening phenomenon still exists in a rigid-flexible coupling system while the overall motion is free.
Study of Rashba spin splitting and intersubband spin-orbit coupling effect in AlGaN/GaN quantum wells
Authors: Li Ming  , Zhang Rong  , Liu Bin  , Fu De-Yi  , Zhao Chuan-Zhen  , Xie Zhi-Li  , Xiu Xiang-Qian  , Zheng You-Dou  ,   Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing National Lab of Microstructures, Nanjing 210093, China
Published: December 2020

Rashba spin splitting coefficients for the first two subbands1,2 and intersubband spin-orbit coupling coefficient 12 are obtained by projecting the characteristic equation into the subspace of conduction band. Then Schrdinger and the Poisson equations are solved self-consistently to calculate1,2 and 12 under different gate voltages. Then contributions to the spin-orbit coupling coefficients from the well, the left and the right heterointerfaces and the left and the right barriers of the quantum well are discussed. Resulsts show that the spin-orbit coupling coefficient can be modulated by the gate voltage, and the intersubband spin-orbit coupling coefficients calculated here are a little smaller than the Rashba coefficients1,2, but they are basically of the same order.
Magnetotransport property of HgCdTe inversion layer
Authors: Gao Kuang-Hong  , Wei Lai-Ming  , Yu Guo-Lin  , Yang Rui  , Lin Tie  , Wei Yan-Feng  , Yang Jian-Rong  , Sun Lei  , Dai Ning  , Chu Jun-Hao  ,   Key Laboratory of Polar Materials and Devices of Ministry of Education, School of Science and Technology of Information, East China Normal University, Shanghai 200062, China;,   National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 200083, China;,   Key Laboratory of Infrared Imaging Material and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 200083, China
Published: December 2020

HgCdTe-based metal-insulator-semiconductor field effect transistor is fabricated by low-cost liquid phase epitaxy technique. Clear SdH oscillation in xx and quantum Hall plateaus of xy are observed, indicating that it is a good transistor. By measuring the magnetoresistance near zero field, we observe the weak antilocalization effect in our sample, suggesting a relatively strong spin-orbit coupling. The experimental data can be well fitted by the ILP theory. The fitting-obtained spin-splitting energy increases with increasing electron concentration, and the maximum reaches up to 9.06 meV. From the obtained spin-splitting energy, we calculate the spin-orbit coupling parameter and find that it increases with increasing electron concentration, which is contrary to the observations in a wide quantum well.
Magnetization reversal in FeCo binary alloy nanowire arrays
Authors: Zhao Rong  , Gu Jian-Jun  , Liu Li-Hu  , Xu Qin  , Cai Ning  , Sun Hui-Yuan  ,   College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050016, China;,   Department of Physics, Hebei Normal University for Nationalities, Chengde 067000, China;,   Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050016, China
Published: December 2020

Arrays of FexCo1-x( 0 x 0.51) binary alloy nanowires are fabricated into the (anodic aluminum oxide) AAO template pores by AC electrodeposition. The XRD pattern indicates that the crystallite structure of Co nanowire is hcp with existence of strong (100) orientation along the nanowire axis. While the crystallites structure of FeCo binary alloy nanowires is bcc with existence of strong (110) orientation along the nanowire axes. The peaks shift toward the lower angle when the Fe content of nanowire increases. At room temperature, magnetic measurement results show that FeCo alloy nanowires exhibit excellent magnetic properties. The introduction of Fe improves the magnetic property of Co nanowire compared with that of the Co nanowire. FeCo binary alloy nanowire has a larger coercive force and squareness ratio. The coercivity of the FeCo alloy nanowire is calculated by using a magnetization reversal model based on chains of spheres with coherence rotation mechanism and symmetric fanning mechanism. The magnetization reversal mechanism is supported by chains of spheres with symmetric fanning mechanism.
One-step hydrothermal process for self-assembly of zinc oxide nanorods array on Al-doped ZnO nanoplate surface
Authors: Liu Jia  , Xu Ling-Ling  , Zhang Hai-Lin  , Lü Wei  , Zhu Lin  , Gao Hong  , Zhang Xi-Tian  ,   Department of Physics, School of Physics and Electronic Engineering, Harbin Normal University, Heilongjiang Key Laboratory for Low-Dimensional System and Mesoscopic Physics, Harbin 150025, China
Published: December 2020

Self-assembly ZnO nanorod array on Al-doped ZnO nanoplate surface is directly synthesized via a simple one-step hydrothermal approach, without using any template, surfactant or pretreated substrates. The morphology of the ZnO nanostructure observed by the scanning electron microscopy shows that the thickness and size of ZnO nanoplate are 200 nm and 2 m, respectively. The diameter and the length of ZnO nanorods are respectively 150 nm and 1.5 m. A possible growth mechanism is proposed for the selective growth of ZnO nanorods array on the nanoplate substrate, which contains two stage nucleation-growth processes. Finally, the influence of Al on the photoluminescence of the sample is been discussed.
Effects of shadowing on the scaling behavior of the ballistic deposition model
Authors: Hao Da-Peng  , Tang Gang  , Xia Hui  , Han Kui  , Xun Zhi-Peng  ,   Department of Physics, China University of Mining and Technology, Xuzhou 221116, China
Published: December 2020

In surface roughening of the growth process, the shadowing effect generated by non-normal incidence of particles is a kind of long-range interaction. It is found that the surface morphology and the bulk property in non-normal incidence are nontrivially affected by shadowing effect. In this paper, the effects of the oblique-incidence angle on scaling exponent, skewness and kurtosis in surface statistics and bulk porosity are investigated by simulating the oblique-incidence ballistic deposition model. The results illustrate that there are a non-monotonic relation between scaling exponents and oblique-incidence angle, and the finite size effects of skewness and kurtosis depend on oblique-incidence angle. The simulation results are also analyzed qualitatively in the paper.
Shape memory effect and superelasticity in single crystal Ni54Fe19Ga27
Authors: Liu Zhu-Hong  , Ma Xing-Qiao  ,   Department of Physics, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

Shape memory effect and superelasticity are studied in this paper. At room temperature, perfect strain plateaus of 3.3%, 2% and 3% are obtained in the [001], [110] and [111] directions. The energies required to induce the martensitic transformation in different crystallographic directions are estimated from the stress-strain results. Each of the magnetization curves in the martensitic phase indicates that a magnetic anisotropy energy density Ku = (1/2)MsHa =4.8× 105 erg/cm3, which is far smaller than the mechanical driving force for variants twinning. This interpretes why only a little magnetic field induced strain in NiFeGa alloy has been observed so far.
The entanglement properties in the system of a two three-level atoms trapped in coupled cavities
Authors: Lu Dao-Ming  ,   Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China
Published: December 2020

We study the entanglement dynamics of the system composed of a Λ-type atom and a V-type atom resonantly interacting with two coupled cavities. The evolution of the state vector of the system is given. We investigate the evolutions of atom-atom entanglement, cavity-cavity entanglement, and atom-cavity entanglement by Negativity. The influences of cavity-cavity coupling coefficient on the entanglements are discussed. The results obtained by the numerical method show that the atom-atom entanglement is strengthened and the cavity-cavity entanglement is weakened with the increase of the cavity-cavity coupling coefficient.
Quantum communication based on the circuit coupled by SQUID and mesoscopic LC resonator
Authors: He Rui  ,   College of Material and Chemical Engineering, West Anhui University, Liuan 237012, China
Published: December 2020

The topic about how to realize quantum computation has aroused great interest of many people. The small quantum device including Josephson junction (SQUID, e.g.) is a very promising physical system to realize quantum computation. In this paper, through the discussion about the Cooper-pair number-phase quantization scheme of the circuit system coupled by SQUID and mesoscopic LC resonator, and through the rational modulation of the parameter, we derive the J-C model of this coupled circuit under the condition of two-level approximation. According to on this model, we propose a protocol which can realize the transfer of quantum information. According to this protocol, we can carry out the transfer of the charge qubits between the two SQUIDs by utilizing the mesoscopic LC resonator as the data bus.
The Novel Block Encryption Scheme Based on Hybrid Chaotic Maps for the Wireless Sensor Networks
Authors: Tong Xiao-Jun  , Zuo Ke  , Wang Zhu  ,   School of Computer Science and Technology, Harbin Institute of Technology, Weihai 264209, China
Published: December 2020

Traditional encryption schemes are not suitable for the Wireless sensor networks (WSNS) due to some intrinsic features of nodes in WSNS such as low energy, limited computation ability and storage resources. This paper presented a novel block encryption scheme based on hybrid chaotic maps dynamically and proposed an integer digital random method, and the Feistel network structure, which is a kind of fast, secure, low resource consumption and suitable for WSNS nodes encryption scheme. The experimental tests show the new encryption scheme has follows prefect performance: the large key space, very good diffusion and disrupt performance, strict avalanche effect, excellent statistical balance and fast encryption speed of the new scheme, and the encryption scheme passes the SP800-22 test; meanwhile, the analysis and testing of speed, time and storage space on the simulator platform shows this new encryption scheme is well able to hide the data information the node in WSNS.
A novel chaotic system and its circuit simulation
Authors: Zhou Xiao-Yong  ,   Department of Electric and Information Engineering, Jiangsu Teachers University of Technology, Changzhou 213001, China
Published: December 2020

In this paper, a novel three-dimensional autonomous chaotic system is reported. The dynamic properties of the new system are investigated via Lyapunov dimension, numerical simulation, Poincare diagrams, Lyapunov exponent spectrum and bifurcation diagrams. The different dynamic behaviors of the system are analyzed especially when each system parameter is changed. Finally, the circuit of this new chaotic system is designed and realized by Multisim software. The simulation results confirm that the chaotic system is different from the exisiting chaotic systems and is a novel chaotic system.
Studyof spectra of even-parity highly excited states of Sm atom
Authors: Zhao Yan-Hong  , Dai Chang-Jian  , Ye Shi-Wei  ,   Key Laboratory of Display Materials and Photoelectric Devices, Ministry of Education, Tianjin 300384, China;,   Schoolof Sicence, Tianjin University of Technology, Tianjin 300384, China
Published: December 2020

Spectra of even-parity highly excited states of the Sm atom have been systematically studied with two color three-step excitation and photoionization detection method. With two different excitation paths, the atom is resonantly excited to given bound states where it is detected by photoionization. The wavelength of the first laser is fixed at 627.50 nm or 624.41 nm so that the Sm atom can be excited to the two different intermediate states with the 4f66s6p configuration. Then the wavelength of the second laser is scanned from 440-700 nm to further excite the atom, so that the highly excited states in the 30040-38065 cm-1energy region can be populated. Based on precise calibration of wavelength and the selection rules, the level energies of 136 even-parity states and their relative line intensities are determined with a unique assignment of the J momentum. Except for the level energies of 71 even-parity states are confirmed by the present work, all information mention above has not been reported previously.
Bohm criterion for an electronegative magnetized plasma sheath
Authors: Liu Hui-Ping  , Zou Xiu  , Zou Bin-Yan  , Qiu Ming-Hui  ,   School of Science, Dalian Jiaotong University, Dalian 116028, China
Published: December 2020

The Bohm criterion for an electronegative magnetized plasma sheath is investigated with a fluid model. It is shown that the existence of negative ions has an effect on the Bohm criterion. And the numerical value of the ion Mach number depends on the magnetic field and the incidence status of the ions.
Cluster separation phenomena in liquid Ga-In alloys
Authors: Yang Lei  , Bian Xiu-Fang  , Pan Shao-Peng  , Qin Jing-Yu  ,   The Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of Education, School of Materials Science and Engineering, Shandong University, Jinan 250061, China
Published: December 2020

Different from the previous experimental and simulating methods, ab initio molecular dynamics simulations are performed to investigate the partial structures of liquid Ga, In and Ga-In alloys. In liquid Ga-In alloys, the positions of first peaks in gGaGa(r) and gInIn(r) are close to those of the pure Ga and In, respectively, and the position of first peak in gGaIn(r) is larger than the average value of pure Ga and In, indicating that inhomogeneous atoms are prone to be repulsed and Ga-Ga and In-In clusters are easy to emerge in the system. The most popular 1311 pair bonds existing in liquid pure Ga and In are dominant in liquid alloys, proving that Ga-Ga and In-In clusters coexist in liquid Ga-In alloy. Through the Voronoi analysis, with In increasing, in the Ga100-xInx (30 ≤x≤50 at.%) region, the main coordination number around Ga atoms abruptly decrease from 12 to 10, proving that Ga-Ga and In-In clusters are prone to be separated. These results are different from those obtained from the micro-inhomogeneous model and reveal the mechanism of cluster separation in liquid Ga-In alloy.
Effect of Cr position and metal deposition direction on two-dimensional Ag nanoparticle array structure during nanosphere lithography
Authors: Kong Ling-Qi  , Zhang Chun-Jing  , Huang Sheng-Li  , Zhu Xian-Fang  ,   Department of Biomaterials, College of Material and China-Australia Joint Laboratory for Functional Nanomaterials, Xiamen University, Xiamen 361005, China;,   Department of Physics, Xiamen University and China-Australia Joint Laboratory for Functional Nanomaterials, Xiamen University, Xiamen 361005, China;,   ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia
Published: December 2020

Ag nanoparticles with 2-dimensional (2D) array structure were fabricated via nanosphere lithography. The influence of Cr interlayer position and metal deposition direction on the array structure was systematically studied. It was found that the structure of the 2D Ag nanoparticle array with Cr interlayer was better than that without interlayers. When the Cr interlayer was deposited on the PS mask, the tips of the acquired triangle nanoparticles were much sharper, and the area of the nanoparticle array was much larger than the other cases. Moreover, the achieved nanoparticle array has a better uniformity and compactness in structure, and higher binding ability to the substrate when Cr and Ag deposition direction was perpendicular to the surface of the substrate. Further absorption spectrum experiment proved the improvement of the structure and feature of the 2D Ag nanoparticle array. All these are very crucial for the future modification and fabrication of biochemical sensors with the 2D Ag nanoparticle array.
First principles calculation of electronic structures and optical properties for -CuX(X = Cl, Br, I)
Authors: Deng Jiao-Jiao  , Liu Bo  , Gu Mu  , Liu Xiao-Lin  , Huang Shi-Ming  , Ni Chen  ,   Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Department of Physics, Tongji University, Shanghai 200092, China
Published: December 2020

We use first-principles calculation with pseudo-potential and plane wave method to study the bulk meduli, electronic structures and optical properties of copper halides CuX (X = Cl, Br, I). A comparison of the calculation results with the available experimental results show that it is more suitable using the generalized gradient approximation to study these properties than using the local density approximation. The results show that valence bands of CuXX(X = Cl, Br, I) are dominated by the d bands of Cu. Conduction bands are mainly from s bands of Cu and halide atoms, as well as from p bands of halide atoms. The calculated refractive indices of CuX(X = Cl, Br, I) are 1.887, 2.015, and 2.199, respectively. These results are in good agreement with the those calculated from the Gladstone-Dale relationship.
Temperature-dependent yield asymmetry between tension and compression in metallic glasses
Authors: Chen Yan  , Jiang Min-Qiang  , Dai Lan-Hong  ,   State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

By taking the pressure effect into account in the free volume evolution, the yield asymmetry between tension and compression of metallic glasses under different temperatures is investigated. The yield strength in MGs with a (T/Tg)1/2 temperature dependence is obtained for both tension and compression. The pressure - sensitive factor is derived to be a constant ～ 0.1 within a broad range of temperatures. Furthermore, it is revealed that, the declining effect of pressure on the free volume evolution causes a weaker tension - compression asymmetry with increasing temperature. The significant structural relaxation at high temperature slows down the free volume evolution and hinders the sharp yield. These results improve our understanding of the underlying mechanisms of the yielding and its asymmetry between tension and compression in MGs.
The optical property of tensile-strained n-type doped Ge
Authors: Huang Shi-Hao  , Li Cheng  , Chen Cheng-Zhao  , Zheng Yuan-Yu  , Lai Hong-Kai  , Chen Song-Yan  ,   Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China;,   State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
Published: December 2020

Tensile-strained germanium is one of the promsing materials for Si-based photonic devices due to its quasi-direct band and compatiblility with silicon technology. The band structure of tensile-strained germanium is investigated based on the theory of van de Walle deformed potential. The carrier distributions in the conduction bands at Γ and L vallies under the strain, and the n-type doping concentratoin in germanium are analyzed. Considering the competition between radiative recombinations at Γ and L vallies and Auger recombination, as well as dislocation induced non-radiative recombination, internal quantum efficiency and optical gain for direct band transition in n-type Ge are calculated. It is shown that 74.6% internal quantum efficiency can be obtained in the 1.5% tensile-strained n-type doped Ge under carrier injection and a strong optical gain is predicted, which is comparable to those of III-V materials.
New observations for electron beam-induced instability of single-wall carbon nanotube
Authors: Li Lun-Xiong  , Su Jiang-Bin  , Wu Yan  , Zhu Xian-Fang  , Wang Zhan-Guo  ,   China-Australia Joint Laboratory for Functional Nanomaterials and Physics Department, Xiamen University, Xiamen 361005, China;,   School of Physics and Mathematics, Changzhou University, Changzhou 213164, China;,   Department of Physics, Jimei University, Xiamen 361021, China;,   ARC Centre of Excellence for Functional Nanomaterials, University of Queensland, St Lucia, Brisbane, Qld 4072, Australia;,   Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

The nanoinstability of single-wall carbon nanotubes(SWCNT) under electron beam irradiation is systematically investigated by in-situ transmission electron microscopie observation at room temperature. Under the same irradiation condition, it is found that with the increasre irradiation time(or electron dose), the SWCNT whose two ends are fixed at ropes of nanotubes shrinks in its radial direction with an increasingly faster rate; the curved SWCNT is more instable than the straight one with a the same diameter; the SWCNT with a free capped end but the other end fixed at a rope of nanotubes shrinks in the axial direction but almost keeps its diameter unchanged. All experimental phenomena could be well accounted for by new concepts of vaporing and diffusing of carbon atoms as strongly driven by the nanocurvature of SWCNT as well as by the electron beam-induced athermal activation.
Study on the structure, optical, electrical and magnetic properties of Mn-Na codoping ZnO nonpolar thin films
Authors: Ye Ying-Hui  , Lü Bin  , Zhang Wei-Guang  , Huang Hong-Wen  , Ye Zhi-Zhen  ,   State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
Published: December 2020

Nonpolar Zn(Mn, Na)O thin films with orientation (a-plane) have been successfully grown on r-plane sapphire substrates by pulsed laser deposition (PLD) through a Mn-Na codoping route. The X-ray diffraction(XRD), field-emission on scanning electron micorscope(FE-SEM), Hall-effect and X-ray photoelectron spectroscopy(XPS) measurements show that substrate temperature and work pressure have a significant influence on the nonpolar growth of Zn(Mn,Na)O thin films. The films prepared under a work pressure of 0.02Pa and substrate temperature of 600 ℃ could achieve a high quality crystallite with fine optical and electrical properties through Mn-Na codoping. Moreover, the influence of the growth orientation on room temperature ferromagnetism (RTFM) of the thin films is investigated by superconducting quantum interference device(SQUID), and the possible mechanism involving the origin of RTFM in the Zn(Mn,Na)O films is discussed as well.
Orbital ordering and its origin of KCrF3
Authors: Wang Guang-Tao  , Zhang Min-Ping  , Li Zhen  , Zheng Li-Hua  ,   College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China
Published: December 2020

The electronic, the magnetic and the orbital structures of KCrF3 are studied by first principles in its recently identified crystallographic phases (tetragonal and cubic) [Margadonna and Karotsis 2006 J. Am. Chem. Soc. 128 16436]. In tetragonal phase, both generalized gradient approximation (GGA) and GGA+U calculations show that the ground state is the A-type antiferromagnetic (A-AFM) configuration with G-type orbital ordering pattern. Our calculations show that the orbital structures and the magnetic configurations can be measured by the optical conductivity. In the cubic state, the GGA calculations show that the ground state is ferromagnetic half metal state, while the GGA+U(Ueff = 3.0 eV) calculations show that the A-AFM insulator phase is the ground state. Our calculations indicate that the electron-electron interactions rather than the electron-phonon interactions are the driving forces behind the orbital order.
Growth and characterization of graphene on SiO2/Si substrate
Authors: Kang Chao-Yang  , Tang Jun  , Li Li-Min  , Yan Wen-Sheng  , Xu Peng-Shou  , Wei Shi-Qiang  ,   National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

Graphene thin films are grown on Si substrates covered by SiO2 layers (SiO2/Si) with the method of directly depositing carbon atoms in the molecular beam epitaxy (MBE) equipment. The structural properties of the samples produced at different substrate temperatures (500℃, 600℃, 900℃, 1100℃, 1200℃) are investigated by Raman spectroscopy (Raman) and near-edge x-ray absorption fine structure (NEXAFS). The results indicate that the thin films grown at lower temperatures are amorphous carbon thin films. While the thin films grown above 700℃ exhibi the characteristics of graphene. As the substrate temperature increases, the crystalline quality of graphene is improved. However, very high temperature can reduce the quality of grapheme. The best graphene films are obtained at a substrate temperature of 1100℃. When the substrate temperature is low, the activity of the carbon atoms is not enough to form the ordered six member rings of C-sp2. While the substrate temperature is too high, the decomposition of some SiO2 induces the deposited carbon atoms to bond with decomposed oxygen atoms or silicon atoms, resulting in the defects on the surface, which leads to the poor crystalline quality of graphene films.
Freshwater flux product reconstruction based on Argo data and mixed layer model
Authors: Wang Hui-Zan  , Zhang Ren  ,   PLA Research Center of Ocean Environment Numerical Simulation, PLA University of Science and Technology, Nanjing 211101, China
Published: December 2020

Sea surface freshwater flux(FWF, evaporation minus precipitation) plays an important role in understanding and modeling atmosphere and ocean processes, but there exists strong disagreement different freshwater flux estimates. In this study, a weekly sea surface FWF product is reconstructed for the period from 2002 through 2008 based on the mixed layer salinity balance model for the first time, by combining the Argo data with OSCAR current data. Compared with the other precipitation and evaporation data from satellite product and TAO observations, the reconstructed FWF can capture not only the seasonal cycle of freshwater flux, but also some high-frequency features of freshwater flux. The FWF product provides a useful tool for studying the climate variation over the ocean.
SPIHT-based joint image compression and encryption
Authors: Yang Hua-Qian  , Liao Xiao-Feng  , Kwok-Wo Wong  , Zhang Wei  , Wei Peng-Cheng  ,   College of Computer Science and Engineering, Chongqing University, Chongqing 400044, China;,   Dept of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China;,   Centre of Network Management, Chongqing Education of College, Chongqing 400067, China
Published: December 2020

A joint of image encryption and compression is investigated, and a novel joint encryption and compression scheme is proposed. In our scheme, the encryption process is performed before compression. Making use of the properties of discrete wavelet transform (DWT) and Set Partitioning in Hierarchical Trees (SPIHT) coding, confusion is restricted to the interior of single subband image itself and so image details are retained. Furthermore, diffusion preserves the two most significant bits (MSBs) and the sign bit, which contain important information about the image. The experiments show that the proposed algorithm possesses a good visual quality of the reconstructed image and a high encryption speed.
Prediction of multivariable chaotic time series using optimized extreme learning machine
Authors: Gao Guang-Yong  , Jiang Guo-Ping  ,   Center for Control & Intelligence Technology, Nanjing University of Posts and Telecommunications, Nanjing 210003, China;,   School of Iniformation Science & Technology Jiujiang University, Jiujiang 332005, China
Published: December 2020

A prediction algorithm of multivariable chaotic time series is proposed based on optimized extreme learning machine (ELM). In this algorithm, a presented composite chaos system and mutative scale chaos method are utilized first to search and optimize the parameters of ELM for improving the generalization performance. Then the optimized ELM is used to predict the multivariable chaotic time series of Rossler coupled system for single step and muti-step, and the scheme is compared with the congeneric method, which shows the validity and stronger ability against noise of the developed algorithm. Finally, the relation between prediction result and number of hidden neurons is discussed.
GaP terahertz emitter with micro-pyramid anti-reflection layer
Authors: Liu Feng  , Hu Xiao-Kun  , Li Yan-Feng  , Xing Qi-Rong  , Hu Ming-Lie  , Chai Lu  , Wang Ching-Yue  ,   Ultrafast Laser Laboratory, Center for Terahertz Waves, College of Precision Instrument and Opto-electronics Engineering, Key Laboratory of Opto-Electronics Information Technology (Ministry of Education), Tianjin University, Tianjin 300072, China
Published: December 2020

We present the generation of terahertz pulses from a bulk GaP emitter fabricated with a micro-pyramid anti-reflection output coupling layer. The anti-reflection layer is designed by the graded effective refractive index principle. The micro-pyramid structure is manufactured by micro fabrication technique. The experimental results demonstrate that the micro structure layer can not only increase the output coupling efficiency but also scatter the transmitted pump power.
First principles study on the structure and mechanical properties of hcp-C3 carbon bulk ring
Authors: Li Qing-Kun  , Sun Yi  , Zhou Yu  , Zeng Fan-Lin  ,   Institute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001, China;,   The Department of Astronautics Science and Mechanics, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

For developing novel high strength materials, we study the crystal structures, electronic properties and mechanical properties of hcp-C3 carbon bulk rings based on the first principles method. Electronic structure analysis shows that the viable sp3 hybridization appears in this carbon allotrope. It caused the mechanical properties of the carbon bulk ring to exhibit strong orientation dependence. Along the [0001] orientation, the carbon bulk ring demonstrates an elastic modulus of 1033 GPa, a Tensile strength of 124.17 GPa, and a compressive strength of 381.83 GPa. Furthermore, along the [2110] orientation, the compressive strength reaches 458.34 GPa, which shows the excellent mechanical properties of hcp-C3 carbon bulk rings.