bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of low-temperature annealing phosphorous gettering process on the electrical properties of multi-crystalline silicon with a low minority carrier lifetime
Authors: Jiang Li-Li  , Lu Zhong-Lin  , Zhang Feng-Ming  , Lu Xiong  ,   Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China;,   TianWei New Energy Holdings CO., LTD, Chengdu 610200, China
Published: December 2020

A new low-temperature annealing phosphorous gettering process (LTAPGP) was developed to improve the electrical properties of multi-crystalline silicon which has a low minority carrier lifetime. LTAPGP combined a multi-plateau temperature phosphorous gettering process and a low-temperature annealing process. LTAPGP can remove the iron impurities and crystallographic defects of multi-crystalline silicon, and improve the electrical properties of silicon solar cells that were produced from low minority carrier lifetime silicon wafers. Compared with multi-plateau and two-plateau temperature phosphorous gettering process, LTAPGP was more effective in gettering iron impurities and repairing crystallographic defects. The multi-crystalline silicon wafers with a low minority carrier lifetime went through an LTAPGP process were utilized to produce solar cells. The IV-measurement data prove that the efficiency of the new solar cells is 0.2% higher than that of specimens subject to the multi-plateau and two-plateau temperature processes. The results indicat that LTAPGP can make the low minority carrier lifetime silicon wafers to be used in solar cell industry, improve the utilization ratio and reduce the production cost of cast polysilicon.
A type of the new exact and approximate conserved quantity deduced from Mei symmetry for a weakly nonholonomic system
Authors: Han Yue-Lin  , Wang Xiao-Xiao  , Zhang Mei-Ling  , Jia Li-Qun  ,   School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

A type of structural equation, new exact and approximate conserved quantity which are deduced from Mei symmetry of Lagrange equations for a weakly nonholonomic system, are investigated. First, Lagrange equations of weakly nonholonomic system are established. Next, under the infinitesimal transformations of Lie groups, the definition and the criterion of Mei symmetry for Lagrange equations in weakly nonholonomic systems and its first-degree approximate holonomic system are given. And then, the expressions of new structural equation and new exact and approximate conserved quantities of Mei symmetry for Lagrange equations in weakly nonholonomic systems are obtained. Finelly, an example is given to study the question of the exact and the approximate new conserved quantities.
Numerical simulation of electrode potential influence on the performance of ionization gauge with carbon nanotubes cathode
Authors: Zhang Hu-Zhong  , Li De-Tian  , Dong Chang-Kun  , Cheng Yong-Jun  , Xiao Yu-Hua  ,   Science and Technology on Vacuum & Cryogenics Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou 730000, China;,   Institute of Micro-nano Structures & Optoelectronic Devices, Wenzhou University, Wenzhou 325000, China
Published: December 2020

Theoretical studies of electrodes potential influence on the sensitivity and ratio of anode current and emission current (Igrid/Ie) will be beneficial for providing theoretical basis and experimental instruction in the research of ionization gauge with carbon nanotubes cathode. In this paper, based on the structure of IE514 extractor gauge, the model of carbon nanotube ionization gauge is built by ion optic simulation software SIMION 8.0. And the influence of electrode potential on the sensitivity and Igrid/Ie is discussed. Results show that with increasing ratio between anode voltage and gate voltage (Vgrid/Vgate), Igrid/Ie increases, while the sensitivity of the gauge decreases with the increase in anode voltage, which would further affect the extension of vacuum measurement lower limit. Moreover, the simulation results are in good agreement with the experimental data reported. Consequently, it is very important to improve the sensitivity, anode current and extension of measurement lower limit to set up an appropriate electrode voltage. In addition, the method adopted in this paper can be extended to the research and development of new-styles of extremely high vacuum ionization gauge of carbon nanotube cathode, which could provide an effective method to resolve the problem of extremely high vacuum measurement.
Spectroscopic properties of AlC (X4∑-, B4∑-) molecule
Authors: Liu Hui  , Xing Wei  , Shi De-Heng  , Sun Jin-Feng  , Zhu Zun-Lue  ,   College of Physics & Electronic Engineering, Xinyang Normal University, Xinyang 464000, China;,   College of Physics & Information Engineering Henan Normal University, Xinxiang 453007, China
Published: December 2020

The potential energy curves (PECs) of X4∑- and B4∑- states of the AlC molecule have been studied using highly accurate internally contracted multireference configuration interaction approach with the Davidson modification. The Dunning's correlation-consistent basis sets, aug-cc-pVnZ (n=D,T,Q,5,6) are used for the present study. To improve the quality of PECs, core-valence correlation and scalar relativistic corrections are considered. Core-valence correlation corrections are calculated with an aug-cc- pCVTZ basis set. Scalar relativistic correction calcualtions are made using the third-order Douglas-Kroll Hamiltonian approximation at the level of a cc-pV5Z basis set. Obvious effect on the PECs by the core-valence correlation and relativistic corrections has been observed. All the PECs are extrapolated to the complete basis set limit. The convergence observations of present calculations are made and the convergent behavior is discussed with respect to the basis set. Using these PECs, the spectroscopic parameters (TeReωeωexeωeyeBe and αe) of the X4∑- and B4∑- states are determined and compared with those reported in the literature. The vibration manifolds are evaluated for each state of non-rotation AlC molecule by numerically solving the radial Schrödinger equation of nuclear motion. For each vibrational state, the vibrational level and inertial rotation constants are obtained, which are in excellent accordance with the experimental findings.
Potential energy function and spectroscopic parameters of SN- molecular ion
Authors: Li Song  , Han Li-Bo  , Chen Shan-Jun  , Duan Chuan-Xi  ,   College of Physical Science and Technology, Yangtze University, Jingzhou 434023, China;,   College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China
Published: December 2020

The molecular structure of the ground electronic state (X3∑-) of SN- molecular ion has been calculated by using the CCSD(T) method in combination with the correlation-consistent basis sets aug-cc-pVXZ (X=D,T,Q,5). The equilibrium internuclear distance Re , harmonic frequency ωe and dissociation energy De of the molecular ion are derived and are extrapolated to the complete basis set limit. Comparisons of corresponding parameters between this work and those reported previously indicate our results agree well with the experimental data. A reliable potential energy curve is obtained and is perfectly reproduced in the form of the Murrell-Sorbie analytical potential function. we utilized have the potential energy curve to calculate the relevant spectroscopic parameters of the ground state of the system. The vibrational levels and corresponding molecular constants for the X3∑- state are obtained by solving the radial Schrödinger equation of the nuclear motion. Calculations in the present work indicate that an improvement in theoretical computations of SN- molecular ion is achieved.
Shielding effectiveness of an apertured rectangular cavity against the near-field electromagnetic waves
Authors: Jiao Chong-Qing  , Niu Shuai  ,   State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
Published: December 2020

The shielding effectiveness of an apertured rectangular cavity against the near-field waves of both electric and magnetic dipoles is investigated theoretically by using an extended equivalent circuit method. Both electric and magnetic shielding effectivenesses are calculated as functions of distance between the dipoles and the enclosure. It is shown that the near-field shielding effectiveness is lower than the far-field (plane-wave) shielding effectiveness. Also, in the near-field region, the shielding effectiveness will reduce obviously with the decrease of the source-to-enclosure distance. Based on Bethe's small aperture coupling theory, analytical formulas are presented to describe the quantitative relation between the near-field and the far-field shielding effectivenesses. It is shown that the results from equivalent circuit method are in good agreement with the relation obtained from the Bethe's theory.
Phase sensitive spectral domain optical coherence tomography for latent fingerprint detection
Authors: Bao Wen  , Ding Zhi-Hua  , Wang Chuan  , Mei Sheng-Tao  ,   State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
Published: December 2020

Despite the advances made in areas such as DNA profiling, fingerprints are still considered to be the best form of personal identification for criminal investigation purposes. A variety of physical chemical and optical techniques are available for the enhancement and detection of latent fingerprints. However, existing frequently-used fingerprint detection methods show some disadvantages such as harm to fingerprints, slow extraction, potential side effects, leaving trails, high contrast demand and so on. A new method based on phase sensitive spectral domain optical coherence tomography (SD-OCT) for latent fingerprints detection is proposed. This method has advantages of non-contact non-destructive, high-speed and high-sensitivity. The experimentel results demonstrate that using this method to deal with fingerprints of low contrast also leads to satisfactory results, proving that the sensitivity of SD-OCT can be used for accurate and reliable patent fingerprint recognition.
An ameliorated fast phase retrieval iterative algorithm based on the angular spectrum theory
Authors: Liu Hong-Zhan  , Ji Yue-Feng  ,   State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China;,   Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou 510006, China
Published: December 2020

For designing the light beam shaper in the optical transmitting antenna in inter-satellite optical communication system, the essential problem is, according to the input optical field and ideal output light field, to determine the shaper of phase distribution, in which its core is in phase recovery. Based on the traditional Gerchberg-Saxton (G-S) iterative algorithm, using the angular spectrum propagation theory, a kind of amplitude gradient addition iterative algorithm is proposed, and the detailed algorithm process and analysis are given. Compared with G-S algorithm, the new one using iterative process, constructs the light field amplitude feedback loop, and searches out the optimal iteration path using the gradient; their joint action accelerates the convergence process. Numerical simulation shows that the iterative error-drop speed caused by unit iterations in the new algorithm is 1.7 times that of the G-S algorithm, its convergence rate is obviously superior to the G-S algorithm; for different random initial phase, the new algorithm can effectively carry out iteration, show the advantages of the strong adaptability and the good convergent consistency. Amplitude gradient addition iterative algorithm gives a new effective way of recovering the complex optical field phase, and provides technical support for designing all kinds of diffraction optical element.
Wigner function of N00N state and quantum interference with N00N state as input
Authors: Xu Xue-Xiang  , Zhang Ying-Kong  , Zhang Hao-Liang  , Chen Yuan-Yuan  ,   College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022, China;,   Guangzhou GCI Science & Technology Corporation Limited, Guangzhou 510310, China
Published: December 2020

Using the formula of Wigner function in coherent representation, we have obtained the analytical expression for Wigner function of N00N state. Based on phase space method, we study the quantum interference with N00N state as input. We derive the analytical expression of conditional probability related with the input parameter N and phase parameter φ and analyze it numerically. It is shown that, when φ is 0 or π, the output is just N00N state. It is also shown that, for 2002 state as input, the output must be 2002 state, which is independent of phase parameters. Moreover, as the number of input photon N increases, the phase probability distributions remain to have one, two, three and four peaks and get narrower. All these results can offer theoretical reference for experiments.
Effect of wall friction on subharmonic bifurcations of impact in vertically vibrated granular beds
Authors: Han Hong  , Jiang Ze-Hui  , Li Xiao-Ran  , Lü Jing  ,  Zhang Rui  , Ren Jie-Ji  ,   Department of Physics, Harbin Institute of Technology, Harbin 150001, China
Published: December 2020

Granular materials consist of a large number of discrete solid particles. When subjected to external vibrations, they exhibit various intricate dynamical behaviors, Which usually depend in a complicated way on many physical factors, such as air dragging, friction from the container wall and so forth. In this work, vertical vibrations are applied to a bed of stainless-steel spheres contained in a glass tube, and the subharmonic bifurcations of impact of particles on the container bottom are investigated. To eliminate the effects of air dragging, we evacuate the container or perforate the container bottom to make it quite permeable to the air. Experiments performed in such containers reveal that the impact bifurcations are controlled solely by the normalized vibration acceleration, but independent of the particle size, the filling height of particles, and the frequency of forced vibration. The sliding friction from the container wall is treated as a constant one with the direction opposite to the velocity relative to the container wall. By involving this damping term into the completely inelastic bouncing ball model, an explanation for the experimental results is made. Simulations on the averaged experimental bifurcation points indicate that the magnitude of wall friction is about 10% of the total weight of the particles.
Influence of addifion of electronegative gases on the properties of capacitively coupled Ar plasmas
Authors: Hong Bu-Shuang  , Yuan Tao  , Zou Shuai  , Tang Zhong-Hua  , Xu Dong-Sheng  , Yu Yi-Qing  , Wang Xu-Sheng  , Xin Yu  ,   Provincial Key Laboratory of Thin Films, School of Physical Science and Technology, Soochow University, Suzhou 215006, China;,   Canadian Solar Inc. Suzhou 215011, China
Published: December 2020

Investigation of electronegative plasmas has now been atrractive due to the advantages of negative-ion assisted etching and charge-free ion implantation in semiconductor manufacture. Langmuir electrostatic probe, as a simple, inexpensive and good spatial resolution diagnosic tool, is popularly used in investigating electronegative plasmas. In this paper, the Langmuir electrostatic probe is proposed to measure the capacitively coupled Ar plasmas with added electronegative gases, such as O2, Cl2 and SF6. The experimental results from the measurements of Ar plasmas with added electronegative gases driven by a 40.68 MHz field indicate that, with increasing flow rate of electronegative gas, high energy peak will occur in electron energy possibility function and shift towards higher energyside. The addition of electronegative gases reduces the electron density significantly as the electron temperature increases. We also calculate the electronegativity of Ar plasmas for the three kinds of electronegative gases. The preliminary interpretations of the above experimental phenomena are presented.
Simulation of hollow cathode discharge by combining the fluid model with a transport model for metastable Ar atoms
Authors: He Shou-Jie  , Ha Jing  , Liu Zhi-Qiang  , Ouyang Ji-Ting  , He Feng  ,   College of Physics Science and Technology, Hebei University, Baoding 071002, China;,   Institute of Science, Hebei Agriculture University, Baoding 071001, China;,   School of Science, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

The characteristics of rectangular hollow cathode discharge are studied based on a fluid model combined with a transport model for metastable Ar atoms in argon. The distribution of potential, density of electrons and ions, and the density of metastable atoms are calculated at a pressure of 10 Torr. The peak density of electron and ion is 4.7×1012 cm-3, and the peak density of metastable atoms is 2.1×1013 cm-3. Results obtained in terms of fluid-metastable hybrid model are compared with that in terms of the fluid model, which show that the electron produced by stepwise ionization is one of the important source of new electrons, and the metastable atoms have an obvious effect on the hollow cathode discharge. Compared with the results calculated in terms of fluid model, the density of electrons obtained in terms of hybrid model increases, and the depth of cathode sheath and the averaged electron energy decrease.
Research on SRAM functional failure mode induced by total ionizing dose irradiation
Authors: Zheng Qi-Wen  , Yu Xue-Feng  , Cui Jiang-Wei  , Guo Qi  , Ren Di-Yuan  , Cong Zhong-Chao  ,   Xinjiang Technical Institute of Physics & Chemistry, CAS, Urumuqi 830011, China;,   Xinjiang Key Laboratory of Electric Information Materials and Devices, Urumuqi 830011, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In the present paper, function test of different test pattern was used to investigate function failure of static random access memory (SRAM) induced by the total dose effect. By comparing the function test results of different test pattern and single error bit, it is shown that the failure mode of the device is data retention fault, and different storage cell had diverse data retention time, the fault module of device is the storage cell. We discussed the reason for these phenomena in detail using simple circuit model of storage cell, and also analyzed the influence of these phenomena on test method to evaluate the total dose radiation damage of SRAM.
The first-principles study on properties of B-doped at interstitial site of Cu∑5 grain boundary
Authors: Meng Fan-Shun  , Zhao Xing  , Li Jiu-Hui  ,   School of Science, Liaoning University of Technology, Jinzhou 121001, China
Published: December 2020

The uniaxial tensile and compression tests of the Cu∑ 5 grain boundary (GB) with and without segregated interstitial boron have been performed using first principles method based on density functional theory. Results show that boron enhances the cohesion of Cu∑5 GB and improves the mechanical property of Cu significantly. The clean boundary has lower density of valence electrons than perfect lattices and will be the point for fracture to start under sufficiently high tensile stress. The Cu∑5 GB with segregated boron has strengthened the cohesion across the boundary because of the strong B-Cu bond. Charge accumulated to Cu-B decreases slightly the strength of neighboring Cu-Cu bonds, which will be the weak point for fracture to initiate. The ultimate tensile stress is enlarged by the addition of boron. There is no significant effects occurring within 20% of the compression strain due to B-doping.
A first-principle study on the interfacial properties of Cu/CeO2(110)
Authors: Lu Zhan-Sheng  , Li Sha-Sha  , Chen Chen  , Yang Zong-Xian  ,   College of Physics and Electronic Engineering and Henan Key Laboratory of Photovoltaic Materials, Henan Normal University, Xinxiang 453007, China
Published: December 2020

Cu-CeO2 systems are widely used in solid oxide fuel cells and water gas shift reaction because of its special catalytic ability. The interfacial properties of the Cu/CeO2 (110) with the adsorption of Cu atom and Cu cluster are investigated in terms of first-principles based on density functional theory. It is found that: 1) the single Cu adatom prefers to be adsorbed on the oxygen bridge site; 2) the adsorbed tetrahedron structure of Cu4 cluster is the most stable cluster configuration on CeO2(110) surface; 3) the metal-introduced gap states in the gap area are mainly from the adsorbed Cu (cluster), its neighboring oxygcr and the reduced cerium ion(s), indicating that the activity of CeO2(110) surface is improved by copper adsorption; 4) the adsorbed Cu adatom and Cu4 cluster are oxidized to Cuδ+ and Cu4δ+ by their neighboring Ce ion(s) with the formation of Ce3+ ion(s), the reaction could be summarized as Cux/Ce4+→ Cuxδ+/Ce3+; 5) the adsorption of small clusters introduces more Ce3+ ions than a single Cu atom does, indicating that more Cuδ+-Ce3+ catalytic active centers are formed. The current study on Cu/CeO2(110) together with our previous results on Cu/CeO2(111) presents a good understanding of the synergies between Cu and ceria, and reveals the improvement of the activity of ceria by Cu adsorption.
Low-temperature growth of AlN thin films by plasma-enhanced atomic layer deposition
Authors: Feng Jia-Heng  , Tang Li-Dan  , Liu Bang-Wu  , Xia Yang  , Wang Bing  ,   Liaoning University of Technology , Jinzhou 121001, China;,   Key Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

The crystalline AlN thin film was fabricated on Si(100) substrates by plasma-enhanced atomic layer deposition. Its growth rate was illustrated by spectroscopic ellipsometer. And the surface morphology, crystal structure and composition were characterized by atomic force microscopy, X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Results show that the lowest temperature for deposition of the crystalline AlN thin film is 200 ℃, and the film coverage on the substrate surface is continuous and homogeneous. The film prepared with a homogeneous concentration distribution is polycrystalline with a hexagonal wurtzite structure. High resolution Al2p and N1s spectra confirm the presence of AlN with peaks located at 74.1 eV and 397.0 eV, respectively.
First-principles calculation of preferential site occupation of Dy ions in Nd2Fe14B lattice and its effect on local magnetic moments of Fe ions
Authors: Hao Hong-Fei  , Wang Jing  , Sun Feng  , Zhang Lan-Ting  ,   Hirano Institute for Materials Innovation, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
Published: December 2020

The ground states of lattice properties, formation energy and magnetizations of R2Fe14B (R: rare-earth element) were calculated by the first-principles method based on the generalized gradient approximation (PAW-GGA). GGA+U method was applied to deal with local magnetic moments from 4f shell of rare-earth elements. Magnetic moments were calculated with and without spin-orbital interactions (SOI). Site occupation of Dy ions in Nd2Fe14B lattice is studied by partial substitution of Dy for Nd on different lattice sites. Calculated substitution energy indicates that the Dy2Fe14B is more stable than Nd2Fe14B and the Dy ions prefer to occupy the 4f sites in Nd2Fe14B lattice. It is also found that rare-earth ions occupying the 4f sites will interact more strongly with Fe ions and thus show a greater impact on the local magnetization of Fe. The interaction between rare-earth ions and Fe ions is positively correlated with distance.
Effects of annealing temperature on the microstructure and p-type conduction of B-doped nanocrystalline diamond films
Authors: Gu Shan-Shan  , Hu Xiao-Jun  , Huang Kai  ,   College of Chemical Engineering and Material Science, Zhejiang University of Technology, Hangzhou 310014, China
Published: December 2020

Annealing of different temperatures was performed on boron-doped nanocrystalline diamond (BDND) films synthesized by hot filament chemical vapor deposition (HFCVD). Effects of annealing temperature on the microstructural and electrical properties of BDND films were systematically investigated. The Hall-effect results show that smaller resistivity and Hall mobility values as well as higher carrier concentration exist in the 5000 ppm boron-doped nanocrystalline diamond film (NHB) as compared with those in 500 ppm boron-doped nanocrystalline diamond film (NLB). After 1000 ℃ annealing, the Hall mobility of NLB and NHB samples were 53.3 and 39.3 cm2·V-1·s-1, respectively, indicating that annealing increases the Hall mobility and decreases the resistivity of the films. HRTEM, UV, and visible Raman spectroscopic results show that the content of diamond phase in NLB samples is larger than that in NHB samples because higher B-doping concentration results in a greater lattice distortion. After 1000 ℃ annealing, the amount of nano-diamond phase of NLB and NHB samples both increase, indicating that a part of the amorphous carbon transforms into the diamond phase. This provides an opportunity for boron atoms located at the grain boundaries to diffuse into the nano-diamond grains, which increases the concentration of boron in the nano-diamond grains and improves the conductivity of nanocrystalline diamond grains. It is observed that 1000 ℃ annealing treatment is beneficial for lattice perfection of BDND films and reduction of internal stress caused by doping, so that the electrical properties of BDND films are improved. Visible Raman spectra show that the trans-polyacetylene (TPA) peak (1140 cm-1) disappears after 1000 ℃ annealing, which improves the electrical properties of BDND films. It is suggested that the larger the diamond phase content, the better lattice perfection and the less the TPA amount in the annealed BDND samples that prefer to improve the electrical properties of BDND films.
Phase field crystal simulation of microscopic deformation mechanism of reverse Hall-Petch effect in nanocrystalline materials
Authors: Zhao Yu-Long  , Chen Zheng  , Long Jian  , Yang Tao  ,   State Key Laboratory of Solidification Processing, Northwestern Ploytechnical University, Xi’an 710072, China
Published: December 2020

The nanocrystalline (NC) materials of several average grain sizes ranging from 11.61 to 31.32 nm were obtained by using the phase field crystal model (PFC), and the microscopic deformation mechanism of strengthening law for the uniaxial tensile deformation was discussed. Simulated results show that grain rotation and grain boundary (GB) migration are mainly responsible for the microscopic deformation. Since small grain size is favorable for grain rotation so that it can make the yield strength reduced; and the NC materials would show a reverse Hall-Petch effect. When the grain size is so small and the strain exceeds the yield point to about 4%, dislocation activities begin to occur. Mainly by the change of GB structure (disorganizing triple grain boundary junction and then promoting grain migration), the GB can play a finite contribution to deformation. With increasing grain size, grain rotation becomes difficult, and the grain serration and emission of dislocations are observed.
Electrical, optical properties and structure characterization of In-doped copper nitride thin film
Authors: Du Yun  , Lu Nian-Peng  , Yang Hu  , Ye Man-Ping  , Li Chao-Rong  ,   Information Engineering School, Hangzhou Dianzi University, Hangzhou 310018, China;,   State Key Laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Sciences, Zhejiang Sec-Tech of University, Hangzhou 310018, China;,   College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018, China
Published: December 2020

Thin films of ternary compounds CuxInyN were grown on Si (100) wafers by RF magnetron cosputtering at a low temperature, low power and pure N2 environment. The effect of In incorporation on the structure and physical properties of copper nitride was obvious, which was evaluated by characterizing the film chemical bonding state, structure, electrical and optical properties. In XPS, shift of binding energy, Auger peak and Auger chemical parameters all reflected the chemical changes in the environment. For samples with In content below 8.2 at.%, either the BE increasing of Cu 2p3/2 and In 3d5/2 or the decreasing of N1s could mainly contribute to the Cu-In-N bond formation. For the Cux InyN sample with 4.6% In, indium atoms were consistently confirmed to be incorporated into the body center of Cu3N anti-ReO3 structure as shown by XRD and TEM. The strong (001) preferred orientation of copper nitride crystalline phase was kept predominant in the films until the In content goes up to 10.8 at.%, the texture changed to (111) orientation. The R-T curves of CuxInyN films changed from typical exponential to linear with increasing In. Near constant electrical resistivity in a large temperature range with small TCR of -6/10000 was investigated in the CuxInyN sample with 47.9 at.% In. Moreover, the optical band gap, due to Burstein-Moss effect, was investigated to enhance from 1.02 to 2.51 eV with the In content increasing from 0% to 26.53%, accompanied with band-gap transition from direct to indirect.
A dynamic light scattering study of counter-ions condensation on DNA
Authors: Lin Yu  , Yang Guang-Can  , Wang Yan-Wei  ,   School of Physics and Electronic Information, Wenzhou University, Wenzhou 325035, China
Published: December 2020

The interaction between DNA and counter-ions of different valence, including sodium chloride (Na+), magnesium chloride (Mg2+), hexammine cobalt III ([Co(NH3)6]3+), and spermine ([C10N4H30]4+), is investigated by dynamic light scattering. It is found that the ratio of electrophoretic motilities of DNA in a buffer containing Na+ and Mg2+ is about 2:1, when the concentration of counter-ions c≥ 5 mM. But the ratio of DNA motilities in a buffer containing Na+ and [Co(NH3)6]3+ is about 4.5:1. When c<5 mM, the ratio grows with increasing concentration of counter-ions. DNA charge reversal can be observed in the case of quadrivalent counter-ion. The experimental results are in good agreement with the Manning counter-ions condensation theory for cases of monovalent or bivalent counter-ions. However, when the valency of counter-ions is equal to three, the experimental data deviates from the expectation of the theory significantly. For the quadrivalent counter-ions, the counter-ions condensation theory, which is based on the average field, fails. Furthermore, through the atomic force microscopy, it is found that DNA molecules will condense into compact structures when the valency of counter-ions is equal to or greater than three. Thus, the conformation of polyelectrolyte in free solution and the ion correlation play an important role in the migration process of polyelectrolyte.
Construction and analysis of complex brain functional network under acupoint magnetic stimulation
Authors: Yin Ning  , Xu Gui-Zhi  , Zhou Qian  ,   Province-Ministry Joint Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability, Hebei University of Technology, Tianjin 300130, China
Published: December 2020

Brain is a complex nonlinear dynamic system consisting of related functional regions that can be described by the complex network model. Acupoint magnetic stimulation is an equivalent external stimulus for brain, which can be used as an important technical method to study the regulation mechanism of complex nervous system. It is of great significance to research the effect of acupoint magnetic stimulation on the structure and characteristics of brain functional network. Magnetic stimulation was applied to Neiguan (PC6) and the acquired EEG data were analyzed using dual-channel nonlinear method of mutual information in time domain. The corresponding brain functional networks before, during and after a magnetic stimulation were constructed and the characteristic parameters were studied based on the complex network theory. Results show that the average degree, average clustering coefficient and global efficiency of the brain functional network were increased under magnetic stimulation frequency of 3 Hz, while the average path length was reduced. The small world attribution of the corresponding functional network was enhanced, which made the information transfer among brain regions more efficiently. The brain functional networks under acupoint magnetic stimulation is studied for the first time as far as we know, which provides a new idea and approach to investigate the effect and regulation mechanism of transcutaneous acupoint magnetic stimulation to the complex nervous system.
An analog modulated simulation source for X-ray pulsar-based navigation
Authors: Zhou Feng  , Wu Guang-Min  , Zhao Bao-Sheng  , Sheng Li-Zhi  , Song Juan  , Liu Yong-An  , Yan Qiu-Rong  , Deng Ning-Qin  , Zhao Jian-Jun  ,   Faculty of Science, Kunming University of Science and Technology, Kunming 650093, China;,   State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

In this paper a high resolution X-ray simulation source is proposed and designed to verify the navigation based on X-ray pulsar in the simulation experience system. The simulation source consists of an arbitrary signal generator and a grid controlled X-ray tube. According to the grid tube's characteristic curve, the data of the pulsar standard pulse template are converted. Then using the method of direct digital frequency synthesis, the converted data are synthesized to waveforms, called the analog modulated grid voltage. In the grid controlled X-ray tube, the grid voltage changes the number of electrons hitting on the target and controls the X-ray intensity. With an analog modulated pulse profile applied on the tube grid electrode, the tube will emit X-rays which will match photons' statistical distribution and simulate the X-ray pulsar profile extremely well. The properties of Crab pulsar simulation source are tested in X-ray pulsar navigation simulation experience system. The results of the test are as follows: Comparing the tested pulse profile with the standard pulsar profile, we have time correlation coefficient is 0.9774, and frequency correlation coefficient is 0.9853. The X-ray photon flux is 1.90 ph·cm-2·s-1, the pulsed fraction is 76.15%, and the half-width half maximum is 1.879 ms. These results show that the X-ray simulation source has several merits, such as: strong ability to simulate the X-ray, low cost and simple operation. So it is an important means for the improvement of X-ray pulsar navigation.
Lie-Mei symmetry and conserved quantities of Nielsen equations for a singular nonholonomic system of Chetaev'type
Authors: Xu Chao  , Li Yuan-Cheng  ,   College of Physics, China University of Petroleum (East China), Qingdao 266580, China
Published: December 2020

Using an invariance of differential equations under the infinitesimal transformations of group, we study the Lie-Mei symmetry of Nielsen equations for a singular nonholonomic system of Chetaev'type. We establish the Lie-Mei symmetry equations. The definitions of weak and strong Lie-Mei symmetry are given, and Hojman conserved quantities and Mei conserved quantities are obtained. An example is given to illustrate the application of the results.
Complex bifurcations in a nonlinear system of moving belt
Authors: Li Qun-Hong  , Yan Yu-Long  , Wei Li-Mei  , Qin Zhi-Ying  ,   College of Mathematics and Information Science, Guangxi University, Nanning 530004, China;,   School of Mechanical Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China
Published: December 2020

A kind of one-degree-of-freedom nonlinear moving belt system is considered. The analytical research of sliding region and existence conditions of equilibrium are first derived by the theory of piecewise-smooth dynamical system. Then, using numerical method, one- or two-parameter continuation of several types of periodic orbits of the system is calculated. We obtain codimension-1 sliding bifurcation curves, codimension-2 sliding bifurcation points, and global bifurcation diagram in parameter space for the system. The investigation of bifurcation behavior shows that the speed of moving belt and amplitude of friction have a great influence on dynamic behavior, and reveals the complex nonlinear dynamic phenomenon of the moving belt system.
Optimization of slow-wave structure in high power 0.34 THz radiation source
Authors: Li Shuang  , Wang Jian-Guo  , Tong Chang-Jiang  , Wang Guang-Qiang  , Lu Xi-Cheng  , Wang Xue-Feng  ,   Northwest Institute of Nuclear Technology, Xi’an 710024, China;,   School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Based on surface-wave oscillator (SWO), the high power 0.34 THz source using over-moded structure is studied. The attention is paid to the influence of the parameters of the slow-wave structure (SWS) on the dispersion curve, and then the SWS is optimized. According to the simulation results, the size of SWS and the requirements for the accuracy in the SWS machining are confirmed. Finally, the source is simulated by the particle-in-cell method. Numerical results show that the structure is capable of radiating a terahertz signal with a frequency of 0.34 THz and a maximum output power of about 7.8 MW. Moreover, the structure works in the state of an SWO stably. The research of the SWS is the foundation of the design of 0.34 THz source, and it is also very meaningful for the realization of the source in engineering.
Study of coded source neutron imaging based on a compact accelerator
Authors: Wang Sheng  , Zou Yu-Bin  , Wen Wei-Wei  , Li Hang  , Liu Shu-Quan  , Wang Hu  , Lu Yuan-Rong  , Tang Guo-You  , Guo Zhi-Yu  ,   State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China
Published: December 2020

Compact accelerator based neutron source has lower cost and better flexibility than nuclear reactor. Neutron imaging using such a neutron source has attracted more and more attention in recent years, in spite of its relatively low neutron fluence. In order to keep a definite neutron flux above a reasonable level on a compact accelerator based neutron imaging system, one could not set the collimation ratio to be as high as the reactor neutron source to obtain a high resolution. Coded source could increase the collimation ratio without reducing the neutron flux much. It may benefit neutron imaging system in the case of low yield neutron source. Since 2005, several laboratories in Germany and USA have carried out simulation and experiments of coded source neutron imaging. Those experiments are based on the reactor neutron sources, which have high neutron yield and low scattered neutron background. Recently, a preliminary coded source neutron imaging experiment was carried out on PKUNIFTY (Peking University Neutron Imaging Facility), which is based on a 2 MeV deuteron RFQ accelerator. It is the first time that coded source neutron imaging has been applied to an accelerator-based neutron source. Projections of coded neutron source are taken with a neutron yield of 2.6×1011 s-1. With Wiener filter deconvolution and Lucy-Richardson maximum likelihood iteration algorithm, the experimental projections are reconstructed successfully. Because the accumulated neutron fluence is low and the neutron background is high, the signal-to-noise ratio of reconstructed images is not good enough, which will be improved by reducing the neutron background.
Study of carbon atomic wire C5 in the laser field by time-dependent density functional theory
Authors: Wang Zhi-Ping  , Chen Jian  , Wu Shou-Yu  , Wu Ya-Min  ,   School of Science, Jiangnan University, Wuxi 214122, China
Published: December 2020

Combining the time-dependent density functional theory with molecular dynamics of ions the excitation of the carbon wire C5 is explored. It is found that the stronger the laser intensity, the more energies are absorbed by C5 and the earlier the ionization takes place and the more electrons are emitted when considering the effect of the laser intensity on the excitation of the carbon wire C5. The study of the influence of the polarization of the laser pulse on the excitation of C5 indicates that the ionization is enhanced and the dipole moment along the laser polarization is strengthened when the laser polarization is along the molecular axis, and the x-direction polarized laser pulse can only excite the dipole oscillation along the x axis, and the y-direction polarized one can only excite Dy. Furthermore, it is found that the synchronicity of the vibration of carbon bonds changes a little due to the enhanced ionization when the laser polarization is along the molecular axis, while the vibration modes of ionized carbon wire C5 are the same as those of the neutral carbon wire C5.
Photonic bandgap properties of one-dimensional superconducting photonic crystals containing metamaterials
Authors: Wu Ji-Jiang  , Gao Jin-Xia  ,   College of Science, Shandong University of Technology, Zibo 255049, China
Published: December 2020

Bandgap properties of one-dimensional superconducting photonic crystals containing metamaterials are investigated by the transfer matrix method. It is shown that the low-frequency band gap can also be present in this superconducting photonic crystal similar to the usual superconducting photonic crystal containing dielectric materials. The low-frequency band gap can be widened considerably when the suitable structure parameters are chosen. However, in certain structural parameters, the low-frequency band gap can not be found in this superconducting photonic crystal just as in one-dimensional dielectric-dielectric photonic crystal. The polarization properties and the influences of the operating temperature and the structure parameters of superconducting photonic crystals on the photonic band gap are also investigated in this paper.
Theoretical and experimental research on district cooling for thin disk-type laser medium
Authors: Mu Jian  , Feng Guo-Ying  , Yang Huo-Mu  , Tang Chun  , Zhou Shou-Huan  ,   College of Electronic Information, Sichuan University, Chengdu 610064, China;,   Institute of Applied Electronics of China Academy of Engineering Physics, Mianyang 621900, China;,   North China Research Institute of Electro-Optics, Beijing 100015, China
Published: December 2020

For the non-uniform pumping and cooling to the thin disk-type laser medium, the district cooling method for thin disk-type laser medium is proposed and examined both experimentally and theoretically. Based on heat conduction equation, the distributions of temperature and stress in end pumping thin disk-type laser medium with evenly cooling and district cooling are calculated. The results show that the tensile stresses on the edge of gain medium with evenly cooling are changed into the low values of compressive stresses for the case of district cooling, and the distribution of temperature in medium with district cooling is much more uniform than with evenly cooling, the ranges of temperature reduces about 86%, and this result is consistent well with the experimental result. The district cooling method could provide a new way of thermal management for thin disk-type laser.
Stimulated Raman spectrum and optical pumping in a Λ-type Rb vapor system
Authors: Pei Li-Ya  , Wang Ru-Quan  , Zuo Zhan-Chun  , Wu Ling-An  , Fu Pan-Ming  ,   Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Theoretical and experimental studies of stimulated Raman spectrum with the D1 line of an 85Rb atomic vapor system are performed. In this Λ-type system, we discover that the influence of the pump on the probe field includes two parts: stimulated Raman excitation and optical pumping. Depending on the pump frequency detuning and field intensity conditions, the Raman spectrum can display either gain or loss. When the optically pumped absorption spectrum is taken as background, either a narrow transparent window or an absorption doublet with widely different linewidths appears. Our theoretical analysis agrees well with our experimental observations. Based on these studies, we present an interpretation from a new viewpoint of the physics of electromagnetically induced transparency (with on-resonance pumping) and Autler-Townes splitting (with far off-resonance pumping) in a Λ-type level atomic system, giving the relationship between these two important phenomena and the Raman spectrum.
Dissipative particle dynamics simulation of macromolecular solutions under Poiseuille flow in microchannels
Authors: Xu Shao-Feng  , Wang Jiu-Gen  ,   Department of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China
Published: December 2020

macromolecular solutions under Poiseuille flow in microchannels are investigated using the dissipative particle dynamics (DPD) approach. The results show that the macromolecular solutions are non-Newtonian fluids which can be described by power-law fluids, and the power-law index decreases with the increase of the macromolecular concentration. The DPD simulations show that the hydrodynamic interaction between the macromolecular chains and the wall, and the gradient of Brownian diffusivity of the chains govern the cross-stream migration of the macromolecules. However, the chain-wall hydrodynamic interaction may not be fully developed and are partly screened in conventional DPD approach. Hence, the chains migrate toward the wall during flow. Simulation results also indicate that the migration toward the wall increases with the increase of the driving force. The competition between the unscreened chain-wall hydrodynamic interaction and Brownian diffusivity leads to two symmetric off-center peaks and a local minimum in the channel centerline in the chain center-of-mass distribution. Under strong confinement, the chain-wall hydrodynamic interaction may be fully screened and the Brownian motion is weak, thus the chains weakly move toward the wall for channel of small width.
Generation of attosecond X-ray pulse of wavelength below 0.4 nm from the interaction of ultra-relativistic intense lasers with thin foil targets
Authors: Bai Yi-Ling  , Zhang Qiu-Ju  , Tian Mi  , Cui Chun-Hong  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

By one-dimensional particle-in-cell simulations, the relativistic electron sheets generated by interaction between the ultra-relativistic intense laser pulse with intensity above 1022 W/cm2 and the thin foil target, as well as the attosecond X-ray pulses induced by Thomson backscattering from electron bunch are studied in this paper. The results indicate that increasing the intensity of the driving laser, reducing the density and thickness of foil target corresponding make the longitudinal momentum of the electrons enhanced and the wavelength of X-ray radiation reduced. Attosecond X-ray pulse with wavelength 1.168 nm can be obtained through optimizing correlated parameters. Especially, using probing laser pulse with doubling frequency and optimizing parameters of the drive light and thin film target can make the wavelength of coherent attosecond X-ray radiation reduced obviously, even below 0.4 nm, and the energy of the scattered photons can achieve more than 2 keV.