bluuebunny/crossref_metadata_2025 huggingface dataset:
An atomistic simulation on melting and breaking relaxation characteristics of Ag nanorods at high temperature
Authors: Lu Min  , Xu Wei-Bing  , Liu Wei-Qing  , Hou Chun-Ju  , Liu Zhi-Yong  ,   Faculty of Science, Jiangxi University of Science and Technology, Ganzhou 341000, China
Published: December 2020

Based on the molecular dynamics simulation method, the evolution of Ag nanorods structure during the Ag nanorods relaxation process at various temperatures and lengths are intensively studied. The results show that there is a critical breaking temperature, which is decreasing with the increasing Ag naorods length. The Ag nanorod is melted to a highly disordered spherical cluster when the temperature is between the melting point and the critical breaking temperature. However, the Ag nanorod is melted to two spherical clusters when the temperature is above the critical breaking temperature.The physical mechanics of the structure evolution processe at various temperatures are presented.
Investigation of the lateral spread of Er ions implanted in 6H-SiC
Authors: Qin Xi-Feng  , Wang Feng-Xiang  , Liang Yi  , Fu Gang  , Zhao You-Mei  ,   College of Science, Shandong Jianzhu University, Jinan 250101,China
Published: December 2020

It is very important to consider the distribution of range, range straggling and lateral spread of ions implanted into semiconductor materials in design and fabrication of semiconductor integration devices by ion implantation. Er ions with energy of 400 keV were implanted in 6H-SiC crystal samples under the angles of 0°, 45° and 60°, respectively. The lateral spread of Er ions with dose of 5×1015 cm-2 at energy of 400 keV implanted in 6H-SiC crystal were measured by Rutherford backscattering technique. The measured lateral spread is compared with TRIM98 and SRIM2006 codes prediction. It is seen that the experimental lateral spread well justifies the theoretical values. The value from TRIM98 agrees somewhat better to the experimental data than the value obtained based on SRIM2006.
Laser-induced voltage effect in Pb(Zr0.3Ti0.7)O3 ferroelectric thin film
Authors: Xie Kang  , Zhang Peng-Xiang  , Hu Jun-Tao  , Zhang Hui  , Zhu Jie  ,   Institute of Advanced Materials for Photoelectronics, Kunming University of Science and Technology, Kunming 650051,China;,   Institute of Advanced Materials for Photoelectronics, Kunming University of Science and Technology, Kunming 650051,China;Key Lab of Broadband Optical Fiber Transmission of Communication Networks,  University of Electronic Science and Technology of China,;,   Key Lab of Broadband Optical Fiber Transmission of Communication Networks, University of Electronic Science and Technology of China, Chengdu 610054,China
Published: December 2020

Pb(Zr0.3Ti0.7)O3(PZT)thin films have been grown by pulsed laser deposition (PLD) on LaSrAlTaO3 (LSATO),LaAlO3(LAO) and SrTiO3(STO) single crystal vicinal cut substrates. Laser-induced voltage(LIV) effect was also found in PZT thin films grown on the three vicinal cut substrates for the first time. LIV signals increased with the single-pulse laser energy following the linear relation in case of c-axis orientation of thin film; but this linear relation was not followed obviously in case of a-axis orientation of thin film. This result shows that the LIV effect in PZT thin film is the atomic layer thermopile effect, in the which anisotropy of Seebeck coefficient plays an important role. Through realizing impedance-matching of thin films and transmission line, LITV signal response time has been optimized, the time of rising edge dropped from 60 ns to 26 ns, the full width at half maximum dropped from 260 ns to 38 ns.
Investigation of dynamics of magneto-optical trap loading by light-induced atom desorption
Authors: Zhang Peng-Fei  , Li Gang  , Zhang Yu-Chi  , Yang Rong-Can  , Guo Yan-Qiang  , Wang Jun-Min  , Zhang Tian-Cai  ,   State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-electronics, Shanxi University, Taiyuan 030006, China
Published: December 2020

The dynamics of magneto-optical trap loading by light-induced atom desorption (LIAD) are investigated theoretically and experimentally. The loading of the MOT has been described by a theoretical model. We have paid close attention to the background gases which are essentially important for the ultimate vacuum pressure. The experiment is done based on a glass cell and all the results are well in agreement with the theory. The decay process of the background vacuum pressure caused by the untrapped cesium atoms after shutting off the desorption light is explained quantitatively. The LIAD effect is proved to be an effective tool to control the loading of the MOT and the neutral single atoms in experiment.
First-principles studies of helical-spin order in frustrated triangular antiferromagnet AgCrO2
Authors: Han Jiu-Rong  , Jiang Xue-Fan  , Liu Xian-Feng  ,   (1)College of Physics Science and Technology, Yangzhou University, Yangzhou 225002, China; (2)Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu 215500, China
Published: December 2020

Based on the collinear and non-collinear magnetic structures, the ground state, magnetism and electronic structure of the frustrated triangular antiferromagnet AgCrO2 have been investigated using the density functional theory (DFT) within the generalized gradient approximation (GGA) with the projected augmented wave (PAW) method. Detailed magnetic structure has been elucidated vividly from the theoretical view. The calculations show that AgCrO2 magnetic ground state has 120° helical-spin order with its spiral plane parallel to the (110)or (11-0) plane. Due to the strong intra- and interlayer geometric spin frustration, parallel helical-spin chains arise along the a,b or a+b direction with the screw-rotation angle 120°. From the non-collinear electronic structure calculation, it is found that due to the spin frustration Cr-3d orbital states near the Fermi level become more localized, indicating an enhanced interaction between Cr-Cr. Nevertheless, the spin-orbit coupling has weak influence on the electron structure.
Magnetic phase transition and electrical transport properties of the Sr-doped Eu1-xSrxMnO3 system
Authors: Zhang Jia-Jia  , Cao Shi-Xun  , Yuan Shu-Juan  , Li Zhe  , Kang Bao-Juan  , Zhang Jin-Cang  ,   Department of Physics, Shanghai University, Shanghai 200444, China
Published: December 2020

The structure and magnetic properties of the Eu1-xSrxMnO3 (ESMO x=0—1) system have been systematically studied. The results indicate that the substitution of Sr for Eu can greatly change the magnetic properties of antiferromagnetic EuMnO3 matrix. In the case of high doping compounds (Eu0.4Sr0.6MnO3 and Eu0.3Sr0.7MnO3), the abnormal magnetic and electrical properties result from the competition between their being ferromagnetic and antiferromagnetic. At low temperature, the conducting behavior of the Eu0.4Sr0.6MnO3 and Eu0.3Sr0.7MnO3 are well fitted by the Mott variable range hopping (VRH) model.
The factors influencing spin-polarized transport in magnetic pn junction
Authors: He Zhi-Gang  , Cheng Xing-Hua  , Gong Min  , Cai Juan-Lu  , Shi Rui-Ying  ,   (1)Department of Microelectronics, Sichuan University, Chengdu 610064, China; (2)Department of Microelectronics, Sichuan University, Chengdu 610064, China;Key Laboratory of Microelectronics Technology of Sichuan Province, Chengdu 610064, China
Published: December 2020

Spin-polarized transport in magnetic pn junction has been theoretically studied by using the drift-diffusive theory. The factors considered include bias voltage, equilibrium spin polarization,spin injection and spin life time, which could effectively affect the current density and resistance. The connection between spin-voltaic effect of the magnetic pn junction and thickness of the junction was also discussed. It is found that the equilibrium spin polarization makes the spin electrons with different orientations (up or down) have different barriers, which makes the current effectively modulated. However, the spin injection modulates the current by providing non-equilibrium spin electrons in the magnetic pn junction. It is also found that the spin-voltaic current is sensitive to quasi-neutral p-type region width.
Study on the exciton dissociation at the NPB-Alq3 interface
Authors: You Yin-Tao  , Wang Ai-Fen  , Sun Xiao-Yu  , Li Wen-Bin  , Zheng Xiao-Yan  ,   (1)School of science , Hangzhou Dianzi University, Hangzhou 310012, China; (2)Surface Physics Laboratory , National Key Laboratory, Fudan University, Shanghai 200433, China
Published: December 2020

Exciton dissociation process and its mechanism at the NPB-Alq3 interface are studied by means of transient photovoltage techniques. For bilayer structured samples made from NPB and Alq3, the transient photovoltage upon 355 nm pulsed laser irradiation was measured. By analysis of the transient photovoltage of samples with different structures or with interface exciton blocking layer that climinates the effect of exciton dissociation at the external interface, it is concluded that the mechanism of exciton dissociation at the NPB-Alq3interface results in holes injected into NPB and electrons injected into Alq3.
Raman spectral analysis of TiO2 thin films doped with rare-earth yttrium and lanthanum
Authors: Yang Chang-Hu  , Ma Zhong-Quan  , Xu Fei  , Zhao Lei  , Li Feng  , He Bo  ,   (1)SHU-SOEN's R&D Lab, Department of Physics, Shanghai University, Shanghai 200444, China; (2)SHU-SOEN's R&D Lab, Department of Physics, Shanghai University, Shanghai 200444, China;School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410004, China
Published: December 2020

TiO2 thin films doped with rare-earth yttrium and lanthanum were prepared on quartz plate by sol-gel/spin-coating technique. The samples were annealed at 700 to 1100 ℃ and the Raman spectra of the samples were obtained. Analysis of Raman spectra shows that with increasing annealing temperature, the anatase form of undoped TiO2 thin film transforms eventually into the rutile phase with mixed anatase/ rutil phase as an intermediate. Yttrium doping and lanthanum doping of TiO2 thin films can inhibit the phase transformation, and the latter effect is stronger. Rare-earth doping refines grain size of TiO2 thin films and increases the internal stress, thereby preventing lattice vibration. The effect of La doping is stronger than yttrium doping. The samples show significant phonon confinement effect. That is to say, the characteristic Raman peaks blue shift and the full widths at half height increase and the peak shap easymmetricaly stretches with decrease of grain size.
Charge order and phase separation in Bi0.5Ca0.5Mn1-xCoxO3 system
Authors: Wang Qiang  ,   Department of Mathematical and Physical Engineering, Shaanxi Institute of Education, Xi'an 710061, China
Published: December 2020

Polycrystalline Bi0.5Ca0.5Mn1-xCoxO3(0≤ x≤0.12) samples are synthesized by using the solid-state reaction. The effects of Co-doping on charge order of Bi0.5Ca0.5MnO3 are studied. The results show that Co doping leads to the melting of the charge order and the enhancement of the ferromagnetic correlation. For x≥0.08, the charge order transition is completely suppressed; however, there are still remaining antiferromagnetic domains inside the system. The phase separation or the coexistence of the charge order and ferromagnetic phase induced by Co-doping plays an important role in the low temperature properties for the system. Moreover, unlike in the case of rare-earth manganites, Co is more efficient to suppress charge order of Bi0.5Ca0.5MnO3 than Cr.
Magnetoresistance effect in an organic spin valve
Authors: Ren Jun-Feng  , Wang Yu-Mei  , Yuan Xiao-Bo  , Hu Gui-Chao  ,   College of Physics and Electronics, Shandong Normal University, Jinan 250014, China
Published: December 2020

Based on the spin diffusion theory and the Ohm’s law, we theoretically studied the magnetoresistance (MR) effect in an organic spin valve with structure of ferromagnetic/organic semiconductor/ferromagnetic system, which takes into account the special characteristics of organic semiconductors. Self-trapped states, such as spin polarons as well as spinless bipolarons are assumed to be the main carriers in organic semiconductors. From the calculation, it is found that MR ratio increases with the increasing of the polaron proportion and rapidly decreases with the increasing of the organic layer thickness. MR ratio can be enhanced remarkably when the interfacial resistances are spin related. Effects of the conductivity match and the spin polarization of the ferromagnetic layer on the MR are also discussed.
Glassy magnetic behaviors in oxygen-deficient Sr2CoO4-δ films
Authors: Chu Hai-Feng  , Li Jie  , Li Shao  , Li Song-Lin  , Wang Jia  , Gao Yan-Li  , Deng Hui  , Wang Ning  , Zhang Yu  , Wu Yu-Lin  , Zheng Dong-Ning  ,   National Laboratory for Superconductivity, Institute of Physics and National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

We have fabricated c-axis-oriented Sr2CoO4-δ thin films under relatively low oxygen pressure by the pulsed laser deposition method (PLD) on LaAlO3 substrates. X-ray diffraction and high-pressure reflection high energy electron diffraction (RHEED) demonstrate that the films were well deposited. There exist two different characteristic temperatures, Tf and Ta, in the ZFC curve of temperature dependence of magnetization. Tf may correspond to the freezing temperature while Ta may be related with the anisotropic field of c-axis. Further investigations including magnetic relaxation, memory effect and hysteresis behaviour measurements suggest a main phase of spin glass, which starts the frozen-in process even above the freezing temperature. We ascribe the spin glass behaviour to the competition betwcen double-exchange and super-exchange interactions which could have originated from the coexistence of Co4+ and Co3+ caused by oxygen deficiency in the films.
Luminescence characteristics of Sr2B5O9Cl: Eu2+ phosphors for white LED
Authors: Ding Xu  , Xu Yan  , Guo Chong-Feng  ,   Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

A series of blue-emitting phosphors M2B5O9Cl: Eu2+(M=Ca, Sr) were synthesized by solid-state methods. And the phosphors were characterized by XRD and photoluminescence emission (PL) and excitation (PLE) spectra. The factors that affect the PL intensity of phosphor Sr2B5O9Cl have been investigated, and the optimal conditions to obtain the blue emitting phosphor are 8 mol% Eu2+concentration, 5.0mol % excess of SrCl2. As Ca partially or completely substituted Sr in the host Sr2B5O9Cl, the emission peak shifts from 425 to 453 nm. The most important is that the phosphors M2B5O9Cl: Eu2+(M=Ca, Sr) show strong absorption in the region of 350—400 nm, which matches well with the emission of the near-ultraviolet or purple LED chips. Comparison with the commercial blue-emitting phosphor, the PL intensity of phosphor Sr1.92Eu0.08B5O9Cl is about 1.8 times that of the commercial blue emitting phosphor BAM. Thus, the phosphors M2B5O9Cl: Eu2+ (M=Ca, Sr) show great potential as the candidate for blue phosphor in n-UV or purple based white LEDs.
The solutions for disturbed El Ni o/La Ni a-southern oscillation model
Authors: Lin Yi-Hua  , Xie Feng  , Mo Jia-Qi  , Lin Wan-Tao  ,   (1)College of Science, Donghua University, Shanghai 201620, China; Division of Computational Science, E-Institutes of Shanghai Universities, at SJTU, Shanghai 200240, China; (2)Division of Computational Science, E-Institutes of Shanghai Universities, at SJTU, Shanghai 200240, China; Anhui Normal University, Wuhu 241003, China; (3)LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

The EI Ni o/La Ni a and the Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific Ocean-atmosphere interactions. This paper, aims at creating an approximate solving method of nonlinear equation for the ENSO models. And based on a class of oscillator of ENSO models, employing the method of homotopic mapping, the approximate and exact solutions of the corresponding problem is studied. The accuracy of approximate solution is discussed. It is proved from the results that homotopic method can be used for analyzing the SST anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere-ocean oscillation for ENSO model.
One Gbit/s random bit generation based on chaotic laser
Authors: Chen Sha-Sha  , Zhang Jian-Zhong  , Yang Ling-Zhen  , Liang Jun-Sheng  , Wang Yun-Cai  ,   Department of Physics, College of Science, Taiyuan University of Technology, Taiyuan 030024, China
Published: December 2020

In this paper, chaotic light generated by optical feedback semiconductor laser is employed as entropy source. The output waveform of chaotic laser is converted into a binary bit stream by an 8-bit ADC. The generated binary sequences are optimized to equalize the ratio of 1 and 0 by the difference between consecutive sampled 8-bit values. Finally a random bit sequence at rates of up to 1 Gbit/s is realized, and the randomness of long bit strings is verified by the NIST Special Publication 800-22 tests.
Hopf bifurcation in a kind of stochastic van der Pol system
Authors: Ma Shao-Juan  ,   School of Information & Computation Science, North University for Nationalities, Yinchuan 750021 China
Published: December 2020

The Hopf bifurcation of van der Pol system with random parameter is studied. Firstly according to the orthogonal polynomial approximation in Hilbert space, the van der Pol system with random parameter can be reduced into the equivalent deterministic system. Then the Hopf bifurcation can be explored by the traditional methods in deterministic bifurcation theory. After the critical point of Hopf bifurcation in stochastic van der Pol system is obtained, the influence of the random parameter on Hopf bifurcation in stochastic van der Pol system is analyzed. At last we verified these results by numerical simulations.
Research on the variable universe fuzzy algorithm of chaotic systems
Authors: Zhang Wei-Wei  , Wang Jing  , Wang Hui  , Zhao Yun-Tao  ,   National Engineer Research Center of Advanced Rolling, University of Science and Technology Beijing, Beijing 100083, China
Published: December 2020

Chaos and chaos control received extensive attention. The fuzzy controller is used to control chaotic systems in this paper. The accuracy of fuzzy controller is not high and there is contradiction between the number of control rules and accuracy. Accordingly a variable universe fuzzy controller based on ant colony optimization algorithm is proposed. By analyzing the two kinds of contraction-expansion factors, one of them was found unable to satisfy the general contraction-expansion factor condition. A method for optimizing the contraction-expansion factors intelligently via ant colony optimization algorithm is proposed. A variable universe fuzzy controller based on ant colony optimization algorithm is constituted and used to control the Duffing chaotic system. Simulation results show that the control method is superior to the others both in convergence speed and steady-state performance.
An example of realizing "order+order=chaos" via synchronization
Authors: Zhang Rong  , Xu Zhen-Yuan  , Yang Yong-Qing  ,   School of Science,Jiangnan University,Wuxi 214122, China
Published: December 2020

It was investigated whether the phenomenon of "order+order=chaos" exists for chaotic continuous systems. It was shown that the bidirectional coupling of two ordered continuous dynamics can originate a chaotic dynamics via synchronization. We provide an explicit example of "order+order=chaos" by taking the Lorenz and Rssler systems in their periodic dynamics.
Electrorotation manipulation of microparticles induced by torque and electroosmotic slip in microsystem
Authors: Jiang Hong-Yuan  , Ren Yu-Kun  , Tao Ye  ,   (1)School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China; (2)School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China;State Key Laboratory of Eluid Pwer Transimission and Control, Zhejiang University, Hangzhou 310027, China
Published: December 2020

Electrorotation is an effective technique to characterize the electrical properties of dispersed particles. For the low Reynolds number microsystem, the mechanism of the electrorotation of microparticles induced by torque was analyzed based on the Maxwell-Wagner polarization. Characteristic frequency corresponding to the peak value of the electrorotation speed was deduced and the effect of the relaxation time on the particles' electrorotation direction was analyzed by the simulation of the electrorotation speed induced by the torque. The mechanism of the electrorotation of the microparticles induced by electroosmotic slip was qualitative analyzed based on the double layer and the idea about the gold surface being favorable to the electrorotation was proposed. Experiments on the electrorotation of the polystyrene with the carboxy surface and gold modified surface were performed, respectively. The results show that, the direction of the electrorotation of polystyrene spheres with carboxy surface is opposite to the electric field and, the corresponding frequency is higher with the torque playing the leading role. On the other hand, direction of the rotation of polystyrene spheres with the gold surface is homodromous with the electric field and the corresponding frequency is lower with the electroosmotic slip playing the leading rose.
Study on the structure of water chain encapsulated in carbon nanotube by density functional theory
Authors: Fan Bing-Bing  , Wang Li-Na  , Wen He-Jing  , Guan Li  , Wang Hai-Long  , Zhang Rui  ,   (1)Zhengzhou University, School of Material Science and Engineering, Zhengzhou 450001, China; (2)Zhengzhou University, School of Material Science and Engineering, Zhengzhou 450001, China;Zhengzhou Institute of Aeronautical Industry Management, Zhengzhou 450015, China
Published: December 2020

The structure of water molecules encapsulated in single-walled carbon nanotubes (SWCNTs) was studied using a self-consistent charge density functional tight binding method with dispersion correction. The most interesting and important feature observed is the diameter shrinkage of SWCNTs when water chains are confined inside them. The diameter shrinking of SWCNTs may be due to the van der Waals and H-π interaction between water chains and SWCNTs. The binding energy decreases with the increase of the nanotube radius. But when the radius is increased to 6.78 ?, the binding energy is a little increased, and the water chain has changed as a "book-like" structure, which suggests that the weak hydrogen bonding in the isolated water chains is larger than the interaction between water chains and the SWCNTs.
Influence of nucleon motion on the effective mass and energy of kaon in dense nuclear matter
Authors: Zheng Yu-Ming  , Wang Yan-Yan  , Zhu Yu-Lan  , Xing Yong-Zhong  ,   (1)College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China; (2)Department of Physics, Tianshui Normal University, Tianshui 741000, China;China Institute of Atomic Energy,  Beijing 102413,China; (3)Department of Physics, Tianshui Normal University, Tianshui 741000, China;College of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

In the present paper, the effective mass and energy of kaon in dense and hot nuclear matter is studied. Our special attention is paid to the comparison of various definitions of quasi-particle model of kaons used in transport theories. The effective mass of kaon defined in popular mean field theory increases with increasing of the density of nuclear matter, while the quantity used in covariant kaon dynamics decreases with the density increasing. The properties of mean field acting on kaon by hot and dense nuclear matter depends not only on the form of quasiparticle model of kaons, but on the motion of nucleons around it.
Superfluidity and quantum localization of para-H2 clusters and ortho-D2 clusters
Authors: Cheng Xin-Lu  , Zhang Hong  , Feng Cheng-Yi  ,   (1)Institute of Atomic and Molecular Physics,Sichuan Univercity,Chengdu 610065,China; (2)School of Physics Science and Tecnology, Sichuan Univercity,Chengdu 610065,China
Published: December 2020

In this paper, Path-integral Monte Carlo calculations have been performed to study structure and superfluid behavior of para-H2 clusters(number of molecules N≤40).Energy difference and superfluid fractions at T=0.4 K and 1.6 K were compared to explore quantum melting of para-H2 clusters. We discussed the interplay between quantum localization and quantum melting of para-H2 clusters, and the differences between quantum localization and superfluidity of para-H2 and ortho-D2 clusters at T = 0.4 K.
S-wave band microstrip antenna with perfect absorbing metamaterial substrate
Authors: Bao Shi  , Luo Chun-Rong  , Zhao Xiao-Peng  ,   Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710129, China
Published: December 2020

Perfect absorbing metamaterial based on model of metallic dendritic cell is fabricated. A S-wave band microstrip antenna with perfect absorbing metamaterial substrate is proposed. The results show that compared to the conventional microstrip antenna, the performance of the novel microstrip antenna with perfect absorbing metamaterial substrate has improved remarkably. The direction of the antenna is enhanced, the gain is improved by 1.8dB and its efficiency is increased by 51%. It is proved that the performance of the microstrip antenna is improved by using perfect absorbing metamaterial as its substrate.
Design and preparation of sub-wavelength antireflective structures on ZnS
Authors: Xu Qi-Yuan  , Liu Zheng-Tang  , Li Yang-Ping  , Wu Qian  , Zhang Miao  ,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

ZnS is one of the excellent materials that are used as long wave window in infrared, but the reflection of the surface is high. In order to reduce the reflection of the ZnS surface, we designed the sub-wavelength antireflective structure on ZnS by coupled-wave theory. The parameters of the sub-wavelength antireflective structure were optimiged and the two-dimensional sub-wavelength antireflective structure on ZnS was fabricated by reactive ion etching technique. The results show that the transmittance of etched ZnS is significantly better than that of bare ZnS at wavelengths of 8—12 μm. This is a new antireflection method using ZnS.
Design of high efficiency photonic crystal terahertz filter
Authors: Chen He-Ming  , Meng Qing  ,   Institute of Optical Communications, Nanjing University of Posts and Telecommunications, Nanjing 210003, China
Published: December 2020

A new type of terahertz photonic crystal filter is presented, which includes the waveguide parts realized by line defects, and the frequency selection parts realized by micro cavities. The band gap property was investigated by using plane wave method (PWM), and then the transmission characteristic of terahertz in this kind of filter was studied by means of the finite difference time domain method (FDTD) simulation. The results show that, the filter can achieve high coupling efficiency filtering of single-channel and single-frequency, by changing the point defects structure and increasing the radius of certain dielectric cylinder. High efficiency THz-band photonic crystal filter was designed in this thesis.
Experimental study of detecting orbital angular momentumstates of spiral phase beams
Authors: Qi Xiao-Qing  , Gao Chun-Qing  ,   School of Optical-Electronics, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

An experimental setup was built to detect orbital angular momentum (OAM) states of light beams. The helical beams with different OAM states were generated by using a spatial light modulator. A Mach-Zehnder (M-Z) interferometer was used to detect helical beams with odd or even OAM number. Sorting of coaxial helical beams was also experimentally realized.
Suppression of time delay feedback signatures in a semiconductor laser with double optical feedback
Authors: Ding Ling  , Wu Jia-Gui  , Xia Guang-Qiong  , Shen Jin-Ting  , Li Neng-Yao  , Wu Zheng-Mao  ,   School of Physics, Southwest University, Chongqing 400715, China
Published: December 2020

In a double optical feedback semiconductor laser chaotic system, by fixing the feedback time and feedback strength of the one mirror (named as fixed cavity M1), the influences of the feedback time and feedback strength of the other mirror (named as tunable cavity M2) on the time delay feedback signatures of the chaotic system have been investigated experimentally. The results show that, for the case of the two cavities with identical feedback strengths, time delay feedback signatures of chaotic output can be suppressed efficiently when the cavity length of M2 is approximately equal (but can not exactly equal) to the cavity length of M1 (or half of the cavity length of M1). Fixing the length of M2 to approximately equal to the cavity length of M1 (or half of the cavity length of M1), the time delay feedback signature suppression can be further improved through adjusting the feedback strength of M2 carefully. Therefore, adopting a double optical feedback semiconductor laser chaotic system can make the system behave with higher security due to the efficient hiding of delay feedback parameter of the system.
The new insight into the optical pulse propagation theory and minimum-distortion propagation based on thefractional Fourier transformation
Authors: Han Qing-Sheng  , Qiao Yao-Jun  , Li Wei  ,   (1)Key Laboratory of Information Photonics and Optical Communication, Ministry of Education, Beijing University of Posts and Telecommunication, Beying 100876, China; (2)Wuhan National Lab for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The theoretical derivation of optical time-domain fractional Fourier transformation is achieved and implemented. Based on the understanding of fractional Fourier transformation, we propose a new method for analyzing the influence of combined effects of dispersion and self-phase modulation on the propagation of optical pulses. And the simulation results show that when the dispersion is dominant in the transmission, a fractional Fourier transformation with a negative order number will help reduce the broadening of optical pulses induced by the dispersion. On the other hand, when the self-phase modulation is dominant, a positive order fractional Fourier transmission can help eliminate the pulse splitting effect.
Transformation kinetics of metal and experimental measurement at nanosecond order
Authors: Zhang Shi-Lai  , Liu Fu-Sheng  , Peng Xiao-Juan  , Zhang Ming-Jian  , Li Yong-Hong  , Ma Xiao-Juan  , Xue Xue-Dong  ,   Laboratory of High Pressure Physics, Southwest Jiaotong University, Chengdu 610031,China
Published: December 2020

This paper reports the temperature relaxation process at melting iron/sapphire interface under shock compression, and interpretes the phenomenon basing on transformation kinetics and heat conduction equation. Analysis shows that if iron keeps melting, the history of interface temperature is affected by the melting speed. The interface temperature undergoes a slow cooling process when the melting speed of iron is finite, which is different from the result of previous researches. Simulation signal can be made accord ant with the experimental signal by adjusting some parameters. It was found that the melting temperature and melting speed of iron at high pressure can be dctermined by researching the relaxation process. So, this paper shows a new theoretical method and its experimental verification.
Application of the quasi-sliding-mode control to traffic bottleneck in pedestrian channel
Authors: Zeng Guang-Xiang  , Xue Yu  ,   Institute of Physical Science and Engineering, Guangxi University, Nanning 53004, China
Published: December 2020

The congestion of pedestrian traffic occurs easily at the bottleneck. Barriers could impede pedestrian channel, but it can ensure the smooth flow of pedestrians. Quasi-sliding mode control will be introduced in LWR model.The control variable can be derived for simulation at the impact of barriers. Based on the three-lane macroscopic traffic flow model, we carry out simulation to verify our control methods.The results indicate that the maximum pedestrian flow can be maintained due to the threshold value of the quasi-sliding mode control variables as the threshold value corresponds to one of the maximum flows in the fundamental diagram. Optimization of control variables can improve efficiency of one-way pedestrian at bottleneck.
Characterization of atmospheric pressuredc gliding arc plasma
Authors: Yu Liang  , Li Xiao-Dong  , Wang Yu  , Ni Ming-Jiang  , Yan Jian-Hua  , Tu Xin  ,   (1)State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China; (2)The University of Manchester, Manchester, M13 9PL, UK
Published: December 2020

The atmospheric pressure dc gliding arc plasma was investigated through its electrical and optical signals. The arc voltages of various gas discharges were compared. The arc voltage, current, power and resistance of a nitrogen gliding arc in one period were studied. Influences of gas type, gas flow rate and external resistor on the gliding arc fluctuation behaviour were studied using FFT spectrum analysis. Increased main oscillation frequency was observed as gas flow rate or external resistance value increased. Furthermore, major radical species in nitrogen, oxygen and air discharges were determined by means of optical emission spectroscopy. Additionally, the effect of external resistor on the relative intensity of radical emission and axial distribution of relative intensity at 337.1 nm (N2(C3Πu→B3Πg), Δv=0) were studied. Experimental results showed that radical emission relative intensity decreases with the increasing of external resistance value. The axial distribution of relative intensity exhibits the tendencies of increasing first and then decreasing. The radical emission relative intensity decreases dramatically out of the plasma area.
Numerical simulation study on characteristic parameters of microcavity discharge in argon
Authors: Xia Guang-Qing  , Xue Wei-Hua  , Chen Mao-Lin  , Zhu Yu  , Zhu Guo-Qiang  ,   (1)Laboratory on Plasma and Conversion of Energy(LAPLACE), Paul Sabatier University, Toulouse 31062, France; (2)School of Aeronautics and Astronautics, State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China; (3)School of Astronautics, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

The two-dimensional numerical model used is based on solutions of fluid equations in the drift-diffusion approximation for the electron and ion transport coupled with Poisson’s equation for electric field to simulate microcavity discharge qualities. The computation results show the potential profile, electron density distribution, ion density distribution, and electron temperature spatial distribution at the argon pressure of 100 Torr. The potential contour shows that the radial component of the electric field becomes very important as the forming of the cathode sheath. The results indicate the peak electron density is 1020 m-3, and the electron temperature is on the order of several to tens of eV.
Influence of grain size on the magnetic orientation growth of films prepared by vapor deposition in high magnetic field
Authors: Ren Shu-Yang  , Ren Zhong-Ming  , Ren Wei-Li  ,   School of Material Science and Technology, Shanghai University, Shanghai 200072, China
Published: December 2020

The vacuum evaporation has been applied to prepare Zn and Bi films with different growth directions in order to investigate the orientation of films in magnetic fields. XRD results showed that magnetic orientation occurred in the Zn films with a smaller difference between magnetic susceptibilities of a-axis and c-axis compared with those of Bi in the magnetic field of 4T but the orientation did not take place in the Bi films prepared in a 5T magnetic field despite of a larger difference in magnetic susceptibilities. It was observed by SEM that the grain sizes in Zn and Bi films were markedly different. The relation between the grain size and the magnetic orientation was established in a magnetic field of 4T. The condition of orientation in films is that the magnetic energy should be 420 times larger than the thermal energy kT. The occurences of magnetic orientation growth in the films depends on the grain size of the film, the difference in magnetic susceptibility of the material and the intensity of the applied magnetic field, respectively.
Effect of the reactive pressure on the structure and optical properties of silver oxide films deposited by direct-current reactive magnetron sputtering
Authors: Zhang Zeng-Yuan  , Gao Xiao-Yong  , Feng Hong-Liang  , Ma Jiao-Min  , Lu Jing-Xiao  ,   Key Laboratory of Materials Physics of Ministry of Education, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450052, China
Published: December 2020

Using direct-current reactive magnetron sputtering technique, a series of silver oxide (AgxO) films were deposited at a substrate temperature of 250 ℃ by modifying the reactive pressure (RP). Effect of the RP on the film structure and optical properties was investigated by X-ray diffractometry, energy dispersive spectroscopy and spectrophotometry. An evolution of the phase structure from biphased (AgO+Ag2O) to single-phased (Ag2O), and then to biphased (Ag2O+AgO) occurred with the RP increasing from 0.5 to 3.5 Pa for the AgxO films. Single-phase Ag2O film, specially, was deposited at RP=2.5 Pa, which was capable of lowering the threshold of thermal decomposition temperature of the AgxO film. The film transmissivity in transparent region increased with the RP increasing, while the film reflectivity and absorptivity decreased with the RP increasing. This result is attributed to the evolution of the phase structure and the decrease of the film thickness. The absorption edge of the biphased (AgO+Ag2O) AgxO film was located near 2.75 eV, whereas the absorption edge of the single-phase (Ag2O) and Ag2O-dominated biphased (Ag2O+AgO) AgxO film was located near 2.5 eV.
Phonon transport through helix nanobelts
Authors: Jin Wei  , Hui Ning-Ju  , Qu Shi-Xian  ,   Institute of Theoretical & Computational Physics, School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

Scalar phonon transport in helix nanobelts is studied by employing differential geometry method and formal scattering theory. Phonon transmission coefficients and thermal conductance are calculated. The numerical results reveal that curvature and torsion induce quantum interference between phonon modes, which makes the quantized stairs of the total transmission coefficient exhibit oscillation behavior which in turn suppresses the thermal conductance considerably.
Hysteresis thermogenous process of polymer material under vibrational force field
Authors: Zeng Guang-Sheng  , Qu Jin-Ping  , Liu Yue-Jun  , Xu Chao  , Xu Cheng  ,   Key Laboratory of New Materials and Technology for Package, Hunan University of Technology, Zhuzhou 412008, China;,   Key Laboratory of New Materials and Technology for Package, Hunan University of Technology, Zhuzhou 412008, China;National Engineering Research Center of Novel Equipment for Polymer Processing, Guangzhou 510640,China;The Key Laboratory of Polymer Processi;,   National Engineering Research Center of Novel Equipment for Polymer Processing, Guangzhou 510640,China;The Key Laboratory of Polymer Processing Engineering, Ministry of Education, South China University of Technology, Guangzhou 510640, China
Published: December 2020

A thorough analysis of the mechanism of vibrational force field on polymer processing was carried out to investigate the effect of vibration parameters on polymer viscoelasticity and plastic forming processing. The relationship between phase angle and lagging heat generation rate as well as the expression of polymer plasticizing rate under vibrational force field was obtained. To verify the theory, PET was adopted for example calculation and in expriments with dynamic capillary rheometer and mlti-dimentional vibration induced plastic forming equimpment. The result from calculation agrees well with that from experiment. Besides, it can be concluded that the plasticizing rate of PET increases at first and decreases afterwards with increasing vibration frequency. It reaches the peak at vibration frequency equivalent to the natural frequency of PET of about 15 Hz. The value remains at 22 g/min with the natural vibration frequency when the vibration amplitude is 6 MPa, being 1.75 fold that with vibration frequency of 10 Hz. Therefore, the plasticizing rate of polymer can be significantly improved by increasing the vibration amplitude. The exploration in this paper supplies reliable thoeretical reference for novel polymer low temperature moulding technique and equipments.
Influence of oxygen pressure on the lattice constants of Ba0.6Sr0.4TiO3 thin films and preparation of BaTiO3/Ba0.6Sr0.4TiO3 superlattices
Authors: Shang Jie  , Zhang Hui  , Cao Ming-Gang  , Zhang Peng-Xiang  ,   Institute of Advanced Materials for Photo-electronics, Kunming University of Science and Technology, Kunming 650093, China
Published: December 2020

Using pulsed laser deposition (PLD) technology, BaTiO3 (BT) and Ba0.6Sr0.4TiO3 (BST) single-layer films were successfully prepared through a series of optimization experiments. X-ray diffraction investigations indicated that BT and BST thin films were nearly (001)-epitaxially grown on LaAlO3 (001) substrates. And functional relation between the lattice constants of BST thin films and the oxygen pressure was close to Boltzmann function from 10-3 to 25 Pa. Then the high-quality BT/BST superlattices were also prepared under these optimal conditions. The surface topography measurement by atomic force microscopy (AFM) demonstrated that the root-mean-square (RMS) roughness of BT/BST superlattice was only 0.3048 nm. The surface smoothness has achieved the atomic scale. In addition, satellite peaks were clearly observed in the XRD spectrum. According to the position of satellite peaks that belong to (002) diffraction peak, the superperiod of superlattices was calculated and the deposition rates of BT and BST thin films were deduced. Finally, laser induced thermoelectric voltage (LITV) effect was measured for the first time in BT/BST superlattices grown on vicinal-cut single crystal substrates, which was not found in BT and BST single-layer films.
Electronic structure and optical properties ofrare earth element (Y,La) doped in ZnO
Authors: Wu Yu-Xi  , Hu Zhi-Xiang  , Li Teng  , Qu Li-Cheng  , Gu Shu-Lin  , Zhang Hao  ,   (1)Department of Aviation Ammunition,Xuzhou Air Force College,Xuzhou 221000,China; (2)Department of Physics & National Laboratory of Solid State Microstructures,Nanjing University,Nanjing 210093,China; (3)Department of Physics, College of Sciences, China University of Mining and Technology, Xuzhou 221116,China
Published: December 2020

The geometrical structures,band structures,density of states(DOS) and optical properties of undoped and doped rare earth elements(Y,La) in ZnO have been calculated from the first principles of plane wave ultra-soft pseudo-potential method based on density functional theory. After doping,the stability of structures are enhanced and the band gap becomes wider. When doped with Y(La), the Fermi energy of the system goes into the conduction band,the system shows metallicity and transforms into degenerate semiconductor. Furthermore, the change of optical properties after doping have been analyzed.
Effect of annealing treatment on the 386 nm and 388 nm emission peaks in unintentionally doped 4H-SiC epilayer
Authors: Cheng Ping  , Zhang Yu-Ming  , Zhang Yi-Men  ,   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

Under different annealing treatment conditions, the low temperature PL properties of unintentionally doped 4H-SiC epilayer have been studied by photoluminescence (PL) technique at 10 K. The results show that there are three emission peaks in the range from 370 nm to 400 nm and the maximum energy is about 3.26 eV, which is in accordance with the energy gaps (Eg) of 4H-SiC at room temperature. The 386 nm and 388 nm peaks (corresponding to ~3.21 eV and ~3.19 eV, respectively) are related with N impurity. When keeping annealing time at 30 min, the PL intensity of 386 nm and 388 nm peaks increases and then decreases with the annealing temperature increasing and reaches a maximum at 1573 K. The PL at 386 nm and 388nm change in quite the same manner with annealing time during isothermal annealing at temperature of 1573 K, whereas the difference is small. With the same annealing treatment, the low temperature PL results of 386 nm and 388 nm coincide with that of intrinsic defects in unintentionally doped 4H-SiC, which results from the interaction of infinitesimal disturbance potential energy between N impurity and native defects.
Localization of conduction electrons in nanometer metal Dy
Authors: Hou Bi-Hui  , Liu Feng-Yan  , Yue Ming  , Wang Ke-Jun  ,   College of Applied Science, and college of Materials Science and engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

The Changes of resistivity with temperature of bulk nanocrystalline metal dysprosium samples with different grain sizes were studied in this paper. The value of the resistivity is a sum of the residual rsistivity ρres=ρ (0), magnetic scatter resistivity ρmag(T) and phonon scatter resistivity ρpho(T). The mean grain sizes are 10 nm, 30 nm, 100 nm and 1000 nm. It was experimentally found that the magnetic scatter resistivity ρmag(T) and phonon scatter resistivity ρpho(T) increase as temperature increases. The measured values of the resistivities of the four samples are in the range of (0.8—252)×10-8Ω ·m, representing metalloid features. Experiments also showed that the residual rsistivity ρ (0) of the sample with 10nm mean grain size is about 98.6×10-8Ω ·m, which is about one order of magnitude greater than those of the other three samples. This is an experimental example of the energy band narrowing and the appearance of electron localization with the increase of disorder degree.