bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulating the three-dimensional dendritic growth of Al alloy using the phase-fi eld method
Authors: Zhao Dai-Ping  , Jing Tao  , Liu Bai-Cheng  ,   清华大学机械工程系，北京  100084
Published: December 2020

Numerical simulation of three-dimensional dendritic growth is performed by using a macro-micro coupled method and a capturing liquid method. The growth of the dendritic is controlled by the solution of the phase field equation. Since it is difficult to compute the microstructure of a whole casting, a scheme is adopted that the temperature field is calculated on the whole casting while the microstructure computation is carried out by selecting a macro-cell in the casting samples. Under the condition of not changing the phase-field model, a calculating method is advanced, which captures the liquid cells into the interface ones. In that method, every calculated micro-cell is endowed with a variable which identifies whether the cell is in the interface region and the phase field equation is only solved for those cells in that region. When the grain grows, the method captures the liquid cells into the interface ones and pushes the interface regi on forward. For the captured liquid cells, the values of the phase variable are modified. We apply the calculating method to improve the calculating efficiency, so the simulation of three-dimensional single grain and multiple grains growth for aluminum alloy samples, can be processed. The simulation results are compared with those obtained experimentally.
Optimal photoluminescence spectrum from Ti-doped ZnTe
Authors: Shao Jun  ,   Physikalisches Institut,Universitt Stuttgart,D-70550 Stuttgart,Germany;中国科学院上海技术物理研究所红外物理国家重点实验室，上海  200083
Published: December 2020

In this paper, experimental conditions are carefully optimized of excitation energy, power and degree of focus, water disturbance and temperature to overcome th e difficulties involved in photoluminescence (PL) study of ZnTe:Ti. It is illust rated that:(i)Higher PL intensity is accessible with excitation energy just belo w the band-gap energy of ZnTe.(ii)Water disturbance not only changes the relative intensities of the PL lines but also increases the measuring error of the transition energies. (iii) Excitation with relatively stronger focus produces better PL spectrum. Two zero-phonon lines (ZPLs) are unambiguously identified at 3903.5 and 3905.9 cm-1, respectively. They are ascribed to be due to Ti3+ in ZnTe with the aid of the crystal field theory, the transition energy, the energy difference of the two ZPLs and the temperature dependence of the relative intensity of the ZPLs. It is the first evidence from PL study for the Ti3+ in Ⅱ-Ⅵ compound semiconductors.
Effects of annealing on the structure and photoluminescence of ZnO films
Authors: Fang Ze-Bo  , Gong Heng-Xiang  , Liu Xue-Qin  , Xu Da-Yin  , Huang Chun-Ming  , Wang Yin-Yue  ,   兰州大学物理系，兰州  730000
Published: December 2020

Highly oriented polycrystalline ZnO films have been prepared by rf actively sputtering technique. We have investigated the structural and optical properties of ZnO films. x-ray diffraction was employed to analyze the influence of the post-treatment on the properties of ZnO thin films. The grain size increases with annealing temperature. The shift of the diffraction peak position from its normal powder value was observed. The photoluminescence (PL) spectra of these samples consist of one emission peak centred at 2.9eV.The intensities of PL peaks decrease with increasing annealing temperature. We propose that the emission comes from the interstitial Zn.
Nonlinear electrical properties of (Sr, Co, Nb)-doped SnO2 varistors
Authors: Qi Peng  , Wang Jin-Feng  , Chen Hong-Cun  , Su Wen-Bin  , Wang Wen-Xin  , Zang Guo-Zhong  , Wang Chun-Ming  ,   山东大学物理与微电子学院晶体材料国家重点实验室，济南  250100
Published: December 2020

The effect of Sr on the microstructure and nonlinear electrical properties of the (Co, Nb)-doped SnO2 varistors was investigated. The breakdown volta ge of the SnO2-based varistors increased significantly from 240 to 1482V/mm w ith increasing SrCO3 concentration from 0 to 1.50 mol%. Measurement of the ba rrier height at grain boundaries reveal that the significant decrease of the SnO2 grain size with increasing SrCO3 concentration from 0 to 1.50 mol%, is the reason of the enhancement of the breakdown voltage. The origin for the reduction of SnO2 grain size with increasing SrCO3 concentration was ex plained. The 1.50 mol% SrCO3-doped SnO2 varistor with ultrahigh breakdown vo ltage (1482V/mm) and larger nonlinear coefficient α(21.4) is a candidate used in the ultrahigh voltage protection system.
Multipeak negative-differential-resistance device by combining SET and MOSFET
Authors: Zhang Zhi-Yong  , Wang Tai-Hong  ,   中国科学院物理研究所，北京  100080
Published: December 2020

A multipeak negative-differential-resistance(NDR) device which comprises a singl e-electron transistor (SET) and a metal-oxide-semiconductor field-effect-transis tor (MOSFET) can achieve infinite number of peaks in principle. The MOS device e liminates the large SD voltage dependence of the peak and volley currents of the SET. The multipeak NDR device can be widely used in multiple-valued logics, and analog-to-digital converters (ADCs). We obtain a multiple-valued memory unit th rough the multipeak NDR device. And by using the folding I-V characteristic, a four-bit ADC is achieved. Compared with the traditional flash ADC, the SET-MO SFET ADC is very simple.
Phase transitions of XY model in ultra-thin magnetic film with a triangular latt ice
Authors: Wang Yi  , Han Ru-Qi  , Liu Xiao-Yan  , Horiguchi Tsuyoshi  ,   (1)北京大学微电子学研究所,北京  100871; (2)东北大学计算机科学系,日本仙台  980-8579
Published: December 2020

Phase transitions and critical phenomena have been clarified for an XY model on the triangular lattice of ultra-thin magnetic films. We have calculated the ther modynamic quantities such as the internal energy, the specific heat, the chirali ty and so on by using Monte-Carlo simulations. The critical behaviours have been clarified by using finite-size scaling analyses. We have found a new critical b ehaviour due to a steep increase of the chirality as a function of temperature f or the XY model on a layered triangular lattice with antiferromagnetic layers an d ferromagnetic layers in some range of interaction parameters, besides the Kost erlize-Thouless transition and the usual chirality transition. In the new chiral ity transition, the value of a critical exponent has not been observed over any thickness dependence of this value as far as the layered systems are concerned. In the other chirality transition, the value of a critical exponent has been obs erved over the thickness.
Structural properties of GaN1-xPx films
Authors: Chen Dun-Jun  , Shen Bo  , Zhang Kai-Xiao  , Deng Yong-Zhen  , Fan Jie  , Zhang Rong  , Shi Yi  , Zheng You-Dou  ,   南京大学物理系,南京  210093
Published: December 2020

X-ray diffraction (XRD) and Raman spectra for a series of high-phosphorus-content GaN1-xPx films, with phosphorus content up to 15%, gr own by means of light-radiation heating, low-pressure metal-organic chemical vapor deposition have been investigated. XRD results show that (0002) peaks of GaN1-xPx samples have shifted to smaller angles compared with t hat of undoped GaN sample. The Raman spectra of GaN1-xPx films exh ibit four new vibrational modes compared with undoped GaN sample. These modes are assigned to gap modes related to the Ga—P bond vibrations, local vibrational mode related to the phosphorus clusters, and disorder-activated scattering, respectively. The frequency of the A1(LO) mode is found to decrease with incre asing x. This redshift is attributed to the effects of alloying and strain.
The photoluminescence characterization of rare earths (Tb, Gd) embedded into por ous silicon
Authors: Peng Ai-Hua  , Xie Er-Qing  , Jiang Ning  , Zhang Zhi-Min  , Li Peng  , He De-Yan  ,   兰州大学物理科学与技术学院,兰州  730000
Published: December 2020

Rare earth (Tb,Gd) ions were embedded into porous silicon films by electrochemical method. Fluorescence photospectrometer and scanning electron microscope were employed to characterize the photoluminescence and surface morphology of samples. The distribution of rare earth ions embedded into porous silicon films was observed by Rutherford backscattering spectrometry. The luminescence intensity of porous silicon after doping is greatly increased. Blue shift of luminescence peak was observed also. It is attributed to the transition luminescence of transitions between 4f energy levels of Tb3+, such as 5D4 —7F3，5D4—7F2 and 5D 4—5F0. Intense blue luminescence was observed after doping with Gd. The luminescence mechanism of porous silicon doped with rare earths was discussed also.
The effect of annealing on the field emission properties of amorphous CNx films
Authors: Li Jun-Jie  , Zheng Wei-Tao  , Bian Hai-Jiao  , Lü Xian-Yi  , Jiang Zhi-Gang  , Bai Yi-Zhen  , Jin Zeng-Sun  , Zhao Yong-Nian  ,   (1)吉林大学材料科学与工程学院,长春  130023; (2)吉林大学超硬材料国家重点实验室,长春  130023; (3)吉林大学超硬材料国家重点实验室,长春  130023;延边大学理工学院,延吉  133002
Published: December 2020

The carbon nitride films deposited by r.f. magnetron sputtering in pure N2 discharge were annealed in vacuum up to 900 ℃. The chemical composition and bonding structure of the films were studied using x-ray photoelectron spectroscopy, Fourier Transform Infrared. The effects of thermal annealing on the bonding structure and the electron field emission characteristics of CNx films wer e investigated. It is found that the sp2 bonds and N content in CNx films are closely related to the filed emission of CNx films. The results show that thermal annealing treatment causes a great loss of N content and a larger formation of sp2 bonds in CNx films, which would influence sign ificantly the field emission properties for the CNx films. The CNx films annealed at 750 ℃ show the optimal electron emission properties. Besides, the correlation between the chemical bonding structures and electron emission properties for the CNx films was also discussed.
The effect of different catalysts on the growth of boron carbonitride nanotubes by thermal decomposition
Authors: Zhang Hong-Rui  , Guo Xin-Yong  , Ding Pei  , Du Zu-Liang  , Lia ng Er-Jun  ,   (1)河南大学润滑与功能材料重点实验室,开封  475001; (2)郑州大学物理工程学院,郑州  450052
Published: December 2020

The effect of cobalt, nickel, cobalt/nickel, cobalt/ferrocene, nickel/ferrocene and ferrocene catalysts on the morphology and yield of boron carbonitride(BCN) nanotubes produced by thermal decomposition at 860℃ was studied. It is found that the catalysts have a strong effect on the growth of BCN nanotubes. Transmission electron microscopy images reveal that bamboo-shaped thinner wall nanotubes with a higher yield are produced with nickel/ferrocene and cobalt/ferrocene as catalysts, whereas thicker wall nanotubes with a lower yield are generated with cobalt, nickel and cobalt/nickel as catalysts. BCN nanotubes cannot be produced with ferrocene alone as catalyst. Catalyst particles were found together with the BCN nanotubes. The morphology and yield of BCN nanotubes depend on the catalysts in the following order: nickel/ferrocene≈cobalt/ferrocene>cobalt≈nickel>cobalt/nickelferrocene. Their Raman spectroscopies were also studied.
The statistical entropy of Dirac field in spherically symmetric non-static black hole
Authors: Meng Qing-Miao  , Su Jiu-Qing  , Li Chuan-An  ,   菏泽师范专科学校物理系,菏泽  274000
Published: December 2020

In terms of the improved brick-wall model, the statistical entropy of Dirac field in the most general spherically symmetric non-static black hole is calculated. It is shown that the entropy of the black hole is proportional to the area of event horizon at any time. It is noteworthy that the calculating formula for the dynamic proportional coefficient is obtained in this paper. Through calculating these dynamic proportional coefficients, the statistical entropies of the Dirac field in all kinds of the spherically symmetric non-static black hole can be obtained directly.
Electron oscillation between coupled quantum wells with periodic driving
Authors: Yin Wen  , Lai Yun-Zhong  , Yan Qi-Wei  , Liang Jiu-Qing  ,   (1)山西大学理论物理研究所，太原  030006; (2)山西大学理论物理研究所，太原  030006;中国科学院物理研究所，北京  100080; (3)中国科学院物理研究所，北京  100080
Published: December 2020

The behaviour of an electron between two quantum wells, is studied by exact solution of a time-dependent Schrdinger equation. The time-dependent electron occupation-probability is obtained analytically as a function of the energy difference between the two wells, coupling constant and driving frequency. The condit ion that electron can be trapped in a single quantum well is obtained.
Study of the crystallization kinetics of Zr60Al15Ni2 5 bulk glassy alloy
Authors: Yan Zhi-Jie  , Li Jin-Fu  , Wang Hong-Hua  , Zhou Yao-He  ,   (1)上海交通大学金属基复合材料国家重点实验室，上海  200030; (2)上海交通大学金属基复合材料国家重点实验室，上海  200030;太原重型机械学院材料工程系，太原  030024
Published: December 2020

This paper reports the investigation on the crystallization kinetics of Zr6 0 Al15Ni25 bulk glassy alloy under isothermal annealin g by differential scanning calorimetry. The results show that the incubation time is very smal l even at a low annealing temperature (743 K) and the exothermic peak width, ref lecting the time for the actual crystallization process, increases greatly when annealing temperature decreases. This suggests a growth-controlled crystallizati on process. The Avrami exponents indicate that the crystallization mechanism cha nges at different annealing temperatures. The change of the crystallization mech anism is attributed to the great change of the mobility of atoms at different te mperatures.
Analysis on the chaotic pseudo-random sequence complexity
Authors: Cai Jue-Ping  , Li Zan  , Song Wen-Tao  ,   (1)上海交通大学电子工程系，上海  200030; (2)西安电子科技大学综合业务网国家重点实验室，西安  710071
Published: December 2020

In this paper, the conventional pseudo-random sequence linear complexity is disc ussed, and a new criterion is proposed, based on the approximate entropy. It is proved that the criterion is able to distinguish different complex chaos and cha otic pseudo-random sequences with short observed sequence. Simulations indicate that the method is effective, and the corresponding theories are proved right.
Measurement of the backscattering yields for protons of H+2, H+3 cluster ions in channeling condition
Authors: Yang Chao-Wen  , V.A. Khodyrev  , V.S. Kulikauskas  ,   (1)莫斯科大学核物理研究所，莫斯科  119899，俄罗斯; (2)四川大学物理科学与技术学院，原子核科学技术研究所,成都  610064
Published: December 2020

Rutherford backscattering spectrum of protons in H+2，H+3 cluster ions have been measured in channeling directions and of silicon crys tal. It has been found that, under the same velocity of 650 keV/p, the backscattering probability for protons of H+2 cluster ions is great er than that of H+ projectile, and the backscattering probability for protons of H+3 is gr eater than that of H+2. The ratio of backscattering yields of channeling di rection to that of random direction is defined and the depth dependence of ratio distribution is calculated.
Numerical simulation of the evolution of highly charged ions in an electron-bea m ion trap
Authors: Yuan Xing-Qiu  , Chen Chong-Yang  , Li Hui  , Zhao Tai-Zhe  , Guo Wen-Kang  , Xu Ping  ,   复旦大学现代物理研究所，上海  200433
Published: December 2020

The physical mechanism，which determines the evolution of highly charged ions in an electron-beam ion trap，is presented. The numerical simulation of the evolut ion of highly charged ions was performed, and the comparision of the result with experiments was carried out. Finally, parameter study was made.
Squeezing effect of light caused by Bose-Einstein condensate composed of interac tive atoms
Authors: Zhou Ming  , Fang Jia-Yuan  , Huang Chun-Jia  ,   长沙电力学院物理与信息工程系,长沙  410077
Published: December 2020

The Hamiltonian operator of a system of single-mode light field interacting with Bose-Einstein condensate(BEC) of two-level atoms is suggested within the rotati ng-wave approximation. The influence of the interaction between atoms in the BEC on the quadrature squeezing properties of single-mode squeezed light interactin g with atomic BEC is studied under Bogoliubov approximation. The results show th at the fluctuations of two quadrature components of light evolve periodically in a cosine law and their squeezing properties are determined mainly by the initia l squeeze factor and squeeze direction angle of light, and that the interaction between atoms in BEC changes the amplitude and period of fluctuation of light.
The production and elimination of the spatial singularity for ultrashort chirp ed pulse-beam propagation in free space
Authors: Yang Zhen-Jun  , Hu Wei  , Fu Xi-Quan  , Lu Da-Quan  , Zheng Yi-Zhou  ,   华南师范大学传输光学实验室，广州  510631
Published: December 2020

We study the propagation of ultrashort chirped pulsed beams in free space. We find that the slowly-varying envelope approximation and complex amplitude envelope are not suitable for ultrashort chirped pulsed beams anymore, because they lead to the spatial singularity that is inconsistent with the physical significanc e of the beam propagation. And the chirp influences the spatial singularity mor e seriously than the width of the pulsed beam does. The spatial singularity can be eliminated by using the complex analytical signal theory. In this paper, we g ive the simulations of spatial singularity about ultrashort chirped pulsed Gauss ian beams with a series of parameters, and the conditions that lead to the spati al singularity etc. We think that the broad spectrum of the ultrashort pulsed be am is the original reason for the spatial singularity.
Effect of spinning single-mode fibres on second-order polarization mode dispersi on
Authors: Dong Hui  , Wu Chong-Ｑing  , Fu Song-Ｎian  ,   (1)北方交通大学电子信息工程学院,北京  100044; (2)北方交通大学理学院,北京  100044
Published: December 2020

This paper describes the effect of spinning single-mode fibres on the second-order polarization mode dispersion(PMD). We find theoretically that spinning fibr es can reduce the first-order PMD, but it may be harmful to the second-order PMD , which is an important problem to the fibre communication system over 10 Gb/s.
Diagnostics and compression of sub-10 femtosecond laser pulses
Authors: Deng Li  , Liao Rui  , Liu Ye-Xin  , Shou Qian  , Wen Jin-Hui  , Lin Wei-Zhu  ,   中山大学光电子材料与技术国家重点实验室,广州  510275;中山大学物理系,广州  510275
Published: December 2020

The amplitudes and phases of femtosecond pulses generated from a home-made KLM Ti: Sapphire laser are diagnosed by using the technique of second-harmonic generation frequency-resolved optical gating. The results indicate that the profiles of the pulses are sech2 shapes and the phases are approximately cub ic dependent of the time. The chirped pulses of 17 fs(FWHM) are compressed to near Fourier transform limited pulses of 8.5 fs with a double-prism system to compensate for the second-order dispersion.
Finite difference time domain method for the study of band gap in two-dimensiona l phononic crystals
Authors: Wang Gang  , Wen Ji-Hong  , Han Xiao-Yun  , Zhao Hong-Gang  ,   国防科技大学机电工程研究所，长沙  410073
Published: December 2020

In this paper, by transforming the isotropy elastodynamic equations into the first-order hyperbolic ones, we have improved the O(2,4) finite difference time domain method with the staggered grid. Using the approach in this paper, we calculated the band gap in two-dimensional phononic crystals. The calculated and measured results match well.
On the absence of some resonance modes in acoustic scattering by spherical scatt erers in isotropic elastic media
Authors: Wu Rui-Xin  , Wang Yao-Jun  ,   (1)南京大学电子科学与工程系,南京  210093; (2)南京大学电子科学与工程系,南京  210093;南京大学近代声学国家重点实验室，南京  210093
Published: December 2020

Resonance scattering by iron spheres in plaxiglass matrix is investigated numer ically. Based on the analysis of the zero and singular points of the scattered l ongitudinal and transverse wave coefficients, the absence of some resonance mode s is found to appear only in the scattered longitudinal wave modes of the lowest order. The absence of some resonance modes results from the fact that the zero points of the numerator and denominator of scattered longitudinal wave coefficie nts are located at the same positions in the complex frequency plane.
Studies on the relationship between acoustic emission characteristics and fractu re toughness of materials
Authors: Zhu Bo  , Cai Xun  , Wang Cheng-Guo  , Cai Hua-Su  ,   (1)山东大学材料科学与工程学院，济南  250061; (2)山东大学计算机科学与技术学院，济南  250014
Published: December 2020

The corelation between acoustic emission characteristics and their fracture toughness has been investigated in this paper based on the study of high-strength al uminum alloy cracking process by using advanced acoustic emission experiment sys tem and smooth tensile specimens as well as DCB specimens with premade cracks. E xperimental results showed that the specimens emitted strong signals with an amp litude above 35 dB when a stable crack extension started at K1C. Stro nger and more complicated acoustic emission signals were found during unstable crack extension, and the cumulative energy of acoustic emission events were found to b e linearly related with the macroscopic fracture energy.
The impurity transport in HT-6M tokamak
Authors: Xu Wei  , Wan Bao-Nian  , Xie Ji-Kang  ,   (1)广州大学物理系，广州  510400;中国科学院等离子体物理研究所，合肥  230031; (2)中国科学院等离子体物理研究所，合肥  230031
Published: December 2020

The space-time profile of impurities has been measured with a multichannel visible spectroscopic detect system and UV rotation-mirror system in the HT-6M tokamak. An ideal impurity transport code has been used to simulate impurities (carbon and oxygen) behaviour during the OH discharge. The profiles of impuritie s diffusion and convection coefficient, impurities ion densities in different io nized state, loss power density and effective charge number have been derived. T he impurity behaviour during low-hybrid current drive has also been analyzed, th e results show that the confinement of particles, impurities and energy has been improved, and emission power and effective charge number have been reduced.
Hamiltonian system approach for simulation of acoustic and elastic wave propagat ion
Authors: Cao Yu  , Yang Kong-Qing  ,   兰州大学物理系，兰州  730000
Published: December 2020

This paper develops a system with quasi-particles on a discrete lattice, Hamiltonian description of this system is presented,which can simulate acoustic and elastic waves. The nine-point interaction models are used and interaction coefficients are determined in this system. The connection between Hamiltonian system approach and acoustic or elastic wave equations are proved, and the relations between their physical quantities are presented. The symplectic algorithms that are used in the given media models and simulation results are presented.
Calculation of surface energy of Cu crystal with modified embedded-atom method
Authors: Zhang Jian-Min  , Xu Ke-Wei  , Ma Fei  ,   (1)陕西师范大学物理学与信息技术学院，西安  710062; (2)陕西师范大学物理学与信息技术学院，西安  710062;西安交通大学金属材料强度国家重点实验室，西安  710049; (3)西安交通大学金属材料强度国家重点实验室，西安  710049
Published: December 2020

The surface energies on 12 different planes of Cu crystal have been calculated with modified embedded-atom method. The results show that the lowest surface ener gy, as predicted, corresponds to the close-packed plane (111) of face-centered c ubic (FCC) structure. The surface energies on other planes show a tendency to in crease with increasing angle between the planes and (111) plane. So the relative values in surface energy for other planes could be estimated by their geometric relationship. The geometric structure factors and the methods applied to determ ine them could be used directly for surface energy and other property calculatio ns in the materials with FCC structure. The (111) texture observed extensively i n Cu, Ag and other FCC films results from the surface energy minimization.
Constitutive study for tungsten alloy under high pressure
Authors: Hua Jing-Song  , Jing Fu-Qian  , Dong Yu-Bin  , Tan Hua  , Shen Zhong-Yi  , Zhou Xian-Ming  , Hu Shao-Lou  ,   (1)中国工程物理研究院冲击波物理与爆轰物理重点实验室，绵阳  621900; (2)中国科学院物理研究所，北京  100080
Published: December 2020

This article describes a method which combines the static pressure experiment,dynamic experiment and theoretical calculation to obtain the parameters in the SCG constitutive model for tungsten alloy under high pressures. By using the constitutive model we obtained in numerical simulation that the calculated profiles of particle velocity are in accordance with the experimental results. We also conducted some other simulations by using different constitutive models and compared them with experimental results. The results show that the constitutive model we obtained was the best.
Nanoelectromechanics in a quantum wire irradiated by a THz electromagnetic field
Authors: Yang Mou  , Zhou Guang-Hui  , Xiao Xian-Bo  ,   湖南师范大学物理系,长沙  410081
Published: December 2020

We study the nanoelectromechanics in a quantum wire connecting two reservoirs irradiated under an external terahertz (THz) electromagnetic field. Using the free-electron model at ballistic regime we calculated the two-level electron wavefunction and the Rabi oscillation of electron probability between the two levels. Using a statistical operator we calculated the nanoelectronic force in the wire. The result consists of two terms, which corresponds to the case with or without external field. The term without field parameter is consistent with the existing experimental observation and theoretical calculation, and the other term from the external field can be explained by the quantum coherent theory.
Piezoelectric activity and its stability of polytetrafluoroethylene(PTFE)films
Authors: Xia Zhong-Fu  , Ma Shan-Shan  , Zhu Jia-Qian  , Qiu Xun-Lin  , Zhang Ye-Wen  , R. Gerhard-Multhaupt  , W. Kuenstler  ,   (1)德国Potsdam大学物理系，Potsdam  D-14469; (2)同济大学波耳固体物理研究所，上海  200092
Published: December 2020

Piezoelectricity of non-polar space charge electret, porous PTFE film with unidi rectional mechanical stretch was studied. Piezoelectricity of double-layer stack s of porous PTFE and non-porous polymer films (such as PTFE, PI, FEP and PCTFE) with space charge layer were investigated. The results of preliminary investigat ion pointed out that under the optimal poling conditions, piezoelectric coeffici ent d33 of porous PTFE with external electrode was up to 186 pC/N whi c h is close to the value of ferroelectric ceramics PZT, and was about one order o f magnitude that of ferroelectric polymer PVDF. Outstanding thermal stability of piezoelectricity for soft PTFE porous film was reported. Influences of poling parameters such as poling time, corona electrical field and charging temperature etc, as well as charge density stored in the material on piezoelectricity were investigated. The influences of charging parameters on piezoelectricity were also explained by means of charge dynamic character and the material property.
Optical properties of InGaAs self-assembled quantum dots with InAlAs wetting lay er
Authors: Zhu Tian-Wei  , Zhang Yuan-Chang  , Xu Bo  , Liu Feng-Qi  , Wang Zhan-Guo  ,   中国科学院半导体研究所半导体材料科学开放实验室，北京  100083
Published: December 2020

A new self-assembled quantum dots system where InGaAs dots are formed on InAlAs wetting layer and embedded in GaAs matrix has been fabricated. The photolumines cence linewidth increases with increasing temperature, which is very different from normal In(Ga)As/GaAs quantum dots. The results are attributed to a higher e nergy of the wetting layer which breaks the carrier transfer channel between dot s and keeps the dots more isolated from each other.
The relationship between fatigue life and grain size of polycrystalline metals
Authors: Li Mei-Juan  , Hu Hai-Yun  , Xing Xiu-San  ,   北京理工大学应用物理系，北京  100081
Published: December 2020

In order to explore the effect of grain size on fatigue life, a formula of fatig ue life for polycrystalline metals,which depends on the grain size and cyclic st rain amplitude, is derived based on the non-equilibrium statistical theory of fa tigue fracture and the model of interface energy. Subsequently, the fatigue life s of pure copper and 70-30 brass with different grain sizes are calculated accor ding to the formula which is achieved in this paper, and the results are in agre ement with the experimental results.
Stefan-Boltzmann's law of the Dirac field of static spherically symmetric black holes
Authors: Meng Qing-Miao  ,   山东省菏泽师范专科学校物理系，菏泽  274015
Published: December 2020

Using the statistical entropy of the Dirac field of static spherically symmetric black hole, the Stefan-Boltzmann's law of static spherically symmetric black ho les is calculated, and we obtain a conclusion that the radiant emittance of a bl ack hole is proportionate to quartic power of temperature of the event horizon o f the black hole. It is found that the value of Stefan-Boltzmann constant in curved space-time is different from that in Euclidean space-time, and the constant has different value in different space-time.
A method for distinguishing dynamical species in chaotic time series
Authors: Li Chun-Gui  , Pei Liu-Qing  ,   (1)北京师范大学电子系,  北京  100875; (2)武汉工业学院基础部, 武汉  430023
Published: December 2020

Two statistical quantities are proposed in this paper,that is Q and R,Q is calle d the exponent of dynamical autocorrelation factor, and R is called the exponent of dynamical cross_correlation factor. Using Q and R,we can identify the dynami cal property of time series or their implicative dynamical structural levels and complexity by estimating the “distance” between diffierent time series or dif fierent segments of same time series.This method has been verified to be valid b y some typical instances.
One-dimensional sensitive driving cellular automaton model for traffic flow
Authors: Lei Li  , Xue Yu  , Dai Shi-Qiang  ,   (1)上海大学上海市应用数学和力学研究所，上海  200072; (2)上海大学上海市应用数学和力学研究所，上海  200072;广西大学物理系，南宁  530004; (3)上海大学上海市应用数学和力学研究所，上海  200072;山东大学能源与动力工程学院,济南  250061
Published: December 2020

Based on the NaSch cellular automaton traffic model, a new one_dimensional cellular automaton model (called SDNaSch model, for short) is proposed through prefer entially considering the sensitive behaviour of drivers, in which the randomizat ion brake is arranged before the deterministic deceleration. According to the ne w update rules of the evolution of vehicles, numerical simulation is conducted a nd leads to some new results. The fundamental diagram obtained by the simulation shows that the traffic capacity of a road is enhanced and closer to the observe d data compared with that of the NaSch model. It is found from the fundamental d iagram that there exist two branches in some density regions, which illustrates the existence of the metastable state near the critical point and the phase sepa ration. According to the evolution pattern of the vehicle speed in space and tim e, the wide moving jams is reproduced with the phase transitions between free fl ow and wide moving jams. With the consideration of the actual traffic situation, i.e., some drivers being sensitive and following the new rules, while others be ing not and following the original NaSch rules, the corresponding simulation ver ifies the remarkable effect of the sensitive driving factor on the characteristi cs of traffic flows. The traffic capacity rises along with the increase in the f raction of sensitive drivers.
Structural transformation of nanocrystalline titania grown by sol-gel technique and the growth kinetics of crystallites
Authors: Hu Lin-Hua  , Dai Song-Yuan  , Wang Kong-Jia  ,   中国科学院等离子体物理研究所, 合肥  230031
Published: December 2020

Structural transformation of nanocrystalline titania prepared by sol_gel method with hydrolysis precursor titanium isopropoxide was investigated. At the same ti me, the growth kinetics of titania powders was also studied. It was found that t he grain size of the powders increased slowly with autoclave heating temperature up to 503K, when hydrolysis pH value was 0.9, but grew rapidly when heating tem perature was higher than 503K. The activation energies for growth of anatase cry stallites in two temperature regions were calculated to be 18.5kJ/mol and 59.7 k J/mol respectively. The x_ray diffraction results show that the transformation f rom anatase phase to rutile phase starts at 503K and structural transformation f inished when temperature raises to 543K, which is a temperature much lower than that of the transformation reported in the literature.
State-to-state dielectronic recombination for Be-like gold ions
Authors: Chen Bo  , Zhu Zheng-He  ,   (1)四川大学原子分子物理研究所，成都  610065; (2)中国工程物理研究院核物理与化学研究所，绵阳  621900
Published: December 2020

Three types of state-to-state dielectronic recombination processes for Be-like i ons Au75+ have been investigated. Based on multi-configuration Hartre e-Foc k-Relativistic and distorted wave approaches, state-to-state dielectronic recomb ination rate coefficients have been calculated at electron temperatures 0.6-10.0 keV. Variations of the coefficient with electron temperature, recombination type s and up-or down-states have also been discussed in detail.
Studies on the analytical propagation equations of Gaussian beams through a mult i-apertured imaging system of B=0
Authors: Ji Xiao-Ling  , Lü Bai-Da  ,   (1)四川大学激光物理与化学研究所，成都  610064; (2)四川师范大学电子工程学院，成都  610066;四川大学激光物理与化学研究所，成都  610064
Published: December 2020

By using the method of matrix decomposition and expanding the aperture function into a finite sum of complex Gaussian functions, the closed-form propagation equ ations of Gaussian beams through a multi-apertured imaging system of B=0 are der ived and are illustrated with a few typical numerical examples. The advantages o f our treatment are pointed out.
The abnormal transmittance of polystyrene photonic crystals
Authors: Chen Hong-Yi  , Guo Hong-Lian  , Ni Pei-Gen  , Zhang Qi  , Cheng Bing-Ying  , Zhang Dao-Zhong  ,   中国科学院物理研究所和凝聚态物理中心光物理实验室，北京  100080
Published: December 2020

The periodic disturbance in transmittance of the polystyrene photonic crystal with a diameter of 3μm is observed in our experiment. According to the peak-to-peak intervals of the periodic disturbance, it can be seen that the periodic disturbance does not come from Mie scattering or Bragg diffraction, but from the propagation of whispering gallery mode in polystyrene spheres. The results show new potential applications of phtonic crystals.
Study on pulse waveform of stimulated Brillouin amplification
Authors: Ding Ying-Chun  , Lü Zhi-Wei  , He Wei-Ming  ,   哈尔滨工业大学光电子技术研究所，哈尔滨  150001
Published: December 2020

Brillouin amplifier was numerically simulated by the theoretic model of transient stimulated Brillouin scattering including depleted pump. Pulse waveform versus power density of the pump and the energy ratio of the seed to the pump was given. Experiment was done so as to verify the theory. The theoretical calculation was in good agreement with the experimental result.
Theoretical and numerical investigation for propagation of ultrashort intense l aser pulse in plasma channel
Authors: Tang Hua  , Guo Hong  , Liu Ming-Wei  , Qiu Yun-Li  , Deng Dong-Mei  ,   华南师范大学传输光学实验室，广州  510631
Published: December 2020

Characteristics of propagation of ultrashort intense laser pulses in a partially stripped pre-formed plasma channel, assumed to be parabolic and unperturbed, are discussed. From Maxwell equations the refractive index equation and Hamilton-Jacobi equation, which describe the evolution of the electric field, are derived including the effects of the diffraction, the third-order intensity-dependent nonlinearity, plasma defocusing, the self-focusing of the plasma channel, and t he relativistic self-focusing. The envelope equation of laser propagating in the plasma channel, and the general expression relating the laser spot size with th e propagation distance and the width of the plasma channel etc., are derived bas ed on the Hamilton-Jacobi equation and the refractive index equation.
Experimental study on the timing jitter of gain-switched laser diodes with photo n injection
Authors: Wang Yun-Cai  ,   太原理工大学理学院，太原  030024
Published: December 2020

A gain-switched laser diode (LD) was used as an external pulse injection source to reduce the timing jitter of gain-switched Fabry-Perot and DFB LDs. The low j itter and frequency-independent optical pulse can be achieved using this techniq ue. Phase noise measurement shows that with external pulse injection, the timing jitter of gain-switched FP LD was reduced from 1.2ps to 830fs and the timing ji tter of gain-switched DFB was reduced from 12ps to 1.2ps.
Similarity study on plasma conditions of some Ne-like and Ni-like x-ray lasers
Authors: Yan Fei  , Zhang Jei  , Lu Xin  ,   中国科学院物理研究所光物理重点实验室,北京  100080
Published: December 2020

The plasma conditions of Ni-like Ag, Cd, In, Sn, Sb, and Ne-like Fe, Co, Ni, Cu, Zn x-ray lasers are numerically simulated, using a one-dimensional hydrodynamic code. The results suggest that there is a correspondence of plasma conditions b etween some Ni-like x-ray lasers and Ne-like x-ray lasers by comparing the hydro dynamic characteristics of electron temperature, ion abundance and ion populatio n density. For example, the plasma condition of the Ni-like Ag x-ray laser is si milar to that of the Ne-like Fe x-ray laser and the Ni-like Cd x-ray laser is si milar to that of Ne-like Co, etc. Due to this correspondence, we can use the sim ulation of those Ne-lie x-ray lasers to give suggestions of performance of this partner Ni-like x-ray lasers.
General procedure to formulate Hamiltonian theory of the completely integrable n onlinear equations and its application to the sine-Gordon equation
Authors: Cai Hao  , Chen Shi-Rong  , Huang Nian-Ning  ,   (1)华中师范大学数学系,武汉  430074; (2)武汉大学物理系,武汉  430072
Published: December 2020

For a completely integrable nonlinear equation, the Poisson bracket of monodramy matrix is known to be expressed in a form of integral with respect to x. The in tegrand is found to be an x-differential of a linear combination of direct produ ct of two pairs of Jost solutions definitely, and the coefficients can be determ ined by comparing the corresponding elements of direct product matrices on two s ides. Hence a general procedure for constructing Hamiltonian formalism is given for a completely integrable nonlinear equation. As an example, the Hamiltonian t heory of sine-Gordon equation is re-examined, which shows the essence of the lin ear combination method for its very complicated Poisson bracket. And the previou s works involve, as is known, some inappropriate violating simultaneity of varia bles in Poisson bracket, which is also revised now.
TiN coating for inner surface modification by grid enhanced plasma source ion im plantation
Authors: Zhang Gu-Ling  , Wang Jiu-Li  , Yang Wu-Bao  , Fan Song-Hua  , Liu Chi-Zi  , Yang Si-Ze  ,   (1)中国科学院物理研究所,北京  100080; (2)中国科学院物理研究所,北京  100080;厦门大学固体表面物理化学国家重点实验室,厦门  361005;三束国家重点实验室,大连理工大学,大连  116024
Published: December 2020

Using the new inner surface modification technique named GEPSⅡ(grid-enhanced pl asma source ion implantation), which is designed for inner surface modification of tubular work piece, has successfully produced TiN coating on 0.45% C steel (4 5# steel). By comparing with the uncoated 45# steel sample, the electrochemical corrosion test on the coated 45# steel samples presents about 5—10 times improv ement in their corrosion resistance. Structural analysis shows that the TiN coat ings have preferred crystal orientation(111) and (2000). And the depth of coatin gs is about 20 nm, with part of which embedding in the substrate.
Numerical simulation study for atomic-resolution x-ray fluorescence holography
Authors: Xie Hong-Lan  , Gao Hong-Yi  , Chen Jian-Wen  , Wang Jun-Yue  , Zhu Pei-Ping  , Xiong Shi-Sheng  , Xian Ding-Chang  , Xu Zhi-Zhan  ,   (1)中国科学院高能物理研究所,北京  100039; (2)中国科学院上海光学精密机械研究所,上海  201800
Published: December 2020

Based on the principle of x-ray fluorescence holography, we numerically simulate d an iron single crystal model of a body-centred cubic lattice. From the fluores cence hologram produced numerically, the Fe atomic images were reconstructed. Th e atomic images of the (001),(100),(010) crystallographic planes were consistent with the corresponding atomic positions of the model. The result indicates that one can obtain internal structure images of single crystals at atomic-resolutio n by using x-ray fluorescence holography.
Molecular dynamics simulation of Gd adatom diffusion on Cu(110) surface
Authors: Xie Guo-Feng  , Wang De-Wu  , Ying Chun-Tong  ,   清华大学工程物理系，北京  100084
Published: December 2020

The diffusion mechanisms of Gd adatom on Cu(110) surface are investigated by means of molecular dynamics.The simulation results show that along ［1 1 0］ direct ion the Gd adatom diffuses by hopping,and the frequency of long jumps is very hi gh.While along［0 0 1］direction,the Gd adatom diffuses by exchanging.The freque ncy of hopping is higher than that of exchanging.The frequency of hopping and ex changing can be described by Arrhenius equation.The calculated diffusion barrier of hopping is 0.097eV and that of exchanging is 0.33eV.Moreover the diffusion b arrier of hopping is calculated by energy relaxation method.
Phase transformation of AlN in AlN/VN nanomultilayers and its effect on the mech anical properties of films
Authors: Lao Ji-Jun  , Hu Xiao-Ping  , Yu Xiao-Jiang  , Li Ge-Yang  , Gu Ming-Yuan  ,   上海交通大学金属基复合材料国家重点实验室，上海  200030
Published: December 2020

AlN/VN nanomultilayers were prepared by reactive magnetron sputtering method. Th e effect of modulation period on the microstructure and mechanical properties of AlN/VN nanomultilayers were studied in this work. The results show that AlN exi sts in metastable cubic structure (c-AlN) at small modulation period and forms c oherent epitaxial grown superlattice with VN. At larger modulation periods, AlN transforms from cubic structure to stable hexagonal structure (h-AlN),and the na nomultilayers form a “brick-wall” structure with nanometer grains. The discuss ion shows that the template effect of VN is beneficial to the growth of c-AlN, b ut cannot increase its critical thickness remarkably.
Ground-state energy and zero-field splitting parameters in GeFe2O4 crystal
Authors: Yin Chun-Hao  , Han Kui  , Ye Shi-Wang  ,   中国矿业大学理学院，徐州  221008
Published: December 2020

GeFe2O4 is a spinel-type compound in which the neighborhoo d of a Fe2+ ion has a trigonal symmetry with respect to an axis which is parallel to one of the three 〈111〉 direction,and varies from site to site . The crystal-field and spin-orbit complete Hamiltonian matrix of 3d4/3d6 ions ha ve been establishe d by irreducible representation method, The zero-field splitting parameters D an d F-a of Fe2+ ions in GeFe2O4 crystal are prese nted by using the cryst al-field and spin-orbit interaction complete diagonalizing Hamiltonian matrix wi th the theory of electron paramagnetic resonance; at the same time, the contribu tions to zero-field splitting from spin-triplet state have been studied. The res ults show that the contributions to zero-field splitting from spin-triplet state are important and strong. The calculated results are in good agreement with the experimental data.
Electronic energy and life span probability distribution of the HgS/CdS/HgS sphe rical nanometer system
Authors: Zheng Rui-Lun  , Chen Zhi-Qian  , Zhang Cui-Ling  , Liu Jun  ,   西南师范大学物理系，重庆  400715
Published: December 2020

The physical Model for the spherical HgS/CdS/HgS nanometer system and equations satistied by the electron motion are built. The energy and life span of s-electr on and the variation of the probability distribution with the width of the poten tial barrier and well are probed. Some important results indicate that the ener gy and life span of the electron increase with the increase of the potential bar rier width; electronic energy decreases with the increase of the potential well width, however the electronic life span is increased. The interaction between la yers has an important influence on the results.
Hysteretic scaling and dynamical phase transition of three-dimension X-Y Model
Authors: Shao Yuan-Zhi  , Zhong Wei-Rong  , Lin Guang-Ming  ,   中山大学物理系，广州  510275
Published: December 2020

We have studied in this paper,by performing the Monte Carlo numerical simulation,both the hysteretic scaling and the dynamical phase transition of a three-dimen sional,(3D) classical X-Y model driven by an sinusoidally oscillating external m agnetic field.A scaling formula has been worked out which relates the hysteresis loop area with the amplitude h0 and frequency ω of the external fie ld as wel l as the reduced temperature T/Tc of the system in the form:Area～hα0ωβ(1-T/Tc)γ.The best-fit expo nents are α=0.57,β=0.34 and γ=0.9.The 3D X- Y model also characterizes a distinctive discrepancy in dynamical transition fea ture after short and long term evolution of magnetization,respectively.Our simul ation disclosed that the short-term evolution of magnetization (period number≤1 0) attains the symmetry-breaking of system with a nonzero dynamical order parame ter (Q≠0) at a either critical amplitude h0c or frequency ωc.The symme try-breaking in short term,however,evolves steadily into a symmetric disorder st ate (Q=0) after a longer term relaxation of system.The specific relaxation times at which the Q value becomes zero from nonzero increase evidently as the temper ature of system drops.
Thermal expansion property of (Pb0.97La0.02)(Zr0.65Sn0.35-xTix)O3 ceramics
Authors: Liu Peng  , Xu Zhuo  , Yao Xi  ,   (1)陕西师范大学物理学与信息技术学院，西安  710062; (2)西安交通大学电子材料研究所，西安  710049
Published: December 2020

The phase transformation and thermal expansion behaviour of (Pb0.97La 0.02(Zr0.65Sn0.35-xTix)O3 (PZST,0.1≤x≤0.14)antiferroelectric ceramics (AFEt)have been investigated as functions of temperature and Ti conte nt x.It was found that for the specimens with 0.1≤x≤0.12,the thermal expansion coefficient (α) curve showed an unusual “bending” at the temperature of T,wh ile the specimens remained a tetragonal phase.For 0.125≤x≤0.14,the specimens s howed a ferroelectric rhombohedral phase (FER) at room temperature.Wh en heated ,the FER phase was changed to an antiferroelectric tetragonal phase ( AFEt) a nd pareoelectroic cubic phase (PEc) at temperatures of TFA and Tc,resp ectively.In addition,T and TFA increased with the increase of Ti cont ent x , while Tc was decreased.The phases were detected by the XRD pattern at differ ent temperatures.The temperature-Ti content (x) phase diagram of (Pb0.97La 0.02)(Zr0.65Sn0.35-xTix)O3 was finally established.The the rmal expansion behaviour of (Pb0.97La0.02)(Zr0.65Sn0.35-xTix)O3 (0.1≤x≤0.14) have been expla ined based upon the nano-size phase s eparation of the PZST complex pervoskite compounds.
High-resolution electron-energy-loss spectroscopy study on the reaction of MgF2 with Alq3(8-hydroxy-quinoline)aluminum
Authors: Zhang Han-Jie  , Bao Shi-Ning  , He Pi-Mo  , Wang Sui-Dong  , Fung Man-Keung  , Zhang Rui-Qin  , Lee Chun-Sing  , Lee Shuit-Tong  ,   (1)香港城市大学物理与材料科学系，超金刚石及先进薄膜中心，香港; (2)浙江大学物理系，杭州  310027;香港城市大学物理与材料科学系，超金刚石及先进薄膜中心，香港
Published: December 2020

The reaction between MgF2 and tris (8-hydroxy-quinoline)aluminum (Alq 3)has b een studied using high-resolution electron-energy-loss spectroscopy (HREELS).The reaction between MgF2 and Alq3 occurs in the cases of MgF 2 deposited on A lq3 and Alq3 on MgF2.The shift of the loss peak corresponding to the out-o f-plane ring bend is observed to be similar to that for Mg deposited on Alq 3.T he HREELS spectra indicate that Mg is produced from MgF2 deposited on Alq3,a nd interacts with Al,O and N in Alq3.Analysis of the HREELS results s uggests that Mg is not in the Alq3 molecule plane.