bluuebunny/crossref_metadata_2025 huggingface dataset:
Light coupling in c-cut doped lithium niobate crystals
Authors: Gao Yuan-Mei  , Liu Si-Min  , Zhao Hong-E  , Huang Chun-Fu  , Guo Ru  , Wang Da-Yun  ,   (1)北方交通大学理学院，北京  100044; (2)南开大学物理学院光子学中心，天津  300071
Published: December 2020

We investigated experimentally the coupling behaviours of the transmitting and reflected light in three c-cut doped lithium niobate crystals.We find that when the direction of the incident light is along the -c axis,the quasi-period oscillation behaviour of the reflectivity and transmissivity is caused by the energy transfer with diffusion and the photovoltaic-effect related transient energy transfer,the directions of these energy transfers are opposite to each other,but not caused by quasi-breakdown of the photovoltaic field.When the direction of the incident light is along +c axis,the directions of energy transfers caused by both mechanisms are the same,so oscillations will not appear.
The index changes of waveguides fabricated by light irradiation in LiNbO3:Fe c rystals
Authors: Yang De-Xing  , Zhao Jian-Lin  , Zhang Peng  , Li Bi-Li  , Feng Xi-Qi  ,   (1)西北工业大学应用物理系光子学研究室，西安  710072; (2)中国科学院上海硅酸盐研究所无机功能材料重点实验室，上海  200050
Published: December 2020

The refractive index changes of waveguides fabricated by light irradiation in LiNbO3:Fe crystals were investigated by using ordinary and extraordinary laser beams at wavelengths of 632.8nm and 532nm. The experimental results show that the waveguide fabricated by ordinary light is better than that by extraordinary lig ht, as the ordinary light causes much less light-induced scattering. The illuminated time must be strictly controlled when the region with a positive index change, formed by a single thin laser beam, is used as waveguide structure. This is beacuse the waveguide properties may be influenced by the strong noise grati ng and the shift of the waveguide region after the LiNbO3:Fe crystal was irrad iated for a long time. For avoiding the influence of the noise grating, the symm etric waveguide structure with high quality can be fabricated by sheet beam illu mination employing the sandwich method at a relatively low exposure intensity. M oreover, waveguides with different index distributions and different dimensions can be fabricated by changing the width of the irradiating beam and the distance between twice irradiations.
Theory of abnormal grain growth in thin films and analysis of energy anisotropy
Authors: Zhang Jian-Min  , Xu Ke-Wei  , Zhang Mei-Rong  ,   (1)陕西师范大学图书馆，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

A theoretical model is proposed for the abnormal grain growth in thin films of columnar grains. In addition to the grain boundary energy usually considered for the grain growth in bulk materials, the influences of surface energy, interface energy and strain energy are also considered in the model. A reviewed analysis is given out for the anisotropy of energy. For fcc and bcc metal films, surface energy minimization generally favours (111) and (110) textures, while strain energy minimization generally favours (110) and (100) textures.
Contributions of fourbody interactions to compressibility of solid helium
Authors: Tian Chun-Ling  , Liu Fu-Sheng  , Cai Ling-Cang  , Jing Fu-Qian  ,   (1)西南交通大学高压物理实验室，成都  610031; (2)西南交通大学高压物理实验室，成都  610031;西南师范大学物理系，重庆  400715; (3)西南交通大学高压物理实验室，成都  610031;中国工程物理研究院流体物理研究所冲击波物理爆轰物理实验室，绵阳  621900; (4)中国工程物理研究院流体物理研究所冲击波物理爆轰物理实验室，绵阳  621900
Published: December 2020

Based on a mangbody expansion of shortrange interatomic force,the fourbody interactions in compressed solid helium are computed by ab initio HartreeFock selfconsistent field technique and the atomic cluster method. It is concluded that fourbody terms give a repulsive contribution to the binding energy. By combination of the present manybody expansions with Aziz's longrange attractive potential, the equation of state(EOS) (T=0K) is calculated and compared with available experimental data. Results emphasize the importance of the fourbody interactions in compressed solid He. If only twobody interactions are included such as in the description of the helium gas, the pressure is much overestimated. Good agreement with experiments can only be extended up to about 10 GPa when the threebody corrections are added to; however, the predicted compression curve is obviously lower than that obtained in recent experiments at above 10 GPa. Our study shows that fourbody corrections can bring the calculated EOS into a good agreement with experimental data at pressures of 10\_27GPa. Our result also implies that the higherorder manybody effects should be taken into account at higher pressures.
Enhanced chromaticity of organic electroluminescence from siliconbased organic microcavity
Authors: Xiong Zu-Hong  , Shi Hua-Zhong  , Fan Yong-Liang  , Zhang Song-Tao  , Zhan Yi-Qiang  , He Jun  , Zhong Gao-Yu  , Xu Shao-Hui  , Liu Yi  , Wang Xiao-Jun  , Wang Zi-Jun  , Ding Xun-Min  , Huang Wei  , Hou XiaoYuan  ,   (1)复旦大学先进材料与技术研究院和高分子科学系，上海  200433; (2)复旦大学应用表面物理国家重点实验室，上海  200433; (3)复旦大学应用表面物理国家重点实验室和先进材料与技术研究院，上海  200433
Published: December 2020

Electroluminescence (EL) from Sibased organic microcavity has firstly been reported in the literature. The microcavity is made up of the central active multilayers sandwiched between a silver film and a porous silicon Bragg reflector (PSDBR), formed by electrochemical etching of p+Si substrate in the electrolyte of HF: C2H5OH:H2O. The central active multilayers consist of Al (1 nm) / LiF (05 nm) / Alq3 / Alq3: DCJTB / NPB / CuPc / ITO / SiO2． The reflectivity (relative to an Al mirror) of the PSDBR is up to 99%, and the stopband is about 160 nm wide. Resonant cavity mode appears as a tip in the reflectivity spectrum of the Sibased organic multilayer films, indicating that the Sibased organic multilayer structure is indeed a microcavity. The peak widths of the EL spetra are greatly reduced from 70 nm to 12 nm as compared with those measured from noncavity structures. Note that the EL emission from the cavity devices is singlemode, and the offresonant optical modes are highly suppressed. Moreover, an increase of a factor of about 4 of the resonant peak intensity is observed. In addition, the currentbrightnessvoltage characteristics and the effect of parameters on the lifetime of the cavity devices are also discussed. The present technique for obtaining enhanced EL emission from Sibased organic microcavity may also be another novel effective method for realizing allSibased photonic devices and optoelectronics device integration.
A model for the yield strength of a thin polycrystalline film
Authors: Zhang Jian-Min  , Xu Ke-Wei  , Zhang Mei-Rong  ,   (1)陕西师范大学图书馆，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

A simple expression for the yield strength of a thin polycrystalline film attached to a substrate and with a passivated layer has been derived from a relationship between stress work for dislocation moving and strain energy. It is shown that, the yield strength of a polycrystalline film is determined by two affecting factors (orientation of grains and type of dislocations) and three strengthening factors (passivated layer strengthening, substrate strengthening, and grainsize strengthening). Predictions from the expression are in agreement with reported experimental results. This shows that the model is reasonable.
Study on lowtemperature growth of AlN single crystal film by ECRPEMOCVD
Authors: Qin Fu-Wen  , Gu Biao  , Xu Yin  , Yang Da-Zhi  ,   (1)大连理工大学材料科学与工程系，大连  116024; (2)大连理工大学三束材料表面改性国家重点实验室，大连  116024;大连理工大学电气工程与应用电子技术系，大连  116024
Published: December 2020

The AlN film with GaN initiallayer (GaN buffer layer and epilayer)has been grown on αAl2O3 (0001)substrate by electron cyclotron resonanceplasmaenhanced metal organic chemical vapor deposition(ECRPEMOCVD) technique at low temperatures using TMAl and high pure N2 as Al and N sources, respectively. The effects of hydrogen plasma cleaning, nitridation and GaN initallayer on the quality of AlN epilayer have been investigated by RHEED(reflection highenergy electron diffraction) , TEM(transmission electron microscope) and XRD(xray diffraction). And highquality hexagonalphase AlN single crystal films whose cleavability is the same as the substrate have been grown at low temperatures. The full width at half maximum of XRD peaks is 12′.
Magnetic and transport properties of perovskite La067Pb033MnO3
Authors: Xiao Chun-Tao  , Han Li-An  , Xue De-Sheng  , Zhao Jun-Hui  , H.Kunkel  , G.Williams  ,   (1)Department of Physics and Astronomy,University of Manitoba,Canada,R3T 2N2; (2)兰州大学磁学与磁性材料教育部重点实验室，兰州  730000; (3)兰州大学磁学与磁性材料教育部重点实验室，兰州  730000;Department of Physics and Astronomy,University of Manitoba,Canada,R3T 2N2
Published: December 2020

Singlephase polycrystalline samples of La067Pb033MnO3 were prepared by conventional solidstate reaction method. The crystal structure and magnetic and transport properties are investigated. The structure revealed by the room temperature xray powder diffraction is rhombohedral(R3C), and the Curie temperature is very close to TMI(=360K). At the Curie point, the magnetic properties show the transition from ferromagnetic to paramagnetic, and the conductivity changes from metal to semiconducting. The resistivity decreases with increasing magnetic field. Magnetoresistance reaches a maximum at the Curie point. The maximum magnetoresistance is 14\^5% at H=1\^2MA/m, and 9% at H=0\^6MA/m. The transport results show that the transport data satisfy ρ(T)=ρ0+ρT2.5 for TTMI. This phenomenon is due to the magoncarrier scattering.
Dielectric behaviour of antiferroelectric lead zirconate titanateunder strong electric field
Authors: Feng Yu-Jun  , Xu Zhuo  , Wei Xiao-Yong  , Yao Xi  ,   西安交通大学电子材料与器件研究所，西安  710049
Published: December 2020

The dielectric behaviour of antiferroelectric lead zirconate titanate has been studied by measuring the polarization and capacitance changes with the electric field.The results show that the differential dielectric constant　εd calculated from the polarization versus electric field curve exhibits sharp peaks at the electric fields that switch an antiferroelectricsferroelectrics transition,and the maximum value of εd can reach up to 41000. The smallsignal dielectric constant εc measured will decrease rapidly during the phase transition from an antiferroelectric state to a polarized ferroelectric state by increasing the dc bias field, and εc　will increase during the ferroelectric state returns to the original antiferroelectric state by reducing dc bias field. It is noticed that the extreme values of the differential dielectric constant εd are electric hysteretic to the extreme of the small signal dielectric constant εc. These phenomena are analyzed by using the electric domain evolution under an electric field.
Synthesis of polyaniline-MWNT composite nanotube and electrical and optical properties
Authors: Feng Wei  , Yi Wen-Hui  , Xu You-Long  , Lian Yan-Qing  , Wang Xiao-Gong  , Katsumi Yoshino  ,   (1)清华大学化工系高分子材料研究所，北京  100084; (2)日本大贩大学电子工学吉野研究室，大阪  565-0871; (3)西安交通大学电子与信息工程学院，西安  710049
Published: December 2020

A composite of polyaniline (PANI) encapsulating mutilwall carbon nanaotube(MWNT) composite nanotube with nanometer size has been synthesized by insitu emulsion polymerization. Nanotube dimensions have been measured and the nature of the association between the components have been observed using SEM and TEM techniques, the diammer of nanocomposite tube is about 6070 nm.The improvement of thermal stability and crystallinity of nanocomposites have been evaluated by using TGA and XRD. The photoconductivity of PANIMWNT composite nanotube has been enhanced markedly and discussed by taking the photoinduced charge transfer between PANI and MWNT into consideration.
FEM study on the influence of oxygen on field emission of singlewalled carbon nanotubes
Authors: Zhang Zhao-Xiang  , Zhang Geng-Min  , Hou Shi-Min  , Zhang Hao  , Gu Zhen-Nan  , Liu Wei-Min  , Zhao Xing-Yu  , Xue Zeng-Quan  ,   (1)北京大学电子学系，北京  100871; (2)北京大学化学与分子工程学院，北京  100871
Published: December 2020

Influence of oxygen on the field emission of singlewalled carbon nanotubes (SWCNTs) was studied using a fieldemission microscope (FEM) and a quadrupole mass spectrometer. After heat treatment at 1000℃, the field emission of clean SWCNTs occurred. Then oxygen was introduced into the vacuum system and the curves of field emission current versus anodecathode voltage (IV curves) were acquired after oxygen adsorption and desorption, respectively. We have observed that oxygen adsorption on SWCNTs leads to a decrease in field emission current, indicating an increase in the work function. Oxidation etching occurred when the SWCNTs were annealed at about 1000℃ under a pressure of 10-4Pa, and the corresponding changes were observed in both field emission images and IV curves.
Dielectric behavior in electric meltingquartz glass irradiated by γray
Authors: Gao Si-Jian  , Ouyang Shi-Xi  ,   中国建筑材料科学研究院，北京100024
Published: December 2020

Dielectric behavior and optical absorption of quartz glasses before and after irradiating were investigated. Experimental results demonstrate that complex dielectric function of quartz glasses is changed by the irradiation. Its magnitude is decreased by the irradiation. In addition, the change in the dielectric function does not relate to the hydroxyl group in quartz glasses. Experiments also show that dielectric function is relating to the color centers in quartz glasses. Contribution of color center to dielectric function is dependent on its sort and amount in quartz glasses. Dielectric constant decreases with increasing the density of color center
Iterative layering approach to multiple scattering and emission from inhomogenou s random scatter media
Authors: Liang Zi-Chang  , Jin Ya-Qiu  ,   复旦大学波散射和遥感中心、信息科学与工程学院，上海  200433
Published: December 2020

Taking into account the multiple scattering of vector radiative transfer (VRT), an iterative layering method is developed by stratifying the random media into m ulti-slabs and employing the lower-order Mueller matrix solution to derive high- order scatterings. This approach is applied to the simulation of polarized brigh tness temperature from an inhomogeneous snowpack of randomly and densely distrib uted spherical particles with nonuniform profiles of particle size, fractional v olume and physical temperature. Numerical results are compared with conventional eigen-analysis approach for a uniform scatter medium. The functional dependence of multiple scattering and emission upon the characteristic parameters such as particle size, fractional volume, physical temperature etc. are discussed, and a re also compared with the microwave remote sensing measurements of the multi-lay ers snowpack.
Quantum corrections to the entropy of the Barriola-Vilenkin black hole due to sp in fields
Authors: Li Gu-Qiang  ,   湛江师范学院信息科技学院，湛江  524048
Published: December 2020

The quantum corrections to the entropy of the Barriola-Vilenkin black hole due to the massless gravitational field are calculated by using the brick-wall model.It is shown that the quantum corrections consist of two parts:One is a quadratic divergent term at the event horizon and is proportional to the surface area of the event horizon.The other is two logarithmically divergent terms which not only depend on the characteristics of the black hole but also on the spin of the field.The whole expression does not take the form of the scalar field.
Quantum entropy of the Vaidya-Bonner-de Sitter black hole arising from gravitati onal fields
Authors: Sun Ming-Chao  ,   陇东学院物理系，庆阳  745000
Published: December 2020

The quantum corrections to the entropy of the Vaidya-Bonner-de Sitter black hole due to gravitational fields are investigated by using the brick-wall model.When the event horizon of the black hole does not depend upon the advanced-time,the results coincide with that of the Reissner-Nordstrm-de Sitter black hole.
Global analysis of stochastic bifurcation in a Duffing-van der Pol system
Authors: Xu Wei  , He Qun  , Rong Hai-Wu  , Fang Tong  ,   (1)佛山科技学院应用数学系，佛山  528000; (2)西北工业大学应用数学系，西安  710072; (3)西北工业大学应用数学系，西安  710072;武警工程学院应用数学系，西安  710086; (4)西北工业大学振动工程研究所，西安  710072
Published: December 2020

Stochastic bifurcation of the Duffing-van der Pol oscillators under both additive and multiplicative random excitations is studied in detail by the generalized cell mapping method using digraph.As an alternative definition,stochastic bifurcation may be defined as a sudden change in character of a stochastic attractor when the bifurcation parameter of the system passes through a critical value.It is found that under certain conditions stochastic bifurcation mostly occurs when a stochastic attractor collides with a stochastic saddle.Our study reveals that the generalized cell mapping method with digraph is also a powerful tool for global analysis of stochastic bifurcation.By this global analysis ,the mechanism of development,occurrence,and evolution of a stochastic bifurcation can be explored clearly and vividly.
Perturbative theory and quantum rate equation of time-dependent double-well tran sport
Authors: Xu Hai-Lei  , Shen Jian-Qi  , Chen Yi-Xin  ,   (1)浙江近代物理中心，浙江大学物理系，杭州  310027; (2)浙江近代物理中心，浙江大学物理系，杭州  310027;浙江大学现代光学仪器国家重点实验室，光及电磁波研究中心，杭州  310027
Published: December 2020

The perturbative evaluation of the time-dependent quantum transport is investigated by making use of the Lewis-Riesenfeld invariant theory and the invariant-related unitary transformation formulation in this paper.We obtain the complete set of solutions of the time-dependent Schrdinger equation governing the behaviour of electrons in a double-well structure. Based on these exact solutions,we obtain the first-order quantum rate equation by regarding the interaction Hamiltonian between the double-well structures and the heat reservoirs as the perturbative Hamiltonian.An approach to the geometric phase factor (Berry's phase factor) in the adiabatic quantum transport process is briefly discussed in this paper.We hold that the formulation presented here has advantages in dealing with transport problem over the method proposed by Gurvitz et al.
Boson inverse operators and associated even and odd coherent states
Authors: Yang Qing-yi  , Wei Lian-Fu  , Ding Liang-En  ,   (1)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062; (2)华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062;广西大学物理系，南宁  530004; (3)上海交通大学物理系，上海  200030
Published: December 2020

A new kind of even and odd coherent states i.e.the photon-added and photon-deple ted states,can be obtained from acting boson inverse operators on the usual even and odd coherent states.The new states are the eigenstates of the operators a^ -ka^k+2 and a^+-ka2a^+k,r espectively.The results show that these states may reveal the anti-bunching and quantum squeezing effects.
Free-electron laser induced nonlinear optical absorption in semiconductors
Authors: Jiang Jun  , Li Ning  , Chen Gui-Bin  , Lu Wei  , Wang Ming-Kai  , Yang Xue-Ping  , Wu Gang  , Fan Yao-Hui  , Li Yong-Gui  , Yuan Xian-Zhang  ,   (1)温州师范学院物理与电子信息科学系，温州  325027; (2)中国科学院高能物理研究所自由电子激光实验室，北京  100080; (3)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

Using a free-electron laser source,we have studied the nonlinear absorption in I nSb,Hg1-xCdxTe and InAs semiconductors.By measuring the tr ansmission,two -photon-absorption(TPA)has been investigated as a function of the input power.In two cases,a distinct saturation of TPA coefficients has been observed.Using an extension of these methods,we demonstrated that the reduced transmission at high intensities is primarily due to free-carrier-absorption(FCA) of the electrons a nd holes generated by TPA,not directly due to the TPA process.Furthermore,by car eful calculation,we have extracted the convincing cross section of FCA.
First-order statistical properties of ultrasonic speckles back-scattered from a kind of weak scattering interface
Authors: Zhu Hong-Mao  , Wu Yan-Yang  , Huang Zhong-Wen  , Wang Yin-Guan  , Zhu Cheng  ,   (1)华中科技大学电子与信息工程系,武汉  430074; (2)华中科技大学力学系,武汉  430074; (3)同济大学声学所,上海  200092
Published: December 2020

First-order statistical properties of ultrasonic speckles back-scattered from an interface with tiny pints on, which is considered as one kind of weak scatterin g interface, are studied in this paper. Based on four assumptions, theoretical a nalyses indicate that the amplitude of ultrasonic speckles in space is in the fo rm of Rice distribution, and the phase probability density function of the ultra sonic speckles is a compound function of Gauss distribution function and Gauss p robability integral function. When the density of the pits on the interface is v ery high, the amplitude of ultrasonic speckles becomes Rayleigh distributed. To verify the theoretical analysis conclusion, the amplitude probability distributi on of ultrasonic speckles is measured by using a set of experimental systems wit h step scanning controlled by a computer, which is built by the authors. The exp erimental results are in good agreement with the theoretical predicted results. So, the assumptions proposed in this paper are suitable for the theoretical anal yses.
Monte Carlo simulation of the electron motion in an Ar microhollow cathode disch arge
Authors: Yao Xi-Lin  , Wang Xin-Bing  , Lai Jian-Jun  ,   华中科技大学激光技术国家重点实验室，武汉  430074
Published: December 2020

In this paper, the electron motion in a submillimeter level microhollow cathode discharge(MHCD) is investigated under high pressures by Monte Carlo simulation. Some swarm parameters have been obtained such as the electron density distribu tion in the field direction for a steady state, the energy and spatial distribut ion under different pressures.The result shows that MHCD under high pressures c an reflect in more detail the essence of the 'oscillating' effect of the hollow cathode discharge.When electrons oscillate in MHC,most of them are scattered st ill forward.With increasing pressure,the effect of lateral scattering will exhib it gradually.
Investigation of magnetic properties at low temperatures on permanent magnetic N d60Al10Fe20Co10 bulk metallic glass
Authors: Li Zheng  , Bai Hai-Yang  , Chen Zhao-Jia  , Pan Ming-Xiang  , Zhao De-Qian  , Wang Wan-Lu  , Wang Wei-Hua  ,   (1)中国科学院物理研究所，北京  100080; (2)重庆大学数理学院应用科学与技术系，重庆  400044; (3)重庆大学数理学院应用科学与技术系，重庆  400044;中国科学院物理研究所，北京  100080
Published: December 2020

The temperature dependence of magnetic properties for Nd60Al10 Fe20Co10 bulk metallic glass is investigated. The re sults indicate that th e Nd60Al10Fe20Co10 bulk metallic gla ss exhibits permanen t magnetic behaviour at room temperature. The coercive force and the shape of hy steresis loops change markedly when temperature decreases. AC magnetic susceptib ility is measured and a peak at about 18K is found. The peak moves torwards high temperatures when the frequency is increased. This indicates that there are spi n glass structures in the bulk metallic glass.
Preparation and characterization of the stable nc-Si/a-Si:H films
Authors: Xu Yan-Yue  , Kong Guang-Lin  , Zhang Shi-Bin  , Hu Zhi-Hua  , Zeng Xiang-Bo  , Diao Hong-Wei  , Liao Xian-Bo  ,   中国科学院半导体研究所,表面物理国家重点实验室,凝聚态物理中心,北京  100083
Published: December 2020

High-quality nc-Si/a-Si:H diphasic films with improved stability were prepared b y using the plasma-enhanced chemical vapor deposition technology. In comparison with typical amorphous silicon, the diphasic silicon films possess higher photoc onductivity (two orders larger than that of the amorphous silicon film) and fair ly good photosensitivity(the ratio of the photo-to dark-conductivity is about 10 4) and higher stability (the degradation of the photoconductivity is less than 10% after 24h long light soaking with 50 mW/cm2 intensity at room te mperature ). In addition, the diphasic silicon film has a better light spectra response in the longer wavelength range. The improvement in photoelectronic properties may be attributed to: the existence of the disorder within the amorphous matrix, whi ch breaks the momentum selection rule in the optical transition and, consequentl y, results in the large light absorption coefficient and high photosensitivity; the improved medium range order and low gap states density. Excess carriers gene rated in the amorphous matrix tend to recombine in the embedded crystallites, wh ich suppresses nonradiative recombination within the amorphous matrix and reduce s the subsequent defect creation.
Preparation and characterization of a new perovskite-type oxide ion conductor KN b1-xMgxO3-δ
Authors: Xiang Jun  , Li Li-Ping  , Su Wen-Hui  ,   (1)华东船舶工业学院数理系，镇江  212003; (2)吉林大学物理系，长春  130023; (3)吉林大学物理系，长春  130023;中国科学院国际材料物理中心，沈阳  110015
Published: December 2020

A series of solid electrolytes KNb1-xMgxO3-δ (x=0.0—0.3) with an orthorhombic perovskite structure was synthesized under high temperature and high pressure（4.0GPa，870℃）. The effect of Mg-doping on the structure transformation and electrical properties was systematically studied in this paper. The Raman spectra at different temperatures and differential thermal analysis results indicate that the structure of the samples transforms from ferroelectric orthorhombic to tetragonal phase, and finally to paraelectric cubic phase with increasing temperature. Weakening of the coupling effect of A-site cation on BO6 octahedra and the B-site cation contribution to spontaneous polarization, as a result of the Mg2+ doping in KNbO3, leads to th e decrease of Curie temperature.The Curie point of KNb0.85Mg0.15 O2.775,decreasing by about 40℃ in comparison with KNbO3 ,is 392℃.Impedance spectroscopic data show that the conductivity of the samples is ionic, the grai n-boundary effect is very significant, and the conductivity of the samples is de termined mainly by the grain-boundary. Mg-doping increases the oxygen ion conduc tivity of the samples. KNb0.9Mg0.1O2.85 has the highest conduc tivity of 1.2×10-3S/cm at 700℃ in all of the samples,which makes it a kind of promising oxygen ionic conduction materials.
Theoretical studies of submillimeter radiation and near-infrared emission due to excitonic recombination in an asymmetric coupled-quantum-well structure
Authors: Hu Zhen-Hua  , Huang De-Xiu  ,   (1)华中科技大学光电子工程系，武汉  430074; (2)华中科技大学光电子工程系，武汉  430074;武汉理工大学物理学系，武汉  430063
Published: December 2020

In this paper the delocalized behaviours of an asymmetric coupled-quantum-well structure (a-CQWS) have been studied and the transfer process of the electrons between the two wells has been analyzed theoretically based on V-type system. We show that an electronic packet of coherent oscillation created by an ultrashort pulse can be viewed as a classical electronic dipole damping oscillator, whose lifetime depends strongly on both the electronic-tunneling transfer time and the carrier-longitudinal optial scattering time.The submillimeter radiative lifetime created by coherent oscillation of an electronic wave packet is related to the oscillation damping rate between the two wells but not to the exitonic recombination rate; the intensity in frequency domain has the Lorentzs profile.It is shown that the transiton frequency of near-infrared radiation generated by the excitonic recombination has a tunable characteristic.This result implys that the high-speed modulator and the tunable source in the near infrared-radiation region can be obtained from the asymmetric double-quantum well structure in the future optical communication.
Spontaneous magnetization of two superconducting coupled π rings
Authors: Wang Ke  , Ling Jian  , Xie Fei-Xiang  , Ma Ping  , Yang Tao  , Wang Fu-Ren  , Dai Yuan-Dong  ,   北京大学物理学院 人工微结构和介观物理国家重点实验室，北京 100871
Published: December 2020

An analytical formula for the free energy of two coupled π rings is presented.Using the formula, the free energy is calculated for equidirectional spontaneous magnetization and inverse spontaneous magnetization of the two coupled π rings. We found that the whole system has a lower free energy in the latter case.
Studies on the improvement of niobium-sputtered quarter wave resonator supercond ucting cavity
Authors: Meng Tie-Jun  , Zhao Kui  , Xie Da-Tao  , Zhang Bao-Cheng  , Wang Li-Fang  , Zhu Feng  , Chu Xiang-Qiang  , Chen Jia-Er  ,   北京大学物理学院重离子物理研究所,北京  100871
Published: December 2020

Quarter wave resonator (QWR) is the best choice of the acceleration cavity for heavy ion superconducting accelerator. Using dc bias-voltage sputtering system, w e can sputter niobium films of several microns on the oxygen-free high-conductiv ity copper(OFHC) substrate. Good superconducting properties and acceleration pro perties of the cavity can be obtained. But compared with niobium cavity, it has very low Q and Eacc. Niobium nitride (NbN) is a good superconducto r, and it has a higher superconducting transition temperature (Tc) th an pu re niobium. Through experiments, we find that the Tc transition point of n iobium films rises to about 9.6K by using NbN interlayer between OFHC substrate and niobium films. So using this method can improve the superconducting properti es and thus the acceleration properties.
Study of properties of lanthanum doped SrBi4Ti4O15 ferroelectric ceramics
Authors: Zhu Jun  , Lu Wang-Ping  , Liu Qiu-Chao  , Mao Xiang-Yu  , Hui Rong  , Chen Xiao-Bing  ,   扬州大学物理科学与技术学院,扬州  225002
Published: December 2020

Ceramic samples SrBi4-xLaxTi4O15 (x =0.00, 0.10, 0.25, 0.50, 0.75, 1.00), have been prepared by solid-state reaction method. T heir structure was analyzed by x-ray diffraction, and their dielectricity and fe rroelectricity were measured. It is found that La-doping does not change the cry stal structure of SrBi4Ti4O15. The remnant pola rization (2P4) in creases at first, then decreases with the increase of La content. The 2P4 reaches a maximum value of 24.2 μC·cm-2, when x is 0.25. The c oerc ive field of SrBi3.75La0.25Ti4O15 is 60.8 kV·cm-1 . The 2P4 increases by about 50% and the Ec decrease s near 25%, compa red with these of SrBi4Ti4O15. Obviously, the f erroelectricity of SrBi 4Ti4O15 is improved by lanthanum doping. The te mperature of p hase transition (Tc) decreased with La cloping. The Tc of SrBi3.75La0.25Ti4O15 is 451 ℃. When x=0.75 and 1.00, the SrBi4-xLaxTi4O15 exhibit the typical characteristics of relaxor ferro electrics.
Effect of radiation trapping on spectroscopic properties of Yb3+-dope d phosphate glasses
Authors: Dai Shi-Xun  , Yang Jian-Hu  , Dai Neng-Li  , Xu Shi-Qing  , Wen Lei  , Hu Li-Li  , Jiang Zhong-Hong  ,   (1)中国科学院上海光学精密机械研究所,上海  201800; (2)中国科学院上海光学精密机械研究所,上海  201800;华南理工大学光通讯材料研究所,广州  510641
Published: December 2020

The absorption and emission properties of the concentrations and thickness of Yb3+-doped phosphate glasses have been investigated. The integrated cro ss section, absorption cross section, emission cross section, the spontaneous emission probability, and the effective line width of fluorescence of Yb3+- doped phosphate glasses were determined. The effect of the radiation trapping on spectroscopic properties was discussed. It was found that the effect of radiation trapping increases remarkably with the concentration and thickness of Yb3+-doped phosphate glasses. Radiation trapping causes significant lengthening of the measured fluorescence lifetime τf which is longer than the radia tive lifetime τrad. The error in measuring the fluorescence lifetime unde r low Yb3+ ion concentration (0.2mol%Yb2O3) is 3 0% and the error is 43% under high Yb3+ ion concentration (6mol%Yb2O3 ) 6mol%. Radiation trapping also significantly increases the effective line width Δλeff. I t will be increased by 14% and 30% larger under low and high Yb3+ ion concentration respectively.
Study on optical properties of Er3+-doped near-stoichiometric LiNbO3 crystals
Authors: Geng Hua  , Yao Jiang-Hong  , Li Wen-Run  , Zhang Guang-Yin  , Ruan Yong-Feng  ,   (1)南开大学物理科学学院光子学中心,天津  300071; (2)天津大学应用物理系,天津  300072
Published: December 2020

Near-stoichiometric Er∶LiNbO3 has many properties superior to the co ngruent one and has aroused extensive interest. It was obtained by the technique of vapor transport equilibration (VTE), its optical properties, including OH- absorption spectra, transmission spectra, emission spectra and the position of absorption edge were studied. The higher transmittance, the narrower of the peak width, the “blueshift" of the optical absorption edge, as well as the significant reduction of the OH- absorption band are indicative of the VTE treatment having brought the crystal closer to the stoichiometric composition. We also observed the increase of Er3+ luminescent intensity, and predicted that the VTE treatment must lead to the increase of fluorescence lifetime. The possible modification of materials in amplifier, self-frequency doubling laser and waveguide laser etc were expected.
Collective radiation of water in cytoskeletal microtubule
Authors: Chen Ying  , Qiu Xi-Jun  ,   上海大学理学院物理系,上海  200436
Published: December 2020

microtubules are the important components and function units in cytoskeletal, an d filled with water inside it. In this paper, by using the quantum field theory, we study the interactions between the electric dipole field of water molecules confined within the hollow core of microtubules and the quantized electromagnetic radiation field, and the characteristic of collective electromagnetic radiation raised from water's electric dipoles. In addition, the coupling between the water molecule system confined within microtubules and the surrounding heatbath is discussed.
Form invariance and Noether symmetry of a relativistic mechanical system
Authors: Fang Jian-Hui  , Yan Xiang-Hong  , Chen Pei-Sheng  ,   石油大学应用物理系，东营  257061
Published: December 2020

In this paper,we study the form invariance and Noether symmetry of a relativistic mechanical system-Firstly,we give the Noether theorem of a relativistic mechanical system,and the definition and criterion and conserved quantity of the form invariance in the system-Next,the relation between the form invariance and Noether symmetry of the system is obtained-Finally,we give an example to illustrate the application of the result-
Inquiry about the exact interior solution to Einstein field equation for a perfe ct fluid sphere
Authors: Zhong Ming-Qian  ,   西北大学物理系，西安  710069
Published: December 2020

When the density of a static spherically symmetric perfect fluid is a function of the radial coordinate, the Oppenheimer-Volkoff (OV) equation turns into a Riccati equation- If a particular solution of the OV equation is given, it can be transformed into an integrable Bernoulli equation, we can obtain a general exact solution and an other particular solution of the OV equation- Further more, the exact interior solutions of Einstein field equation for the perfect fluid sphere are also obtained, i-e- the analytical expressions of the metric compone nts-
Experimental study for impulsive synchronization of a discrete chaotic system
Authors: Chen Ju-Fang  , Zhang Ru-Yuan  , Peng Jian-Hua  ,   (1)东北师范大学数学系，长春  130024; (2)东北师范大学物理系，长春  130024; (3)东北师范大学物理系，长春  130024;深圳大学理学院，深圳  518060
Published: December 2020

A two-dimensional discrete system with chaotic and hyperchaotic characteristics has been designed and its dynamic behaviour has been analyzed, and the impulsiv e synchronization conditions have been obtained by mathematical analysis- In our experiment, impulsive synchronization of the circuit system has been realiz ed- The experimental data are in good agreement with the results of theoretical analysis and numerical calculation- In addition, the experimental results demons trate the effectiveness and robustness to noise by means of the above method-
Projective synchronization in a unified chaotic system and its control
Authors: Liu Jie  , Chen Shi-Hua  , Lu Jun-An  ,   (1)武汉大学数学与统计学院，武汉  430072; (2)武汉大学数学与统计学院，武汉  430072;咸宁学院数学系，咸宁  437005
Published: December 2020

Projective synchronization phenomenon in unidirectionally coupled unified systems is studied- A scheme is proposed to control the scaling factor formed in the projective synchronization- Under the control strategy, one can arbitrarily mani pulate the scaling factor to a desired value- This special phenomenon and the co ntrol scheme can be used in some secure communication schemes- Illustrations ar e also given to show the rightness of the theoretical analysis and the effective ness of the method proposed-
Study of the dynamics of a first-order cellular neural networks with delay
Authors: Zhang Qiang  , Gao Lin  , Wang Chao  , Yuan Tao  , Xu Jin  ,   (1)华中科技大学控制科学与工程系，武汉  430074; (2)西安电子科技大学电子工程研究所，西安  710071
Published: December 2020

The dynamics of a first-order cellular neural network with delay has been studied in this paper- By using the delay as a bifurcation parameter, the Hopf bifurc ations are proved- Furthermore, by choosing suitable parameters and delay, chaot ic behaviour has been observed- Computer simulations, as well as Lyapunov ex ponent, are presented to support our results- Due to the simple structure of thi s network, it can serve as a chaos-generator in practice-
Investigations of concentration effects of La on the infrared optical properties of PLZT thin films
Authors: Hu Zhi-Gao  , Shi Fu-Wen  , Huang Zhi-Ming  , Wang Gen-Shui  , Meng Xiang-Jian  , Lin Tie  , Chu Jun-Hao  ,   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

Lead lanthanum zirconate titanate (PLZT) thin films with different La concentrations (x), whose composition is x/40/60, have been grown directly on Pt/Ti/SiO2/Si substrates by a modified sol-gel method. x-ray diffraction analysis shows that the PLZT thin films are polycrystalline with a single perovskite p hase. The infrared optical properties of the PLZT thin films are investigated us ing the infrared spectroscopic ellipsometry in the spectral range of 2.5—12.6μ m. By fitting the measured ellipsometric parameters, and a classical dispers ion relation for the thin films, the optical constants and thickness of the thin films have been obtained. The refractive index of the PLZT thin films decreases with increasing La concentration; however, the extinction coefficient increases with increasing La concentration except for the PLZT (4%) thin films. It is bel ieved that the decrease in the refractive index for the PLZT thin films with inc reasing La concentration is mainly due to the crystallinity and the electronic b and structure of the PLZT thin films. The absorption coefficient of the PLZT thi n films is larger than that of the PZT thin films. The values of the effective s tatic charge in the PLZT thin films, which are smaller than those of the purely ionic materials for the PLZT thin films, decrease with increasing La concentrati on. This indicates that PLZT belongs to a mixed ionic-covalent compound.
Properties of the injected atomic inversion in the micromaser
Authors: Wu Shu-Dong  , Chen Ai-Xi  , Jin Li-Xia  ,   华中科技大学物理系，武汉  430074
Published: December 2020

In this paper, we establish the expression of photon statistics in the steady state in the micromaser with Kerr medium cavity, study the properties of the atomi c inversion in a stationary state when the atom is in thermal-atom, critical or ultracold-atom regimes in a micromaser. The results show that the properties of the atomic inversion in different regimes are very distinct. In the thermal-atom regime, there are some regions of the cavity length L where the atoms are i nversive, with the increase of the atomic injection rate r, the regions of a tomic inversion and the probability of the atomic inversion increase. In the cri tical regime, atomic inversion exhibits the collapse and revival phenomena. Howe ver, in ultracold-atom regime, there are all regions of the cavity length L where the atoms are not inversive. Kerr effect and the detuning make the probabi lity of the atomic inversion smaller.
Parametric study of plasma resistance in gas pulsed discharges
Authors: Chen Gang  , Pan Bai-Liang  , Yao Zhi-Xin  ,   浙江大学物理系，杭州  310027
Published: December 2020

The dependences of dynamic plasma resistances on discharge voltage, repetitive frequency and buffer gas pressure are studied and measured. It is found that the plasma resistance reduced with the increase of discharge voltage and repetit ive frequency, but increased with enhancing buffer gas pressure. The experimenta l formula of plasma resistance depending on discharge voltage, repetitive freque ncy and buffer gas pressure was proposed and the pulsed discharge current was si mulated using the experimental formula of plasma resistance.
Analysis of the existence of one-dimensional dark and gray spatial solitons in l ogarithmically nonlinear media
Authors: Wei Qing  , Wang Qi  , Shi Jie-Long  ,   上海大学物理系,上海  200436
Published: December 2020

The existence of dark and gray spatial solitons in logarithmically nonlinear media is investigated. It is shown that both dark and gray solitons are possible in corresponding nonlinear media. The spatial width for dark solitons is analyzed .It is revealed as follows: the beam width decreases dramatically with increasing power when the peak power is much lower, exhibiting the good nonlinear effects in such cases. The variation of beam width is slow at first and then becomes constant when the peak power continuously increases .
Numerical studies of neon gas-puff Z-pinch dynamic processes
Authors: Ning Cheng  , Yang Zhen-Hua  , Ding Ning  ,   北京应用物理与计算数学研究所，北京  100088
Published: December 2020

Dynamic processes of neon gas-puff Z-pinch are studied numerically in this paper.A high temperature plasma with a high density can be generated in the process.Based on some physical analysis and assumption,a set of equations of one-dimensional Lagrangian radiation magneto-hydrodynamic (MHD) and its code are developed to solve the problem.Spatio-temporal distributions of plasma parameters in the processes are obtained,and their dynamic variations show that the major results are self-consistent.The duration for the plasma pinched to centre,as well as the width and the total energy of the x-ray pulse caused by the Z-pinch are in reasonable agreement with experimental results of GAMBLE-Ⅱ.A zipping effect is also clearly shown in the simulation.
Absorption of femtosecond laser pulses in metallic and dielectric slabs
Authors: Chen Zheng-Lin  , Zhang Jie  , Chen Li-Ming  , Teng Hao  , Dong Quan-Li  , Zhao Li-Zeng  , Wei Zhi-Yi  ,   中国科学院物理研究所光物理开放实验室，北京  100080
Published: December 2020

Laser absorption, and hot electron emission and its energy spectrum are studied in the interaction between P-polarized femtosecond laser pulses at 8×1015 W/cm2 and solid-density plasmas. Comparison is made between th e different b ehaviours of metallic and dielectric slabs irradiated by femtosecond laser pulse s. It appears that there are less laser absorption, fewer hot electrons and high er hot electron temperature from dielectric slabs compared with metallic ones. T hese are concluded to be due to the lower conductivity and consequently lower ch arge separation potential of the dielectric slabs.
Study of the hollow cathode plasma electron-gun
Authors: Zhang Yong-Hui  , Jiang Jin-Sheng  , Chang An-Bi  ,   中国工程物理研究院应用电子学研究所，绵阳  621900
Published: December 2020

For developing a novel high-current, long pulsewidth electron source, the theoretics and mechanism of the hollow cathode plasma electron-gun are analyzed in detail in this paper, the structure and the physical process of hollow cathode pl asma electron-gun are also studied. This gun overcomes the limitations of most high-power microwave tubes, which employ either thermionic cathodes that produce low current-density beams because of the limitation of the space charge, or f ield-emission cathodes that offer high current density but provide only short pu lsewidth because of plasma closure of the accelerating gap. In the theories stud ying on hollow cathode plasma electron-gun, the characteristic of the hollow-cat hode discharge is introduced, the action during the forming of plasma of the sti mulating electrode and the modulating anode are discussed, the movement of elect rons and ions and the primary parameters are analyzed, and the formulas of the e lectric field, beam current density and the stabilization conditions of the beam current are also presented in this paper. The numerical simulation is carried o ut based on Poisson's equation, and the equations of current continuity and move ment. And the optimized result is reported. On this basis, we have designed a ho llow-cathode-plasma electron-gun, whose output pulse current is 2kA, and pulse w idth is 1 microsecond.
Numerical simulation of dielectric-barrier-controlled glow discharge at atmosphe ric pressure
Authors: Wang Yan-Hui  , Wang De-Zhen  ,   大连理工大学物理系，三束材料改性国家重点实验室，大连  116023
Published: December 2020

The space and time distributions of the electric field and the electron and ion densities, as well as the time evolutions of the discharge current density and the surface charge density of the dielectric layer in He dielectric-barrier-controlled glow discharge at atmospheric pressure are calculated by solving the on e-dimensional continuity and momentum equations for electrons and ions, coupled to the current continuity equation. The properties of uniform atmospheric pressu re glow discharge under the conditions of different driving frequency, voltage o r dielectric layer are discussed and analyzed. When the driving frequency is hig h enough, a large number of ions are trapped and the induced space charge field makes a great many of electrons stay in the discharge volume. These seed electro ns lead to a Townsend discharge at atmosphere pressure. The structure of this di scharge is similar to that of low-pressure glow discharge, i.e. there exist four specific regions: the cathode fall, the negative glow, the Faraday dark space a nd the positive column. The discharge current becomes small with decreasing voltage amplitude applied. The secondary electron emission from the dielectric layer makes the discharge current increase. The thicker the dielectric layer is or the smaller the permittivity, the smaller the discharge current is.
Deposition of vinyl acetic acid through the pulsed rf plasma polymerization
Authors: Zhang Jing  , Feng Xiang-Fen  , Xie Han-Kun  , Shi Yun-Cheng  , Pu Tian-Shu  ,   东华大学理学院，上海  200051
Published: December 2020

In this paper, pulsed rf plasma polymerization using vinyl acetic acid was investigated to obtain plasma polymers with less cross-linked structure and high-degr ee retention of the starting monomer groups. The chemical structure and the surf ace morphology of the polymerized vinyl acetic acid were characterized by Fourie r transform infrared ( FTIR) spectroscopy, x-ray photoelectron spectroscope (XPS ) and scanning electron microscope (SEM). The duty cycles were observed to be on e of the key parameters to change the film structure. The FTIR results showed th at more carboxylic groups could be “retained” with the decrease of the duty cy cles. The XPS results were consistent with the FTIR measurements. Surface energy measurements indicated that the plasma films were hydrophilic. So controlling t he chemical composition with some special surface functional groups being “rete nted” or “tailored” was available by pulsed plasma technologies. Some regular graft “lighting” network patterns were interestingly found in the plasma fil ms kept at room temperature for some time by SEM. It was estimated that the plas ma polymerization proceeded differently along the “lighting” network and on th e valley of the pattern. The details need to be further studied.
Experimental investigation of bublles by underwater wire exploding
Authors: Gao Bo  , Zhang Han-Hong  , Zhang Chi  ,   (1)中国科学技术大学近代物理系，合肥  230026; (2)中国科学技术大学力学与机械工程系，合肥  230026
Published: December 2020

The pulsation of bubbles generated by underwater wire exploding is studied by means of high-speed photography. We discovered that mechanical parameters of the b ubbles are mainly determined by the total discharge energy and related not much to the voltage and the capacitance. Boundary influence is also not too large in the experiment. The energy of pulsation occupies 20%—40% of the total discharg e energy, and the proportion between the pulsation energies of the first time an d the second time is about this value. The bursting forth phenomenon is the main reason of the decline of bubble's energy.