bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between energy distribution and space distribution of charge traps in linear low density polyethylene
Authors: Yang Qiang  , An Zhen-Lian  , Zheng Fei-Hu  , Zhang Ye-Wen  ,   同济大学波耳固体物理研究所，上海  200092
Published: December 2020

Space charge formation and evolution, charge trap distribution, and depolarization process in linear low density polyethylene (LLDPE) samples with semiconducting electrodes subjected to dc electric stress were systematically studied using the techniques of laser induced pressure pulse and thermally stimulated discharge. Space charge distribution and evolution in the samples showed obviously the characteristics of rapid and symmetrical injection of homo-charges from the two electrodes. The interface between the semiconducting electrode and LLDPE showed approximately ohmic contact properties. The charge trap distribution in LLDPE was characterized by shallow bulk traps and deep surface layer traps. Hot-pressing conditions between the semiconducting electrode and LLDPE or contamination of the surface layer of LLDPE by the semiconducting electrode material has a remarkable effect on energy distribution of the surface layer traps, resulting in depth and density decrease of the deeper traps and density increase of the shallower traps in the surface layer. During the whole short-circuit depolarization process, the centers of positive charges and negative charges in the sample shifted to their nearer electrodes, respectively, whereas behaviors different from the short-circuit depolarization were seen in the later stage of the open-circuit depolarization, that is, the positive charges captured in the deep surface layer traps were detrapped and shifted to the rearer electrode.
The influence of the matrix electrical conductivity on the dc poling behaviors and the loss of 0-3 ferroelectric composites
Authors: Yang Feng-Xia  , Zhang Duan-Ming  , Deng Zong-Wei  , Jiang Sheng-Lin  , Xu Jie  , Li Shu-Dan  ,   (1)华中科技大学电子系，武汉  430074; (2)华中科技大学物理系，武汉  430074
Published: December 2020

A dc poling model is developed for the 0-3 ferroelectric composite by employing Laplace equation, combined with certain boundary conditions and taken account of the initial conditions of the polymer/ferroelectric ceramic interfacial charges. Two kinds of 0-3 composites with different matrixes, namely the PZT/epoxy and PZT/P(VDF-TrFE) composites, were prepared. The influences of matrix electrical conductivity on the poling behaviors were studied experimentally and theoretically. The results showed that the experimental dates are fitted well with the theoretical results：with increased electric conductivity of the matrix, the poling time is shortened, and the polarization of ferroelectric ceramic and the total electric properties of composites are improved.Howerer,the leakage current and dielectric loss are increased,too.
X-ray absorption near-edge structure spectroscopy research on electronic structures and magnetic properties of (Fe1-xNix)2P
Authors: Ma Chen-Yan  , Cui Ming-Qi  , Zhang Ling-Yun  , Wu Xiang  , Zhou Ke-Jin  , Wu Zi-Yu  , Chen Xing  , Zhao Yi-Dong  , Zheng Lei  ,   (1)台湾同步辐射研究中心,新竹  30076; (2)中国科学院高能物理研究所,北京  100049
Published: December 2020

The Fe2P, Ni2P and (Fe1-xNix)2P compounds (x=01,025,05) are studied by X-ray absorption near- edge structure (XANES) spectroscopy at the Fe, Ni and P K-edges. Combined with full multiple-scattering approach calculations of XANES, different contributions of 3f, 3g crystallographic positions to XANES spectra for metal atoms are discussed. It was found that the Ni atom prefers to substitute Fe (3f) sites when introducing Ni atoms. The first-principle density of states calculations were performed and the results show that unoccupied P p-projected DOS of paramagnetic Fe2P and Ni2P are matched with their K-edges XANES spectroscopy. Comparison with DOS calculations for ferromagnetic Fe2P, indicates that the magnetism of Fe2P is mostly due to Fe(3g) sites. The magnetic moments calculated for Ni(3f) and Ni(3g) sites of ferromagnetic Ni2P approach zero, which is in accordance with the conclusion that Ni2P generally appears paramagnetic.
The influence of n-layer on structural properties of i-layer in n-i-p μc-Si∶H thin film solar cells
Authors: Yuan Yu-Jie  , Hou Guo-Fu  , Xue Jun-Ming  , Han Xiao-Yan  , Liu Yun-Zhou  , Yang Xing-Yun  , Liu Li-Jie  , Dong Pei  , Zhao Ying  , Geng Xin-Hua  ,   南开大学光电子薄膜器件与技术研究所，光电信息技术科学教育部重点实验室，光电子薄膜器件与技术天津市重点实验室,天津  300071
Published: December 2020

The intrinsic layers with different thickness were deposited on amorphous n-type layers and microcrystalline n-type layers respectively, and all samples were prepared by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). The effect of different n-type layers on structural properties of i-layer was studied. It is concluded that the highly microcrystalline n-layer can reduce the thickness of incubation layer, promote structural uniformity of i-layer and improve the performance of n-i-p μc-Si:H thin film solar cells.
An improved single molecule manipulation apparatus and its applications
Authors: Wang Xiao-Ling  , Zhang Xing-Hua  , Wei Kong-Ji  , Sun Bo  , Li Ming  ,   中国科学院物理研究所,北京凝聚态物理国家实验室,北京  100080
Published: December 2020

We report an improvement to the lateral-magnetic-tweezers which can be used to stretch and twist DNA molecules, and to probe the interaction between DNA and proteins. The apparatus enables not only direct measurement of the extension and rotation of DNA but also easy refreshing of the buffer in the flow chamber. With this apparatus, the experimental efficiency can be greatly improved by manipulating several DNA molecules simultaneously. The force exerted on DNA molecules ranges from 0.1 to 40pN, satisfying the requirement of most single molecule experiments. To demonstrate the applicability of the apparatus, we measured the extension-force curve and the extension-rotation curve of DNA and studied the translocation of DNA by a motor protein. The results agree well with those reported in the literature.
Stacking fault tetrahedra in single-crystal aluminum induced by high-current pulsed electron beam
Authors: Guan Qing-Feng  , Chen Bo  , Zhang Qing-Yu  , Dong Chuang  , Zou Guang-Tian  ,   (1)大连理工大学三束材料国家重点实验室，大连  116024; (2)吉林大学超硬材料国家重点实验室，长春  130012; (3)江苏大学材料学院，镇江  212013；吉林大学超硬材料国家重点实验室，长春  130012; (4)中国科学院长春光学精密机械及物理研究所应用光学国家重点实验室，长春  130033
Published: December 2020

The specimens of single-crystal aluminum were irradiated with high current pulsed electron beam (HCPEB). The vacancy cluster defect microstructure has been investigated by using transmission electron microscopy (TEM). The results show that three types of vacancy clusters including dislocation loop, void and even stacking fault tetrahedron (SFT), which are not normally formed in metals with high SFT formation energy, can be formed in single-crystal aluminum specimens irradiated with HCPEB. The nucleation process of three types of vacancy clusters do not appear at the same time. There is a close relationship between the three types of vacancy clusters. Based on the experimental results, a possible mechanism of SFT formation and evolution was presented.
The research of durative characteristics of dry/wet series of China during the past 1000 years
Authors: Gong Zhi-Qiang  , Feng Guo-Lin  ,   (1)扬州大学物理科学与技术学院,扬州  225002；中国科学院大气物理研究所东亚区域气候-环境重点实验室,北京  100029; (2)中国科学院大气物理研究所东亚区域气候-环境重点实验室,北京  100029；国家气候中心,中国气象局气候研究开放实验室,北京  100081
Published: December 2020

Using dry/wet index series of China during the past 531 years and 1041 years, by defining the dry (wet) grade and making running calculation of the appearance times of each dry (wet) grade in the original index series, it was shown that there is a exponential distribution P(x)=A*e-γx of the appearance times of each grade with respect to the window size. We defined 1/γ as the scale factor to characterize the dry (wet) durative and used it to analyze the dry (wet) durative of north China and the area between Yangtze and Huai rivers. Results show that the dry factor has the semi-belt wave distribution from north to south, the dry durative in north China is somewhat longer than that between Yangtze and Huai rivers, the average dry factors of area A, B and C are 1.87, 1.62 and 1.82, respectively. The dry (wet) durative is rather obvious in those intervals in which dry or wet are comparatively concentrated, so the large spatial scale and synchronized extreme dry accidents are easier to happen during the end of 12th century, the beginning of 13th century, the beginning of 17th century and the end of 20th century, which verifies the existence of cluster phenomena in the dry/wet index. The influence to dry durative in north China caused by the dry/wet index during 1260—1280 (the climate back ground being the end of the middle ages warm) was much lavger than that caused by the index during 1980—2000 (the climate background being the global warming). Furthermore, the number of dry years during 1260—1280 was also larger than that of 1980—2000. Obviously, serious, larger spatial scale and synchronized extreme dry accidents are easy to happen in warm periods, and the drought since 1970s in north China might be caused by co-operation of human and natural factors, in which the natural factor might have played the more important role.
Simulation of multiphase micro-drop dynamics using dissipative particle dynamics
Authors: Chang Jian-Zhong  , Liu Mou-Bin  , Liu Han-Tao  ,   (1)新加坡南洋理工大学化学与生物医学工程系，新加坡  649798; (2)中北大学机电工程学院，太原  030051
Published: December 2020

This paper presents a modified dissipative particle dynamics (DPD) method，which employs an interaction potential with short-range repulsion and long-distance attraction. The modified DPD method is capable of simulating liquids with free surfaces，the behavior of bubbly liquids，drop dynamics and other important multiphase fluid flow processes. The modified DPD method was used to investigate the formation of micro-drops，and the large-amplitude oscillations of an initially oblate liquid drop. The numerical results clearly demonstrate that the modified DPD method involving the interaction potential of short-range repulsion and long-distance attraction is capable of capturing the physics of multiphase micro-drop dynamics，and is of significant importance for investigating complex multiphase systems at micro-meso-scales.
Expressions of coordinate eigen vectors and their integration over non-symmetric coordinate projective operators
Authors: Li Ti-Jun  ,   菏泽学院物理系，菏泽  274015
Published: December 2020

The coordinate state vector 〈f(x)| is expressed with 〈x| in virtue of particle number states and the eigen equations of coordinate operator functions，accordingly we can convert non-symmetric projective operators into symmetric，the integrations over non-symmetric projective operators are obtained by the completeness relation of coordinate eigenstates.
A two-dimensional dark energy star model at finite temperature
Authors: Deng Qiang  , Yan Jun  ,   四川师范大学物理系，成都  610066
Published: December 2020

A 2-D dark energy star model with the action of strange matter is studied in this article. Equation set of the field and balance equation of star have been deduced，and some analytical solutions are obtained，which can be used to calculate the mass of the star. Moreover，we also investigated the influence of temperature on the mass of star and find that the gross mass of star has a upper limit in each case.
Effect of colored cross-correlated noise on the gene transcriptional regulatory system
Authors: Wang Can-Jun  , Mei Dong-Cheng  ,   (1)宝鸡文理学院非线性研究所，宝鸡  721007; (2)云南大学物理系，昆明  650091；宝鸡文理学院非线性研究所，宝鸡  721007
Published: December 2020

The transient properties (e.g., the mean first passage time T) of the gene transcriptional regulatory system driven by colored cross-correlated noise are investigated. The approximate Fokker-Planck equation is obtained based on the Novikov theorem and the Fox approach and the explicit expression of the mean first passage time is derived. The numerical computation results show that for the case of strong correlation intensity and short correlation time，a successive switch process (i.e.，“on”→“off”→“on”) occurs; for tha case of weak correlation intensity and long correlation time，only one switch process occurs (i.e.，“on”→“off”). The reentrance phenomena appear in the gene transcriptional regulatory system.
The principle of the phase track of Canard
Authors: Xu Yun  , Zhang Jian-Xia  , Xu Xia  , Zhou Hong  ,   (1)广东政法学院基础系，广州  510232; (2)贵州大学电工学院，贵阳  550003; (3)清华大学电机工程与应用电子技术系，电力系统及大型发电设备安全控制国家重点实验室，北京  100084
Published: December 2020

The complex phase tracks of Canard have caused concern of the scientists in the fields of physics，biology and chemistry. In order to find the accurate function describing the phase track of Canard，a nonlinear model involving consecutive segments is suggested，from which the analytical solution of the phase track function of a nonlinear second order autonomous function can be readily obtained，therefore the function describing the phase track of a Canard and its parametric conditions can be obtained analytically. It follows that all the phase tracks can be simply described by two kinds of functions.
Experimental research of human vision characteristic in the range of luminance of cathode ray tube display
Authors: Yao Jun-Cai  , Shen Jing  , Wang Jian-Hua  ,   (1)陕西理工学院计算机科学与技术系，汉中  723003; (2)陕西理工学院物理系，汉中  723003
Published: December 2020

The goal gratings of five frequencies with different mean luminance were displayed on a CRT display，the contrast detection thresholds under different condition were measured for 9 young observers，and the curve reflecting the relationship between luminance and contrast detection threshold was obtained. Thus，human vision characteristic for transferring luminance was discussed in the range of luminance of CRT. The experimental results showed that the contrast thresholds of different observers were very similar for gratings with frequencies of 3.79 and 4.97cpd，while they were quite different for gratings with frequencies of 1.23，1.97 and 9.86cpd，and the contrast detection threshold could be lowered by increasing the luminance of grating，but the resolving power went to a limit with the luminance increasing，and effect of the CRT display matched with human vision characteristic very well when the luminance was 60cd/m2. The results would make a good foundation for research and application in image manipulation，display manufacture，photography，printing，color matching and so on.
Study of Ba 6pnd(J=1, 3)autoionizing states
Authors: Yuan Wei-Guo  , Dai Chang-Jian  , Jin Song  , Zhao Hong-Ying  , Guan Feng  ,   天津理工大学理学院，天津  300384
Published: December 2020

Ba 6p3/2nd (J=1,3) autoionizing states, especially those with lower principal quantum numbers, have been experimentally studied using the isolated core excitation scheme with three dye lasers. Level energies and widths of 6p1/2nd and 6p3/2nd (J=1,3)autoionizing states, which are excited from 6snd1D2 Rydberg states with n=7—15 and 6snd3D2 Rydberg states with n=7—12, are reported. Examination of autoionizing states with lower principal quantum number (n=7—9) exhibited the admixture between states converging to 6p3/2 and 6p1/2 ionization threshold. Moreover, some discussion is made based on comparison between different autoionizing series, so that one may explain the complex spectral structures of these states.
Potential energy functions of Pb2 and PdPb2 molecules
Authors: Zhu Yu  , Fang Fang  , Jiang Gang  , Zhu Zheng-He  ,   (1)湖北民族学院理学院，恩施  445000; (2)湖北民族学院信息工程学院，恩施  445000; (3)四川大学原子与分子物理研究所，成都  610065
Published: December 2020

Density function method (B3LYP) has been used to optimize the possible structures of Pb2 and PdPb2 molecules by basis set (LANL2DZ) for Pd and Pb atoms. The Murrell-Sorbie potential energy function of Pb2 molecule has been fitted through the least square fitting, and the potential energy function of PdPb2is given by many-body expansion theory. The potential energy contours describe the structure character of PdPb2 ground state molecule rightly. Furthermore, molecular static reaction pathway based on this potential energy function is investigated.
Influences of temperature and polaron effect on the ground state of quasi-two-dimensional strong-coupling exciton
Authors: Eerdunchaolu  ,   河北科技师范学院数理系，秦皇岛  066004
Published: December 2020

The influences of temperature and polaron effect on the ground state of the system，for which the exciton is strongly coupled with interface-optical (IO) phonons but weakly coupled with bulk-longitudinal-optical (LO) phonons in a quantum well, are studied by using the Huybrechts' linear-combination operator and Lee-Low-Pines (LLP) transformation method. The expressions for the induced potential and energy shift of the ground state of the exciton were derived. Numerical calculations for AgCl/AgBr QW, as an example, are performed. The result indicates that the induced potential and the energy shift increases for strong exciton-IO-phonon coupling but decreases for weak exciton-LO-phonon coupling with temperature.
Research on the tunable left-handed properties of split-ring resonator with ferrite substrate
Authors: Ai Fen  , Bai Yang  , Xu Fang  , Qiao Li-Jie  , Zhou Ji  ,   (1)北京科技大学材料科学与工程学院环境断裂教育部重点实验室,北京  100083; (2)清华大学新型陶瓷与精细工艺国家重点实验室,北京  100084
Published: December 2020

The left-handed material, whose permittivity and permeability are simultaneously negative, has some exotic electromagnetic properties, and is one of the most absorbing subjects in recent physical academic domain. This paper suggests that a tunable left-handed metamaterial can be realized by using ferrite as the substrate of metallic wire structure, owing to the field dependence of ferrite's permeability. Finite element method was used to simulate the effect of substrate properties on the effective properties of a metamaterial slab. With the rise of substrate permittivity or permeability, the resonance frequency drops significantly. Ferroxplana has been prepared, and the field dependence of its permeability was studied.
Characteristic of a narrow beam under the grazing reflection condition
Authors: Yu Hui  , Jiang Xiao-Qing  , Yang Jian-Yi  , Qi Wei  , Wang Ming-Hua  ,   浙江大学信息与电子工程学系，杭州  310027
Published: December 2020

For the grazing incidence of a narrow beam, a part of plane wave components can not reach the reflecting interface directly, so they can not be reflected and transmitted in the traditional way. The inverse mode of reflection and transmission is proposed in this paper to describe the interaction between the non-incident plane wave components and the reflection region. Based on the two modes, the plane wave expansion method is utilized to derive exact distribution of the output optical field. Theoretical calculation agrees well with the simulation result which employs the BPM algorithm.
The experimental research on a stable free-space quantum key distribution system with low noise
Authors: Wang Jin-Dong  , Lu Wei  , Zhao Feng  , Liu Xiao-Bao  , Guo Bang-Hong  , Zhang Jing  , Huang Yu-Xian  , Lu Yi-Qun  , Liu Song-Hao  ,   (1)华南师范大学信息光电子科技学院光子信息技术广东省高校重点实验室，广州  510631; (2)中国科学院合肥智能机械研究所，合肥  230031
Published: December 2020

A free-space quantum key distribution system is demonstrated experimentally which makes use of polarized coherent short laser pulses and the differential phase shift scheme with a Faraday-Michelson interferometer. The system features low noise, high stability and low bit-error rate. In the proposed experimental scheme, polarizated short laser pulse of several nanoseconds duration is made to transmit through the free space to decrease noise and a low bit-error rate less than 6% is achieved.
Experimental study on laser pattern formation by strong nonlinear effects in rubidium atomic hot vapor
Authors: Guo Lu  , Wei Dong  , Chen Hai-Xia  , Xiong De-Zhi  , Wang Peng-Jun  , Zhang Jing  ,   山西大学光电研究所，量子光学与光量子器件国家重点实验室，太原  030006
Published: December 2020

There are abundant nonlinear effects in atomic vapor. In this paper, the phenomenon of laser breaking up into filaments is studied in the near-resonant rubidium atomic vapor，which is induced by the strong nonlinear Kerr effect. When the continuous-wave laser beam with transverse Gaussian distribution passes through the atomic vapor, the pattern arising from the coherent superposition of the diffraction patterns of filaments is observed. We also investigated the influence on the mode pattern by input power of laser, the temperature of the vapor cell and the frequency detuning of pump light. Due to the hyperfine structure of rubidium atoms, the four-wave mixing effect exists in hot rubidium atomic vapor, which is related to the third-order nonlinear effect closely. The Raman gain of the Stokes and anti-Stokes photons is observed by scanning the frequency of the probe beam.
A study based on diffusion theory for exchange-reaction of RLA model
Authors: Zheng Xiao-Ping  , Zhang Pei-Feng  , Fan Duo-Wang  ,   (1)兰州城市学院电子信息科学与技术研究所，兰州  730070；兰州交通大学光电技术与智能控制教育部重点实验室，兰州  730070; (2)兰州交通大学光电技术与智能控制教育部重点实验室，兰州  730070; (3)兰州交通大学光电技术与智能控制教育部重点实验室，兰州  730070；兰州大学数学与统计学院，兰州  730000
Published: December 2020

In the research work, on the basis of the classic diffusion theory we have advanced a novel model of the reaction limited aggregation (RLA), which involues the basic micro-processes. We firstly introduced the concept of exchange rate and have also simulated the growing process of surfactant-mediated epitaxial thin film growth with the kinetic Monte Carlo (KMC) method. By simulating, it was found that both surfactant atoms and adatoms would diffuse from one layer to another. This kind of diffusion mainly happens beween single atoms and the number of this diffusion increases with increasing growth temperature or increasing deposition depth. The exchange reaction of RLA model is the combination of several basic micro-processes. The majority of exchanges are not complete position exchange and the exchange ratio is not always equal to unity.
Reconstruction algorithm of relaxation attenuation spectrum in polyatomic gas
Authors: Yan Shu  , Wang Shu  ,   华中科技大学电子与信息工程系，武汉  430074
Published: December 2020

A reconstruction algorithm that synthesizes the relaxation attenuation spectrum in a wide frequency range is presented. And the effective relaxation time of gas can be estimated by two approaches, which are base on SSH theory and experimental data, respectively. The acoustic attenuation spectra of various polyatomic gas mixtures, consisting of nitrogen, methane, oxygen, carbon dioxide and water, were estimated by the reconstruction algorithm. The sound frequency rang of interest is from 1 Hz to 10 GHz. Comparing with the results of the relaxation attenuation based on the DL model, the estimations of relaxation attenuation of the reconstruction algorithm agreed with the latter. The precision of the reconstruction algorithm depends upon the knowledge of the physical mechanism of molecular relaxation processes. In addition, the reconstruction algorithm was applied to quantitatively determining the concentrations of water and carbon dioxide in some polyatomic gas mixtures. The results show that the relaxation attenuation can be used as a quantitative probe of the composition of polyatomic gas mixtures. And this could lead to the development of smart acoustic gas sensors capable of determining the precise compositions of gas mixtures.
Structure and magnetic properties of Zn1-xCoxO thin film
Authors: Wu Wen-Qing  , Shi Tong-Fei  , Zhang Guo-Bin  , Fu Yi-Bing  , Pan Zhi-Yun  , Sun Zhi-Hu  , Yan Wen-Sheng  , Xu Peng-Shou  , Wei Shi-Qiang  ,   中国科学技术大学国家同步辐射实验室，合肥  230029
Published: December 2020

Zn1-xCoxO (x=0.01, 0.02) dilute magnetic semiconductor thin films deposited on Si (001) substrates at 650℃ by pulsed laser deposition method were studied by X-ray absorption fine structure, X-ray diffraction and magnetic measurement. The typical ferromagnetic hysteresis curves were obtained by superconducting quantum interference device magnetometry at room temperature. The X-ray diffraction results showed that Zn1-xCoxO films were of the wurtzite structure. The X-ray absorption fine structure results revealed that the Co atoms were incorporated into the ZnO lattice and located at the substitutional Zn sites, and a homogeneous phase of Zn1-xCoxO was formed. Comparing the experimental curves with the theoretical calculation results, the additional peak C was assigned to the oxygen vacancies, which indicated that the ferromagnetism of Zn1-xCoxO films was strongly correlated with the existence of oxygen vacancies.
Study on the magnetic susceptibility of quasi-one-dimensional spin ladder compounds (Sr1-xCax)14Cu24O41-δ with oxygen deficiency
Authors: Wang Li-Li  , Xiong Rui  , Wei Wei  , Hu Ni  , Lin Ying  , Zhu Ben-Peng  , Tang Wu-Feng  , Yu Zu-Xing  , Tang Zheng  , Shi Jing  ,   (1)武汉大学物理系声光材料与器件教育部重点实验室，武汉  430072; (2)武汉大学物理系声光材料与器件教育部重点实验室，武汉  430072；中国科学院国际材料物理中心，沈阳  110016
Published: December 2020

Three samples of spin ladder compounds (Sr1-xCax)14Cu24O41-δ (x=0, 0.25, 0.43) were prepared by conventional solid-state reaction in air. The EDS results revealed that all three samples are in the state of oxygen deficiency (δ＝7.64，6.99　and 6.67, respectively). X-ray diffraction showed that the samples have single phase, and the lattice parameters a, b, c decrease continuously with the increase of oxygen content. For the sample withoutca Ca doping, the measurement of magnetic susceptibility showed that oxygen deficiency reduces the number of holes and Z-R singlets, and leads to the increase of free spins and the decrease of dimer spins. For Ca doped samples, the oxygen deficiency decreases with the increase of Ca content, but Ca doping enhances the transfer of holes from spin chains to spin ladders.
Theoretical study of ignition-proof mechanism of RE element in Mg alloys
Authors: Liu Gui-Li  ,   沈阳工业大学建筑工程学院，沈阳  110023
Published: December 2020

The atomic cluster models of α-Mg, liquid Mg and the interface between liquid/solid have been founded by computer program. The environment-sensitive embedding energy of RE elements in α-Mg, liquid Mg, liquid/solid interface has been calculated by recursion method. The atomic affinity energy between Mg, La, Y with O has been defined and calculated. The calculated results show that the solid solubility of La and Y is very small in α-Mg, because their higher environment-sensitive embedding energy leads to instability in α-Mg crystal. The RE elements diffuse to the liquid Mg, which has lower environment-sensitive embedding energy than the solid, and congregate on the surface of liquid Mg as the alloy solidifies. Because the atomic affinity energy of RE-O is lower than Mg-O(The atomic affinity energy between Mg, La, Y with O are Mg-O：-14.9338eV，La-O：-19.0608 eV，Y-O：-19.5050 eV, respectively), the RE elements congregating on the surface of liquid Mg will priorily combined with O, forming compact RE oxides, which prevent Mg alloys from burning.
Novel silicon nanostructures based on graphene ribbons
Authors: Li Ai-Hua  , Zhang Kai-Wang  , Meng Li-Jun  , Li Jun  , Liu Wen-Liang  , Zhong Jian-Xin  ,   湘潭大学材料与光电物理学院,湘潭  411105
Published: December 2020

In this paper，we have studied formation processes of silicon nanostructures on edges of graphene ribbons by molecular dynamics simulation.We found that，Si atoms in a gas state can be absorbed on the edges of zigzag graphene ribbons，forming different types of silicon nanostructures under different temperature T，namely，amorphous clusters，chain structures and defective chain structures in the intervals 300K≤TT≤2800K and 2800KTT≥3900K，carbon atoms on the edges of graphene ribbons are gradually replaced by Si atoms.For the graphene ribbons with armchair edges，existence of multiple adsorption sites does not allow growth of chain-like Si nanostructures.
On epitaxial structure and flux pinning of NdBa2Cu3O7-δ/YBa2Cu3O7-δ superconducting multilayers
Authors: Chen Chang-Zhao  , Cai Chuan-Bing  , Liu Zhi-Yong  , Ying Li-Liang  , Gao Bo  , Liu Jin-Lei  , Lu Yu-Ming  ,   上海大学物理系，上海  200444
Published: December 2020

By using pulsed-laser deposition technique, a series of multilayers of NdBa2Cu3O7-δ/YBa2Cu3O7-δ, namely with the structures of p×［NdBa2Cu3O7-δ(m)/YBa2Cu3O7-δ(n)］, are prepared on single-crystal SrTiO3, where m and n denotes the number of laser pulses and p is the number of repetetions. XRD patterns indicate that all samples are highly c-axis oriented, and the superconducting transition temperatures of these samples are in the range of 87—91 K, depending on different modulating structures. The larger the modulation period p and consequently the more the interfacial surfaces, the lower the superconducting transition temperature. Magneto-transport measurements reveal that the quasi-multilayers such as NY3［40×(75/5)］ (island-like YBa2Cu3O7-δ distributed in NdBa2Cu3O7-δ films) exhibit not only the highest Tc, but also the best magnetic properties. The critical current density of such a quasi-multilayers can be as high as 4×106 A/cm2 under self fields, showing the promising potential application for coated conductors.
Quantum behavior of a hydrogen atom in metal Nb
Authors: Liu Zhi-Ming  , He Zhi  , Ma Yan-Ming  , Cui Tian  , Liu Bing-Bing  , Zou Guang-Tian  ,   吉林大学超硬材料国家重点实验室，长春  130012
Published: December 2020

The potential that a hydrogen atom experiences in a metallic niobium crystal is calculated using the pseudopotential plane-wave method based on density functional theory. The quantum states of the hydrogen atom in such a potential are obtained by solving Schrdinger equation directly. The ground state and the first excited state are shown to be local, while the others are delocalized. A hydrogen atom in high excited states may move on a 4T or 6T ring.
Influences of atom vacancies on buckling properties of armchair single-walled carbon nanotubes shown by molecular dynamics simulation
Authors: Xin Hao  , Han Qiang  , Yao Xiao-Hu  ,   华南理工大学土木与交通学院工程力学系，广州  510640
Published: December 2020

Molecular dynamics simulations are employed to simulate the axial compression of both perfect and defective armchair single-walled carbon nanotubes (SWCNTs). Three temperature conditions are considered. It is revealed that the vacancy defects in SWCNTs have remarkable influences on their buckling properties, especially at low temperature. It is noticed that the single vacancy defect leads to excessive stress concentration, as a result of which the local buckling occurs easily at the defective position. Thus, the (7, 7) tube with single vacancies seems inferior to that with double vacancies.
Oxygen pressure effect on lattice parameters of SrTiO3 and SrNb0.2Ti0.8O3 thin films and laser-induced thermoelectric voltages effect
Authors: Liu Ting  , Tan Song-Lin  , Zhang Hui  , Qin Yi  , Zhang Peng-Xiang  ,   昆明理工大学光电子新材料研究所，昆明  650051
Published: December 2020

SrTiO3 and SrNb0.2Ti0.8O3 thin films were prepared by pulsed laser deposition technique on LaAlO3 (100) single crystal substrates. X-ray diffraction shows that all the thin films have［001］ orientation. With the oxygen pressure increasing, the lattice parameter c of SrTiO3 thin films decreases, while the lattice parameter c of SrNb0.2Ti0.8O3 thin films decreases and then increases. Meanwhile, the optimal oxygen pressure to prepare (SrTiO3/SrNb0.2Ti0.8O3)L multilayer of two-dimensional electron gas was found to be 1.0×10-2Pa. In addition, laser-induced thermoelectric voltage effect was observed on SrNb0.2Ti0.8O3 thin film prepared on vicinal-cut LaAlO3 (100) substrate for the first time.
Effect of impurity P on electronic structure of kink in the edge dislocation of α-iron
Authors: Chen Li-Qun  , Yu Tao  , Wang Chong-Yu  , Qiu Zheng-Chen  ,   (1)钢铁研究总院功能材料研究所，北京  100081; (2)钢铁研究总院功能材料研究所，北京  100081；清华大学物理系,北京  100084; (3)中南林业科技大学理学院，长沙  410004
Published: December 2020

Using the first-principles self-consistent discrete variational method based on density functional theory, we have investigated the effect of impurity P on the electronic structure of the kink on the ［100］(010) edge dislocations in bcc iron. Furthermore，we have calculated the segregation energy, the interatomic energy, the local density of states and the charge density. Our results show that the P atom proeures electrons from its neighboring Fe atoms when trace P is introduced into interstitial sites in the kink. It is found that the interactions between impurity P atom and neighboring Fe atoms are strengthened due to the strong hybridizations between P-p with Fe-3d4s4p states. The migration of kink and dislocation motion are impeded by P, which may be beneficial to increase the strength of material. Meanwhile, the bonding between the impurity P and the host Fe atoms are mainly ascribed to contribution of p and d states, which leads to the bonding between them to have strong orientation. This is not beneficial to the toughness of materials.
Properties of quantum bit in quantum ring
Authors: Gao Kuan-Yun  , Zhao Cui-Lan  ,   内蒙古民族大学物理与电子信息学院,通辽  028043
Published: December 2020

Electronic states of quantum ring are obtained by solving precisely the energy eigen-equation and a quantum bit is formed by both the ground state and the first excited state of the electron in the quantum ring. The numerical results for InAs/GaAs quantum ring indicate that when the size of quantum ring has been determined, the probability density distribution of an electron is related to its position in the quantum ring and time, there is a maximum of probability density for the given angle and time, and the probability density distribution of electron makes periodical oscillations in time and space.
Effect of control oxide on the performance of nanocrystalline silicon based double-barrier floating gate memory structure
Authors: Ding Hong-Lin  , Liu Kui  , Wang Xiang  , Fang Zhong-Hui  , Huang Jian  , Yu Lin-Wei  , Li Wei  , Huang Xin-Fan  , Chen Kun-Ji  ,   南京大学物理系，固体微结构国家重点实验室，南京  210093
Published: December 2020

The silicon dioxide (SiO2) film was fabricated from layer-by-layer depositing amorphous silicon (a-Si) film combined with step-by-step plasma oxidation in the plasma-enhanced chemical vapor deposition (PECVD) system. The capacitance-voltage(C-V) and conductance-voltage(G-V) characteristics show that the fixed charge and interface state densities of the SiO2 film are 9×1011 cm-2 and 2×1011 cm-2·eV-1, respectively. Furthermore, the breakdown field strength is as high as 4.6 MV/cm, which is comparable to that formed by hot oxidation. The prepared SiO2 is employed as control oxide in nc-Si based double-barrier floating gate memory structure and is found to be an effective way to prevent the charge exchange between the gate electrode and nc-Si, which also lead to an enhancement in the retention time. The improved performance of the memory is discussed and is ascribe to the moderate-thickness of SiO2 as well as its excellent electrical properties.
Study on mechanism of AlGaN/GaN high electron mobility transistors by high temperature Schottky annealing
Authors: Lin Ruo-Bing  , Wang Xin-Juan  , Feng Qian  , Wang Chong  , Zhang Jin-Cheng  , Hao Yue  ,   西安电子科技大学微电子学院，宽禁带半导体技术重点实验室，西安  710071
Published: December 2020

Under different stress, the current collapse, gate current leakage and breakdown voltages of AlGaN/GaN high electron mobility transistors change before and after high temperature annealing. The results show that characteristics of devices are greatly improved for AlGaN/GaN high electron mobility transistor after Schottky high temperature annealing. Interface of Schottky contacts is studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) before and after high temperature annealing. The analysis indicates that eliminating the medium between Ni and AlGaN and reducing of traps near the surface of AlGaN can improve the effective Schottky barrier, which can enhance the electric characteristics of the devices.
Magnetic interactions as well as microscopic origins of the spin-Hamiltonian parameters for 6S(3d5) state ions in cubic symmetry crystal filed
Authors: Yang Zi-Yuan  ,   宝鸡文理学院物理系，宝鸡  721007
Published: December 2020

The magnetic interactions as well as the microscopic origins of the spin-Hamiltonian(SH) parameters including a, g, and Δg for 6S(3d5) state ion in cubic symmetry crystal field, taking into account the spin-spin (SS), the spin-other-orbit (SOO), the orbit-orbit (OO) magnetic interactions besides the well-known spin-orbit (SO) magnetic interaction, have been investigated using the complete diagonalization method (CDM). It is shown that the SH parameters arise from the five microscopic mechanisms of SO coupling, SS coupling, SOO coupling, OO coupling, and SO-SS-SOO-OO combined coupling. The relative importance of the contributions of the mechanisms to the SH parameters are investigated. It is shown that the SO coupling mechanism and the SO-SS-SOO-OO combined coupling mechanism are the most important of these coupling mechanisms. The contributions from SS coupling mechanism, SOO coupling mechanism, OO coupling mechanism to the SH parameter are quite small but their combined effects (SO-SS-SOO-OO combined coupling mechanism) is appreciable. The zero-field splitting (ZFS) arises from the net spin quartet states as well as the combined effects between the spin doublet states and the spin quartets states whereas the Zeeman g (or Δg)factor arises from the net spin quartet states. The contributions to the SH parameters from the net spin doublet states are zero. It is found that the relations: a>0，a(-|Dq|)a(|Dq|)，g(-Dq)=g(Dq)，a(-Dq,-ξd, B, C)=a(Dq,ξd, B, C) and Δg(-Dq, -ξd, B, C)=Δg(Dq, ξd, B, C) always hold for the selected crystal field area.Illustrative evaluations are performed for the four typical materials. Mn2+: KZnF3, Mn2+: RbCdF3, Mn2+: MgO and Mn2+: CaO. Good agreement between the theoretical values and the experimental results are obtained.
Fabrication and magnetic properties of CoxCu1-x composite nanowire arrays
Authors: Liu Xiao-Xu  , Chen Gui-Feng  , Li Yang-Xian  , Xu Shi-Feng  , Wu Guang-Heng  , Xu Qiu  , Wang Hong-Yan  , Liu Bao-Hai  , Shi Hong-Wei  , Wang Ji-Xia  , Zhao Yu-Hai  ,   (1)河北工业大学材料学院，天津  300130; (2)河北科技师范学院数理系，秦皇岛  066004; (3)中国科学院物理研究所北京凝聚态物理国家实验室，北京  100190
Published: December 2020

A series of composite structured CoxCu1-x(x=0.38—0.87) nanowire arrays have been successfully deposited in the same Co2+/Cu2+=10∶1 solution by applying various depositing potentials. We found that the structures of CoxCu1-x composite nanowires regularly changed with increase of Cu content, thus causing regular change of the magnetic properties of CoCu nanowires. With the percent content of Cu increasing, part of Cu and Co form metastable face-centred cubic (fcc) CoCu solid solution which decreases the competition between the crystallographic anisotropy and shape anisotropy and improves the squareness of CoCu nanowires; the remaining part of Cu exists in the nanowires as fcc Cu crystals which destroy the crystallographic anisotropy and increases the pinning of domain walls, thus improves the squareness and coercivity of CoCu nanowires. Comparing CoxCu1-x nanowires of different compositions, we found that the nanowires have their maximum of the squareness (Mr/Ms) and coercivity (Hc) values for Co75Cu25 and Co60Cu40, respectively. Because of the special composite structures, the values exceed those of single phase CoCu nanowire with the same diameter.
Effect of annealing on the high Co-doped Ti1-xCoxO2 magnetic semiconductor
Authors: Song Hong-Qiang  , Wang Yong  , Yan Shi-Shen  , Mei Liang-Mo  , Zhang Ze  ,   (1)北京工业大学,北京  100022; (2)山东大学威海分校空间科学与应用物理系,威海  264209；山东大学物理与微电子学院,济南  250100; (3)山东大学物理与微电子学院,济南  250100; (4)中国科学院物理研究所,北京  100190；澳大利亚昆士兰大学工学院，澳大利亚
Published: December 2020

High Co doping concentration Ti1-xCoxO2 magnetic semiconductor films were prepared by rf co-sputtering and then annealed for 2 hours at 200℃, 300℃ and 400℃ respectively. Microstructure and composition analysis by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) indicated that the films were in the metastable state and the annealing has large effect on their microstructure, composition and magnetism.
Research on the performace of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 single crystal/polymer 1-3 piezoelectric composite material
Authors: Zhou Dan  , Luo Lai-Hui  , Wang Fei-Fei  , Jia Yan-Min  , Zhao Xiang-Yong  , Luo Hao-Su  ,   (1)中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室，上海  201800; (2)中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室，上海  201800；中国科学院研究生院，北京  100049
Published: December 2020

The electrical properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-0.3PT) single crystal/polymer 1-3 composites were simulated under different volume fraction of the piezoelectric phase. It was concluded that the composites exhibit optimal properties when the PMN-0.3PT volume fraction is around 64%. Under this volume fraction, the composites with different polymer phases were fabricated using dice-and-fill method. Experiment shows that the stiffness coefficient c, density ρ, as well as the bonding strength have great influence on the obtained properties of the composites. The composites exhibit excellent properties, with electromechanical coupling factor kt as high as 90.1%, piezoelectric d33 larger than 1000 pC/N, mechanical quality factor Qm only 10.39, and acoustic impedance Z less than 20 MRayls. The results indicate that these piezoelectric composites are promising candidates for transducer and sensor applications.
Optical microwave generation based on DFB lasers
Authors: Xie Hong-Yun  , Jin Dong-Yue  , He Li-Jian  , Zhang Wei  , Wang Lu  , Zhang Wan-Rong  , Wang Wei  ,   (1)北京工业大学电子信息与控制学院，北京  100022; (2)中国科学院半导体研究所，集成光电国家重点实验室，北京  100083
Published: December 2020

A new device of two parallel distributed feedback (DFB) lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB lasers in parallel, which had a small difference in frequency. Continuous rapidly tunable optical microwave signals from 13 GHz to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.
Simulation of the influence of convection velocity on upstream dendritic growth using phase-field method
Authors: Chen Yu-Juan  , Chen Chang-Le  ,   西北工业大学凝聚态结构与性质陕西省重点实验室，西安  710072
Published: December 2020

The phase-field model based on the Tong and Beckermann model coupled with the flow field is used to simulate two-dimensional microstructural dendrite growth of metal by way of finite difference method. The effect of different convection velocities on metal dendritic crystal growth is studied. The result shows that the upstream and downstream dendritic crystal present asymetric pattern: the growth velocity of upstream is much fasfer than downstream. As the velocity of convection increases，actual supercooling of upstream dendritic crystal increases，the growth velocity of dendritic crystalis also speeded up. This is because of the bigger convection velocity leads to stronger flushing to the upstream dendritic crystal and the greater actual supercooling of upstream dendritic crystal，making the dendritic crystal to grow faster.
A novel parameter estimation method of signal in chaotic background
Authors: Chen Zheng  , Zeng Yi-Cheng  , Fu Zhi-Jian  ,   湘潭大学材料与光电物理学院，湘潭  411105
Published: December 2020

To estimate the parameters of signal in chaotic background is very important. A novel method named minimization of relative singular value(MRSV) is proposed in this paper, which is based both on the fact that points reconstructed from the mixed signal time series typically lie off the embedded image of the manifold for the dynamics underlying the chaotic time series, and also on the characteristic of the signal in chaotic background. The parameter estimation can be achieved by minimizing the relative singular value of the output of an inverse filter of the received signal in a reconstructed phase space. Several experiments of estimating the AR model parameters and sinusoidal signal frequency are carried out to confirm the effectiveness of the method.
Analysis of extreme events in China’s temperature in recent 50 years using detecting method based on median
Authors: Zhang Da-Quan  , Qian Zhong-Hua  ,   (1)扬州大学物理科学与技术学院，扬州  225009；国家气候中心气候研究开放实验室，北京  100081; (2)扬州大学物理科学与技术学院，扬州  225009；中国科学院大气物理研究所东亚区域气候-环境重点实验室，北京  100029
Published: December 2020

Based on daily and monthly temperature records from 1957 to 2001 of China，using climate extreme detecting method based on average and median，we have analyzed the transition and distribution of frequency of temperature extremes.The results indicate that while the average number of extreme high temperature events per year has been increased in the last 50 years,the extreme low temperature events decreased.Except for some stations located in southwest China，the frequency of extreme low temperature events in most regions over China decreased.The spatial pattern of transition of frequency of extreme high temperature events showed decreased in southeast coastal regions and increase in inland regions.
Generalized variational iteration solving method for gain gluence of a laser pulse amplifier
Authors: Lin Wan-Tao  , Mo Jia-Qi  , Zhang Wei-Jiang  , Chen Xian-Feng  ,   (1)安徽师范大学数学系,芜湖  241000; (2)上海交通大学数学系,上海  200240; (3)中国科学院大气物理研究所,北京  100029
Published: December 2020

The model for gain fluence of a laser pulse amplifier is studied. Firstly, using the generalized variational iteration method, the Lagrange multipicator is determined. Then the iteration expansions are constructed. Thus approximate solutions for the corresponding model are obtained.
An inverse problem of dynamics of a generalized Birkhoff system
Authors: Mei Feng-Xiang  , Xie Jia-Fang  , Gang Tie-Qiang  ,   北京理工大学力学系  北京  100081
Published: December 2020

For the generalized Birkhoff system dynamics, the authors present a kind of inverse problem. The generalized Birkhoff system equations are established by using given integral manifolds. The solution of the problem, in general, is not unique. In order to obtain a determining solution, some additional conditions are required. An example is given to illustrate the application of the result.
Non-Noether conserved quantity for relativistic nonholonomic controllable mechanical system with variable mass
Authors: Xia Li-Li  , Li Yuan-Cheng  ,   (1)河南教育学院物理系,郑州  450014; (2)中国石油大学(华东)物理科学与技术学院,东营  257061
Published: December 2020

The non-Noether conserved quantity for relativistic nonholonomic controllable mechanical system with variable mass is discussed under special infinitesimal transformations in which the time is not a variable. The differential equations of motion of the system are established. The definition and criterion of the form invariance of the system under special infinitesimal transformations are discussed. The necessary and sufficient conditions under which the form invariance is a Lie symmetry is presented. The conditions under which a non-Noether conserved quantity can be induced by the form invariance and the form of the conserved quantity are obtained. An example is presented to illustrate the application of the result.