bluuebunny/crossref_metadata_2025 huggingface dataset:
Photocatalytic activity of tungsten trioxide/silver oxide composite under visible light irradiation for methylene blue degradation
Authors: Shao Zi-Qiao  , Bi Heng-Chang  , Xie Xiao  , Wan Neng  , Sun Li-Tao  ,   FEI Nano-Pico Center, Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096, China
Published: December 2020

Dye pollution,one of the most serious problems in water pollution,has attracted the attention of scientists.There are many methods,such as chemical oxidation,physical adsorption,biodegradation,photocatalysis,etc.,that have been adopted to handle the crisis of dye polultion. Compared with other strategies,photocatalysis has its unique advantages including low energy consumption,environment amicableness and high efficiency.Tungsten trioxide (WO3),a semiconductor with a band gap of 2.8 eV,has unique physical and chemical properties,and it has been applied to the area of photocatalysis to solve the problem of water pollution in recent years.However,the photocatalytic efficiency of bulk tungsten oxide fails to reach the expected.In this paper,a one-dimensional complex of tungstun trioxide and silver oxide (WO3/Ag2O) is synthesized via a simple hydrothermal method for photocatalytic degradation of methylene blue.The crystal structure,morphology and photocatalytic degradation ability towards methylene blue are characterized and analyzed via X-ray diffraction,scanning electron microscopy,transmission electron microscope,X-ray photoelectron spectroscopy,and UV-Vis spectrophotometer.Silver oxide (Ag2O),with a band gap of 1.2 eV,is found to be sensitive to visible light.The combination of tungsten trioxide and silver oxide promotes its photocatalytic efficiency dramatically under visible light illumination. Results show that WO3 nanorods in the composite possess a one-dimensional,hexagonal structure with an average length of 4μm and a diameter of 200 nm.The Ag2O attached to WO3 nanorods forms hexagonal nanoparticles and their average diameter reaches 20 nm.It is observed that WO3/Ag2O composite displays a loose structure and a high specific surface area,which provides more reactive sites.Comparing with single component,UV-Vis spectrophotometry shows that the composite has a highabsorbance in the range of visible light.The combination of tungsten trioxide and silver oxide can change the band gap of the photocatalyst whereas the photocatalytic efficiency of the composite reaches 98% in 60 min under visible light.Therefore,the synergistic effect of WO3 and Ag2O plays a vital role in enhancing the photocatalytic performance.Moreover,the stability of photocatalyst is one of the most important indicators of its recycling and long-term effectiveness,and the present WO3/Ag2O composite has good catalytic and chemical stability.This investigation proves that the combination of wide bandgap photocatalysts with visible-light sensitive metal oxide with large specific area will improve photocatalytic activity efficiently under visible light.
Experimental study on Ti K shell ionization cross sections induced by 8-9.5 keV positrons
Authors: Qian Yu-Rui  , Wu Ying  , Yang Xia-Tong  , Chen Qiu-Xiang  , You Jun-Dong  , Wang Bao-Yi  , Kuang Peng  , Zhang Peng  ,   Beijing Key Laboratory of Passive Safety Technology for Nuclear Energy, North China Electric Power University, Beijing 102206, China;,   Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049, China
Published: December 2020

Due to lack of experimental data of the inner shell ionization cross sections induced by low-energy positron, advanced theoretical models developed in recent years cannot be correctly evaluated, and the application of slow positron beam technique is greatly limited. Here we present the method of obtaining reliable experiment data of atomic inner-shell ionization cross section by positron impact. In this work, the slow positron beam device is used to generate 8-9.5 keV positron beams impacting on a pure thick Ti target, and the silicon drift detector (SDD) is adopted to collect the X-ray spectra produced by positrons impacting on thick Ti target, and the incident positron numbers are obtained by applying an HPGe detector to on-line collect annihilation photons. Then the experimental characteristic X-ray yields of Ti K shell impacted by 8-9.5 keV positron could be acquired. Meantime, the simulated characteristic X-ray yields are acquired by the PENELOPE program simulating the experiments. In the comparison between the experimental yields and the simulated yields based on two sets of different inner shell ionization cross section database in the PENELOPE code, i.e. the optical data model (ODM) and the distorted-wave Born approximation model (DWBA), there is a large difference between the simulated data from the ODM theoretical model and the experimental values, while the simulated yields from the DWBA theoretical model are in good agreement with the experimental results. Accordingly, a correction factor is introduced to modify the DWBA theoretical model database which is used in the PENELOPE, and then the experimental process is re-simulated. When the simulated yields and the experimental yields are in the highest consistence, the reliable Ti K shell ionization cross sections impacted by 8-9.5 keV positron could be obtained. The biggest advantage of using this method to obtain atomic inner-shell ionization cross section impacted by positron is that the effects of the multiple scattering of incident positrons in the thick target, from the bremsstrahlung and annihilation photons, and other secondary particles on the experimental characteristic X-rays do not need calculating (the calculation method that has been developed previously cannot give the more correct result about the contribution of the multiple scattering of incident positrons, from the bremsstrahlung and annihilation photons, and other secondary particles to characteristic X-rays).
Recent progress of the glassy materials and physics
Authors: Sun Yi-Tao  , Wang Chao  , Lü Yu-Miao  , Hu Yuan-Chao  , Luo Peng  , Liu Ming  , Xian Hai-Jie  , Zhao De-Qian  , Ding Da-Wei  , Sun Bao-An  , Pan Ming-Xiang  , Wen Ping  , Bai Hai-Yang  , Liu Yan-Hui  , Wang Wei-Hua  ,   Key Laboratory of Extreme Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

Owing to combining the properties of both metal and glass, metallic glasses exhibit superior physical and mechanical properties along with exotic phenomena, so they have a wide application prospect in many areas. In addition, their continuously adjustable composition and simple disordered atomic structure provide ideal model material systems for the study of fundamental questions commonly existing in glassy materials. The discovery of metallic glasses that can form bulk materials has pushed the relevant research to the frontier of condensed matter physics and material science. The EX4 group of the Institute of Physics, Chinese Academy of Sciences, has devoted to the study of glassy materials and physics for many years, and made important contributions to this field. In this paper, we summarize our recent progress of metallic glasses, including the relaxation behavior and stability, surface dynamics, materials functionalities, and new method on materials discovery.
Fundamental circuit element and nonvolatile memory based on magnetoelectric effect
Authors: Shen Jian-Xin  , Shang Da-Shan  , Sun Young  ,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

The magnetoelectric coupling effect in materials provides an additional degree of freedom of physical states for information storage and shows great potential in developing a new generation of memory devices. We use an alternative concept of nonvolatile memory based on a type of nonlinear magnetoelectric effects showing a butterfly-shaped hysteresis loop. The state of magnetoelectric coefficient, instead of magnetization, electric polarization, or resistance, is utilized to store information. Because this memory concept depends on the relationship between the charge and magnetic flux, it is actually the fourth fundamental circuit memory element in addition to memristor, memcapacitor, and meminductor, and is defined as memtranstor. Our experiments in memtranstor comprised of the[Pb(Mg1/3Nb2/3)]0.7[PbTiO3]0.3(PMN-PT)/Terfenol-D and Ni/PMN-PT/Ni multiferroic heterostructures clearly demonstrated that the magnetoelectric coefficient can be repeatedly switched not only between positive and negative polarities but also between multilevel states by applying electric fields, confirming the feasibility of this principle. In addition to nonvolatile memory, the nonvolatile logic functions, such as NOR and NAND and synaptic plasticity functions, such as long-term potentiation/depression and spiking-time-dependent plasticity are implemented in a single memtranstor by engineering the applied electric-field pulses. The combined functionalities of memory, logic, and synaptic plasticity enable the memtranstor to serve as a promising candidate for future computing systems beyond von Neumann architecture.
Transient heat transfer analysis of laminated materials based on extended separation of variables
Authors: Li Chang-Yu  , Lin Shui-Mu  , Dai Hai-Yan  , Lü Dong-Lin  ,   School of Automotive and Traffic Engineering, Guangzhou College of South China University of Technology, Guangzhou 510800, China;,   Mechanical Engineering Department, Kun Shan University, Taiwan 710030, China
Published: December 2020

In general, when the one-dimensional heat conduction equation is solved by the method of separation of variables, we need to know the governing equations, two boundary conditions and initial condition. Because the thermophysical parameters in different layers of laminated materials are different, the heat conduction model cannot be expressed by the same governing equation. For each layer of laminated material, the boundary condition is unknown. That equation can-not be solved directly by the general separation variable method. In this work the separation of variable method is extended. The temperature field of laminated material's heat transfer is divided into many minute time intervals on the time axis. Based on differential conception, in a minimum time interval, the temperature at the junction of laminated materials can be considered to be proportional to time. Assume that the slope coefficient makes the boundary condition known, then for each layer of laminated materials, the general separation of variables method will be used to solve the temperature field. According to the same temperature and the energy continuity at the junction of laminated materials, one can solve the slope coefficient. The temperature field in the whole time domain can be obtained through cycling. Then the three-layer insulation materials are analyzed by the extended separation variable method. The correctness of the method is verified by comparing the calculated results with those from the finite element method. The influences of the type and thickness of heat insulation layer, heat transfer coefficient, air temperature on the heat insulation are studied. It is found that the thermal conductivity of the thermal insulation layer has a great influence on the insulation. The material with low heat conduction coefficient can enhance the heat insulation effect. The thicker the thickness of the insulation layer, the more slowly the surface temperature of the heat insulation material rises, and the lower the final temperature, the better the insulation effect is. The thicker the thickness of the insulation layer, the smaller the heat flux density of the heat insulation material shell is, and the better the heat insulation effect when the heat transfer reaches a stable state. All calculation results are consistent with physical phenomena. In this work, the analytical method is used to solve the heat transfer problem of laminated materials. Compared with the general numerical methods, the analytical method presents clear physical meaning and high efficiency of operation as well.
Progress on the failure analysis of lithium battery
Authors: Wang Qi-Yu  , Wang Shuo  , Zhou Ge  , Zhang Jie-Nan  , Zheng Jie-Yun  , Yu Xi-Qian  , Li Hong  ,   Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Tianmu Lake Institute of Advanced Energy Storage Technologies, Liyang 213300, China
Published: December 2020

The failure problems, associated with capacity fade, poor cycle life, increased internal resistance, abnormal voltage, lithium plating, gas generation, electrolyte leakage, short circuit, battery deformation, thermal runaway, etc., are the fatal issues that restrict the performances and reliabilities of the lithium batteries. The main tasks of failure analysis of lithium batteries are to accurately diagnose, which is vital for revealing the failure modes or failure mechanisms. These information has profound significance for improving the performances and technology of lithium batteries. In order to have a comprehensive understanding of the recent progress on failure analysis research of lithium batteries, the failure analyses from the respect of definition, phenomenon, reason, analysis content, process, difficulty, etc. are briefly reviewed. We hope this review will helpful to the researchers engaged in the field of failure analysis as well as battery field.
Solid quantum sensor based on nitrogen-vacancy center in diamond
Authors: Dong Yang  , Du Bo  , Zhang Shao-Chun  , Chen Xiang-Dong  , Sun Fang-Wen  ,   Chinese Academy of Sciences Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

Solid-state electronic spin system of the nitrogen-vacancy (NV) center in diamond is attractive as a nanoscale quantum sensor under room-temperature dueto its unique characteristics such as stable fluorescence, long coherent time, and near-atomic size under ambient conditions. Nowadays, the NV center plays a significant role in super-resolution microscopies. Different super-resolution microscopies have been used on NV center to archievenanoscale spatial resolution. Moreover, the spin state in NV center can be regraded as a solid-state qubit, which can be optically polarized and read out. The spin state can couple with electromagnetic fields and strain, which enables the NV center to be an excellent quantum sensor with high spatial resolution and high sensitivity. Such an NV-center based quantum sensing technique is being developed for applications in newmateriales, single protein nuclear spin dynamic field, life science, etc. This review will introduce the basic principle of such a nanoscale quantum sensor, the experimental realization, methods of enhancing the sensitivity, and some applications in high-spatial-resolution and high-sensitivity sensing.
Reduction of surface plasma loss of indium tin oxide thin films by regulating substrate temperature
Authors: Cai Xin-Yang  , Wang Xin-Wei  , Zhang Yu-Ping  , Wang Deng-Kui  , Fang Xuan  , Fang Dan  , Wang Xiao-Hua  , Wei Zhi-Peng  ,   State Key Laboratory of High Power Semiconductor Laser, School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China;,   State Key Laboratory of Supramolecular Structures, Material Institute of Theoretical Chemistry, Jilin University, Changchun 130012, China
Published: December 2020

Indium tin oxide (ITO) thin films,as a heavy doping n-type semiconductor material with a high carrier concentration,can realize the surface plasma effect and regulation of surface plasmon resonance wavelength in the near infrared region:the surface plasma has broad application prospect in surface plasmon devices.The ITO thin films are deposited on float glass substrates (20 mm20 mm) via the direct current (DC) magnetron sputtering by regulating substrate temperature from 100 ℃ to 500 ℃.The deposited ITO thin films present a cubic polycrystalline iron manganese structure,in which the ITO film shows the strong crystallinity at 400 ℃,so that it is conducive to reducing the defects of bound electrons and the damping force of thin film.The surface roughness of ITO thin film first decreases and then increases with the temperature increasing,correspondingly the root-mean-square roughness (Rq) of these films decreases from 4.11~nm to 2.19 nm,then increases to 2.56 nm.The Rqvalue of 2.19 nm corresponds to a preferable surface smoothness of ITO thin film,indicating that it can effectively increase carrier concentration of ITO thin film at 400 ℃.The effects of the different substrate temperature on the photoelectric and surface plasma properties of ITO thin films are analyzed by UV-Vis absorption spectra,Hall measurement,refractive index and dielectric constant.As the temperature increases from 100 ℃ to 500 ℃,the carrier concentration of ITO thin film is enhanced from 4.11020 cm-3 to 2.481021 cm-3,and thus increasing the probability of the Fermi level to the conduction band of ITO thin film.And the enhancement of carrier concentration induces the Moss-Burstein effect,which makes the edges of absorption spectrum of the ITO thin film gradually blue-shift from 340 nm to 312 nm,correspondingly broadening the optical band gap from 3.64 eV to 3.97 eV.These results cause the difficulties of electrons interband transition to be enhanced,and thus suppressing the phenomenon of absorbing photons for the electron transition from low level to high level,which ultimately reduces the optical loss of ITO thin film.In addition,the surface plasma effect is realized in a range from 1100 nm to 1700 nm for ITO thin film by regulating the substrate temperature.Meanwhile,the electronic mobility in the ITO thin film is also improved from 24.6 cm2V-1s-1 to 32.2 cm2V-1s-1,which reduces the electronic scattering,and is beneficial to the increase of propagation length of surface plasma waves.The above results imply that we have attained the goal of the reducing the electrical loss of ITO thin film.
Growth and characterization of grid-like β-Ga2O3 nanowires by electric field assisted chemical vapor deposition method
Authors: Feng Qiu-Ju  , Li Fang  , Li Tong-Tong  , Li Yun-Zheng  , Shi Bo  , Li Meng-Ke  , Liang Hong-Wei  ,   School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029, China;,   School of Microelectronics, Dalian University of Technology, Dalian 116024, China
Published: December 2020

Gallium oxide (Ga2O3) has five crystalline polymorphs, i.e. corundum (α-phase), monoclinic (β-phase), spinel (γ-phase), bixbite (δ-phase) and orthorhombic (ε-phase). Among these phases, the monoclinic structured β-Ga2O3 is the most stable form, and is a ultraviolet (UV) transparent semiconductor with a wide band gap of 4.9 eV. It is a promising candidate for applications in UV transparent electrodes, solar-blind photodetectors, gas sensors and optoelectronic devices. In recent years, one-dimensional (1D) nanoscale semiconductor structures, such as nanowires, nanobelts, and nanorods, have attracted considerable attention due to their interesting fundamental properties and potential applications in nanoscale opto-electronic devices.Numerous efforts have been made to fabricate such devices in 1D nanostructures such as nanowires and nanorods. Comparing with the thin film form, the device performance in the 1D form is significantly enhanced as the surface-to-volume ratio increases. In order to realize β-Ga2O3 based nano-optoelectronic devices, it is necessary to obtain controlled-synthesis and the high-quality β-Ga2O3 nanomaterials. According to the present difficulties in synthesizing β-Ga2O3 nanomaterials, in this paper, the grid-like β-Ga2O3 nanowires are prepared on sapphire substrates via electric field assisted chemical vapor deposition method.High-purity metallic Ga (99.99%) is used as Ga vapor source. High-purity Ar gas is used as carrier gas. The flow rate of high-purity Ar carrier gas is controlled at 200 sccm. Then, oxygen reactant gas with a flow rate of 2 sccm enters into the system. The temperature is kept at 900℃ for 20 min. The effect of the external electric voltage on the surface morphology, crystal structure and optical properties of β-Ga2O3 nanowires are investigated. It is found that the external electric voltage has a great influence on the surface morphology of the sample. The orientation of the β-Ga2O3 nanowires grown under the action of an applied electric field begins to improve. Only a grid composed of three different growth directions appears. And with the increase of applied voltage, the distribution of nanowires becomes denser and the length increases significantly. In addition, it is found that the chemical vapor deposition method assisted by this external electric field can significantly improve the crystallization and optical quality of the samples.
Morphological evolution and liquid-like behavior of gold nanofilm on the suspended graphene
Authors: Tian Shi-Bing  , Gu Chang-Zhi  , Li Jun-Jie  ,   Laboratory of Microfabrication, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

The morphological evolutions of gold nanofilm on the suspended graphene is investigated before and after an annealing process, and two important phenomena are observed. First, the layer number of suspended graphene can be determined by the morphological change of gold nanofilm, and it is noteworthy that as-observed results without the substrate supporting effect are completely contrary to previously reported results of the graphene supported by the substrate. Second, after a rapid and careful annealing process, the gold nanofilm on the suspended graphene shows a liquid-like behavior as if the water is on the lotus leave surface. The mechanisms behind these phenomena are discussed in detail. These results provide very useful information for many applications such as metal intercalation in graphene, electronic contact between metal and graphene, fabrication of patterned suspended graphene device, etc.
X-ray source with quasi-monochromatic parallel beam
Authors: Wang Rui-Rong  , An Hong-Hai  , Xiong Jun  , Xie Zhi-Yong  , Wang Wei  ,   Shanghai Institute of Laser Plasma, Shanghai 201800, China
Published: December 2020

In inertial confined fusion experiments, an excellent-performance and high-efficiency X-ray source plays an important role in X-ray radiography schemes. Indeed, it can be used in a variety of X-ray experimental techniques. The mono-chromaticity, flux intensity, degree of collimation (the radiation can be transported long distances without loss), and spot size of the X-ray source affect the quality of imaging. Ray-tracing simulations, which are validated by experimental results, demonstrate that high-intensity collimated X-ray beams can be produced from an isotropic X-ray source. Therefore, a method of improving the performance of an X-ray source from a laser-produced plasma is presented. A spherically bent crystal is used to collimate mono-chromatic X-rays emitted from a laser-produced plasma. Here we design a spherically bent crystal spectrometer system for collimating the laser-produced X-rays. The system performance is experimentally tested at the Shenguang Ⅱ (SGⅡ) laser facility located in Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences. The beam divergence is measured by using a metal grid placed downstream from the crystal, the metal grid that possesses wires with 60 μm in diameter and 127 μm in period. An imaging plate (IP) is placed at various distances downstream from grid. The quality of the generated beam is monitored by measuring the dimensions of the grid image formed by the beam on IP. While the narrow range of wavelength is measured with a spherically bent crystal spectrometer. Experimental results show that the spherically bent crystal spectrometer system can produce quasi-monochromatic (10-3 < △ λ/λ <10-2) X-ray beams with a high degree of collimation (less than 2 mrad divergence), uniform spot size (~500 μm), and a relative tenability in the wide spectral range. The influences of various experimental parameters on the quality of beam collimation are evaluated in two ways. They can be investigated in test experiments by representing the beam divergence distribution as a function of Bragg angle. In another study of the effect of the aberrations, when the incident beam on the spherically bent crystal is not normal, the beam is less collimated in the tangential plane, and out of collimation in the sagittal plane. Following the ray-tracing method, we analyze the diffracted beam divergence produced by the astigmatic aberration. The qualitative conclusion is that the good agreement with the experimental results is obtained. By fully utilizing limited Bragg angle range, the spherically bent crystal spectrometer system can realize collimated diffracted X-ray beams with divergence of less than 1 mrad by using a laser-produced plasma X-ray source under the appropriately experimental parameters.
Resistance switching of La doped SrTiO3 single crystals
Authors: Li Guang-Hui  , Xia Wan-Ying  , Sun Xian-Wen  ,   Henan Key Laboratory of Photovoltaic Materials and School of Physics and Electronics, Henan University, Kaifeng 475004, China
Published: December 2020

To date, there has not been a consensus about the resistance switching mechanism of donor-doped SrTiO3. The La doped STO (LaSTO) single crystal is a donor-doped material and has an N-type conductivity since La3+ could easily substitute Sr2+. In this study, the Pt/LaSTO/In memory device is fabricated based on (100) LaSTO single crystal with 0.5 wt% La doping. Through a series of electrical tests, it is found that the Pt/LaSTO/In memory device has a stable multi-stage resistive switching property, and the maximum switching ratio is 104. The fitting I-V curve at the high resistance state (HRS) shows that there is an interface barrier in the memory device. However, the fitting I-V curve at low resistance state (LRS) is consistent with the characteristic of the electron tunneling model. The spectrum of electron paramagnetic resonance (EPR) indicates that LaSTO single crystal has only one EPR signal of g=2.012. Considering the fact that g=gobs-ge (where gobs is the g factor obtained from the sample, ge=2.0023 is the free electron value) is positive, the signal can be regarded as being due to hole center. The hole center is positively charged and can trap electrons. Comprehensive analysis indicates that the transition between the HRS and LRS of the device can be explained by the modulation of Pt/LaSTO interface barrier, which is caused by the electron trapping and detrapping of interfacial vacancy defects. In addition, it is found that illumination could reduce the low resistance of the Pt/LaSTO/In device. This is due to the photo-generated carriers causing a tunneling current because of the narrow Schottky barrier when the Pt/LaSTO/In device is in the LRS. However, the Schottky barrier plays a leading role in HRS, so the change in carrier concentration, caused by illumination, does not lead to a significant change in current for HRS. The experimental results provide theoretical and technical guidance for the applications of LaSTO single crystals in resistive memory devices.
Simulation of multiband imaging technology of large aperture spatial heterodyne imaging spectroscopy
Authors: Cai Qi-Sheng  , Huang Min  , Han Wei  , Liu Yi-Xuan  , Lu Xiang-Ning  ,   Key Laboratory of Computational Optical Imaging Technology, Academy of Opto-Electronics, Chinese Academy of Sciences, Beijing 100094, China
Published: December 2020

A multiband imaging technology based on large aperture spatial heterodyne imaging spectroscopy (LASHIS) is proposed in this paper. It retains the advantages of high spectral resolution, high stability and high detection sensitivity of LASHIS. In addition, by using the multistage diffraction gratings, several spectral bands can be detected simultaneously in this system, thus the spectral range is broadened. The basic principle of this multiband imaging technology based on LASHIS is described. The difference between optical path differences produced by the Sagnac lateral shearing interferometer and the parallel gratings is calculated. The mathematical expressions, the interferogram calculation procedures, and the spectrum reconstruction method are presented. As a pair of multistage diffraction gratings is introduced into the Sagnac interferometer, the rays of different diffraction orders corresponding to different spectral bands are mixed together in the interferometer. The spectral bands should be separated before they are imaged on the detector. Two separation methods are proposed:introducing a filter array in front of the detector and introducing dichroic mirrors to assign different spectral bands to different detectors. Finally, a design example is given and an optical model is setup in ZEMAX. In this example, a pair of parallel echelon gratings with 316 lines/mm is introduced into the Sagnac interferometer. Two dichroic mirrors and three detectors are used to separate and detect three spectral bands simultaneously. The three spectral ranges are from 529.2 nm to 532.96 nm, from 588 nm to 592.18 nm, and from 661.5 nm to 666.20 nm. The average spectral resolutions are 0.015 nm, 0.016 nm, and 0.018 nm respectively. Two kinds of sources are analyzed:one is a sodium lamp with two emission peaks at 589 nm and 589.6 nm, and the other is a source with three monochromatic wavelengths at 530 nm, 589 nm, and 662 nm. The interferograms of these two sources traced in the optical model are consistent with the theoretical results. The recovered spectra show good agreement with the input spectra. These verified the correctness of the principle and the spectrum reconstruction method. The multiband imaging technology based on LASHIS with the advantages of high spectral resolution, high detection sensitivity, and multiband detection capability, is especially suitable for multiband hyperspectral highstability and high-sensitivity detection, such as the detection of greenhouse gases.
Wet granular matter mechanical spectroscopy under low-frequency shear
Authors: Tang Han-Yu  , Wang Na  , Wu Xue-Bang  , Liu Chang-Song  ,   Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
Published: December 2020

Dry granular materials consist of a collection of macroscopic discrete particles interacting solely via contact forces. By changing the external conditions, the granular packing displays rich phenomena ranging from fluid-like properties to jamming glassy behavior and to aging observed when these grains are trapped in a frozen state. Once the grains contact liquid, the force between the liquid and grains has an influence on the mechanical properties of the wet granular materials, and some mechanical behaviors are quite different from those of the dry granular materials. However, the underlying mechanism of the complex dynamics of granular assemblies is still not completely understood.
In this paper, mechanical spectroscopy (the shear modular G and the related energy dissipation tan) of NaCl wet granular system is investigated with different liquid content (weight fraction) under the constant temperature 25℃ and air humidity by a modified low-frequency inverted torsion pendulum. The NaCl wet granular system also displays jamming behavior when subjected to an external vibration with increasing intensity, which is quiet similar to dry granular matter. With the increase of water content, all the spectra of tan and modular G show a peak at the water content about 11% (critical water content). At the same time, the applied shear force has little influence on the positions of these peaks. All of these behaviors illustrate that the main interaction forces among granular matters in the system are changed at the moment.
Wave solitons of hyper-elliptic function in anisotropic Heisenberg spin chain
Authors: Xie Yuan-Dong  ,   Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006, China
Published: December 2020

There are various nonlinear solutions in the anisotropic Heisenberg spin chain model (AHSCM), such as soliton solutions. In consideration of high-order nonlinear terms, a good modified nonlinear analytical solution can be obtained under reasonable simplification conditions. The purpose of this paper is to find the nonlinear solutions other than soliton of AHSCM. We use Holstein-Primakoff representation to study the AHSCM. Under the semi-classical approximation, considering the high order nonlinear term and the periodic boundary condition, an improved nonlinear Schrodinger equation and its wave solutions of the hyper-elliptic function expressed by the combination of the inverse function of Jacobi elliptic function are obtained through using the coherent state. These solutions can be expressed by the combination of the inverse functions of the first kind of elliptic functions. In the limit case, these solutions are reduced to wave solutions of sinusoidal (or cosine) functions, or wave solutions that can be represented by hyperbolic tangent functions. The energy levels of these nonlinear solutions can be obtained theoretically by the normalized conditions, but even by using hyper-elliptic functions, it is difficult to express them as analytic expressions.
Controllable synthesis and performance of magnetic nanocomposites with core/shell structure
Authors: He Xue-Min  , Zhong Wei  , Du You-Wei  ,   Research Center of Information Physics, School of Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China;,   National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China
Published: December 2020

Magnetic nanocomposites with core/shell structure are an important class of functional materials, and their comprehensive properties are affected by the microstructures of materials: they are largely dependent on the controlled sysnthesis of the composite systems. In this paper, we review the research advances in the preparation, characterization and performance of core/shell-structured magnetic nanocomposites, focusing on the following systems: 1) ferrite-based permanent-magnet/soft-magnetic (or antiferromagnetic) composite nanomaterials; 2) nanocomposites comprised of the magnetic core particles and the nonmagnetic coating layers; 3) carbon-based nanocomposites obtained by the catalytic synthesis of magnetic particles; 4) nanocomposites with exchange bias effect; 5) one-dimensional nanocomposites with coaxial core/shell structure; 6) core/shell/shell structured magnetic ternary nanocomposites. The components of these composite systems include M-type permanent-magnet ferrites, 3d transition metals (and their alloys, oxides and carbides), multiferroics, nonmagnetic (such as insulator, semiconductor and organic molecule), and carbon materials. And the emphasis is placed on the analysis of thermal stability, photoluminescence performance, photoelectrocatalytic capacity, electrochemical characteristics, microwave absorption properties, magnetoresistance effect, permanent magnetic property, high-frequency soft-magnetic properties, exchange bias effect and related phenomenology for the core/shell-structured nanocomposites. Finally, the future developing trend of the magnetic nanocomposites with core/shell structure is presented, and some fundamental researches and modified applications are also proposed.
Generation of twin-Fock states for precision measurement beyond the standard quantum limit
Authors: Tey Meng-Khoon  , You Li  ,   State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China;,   Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
Published: December 2020

The highest precision achievable for a two-mode (two-path) classical interferometer is bounded by 1/√N (with NN</span/2) in each mode). In the past, either through optical spontaneous parametric-down-conversion or through quantum-gate operations on trapped ions, twin-Fock states consisting of no more than 10 photons or ions have been realized. In recent years, twin-Fock states made up of a few thousand atoms have been generated using spin-mixing dynamics in spinor Bose-Einstein condensates (BECs). However, these twin-Fock states exhibit huge fluctuation in particle numbers, thereby limiting their potential applications. We recently generated twin-Fock states of about 11000 atoms in a deterministic manner by driving a spin-1 BEC through quantum critical points (QCPs) slowly. Even though substantial excitations occur while crossing the QCP regions during the drive, this method is capable of generating highly entangled twin-Fock states because of the very different structures of the system's low-lying eigenstates across the QCPs. The samples we prepare feature a number squeezing of 10.7±0.6 decibels and a normalized collective spin length of 0.99±0.01. Together, they infer a minimum entanglement cluster (or entanglement breadth) of 910 atoms. This article introduces the background and advancement of this research.
Research of a wide-angle backscattering enhancement metasurface
Authors: Feng Mao-Chang  , Li Yong-Feng  , Zhang Jie-Qiu  , Wang Jia-Fu  , Wang Chao  , Ma Hua  , Qu Shao-Bo  ,   Department of Basic Sciences Air Force Engineering University, Xi'an 710051, China
Published: December 2020

To enhance backscattering, corner reflector and Luneburg lens are usually used. They can operate effectively in a broad angle range and also in a quite wide band. However, corner reflector as a typical structure of backscattering enhancement device, has obvious disadvantages in practical application. For example, it is usually made of metal material, which causes it to be too heavy and bulky. Luneburg lens is generally made of dielectric with strong loss and high cost, which is unfavorable for applications. Thus, it is necessary to explore a new way to realize wide-angle backscattering enhancement. In this paper, a phase gradient metasurface with wide-angle radar cross section (RCS) enhancement property is proposed and demonstrated, which consists of two phase gradients with equal magnitude but in opposite directions. Through designing a reflective phase profile along the surface, an equivalent wave vector can be generated, with doubled magnitude but in an opposite direction to the parallel component of the wave vector of the incident wave. At the incidence angles =-45 and 45, electromagnetic (EM) waves are reflected to the directions just opposite to the directions of incident waves. And at incidence angle =0, the incident EM wave is coupled into spoof surface wave and then guided to another region to decouple into a free space wave. These guarantee RCS enhancement property in a related angular domain. The polarization independent Jerusalem cross unit is used to design the phase gradient, and a wide-angle RCS enhancement metasurface is designed. The simulated results indicate that at the designed incidence angles, directions of the reflected waves are all opposite to the directions of incidence waves for both x and y polarized wave. In order to evaluate the RCS enhancement performances, the mono-static RCS of the designed wide-angle RCS enhancement metasurface is measured. Both the simulations and experiments are in good agreement with each other, and show that the designed metasurface obtains tremendous RCS enhancement performances in a wide-angle domain (-45-45) for both x and y polarized wave with frequencies ranging from 9 GHz to 12 GHz.
p-GaN hybrid anode AlGaN/GaN diode with 1000 V operation
Authors: Tang Wen-Xin  , Hao Rong-Hui  , Chen Fu  , Yu Guo-Hao  , Zhang Bao-Shun  ,   Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123, China;,   School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

GaN plays an important role in compound semiconductor, which exhibits excellent electrical properties such as wide band gap (3.4 eV), high breakdown field strength (3.3 MV/cm), and high electron mobility (600 cm2/(Vs)). AlGaN/GaN heterojunction produces two-dimensional electron gas (2DEG) with high density (11013 cm-2) and high electron mobility (2000 cm2/(Vs)) which are caused by strong piezoelectric and spontaneous polarization. The Si-based AlGaN/GaN devices emerge as a promising candidate for the nextgeneration switching application in power system due to 2DEG of AlGaN/GaN heterojunction. Turn-on and breakdown voltage are key parameters for diodes and they have a tradeoff between each other. These two parameters affect diode loss and power handling capability. For better properties, we propose a novel p-GaN hybrid anode AlGaN/GaN diode with high-resistance-cap-layer (HRCL) to optimize turn-on voltage and breakdown characteristics. Based on the p-GaN/AlGaN/GaN material structure, an HRCL is fabricated in the channel region by self-aligned hydrogen plasma treatment to improve the breakdown voltage. Hydrogen plasma is adopted to compensate for holes in the p-GaN to release electrons from the 2DEG channel, forming a high-resistivity area. The transmission line method tests the material after passivation, showing that its sheet resistance is 570 /□ and a contact resistance is 0.7 mm. In the HRCL p-GaN diode, negative charges can appear at the interface of HR-GaN/AlGaN due to polarization effect, which increases the vertical electric field in AlGaN and reduces the lateral electric field near the cathode in the p-GaN, compared with in the p-GaN diode without HRCL. The p-GaN in the anode region is reserved to regulate the turn-on voltage by depleting the underlying 2DEG. The p-GaN structure raises conduction band beyond the Fermi level, ensuring the reduction of 2DEG. The fabricated HRCL p-GaN diode exhibits a high breakdown voltage over 1000 V at Ileakage=110-4 A/mm with a cathode-anode distance Lac of 10 m and a turn-on voltage of +1.2 V when forward current is 1 mA/mm. These results indicate that the introduction of p-GaN hybrid anode and HRCL can enhance the electrical properties of AlGaN/GaN diode effectively. However, little attention has been paid to doping concentration in p-GaN. Study of the regulation of Mg2+ doping concentration on the turn-on voltage in p-GaN will be investigated in future to achieve a low forward turn-on voltage of the p-GaN HRCL diode.
Experimental study about single event functional interrupt of ferroelectric random access memory induced by 30-90 MeV proton
Authors: Ju An-An  , Guo Hong-Xia  , Zhang Feng-Qi  , Guo Wei-Xin  , Ouyang Xiao-Ping  , Wei Jia-Nan  , Luo Yin-Hong  , Zhong Xiang-Li  , Li Bo  , Qin Li  ,   1. Academic Instituton of Material Science and Engineer, Xiangtan University, Xiangtan 411105, China;,   2. Northwest Institute of Nuclear Technology, Xi'an 710024, China;,   3. Academic Institution of Nuclear Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China
Published: December 2020

Ferroelectric random access memory (FRAM) is a promising memory for space application. The performance of FRAM under irradiation environment should be investigated, especially under proton irradiation environment, which dominates the particles in the space environment. The experiments on single event effects are carried out for two types of FRAMs (FM22L16 and FM28 V100) based on the proton cyclotron of China institute of atomic energy. Both dynamic and static mode are tested for each chip under the irradiation of proton in an energy range from 30 MeV to 90 MeV. Single event upsets (SEUs) and single event functional interrupts (SEFIs) are observed only on FM22L16, where the SEFI is recorded as a significantly transient error with or without memory cell upsets. The SEFI can be subdivided into soft SEFI and hard SEFI according to whether those significantly transient errors disappear or not when the irradiation is paused. Single event effect performances of FM22L16 are accurately described, and the SEFI cross section in an energy range from 50 MeV to 90 MeV is obtained experimentally. The cross section of SEFI increases with proton energy increasing and reaches 10-3/cm2 at 90 MeV. To further study the mechanism of SEFI, the pulsed laser beam with a wavelength of 1064 nm is used to pinpoint the sensitive area of SEFI in the FRAM. Pulsed laser experiment is easy to carry out when single pulsed laser radiates on the device from the back side. Results show that a certain part in peripheral circuit is detected as a sensitive area to SEFI. The sensitive area could be a register or buffer which is vulnerable to irradiation. Only SEUs are observed when the pulsed laser radiates others area of peripheral circuit and memory cell. A hypothesis that a micro latch-up in the CMOS-based peripheral circuit leads to the SEFI is proposed to explain the test results, for the CMOS-based peripheral circuit is sensitive to irradiation. The further reason is the energy deposition in silicon substrate by protons with energies ranging from 30 MeV to 90 MeV through nuclear reaction, which triggers the silicon controlled rectifier structure in the FRAM peripheral circuit. According to the hypothesis, a transient current should be generated in the peripheral circuit when the micro latch-up happens. The transient current is observed on the output of device by using a high frequency oscilloscope which demonstrates the reasonability of the hypothesis.
Full focal imaging of ultrasonic Lamb waves using diffuse field information
Authors: Zhang Hai-Yan  , Xu Meng-Yun  , Zhang Hui  , Zhu Wen-Fa  , Chai Xiao-Dong  ,   School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China;,   School of Urban Railway Transportation, Shanghai University of Engineering Science, Shanghai 201620, China
Published: December 2020

In this paper, a method is presented in which that the diffuse field information of Lamb waves is used to realize the full focal imaging of the defect that is near the transducer array. The near distance means that the defect is located in the near field of ultrasonic phased array and satisfies the near field calculation formula. Near field acoustic information of the defect is obscured by the nonlinear effects of early time saturation present in a directly acquired ultrasonic inspection. The approach proposed here is to recover near filed information through cross-correlation of diffuse fields. The diffuse field is generated through multiple scattering and reflection effects after sufficiently long time transmission of ultrasonic signal in a bounded medium. The near field information is implicitly contained throughout the diffuse field. By cross-correlating the diffuse fields of ultrasonic responses recorded at two monitoring points, the Green's functions between the two points is recovered and the direct response between them is obtained. This idea is applied to the full matrix capture of ultrasonic phased array in which the full matrix is formed by sequential acquisition of responses for each transmitter-receiver pair. A virtual array of emitters and receivers is therefore established. Typically, phase delays are used in post-processing to achieve advanced imaging. Here an undelayed full matrix of inter-element responses is reconstructed through cross-correlation of a later time diffuse full matrix. In order to evaluate the applicability of the method for ultrasonic non-destructive testing, the process of full matrix reconstruction is demonstrated experimentally on an aluminium plate containing the near field defect. Combining the full focal imaging, it is shown that a hybrid full matrix formed through a temporally weighted sum of coherent and reconstructed matrices reduces the background noise and allows the effective imaging of near field defect by direct contact experimental measurements. However, the near field defect is hidden by the region of artificial noise in conventional coherent capture images. The proposed imaging method presents a theoretical guidance for detecting and imaging near field defect in plate-like configurations by using the Lamb wave nondestructive testing method.