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Chinese Physics B 2021年第6期30卷 617-624页

作者： Yao Wang Sheng-Wang Yu Yan-Peng Xue hong-jun hei Yan-Xia Wu Yan-Yan Shen Institute of New Carbon Materials Taiyuan University of TechnologyTaiyuan 030024China National Center for Materials Service Safety University of Science and Technology BeijingBeijing 100083China

Nano-diamond particles are co-deposited on Ti substrates with metal(Ti/Ni) nanoparticles(NPs) by the electrophoretic deposition(EPD) method combined with a furnace annealing at 800℃ under N_(2) atmosphere. Modifications of structural and electron field emission(EFE) properties of the metal-doped films are investigated with different metal NPs concentrations. Our results show that the surface characteristics and EFE performances of the samples are first enhanced and then reduced with metal NPs concentration increasing. Both the Ti-doped and Ni-doped nano-diamond composite films exhibit optimal EFE and microstructural performances when the doping quantity is 5 mg. Remarkably enhanced EFE properties with a low turn-on field of 1.38 V/μm and a high current density of 1.32 mA/cm^(2) at an applied field of 2.94 V/μm are achieved for Ni-doped nano-diamond films, and are superior to those for Ti-doped ones. The enhancement of the EFE properties for the Ti-doped films results from the formation of the TiC-network after annealing. However, the doping of electron-rich Ni NPs and formation of high conductive graphitic phase are considered to be the factor, which results in marvelous EFE properties for these Ni-doped nano-diamond films.

关键词： diamond films metal doping electrophoretic deposition field emission properties

Structure and tribological properties of Si/a-C:H(Ag)multilayer film in stimulated body fluid

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Chinese Physics B 2020年第11期29卷 412-419页

作者： Yan-Xia Wu Yun-Lin Liu Ying Liu Bing Zhou hong-jun hei Yong Ma Sheng-Wang Yu Yu-Cheng Wu Institute of New Carbon Materials Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of Interface Science and Engineering in Advanced Materials(Taiyuan University of Technology) Ministry of EducationTaiyuan 030024China

Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human *** composition,microstructure,mechanical and tribological properties in the simulated body fluid are *** results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 *** the C content has an opposite variation ***,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer *** a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body *** appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and *** work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.

关键词： Si/a-C:H(Ag)multilayer film modulation periods Ag concentration tribological properties

Effects of preparation parameters on growth and properties of β-Ga_(2)O_(3) film

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Chinese Physics B 2023年第1期32卷 440-447页

作者：陈子豪王永胜张宁周兵高洁吴艳霞马永黑鸿君申艳艳贺志勇于盛旺 College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China

The Ga_(2)O_(3) films are deposited on the Si and quartz substrates by magnetron sputtering, and annealing. The effects of preparation parameters(such as argon–oxygen flow ratio, sputtering power, sputtering time and annealing temperature)on the growth and properties(e.g., surface morphology, crystal structure, optical and electrical properties of the films) are studied by x-ray diffractometer(XRD), scanning electron microscope(SEM), and ultraviolet-visible spectrophotometer(UV-Vis). The results show that the thickness, crystallization quality and surface roughness of the β-Ga_(2)O_(3) film are influenced by those parameters. All β-Ga_(2)O_(3) films show good optical properties. Moreover, the value of bandgap increases with the enlarge of the percentage of oxygen increasing, and decreases with the increase of sputtering power and annealing temperature, indicating that the bandgap is related to the quality of the film and affected by the number of oxygen vacancy defects. The I–V curves show that the Ohmic behavior between metal and β-Ga_(2)O_(3) films is obtained at 900℃. Those results will be helpful for the further research of β-Ga_(2)O_(3) photoelectric semiconductor.

关键词： β-Ga_(2)O_(3) magnetron sputtering growth parameters optical and electrical properties

Existence and Stability of Positive Solutions for an Elliptic Cooperative System

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Acta Mathematica Sinica,English Series 2005年第5期21卷 1113-1120页

作者： Li jun hei Jian Hua WU College of Mathematics and Information Science ShaanXi Normal University Xi'an 710062 P. R. China Department of Mathematics Tianjin University Tianjin 300072 P. R. China College of Mathematics and Information Science ShanXi Normal UniversityXi'an 710062 P. R. China

By discussing the properties of a linear cooperative system, the necessary and sufficient conditions for the existence of positive solutions of an elliptic cooperative system in terms of the principal eigenvalue of the associated linear system are established, and some local stability results for the positive solutions are also obtained.

关键词： Cooperative system Positive solution Sub- and supersolution methods Principal eigen value

Energy consumption of electrooxidation systems with boron-doped diamond electrodes in the pulse current mode

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International Journal of Minerals,Metallurgy and Materials 2013年第1期20卷 106-112页

作者： jun-jun Wei Xu-hui Gao Li-fu hei Jawaid Askari Cheng-ming Li Institute of Advanced Materials and Technology University of Science and Technology Beijing Institute of Manufacturing Engineering National University of Sciences & Technology (NUST)

A pulse current technique was conducted in a boron-doped diamond （BDD） anode system for electrochemical waste- water treatment. Due to the strong generation and weak absorption of hydroxyl radicals on the diamond surface, the BDD elec- trode possesses a powerful capability of electrochemical oxidation of organic compounds, especially in the pulse current mode. The influences of pulse current parameters such as current density, pulse duty cycle, and frequency were investigated in terms of chemical oxygen demand （COD） removal, average current efficiency, and specific energy consumption. The results demon- strated that the relatively high COD removal and low specific energy consumption were obtained simultaneously only if the current density or pulse duty cycle was adjusted to a reasonable value. Increasing the frequency slightly enhanced the COD re- moval and average current efficiency. A pulse-BDD anode system showed a stronger energy saving ability than a constant-BDD anode system when the electrochemical oxidation of phenol of the two systems was compared. The results prove that the pulse current technique is more cost-effective and more suitable for a BDD anode system for real wastewater treatment. A kinetic analysis was presented to explain the above results.

关键词： diamond fihlls boron doping electrochemical oxidation hydroxyl radicals energy consumption wastewater treat- ment

Optical characterization of single-crystal diamond grown by DC arc plasma jet CVD

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International Journal of Minerals,Metallurgy and Materials 2017年第12期24卷 1424-1430页

作者： Li-fu hei Yun Zhao jun-jun Wei Jin-long Liu Cheng-ming Li Fan-xiu Lü Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China

Optical centers of single-crystal diamond grown by DC arc plasma jet chemical vapor deposition(CVD) were examined using a low-temperature photoluminescence(PL) technique. The results show that most of the nitrogen-vacancy(NV) complexes are present as NV-centers, although some H2 and H3 centers and B-aggregates are also present in the single-crystal diamond because of nitrogen aggregation resulting from high N_2 incorporation and the high mobility of vacancies under growth temperatures of 950–1000°C. Furthermore, emissions of radiation-induced defects were also detected at 389, 467.5, 550, and 588.6 nm in the PL spectra. The reason for the formation of these radiation-induced defects is not clear. Although a Ni-based alloy was used during the diamond growth, Ni-related emissions were not detected in the PL spectra. In addition, the silicon-vacancy(Si-V)-related emission line at 737 nm, which has been observed in the spectra of many previously reported microwave plasma chemical vapor deposition(MPCVD) synthetic diamonds, was absent in the PL spectra of the single-crystal diamond prepared in this work. The high density of NV-centers, along with the absence of Ni-related defects and Si-V centers, makes the single-crystal diamond grown by DC arc plasma jet CVD a promising material for applications in quantum computing.

关键词： diamond single crystals direct current arc plasma jet chemical vapor deposition photoluminescence optical spectra

Treatment of adult congenital anal atresia with rectovestibular fistula:A rare case report

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World Journal of Clinical Cases 2023年第33期11卷 8065-8070页

作者： jun Wang Xin-Yi Zhang Ji-Han Chen hei-Ying Jin Department of Anorectal Surgery The Second Affiliated Hospital of Nanjing University of Chinese MedicineNanjing 210017Jiangsu ProvinceChina

BACKGROUND Female anorectal malformation is a correctable congenital *** manifestations in patients with anal deformities are uncommon,especially after *** SUMMARY The clinical data of a 19-year-old adult female patient with congenital anal atresia accompanied by rectovestibular fistula as the main manifestation was retrospectively *** was made based on the patient's clinical symptoms,signs,imaging showing the fistula,X-ray and magnetic resonance imaging *** preoperative examination was *** was *** patient exhibited an improvement in quality of life and presented no evidence of fecal incontinence during the 6-mo *** Transfistula anorectoplasty is a reasonable and reliable surgical method for the treatment of adult congenital anal atresia and rectovestibular fistula.

关键词： Anorectal malformations Congenital anorectal atresia Rectovestibular fistula Transfistula anorectoplasty Case report

Surface Carbonization of GaN and the Related Structure Evolution during the Annealing Process

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Chinese Physics Letters 2018年第1期35卷 51-54页

作者： Jin-Long Liu Liang-Xian Chen jun-jun Wei Li-Fu hei Xu Zhang Cheng-Ming Li Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083 Institute of Low Energy Nuclear Physics Beijing Normal UniversityBeijing Radiation CenterBeijing 100875

To explain the stabilization mechanism of the carbon-ion-implanted GaN under the diamond growth environment,the luminescence characteristics and structure evolution correlative with sites'carbon atoms located for highfluence carbon-ion-implanted Ga N are *** is implanted with carbon ion using fluence of 2×10^(17)cm^(-2)and energy of 45 *** the implanted samples are annealed at 800℃for 20 min and 1 h under the N_(2) *** luminescence characteristics of carbon-ion-implanted GaN are evaluated by photoluminescence spectrum at wavelength 325 *** lattice damage of Ga N is characterized by Raman spectrum and the corresponding vacancy-defect evolution before and after annealing is measured by slow positron *** results show that most of the carbon atoms will be located at the interstitial sites after carbon ion implantation due to the weak *** the implanted samples are annealed,strong yellow luminescence is emitted and the vacancies for Ga(V_(Ga))are reduced resulting from the migration of interstitial carbon(C_(i))and formation of complexes(CGaand/or C_(Ga)-C_(i))between *** the annealing time is prolonged,the carbon ions accommodated by the vacancies are saturated,vacancy clusters with carbon atoms appear and the concentration of C_(Ga)diminishes,which will have an adverse effect on the diamond film nucleation and growth.

关键词： Gallium nitride

Observation and mitigation of image distortion in high-energy electron radiography

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Nuclear Science and Techniques 2023年第6期34卷 69-77页

作者： Hao-Qing Li Liang Sheng Chang-Qing Zhang Ying-Chao Du Zheng Zhou Xiu-Feng Weng Jia-Hao Xiao hong-Qiao Yin Bin Sun Kun Wei Yang Li Bao-jun Duan Yong-Tang Liu Yan-hong Zhang Mei Zhang Yan Song Xiao-Dong Zhang jun Liu Zhu-Ming Fu Qing Xu Xue Du Jian-Peng Gao Xin-Yi Wang Xin-Jian Tan Dong-Wei hei Department of Engineering Physics Tsinghua UniversityBeijing100084China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi’an710024China Institute of Applied Electronics China Academy of Engineering PhysicsMianyang621900China Institute of Intelligent Machines Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei230031China Zhongke Hefei Institutes of Collaborative Research and Innovation for Intelligent Agriculture Hefei231131China

Image distortion caused by the angular misalignment of quadrupole magnets in high-energy electron radiography has been studied *** propose that the distortion originates from the coupling of the electron motions in the transverse directions,based on a theoretical analysis and the transfer-matrix *** relative angular rotation between the second and third magnetic quadrupoles was identified as the main contributor to image *** was verified by both a beam-dynamics simulation and *** strategies to mitigate this image distortion are also explored,including magnets online tuning,higher beam energy and larger magnification *** study provides criteria for designing experiments and paves the way for achieving higher image precision.

关键词： Misalignment Angular rotation Russian quadruplet Transfer matrix

Comparison of α particle detectors based on single-crystal diamond films grown in two types of gas atmospheres by microwave plasma-assisted chemical vapor deposition

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International Journal of Minerals,Metallurgy and Materials 2020年第5期27卷 703-712页

作者： Yan-zhao Guo Jin-long Liu Jiang-wei Liu Yu-ting Zheng Yun Zhao Xiao-lu Yuan Zi-hao Guo Li-fu hei Liang-xian Chen jun-jun Wei Jian-peng Xing Cheng-ming Li Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Optical and Electronic Materials Unit National Institute for Materials Science(NIMSIbaraki 305-0044Japan Key Laboratory of Microelectronic Device and Integration Technology Institute of Microelectronics of the Chinese Academy of SciencesBeijing 100029China

Chemical vapor deposition(CVD)-grown diamond films have been developed as irradiation-resistant materials to replace or upgrade current detectors for use in extreme radiation environments. However, their sensitivity in practical applications has been inhibited by space charge stability issues caused by defects and impurities in pure diamond crystal materials. In this study, two high-quality CVD-grown single-crystal diamond(SCD) detectors with low content of nitrogen impurities were fabricated and characterized. The intrinsic properties of the SCD samples were characterized using Raman spectroscopy, stereomicroscopy, and X-ray diffraction with the rocking curve mode, cathode luminescence(CL), and infrared and ultraviolet-visible-near infrared spectroscopies. After packaging the detectors, the dark current and energy resolution under α particle irradiation were investigated. Dark currents of less than 5 pA at 100 V were obtained after annealing the electrodes, which is comparable with the optimal value previously reported. The detector that uses a diamond film with higher nitrogen content showed poor energy resolution, whereas the detector with more dislocations showed poor charge collection efficiency(CCE). This demonstrates that the nitrogen content in diamond has a significant effect on the energy resolution of detectors, while the dislocations in diamond largely contribute to the poor CCE of detectors.

关键词： single-crystal diamond nitrogen impurity detector αparticle