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Thermal stability of nanocrystalline W-Ti diffusion barrier thin films

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Science China(Technological Sciences) 2010年第4期53卷 1049-1055页

作者： WANG QingXiang,FAN ZhiKang & LIANG ShuHua School of Materials Science and Engineering,Xi’an University of Technology,Xi’an 710048,China School of Materials Science and Engineering Xi’an University of Technology Xi’an China

Nanocrystalline W-Ti diffusion barrier thin films with different phase structures and Cu/barrier/Si multilayer structures were deposited on p-type Si(100) substrates by DC magnetron sputtering.These films were annealed at different temperatures for 1 h.The diffusion barrier properties and thermal stability were studied using four-probe tester(FPP),XRD,AFM,XPS,FESEM,and HRTEM.The experimental results showed that the films were stable up to 700℃.When the annealing temperature was increased,the Cu and Ti atoms began to react and CuTi3 was formed.In addition,the high resistance Cu3Si was formed due to inter-diffusion between the Si and Cu atoms which made the surface rougher and caused the sheet resistance to increase abruptly.At the same time,failure mechanism of the nanocrystalline W-Ti diffusion barrier thin films during annealing process was also discussed.

关键词： nanocrystalline W-Ti thin films diffusion barrier anneal sheet resistance

Atomic scale epitaxial growth of BaTiO_3 thin films by laser molecular beam epitaxy

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Science China Mathematics 1997年第5期40卷 522-527页

作者：王会生马昆刘彦巍彭志强崔大复吕惠宾周岳亮陈正豪李林杨国桢 Laboratoryof Optical Physics Institute of Physics and Center for Condensed Matter Physics Chinese Academy of Sciences Beijing 100080 China

By using laser molecular beam epitaxy (L-MBE), atomic scale epitaxial growth of BaTiO3(BTO) thin films on SrTiO3 (STO) substrates is achieved. Measurements of reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy reveal that the BTO films are c-axis oriented single crystals with smooth surface. The multi-layer ferroelectric/superconducting heterostructures are also prepared and the ferroelectric properties of BTO films are studied. The results show that by using L-MBE technique, high quality BTO films and improved device performance can be obtained.

关键词： laser molecular beam epitaxy BaTiO3 thin films structural analysis ferroelectric properties.

Nonlinear interval analysis of rotor response with joints under uncertainties

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Chinese Journal of Aeronautics 2020年第1期33卷 205-218页

作者： Yanhong MA Yongfeng WANG Cun WANG Jie HONG School of Energy and Power Engineering Beihang UniversityBeijing 100083China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100083China

The dynamic influence of joints in aero-engine rotor systems is investigated in this paper.Firstly,the tangential stiffness and loss factor are obtained from an isolated lap joint setup with dynamic excitation experiments.Also,the influence of the normal contact pressure and the excitation level are examined,which revel the uncertainty in joints.Then,the updated thin Layer Elements(TLEs)method with fitted parameters based on the experiments is established to simulate the dynamic properties of joints on the interface.The response of the rotor subjected to unbalance excitation is calculated,and the results illustrate the effectiveness of the proposed method.Meanwhile,using the Chebyshev inclusion function and a direct iteration algorithm,a nonlinear interval analysis method is established to consider the uncertainty of parameters in joints.The accuracy is proved by comparison with results obtained using the Monte-Carlo method.Combined with the updated TLEs,the nonlinear Chebyshev method is successfully applied on a finite model of a rotor.The study shows that substantial attention should be paid to the dynamical design for the joint in rotor systems,the dynamic properties of joints under complex loading and the corresponding interval analysis method need to be intensively studied.

关键词： Aero-engine Bolted joints Nonlinear interval analysis method Rotor dynamics Uncertainties Updated thin Layer Elements(TLE)method

Micro-porous TiO2 thin films grown on surface of Ti substrate

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中国有色金属学会会刊：英文版 2004年第Z1期14卷 178-181页

作者： WU Xiao-hong QIN Wei JIANG Zhao-hua HU Xin-guo Li Qing-fen Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China School of Mechanics and Electronics Engineering Harbin Engineering University Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China School of Mechanics and Electronics EngineeringHarbin Engineering University Harbin 150001 China

Microporous titanium dioxide thin films have been grown on titanium plates by the micro-plasma oxidation method with different current densities (4, 6, 10 and 14 A/dm2). X-ray diffraction, scanning electronic microscopy and UV-Vis spectrophotometry were used to characterize the films. It is found that the films grown are microporous and consist of crystalline titanium dioxide. The micropore size and the content of anatase and rutile TiO2 phase increase with the applied voltage. The relatively higher degradation efficiency for rhodamine B is obtained in the film produced with a current density of 10 A/dm2.

关键词： micro-plasma oxidation TiO2 thin film photo-catalytic activity rhodamine B

Absorption spectra of C_(60) and C_(70) thin films

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Science China Mathematics 1996年第8期39卷 864-875页

作者：周维亚解思深钱生法周棠赵日安王刚钱露茜李文治 Institute of Physics Chinese Academy of Sciences Beijing 100080 China Department of Physics the Central University of Nationality Beijing 100087 China.

The spectra of Cm and Cm thin films over a wide energy range (0.6 to 6.5eV) are measured by transmission spectroscopy and photothermal deflection spectroscopy (PDS), and the optical absorption coefficients are obtained. The optical transitions for the Cm and Cw thin films are analyzed according to the molecular orbital model. The weak absorption spectra of the fullerenes are similar to that of amorphous silicon. The optical energy gaps are given by Tauc’s plots as 1.75 and 1.65eV for C60 and C70 thin films, respectively. The disorders in the fullerene films, which resulted in band-tail state or defect state, are indicated by Urbach edge and sub-gap absorption. It is the disorder that brought the difficulty in determination of the energy gap for fullerenes. The effects of the deflection medium and substrate on the weak absorption spectra of fullerene films are also discussed.

关键词： C60 C70 thin film optical absorption photo thermal deflection spectroscopy.

The domain structure and polarization retention properties of PT/PZT/PT ferroelectric thin film

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Science China(Technological Sciences) 2007年第2期50卷 190-198页

作者： WANG LongHai Yu Jun ZHAO SuLing ZHENG ChaoDuan WANG YunBo GAO JunXiong School of Electric and Information Engineering Wuhan Institute of TechnologyWuhan 430073China Department of Electronic Science and Technology Huazhong University of Science and TechnologyWuhan 430074China The Research&Test Center of Materials Wuhan University of TechnologyWuhan 430070China

The highly oriented perovskite-phase PT/PZT/PT ferroelectric thin film was pre- pared by sol-gel method. The domain structures and polarization retention proper- ties were investigated by scanning force microscopy. The amplitude and phase images of piezoresponse show complex various contrasts of dark, bright and gray. The complex variation of contrast in piezoresponse images results from the per- plexing orientation of grains and arrangement of domains in the ferroelectric films. The bright and dark areas in phase images correspond to top-to-bottom and bot- tom-to-top polarization oriented c-domain, respectively. The gray areas are c-domains with the polarization vector deviating from the direction normal to the film plane. The surface potential images of EFM are bright contrast, which is due to positive charges trapped on the film surface after being polarized by positive volt- age. And the brighter contrast is obtained from the higher electric field. The time-dependent surface potential images and line potential profiles show that the potential decays with time. And the decay in the region polarized by higher electric field is faster, especially at 15 min. This indicates that the polarization retention is related to the polarized electric field. Better retention properties may be obtained from a proper polarized electric field.

关键词： ferroelectric thin film domain polarization retention scanning force microscope (SFM)

Sliding wear behavior of fully nanotwinned Cu alloys

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Friction 2019年第3期7卷 260-267页

作者： Jianfeng YAN Andrew LINDO Ruth SCHWAIGER Andrea MHODGE Department of Aerospace and Mechanical Engineering University of Southern CaliforniaLos AngelesCA90089USA Department of Mechanical Engineering Tsinghua UniversityBeijing100084China Institute for Applied Materials Karlsruhe Institute of Technology(KIT)Eggenstein-Leopoldshafen76344Germany

Highly nanotwinned(NT) metals have advantages such as high strength,good ductility,favorable corrosion resistance,and thermal stability.It has been demonstrated that the introduction of high density NT microstructures can enhance the tribological properties of metals.However,the influence of the microstructure and the composition of NT alloys on the tribological behavior are not clear.In this work,the sliding wear behavior of fully NT materials,specifically Cu-Al and Cu-Ni alloys,are studied by a nanoscratch technique using a nanoindenter.The effects of microstructure and chemical composition on the wear properties are also studied.The results show that the chemical composition has an obvious influence on the wear resistance and microstructural deformation.For NT Cu-Al alloys,the hardness and sliding wear resistance improve with increased Al content from Cu-2 wt.%Al to Cu-6 wt.%Al.NT Cu-10 wt.%Ni alloy shows even better wear resistance than Cu-6 wt.%Al.The microstructural analysis shows that NT Cu alloys with higher wear resistance correspond to a smaller deformation-affected zone.The improvement of sliding wear properties of Cu-Al alloys with higher Al content may be ascribed to their decreased stacking fault energy.NT Cu-Ni alloy shows better wear resistance than Cu-Al alloy,this may be related to the formation of intermetallic compounds in Cu-Al system.This study broadens the knowledge about tribological properties of NT materials and provides a potential method to optimize their sliding wear resistance by altering the chemical composition of NT Cu alloys.

关键词： nanotwinned alloys thin film stacking fault energy tribology

Birefringent non-polarizing thin film design

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Science China(Technological Sciences) 2005年第1期48卷 61-69页

作者： QI Hongji HONG Ruijin HE Hongbo SHAO Jianda FAN Zhengxiu Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China

In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations, which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin film over visible spectral region are obtained at oblique incidence.

关键词： birefringent thin film, non-polarization, design.

Epitaxial growth and electrical transport properties of La_(0.5)Sr_(0.5)CoO_3 thin films prepared by pulsed laser deposition

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Science China Mathematics 1999年第8期42卷 865-872页

作者：李美亚熊光成王忠烈范守善赵清太林揆训 Science Center Shantou University Shantou 515063 China Department of Physics Peking University Beijing 100871 China Microelectronic Institute Peking University Beijing 100871 China Department of Physics Tsinghua University Beijing 100084 China

Epitaxial growth of the La0.5Sr0.5CoO3（LSCO） thin films has been realized on LaAlO3, SrTiO3 and MgO substrates by pulsed laser deposition. The epitaxial growth behavior and the electrical transport properties of these films were studied systematically. The temperature dependencies of the resistivity of the film have been determined. Studies indicate that close dependencies exist between the crystal structures and the electrical transport properties of the epitaxial LSCO films, and that the epitaxial thin films are of low resistivity and metallic conductive features. The epitaxial films deposited on the LaAlO3 substrates at about 700℃ possess the optimal properties compared with the others. Discussions of the dependencies and the mechanisms of the epitaxial structures on the electrical transport properties of the LSCO films have been made.

关键词： epitaxial growth pulsed laser deposition La0.5Sr0.5CoO3 thin film electrical transport properties.