Based on the theory of unsteady hydrodynamic lubrication and relevant mathematic and physical methods, a basic model was developed to analyze the unsteady lubrication film thickness, pressure stress and friction stres...Based on the theory of unsteady hydrodynamic lubrication and relevant mathematic and physical methods, a basic model was developed to analyze the unsteady lubrication film thickness, pressure stress and friction stress in the work zone in strip rolling. The distribution of pressure stress and friction stress in the work zone was obtained. A numerical simulation was made on a 1850 cold rolling mill. The influence of back tension stress and reduction on the distribution of pressure stress and friction stress between the roll gaps was qualitatively analyzed by numerical simulation. The calculated results indicate that the higher the back tension, the lower the pressure stress and the friction stress in the work zone, and the largest friction stresses are obtained at the inlet and outlet edges. The pressure and friction gradients are rather small at high back tension. The pressure-sensitive lubricant viscosity increases exponentially with the increase of pressure. The unsteady lubrication phenomenon in the roll bite is successfully demonstrated.展开更多
In this paper the fabrication technique of amorphous SnO2：（Zn, In） film is presented. The transmittance and gap-states distribution of the film are given. The experimental results of gap-states distribution are com...In this paper the fabrication technique of amorphous SnO2：（Zn, In） film is presented. The transmittance and gap-states distribution of the film are given. The experimental results of gap-states distribution are compared with the calculated results by using the facts of short range order and lattice vacancy defect of the gap states theory. The distribution of gap state has been proved to be discontinuous due to the short-range order of amorphous structure.展开更多
Amorphous silicon （a-Si）, nanocrystalline silicon （nc-Si） and hydrogenated nanocrys- talline silicon （nc-Si：H） films were fabricated by using chemical vapor deposition （CVD） system. The a-Si and nc-Si thin fi...Amorphous silicon （a-Si）, nanocrystalline silicon （nc-Si） and hydrogenated nanocrys- talline silicon （nc-Si：H） films were fabricated by using chemical vapor deposition （CVD） system. The a-Si and nc-Si thin films were irradiated with 94 MeV Xe-ions at fluences of 1.0 × 10^11 ions/cm2, 1.0 × 10^12 ions/cm^2 and 1.0 × 10^13 ions/era2 at room temperature （RT）. The nc-Si：H films were irradiated with 9 MeV Xe-ions at 1.0 ×10^12 Xe/cm^2, 1.0 × 10^13 Xe/cm2 and 1.0×10^14 Xe/cm2 at RT. For comparison, mono-crystalline silicon （c-Si） samples were also irradiated at RT with 94 MeV Xe-ions. All samples were analyzed by using an UV/VIS/NIR spectrometer and an X-ray powder diffractometer. Variations of the optical band-gap （Eg） and grain size （D） versus the irradiation fluence were investigated systematically. The obtained results showed that the optical band-gaps and grain size of the thin films changed dramatically whereas no observable change was found in c-Si samples after Xe-ion irradiation. Possible mechanism underlying the modification of silicon thin films was briefly discussed.展开更多
We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide.Layer-by-layer growth of CuS_（2 ）films with a preferential orientation of（111）on SrTiO_3（001）and...We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide.Layer-by-layer growth of CuS_（2 ）films with a preferential orientation of（111）on SrTiO_3（001）and Bi_2Sr_2Ca Cu_2O_（8＋）substrates is achieved by molecular beam epitaxy growth.For ultrathin films on both kinds of substrates,we observe symmetric tunneling gap around the Fermi level that persists up to^15 K.The tunneling gap degrades with either increasing temperature or increasing thickness,suggesting new matter states at the extreme twodimensional limit.展开更多
The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 an...The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.展开更多
Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films...Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films have been investigated using optical spectroscopy, band structure analyses and ultraviolet photoelectro n spectroscopy (UPS). ZnO films have direct allowed transition band structure, w hich has been confirmed by the character of the optical absorption coefficient. The apparent band gap has been found directly proportional to N2/3, showing that the effect of Burstein-Moss shift on the band gap variations dominates over the many-body effect. With only standard cleaning protocols, the work function of ZnO: (Al, Mn) and ZnO: Al films have been measured to be 4.26 and 4.21eV, respec tively. The incorporation of Mn element into the matrix of ZnO, as a relatively deep donor, can remove some electrons from the conduction band and deplete the d ensity of occupied states at the Fermi energy, which causes a loss in measured p hotoemission intensity and an increase in the surface work function. Based on th e band gap and work function results, the energy band diagram of the ZnO: (Al, M n) film near its surface is also given.展开更多
The Ga203/ZnO multilayer films are deposited on quartz substrates by magnetron sputtering, the thickness values of Ga203 layers are in a range of 19 nm-2.5 nm and the thickness of ZnO layer is a constant of 1 nm. Form...The Ga203/ZnO multilayer films are deposited on quartz substrates by magnetron sputtering, the thickness values of Ga203 layers are in a range of 19 nm-2.5 nm and the thickness of ZnO layer is a constant of 1 nm. Formation of spinel ZnGa204 film is achieved via the annealing of the Ga203/ZnO multilayer film. The influences of original Ga203 sublayer thickness on the optical and structural properties of Ga203/ZnO multilayer films and annealed films are studied. With the decrease of the thickness of Ga203 sublayer, the optical band-gap of Ga203/ZnO multilayer film decreases, the intensity of UV emission diminishes and the intensity of violet emission increases. The annealed film displays the enlarged optical band gap and the quenched violet emission. UV fluorescence bands are observed from Ga203 and ZnGa204.展开更多
Cobalt doped ZnO film assembled by the nanoparticles was prepared by low energy cluster beam deposition.The microstructure,phase structure and optical properties were investigated for the nanostructured films.The resu...Cobalt doped ZnO film assembled by the nanoparticles was prepared by low energy cluster beam deposition.The microstructure,phase structure and optical properties were investigated for the nanostructured films.The results show that the nanostructured film was assembled by monodisperse spherical nanoparticles with average diameter of about 29.3 nm which are distributed uniformly and compactly.The results of X-ray diffraction(XRD)show that cobalt doped ZnO nanostructured film is indexed to a wurtzite structure of ZnO,and no Co-phase structure and other phases are observed.The UV-visible absorption spectra show that the optical band-gap of the film is broadened after doping.展开更多
Optical absorption properties of electron beam evaporated a-Si films(a-Si_(1-x)Gd_x films)are studied for various composition x.It is shown from the experimental results that variation of chemical composition in this ...Optical absorption properties of electron beam evaporated a-Si films(a-Si_(1-x)Gd_x films)are studied for various composition x.It is shown from the experimental results that variation of chemical composition in this kind of materials will lead to a change in near infrared absorption.For 0.1 at%<x<1.0 at%,the changes of op- tical absorption in the films are more sensitive.The optical band gap narrows with increasing content x from 1.52 to 1.36 eV.Doping Gd element properly will be able to compensate the dangling bonds in a-Si films to improve thermal stability and mechanical properties of a-Si films.展开更多
基金Project(51175133)supported by the National Natural Science Foundation of China
文摘Based on the theory of unsteady hydrodynamic lubrication and relevant mathematic and physical methods, a basic model was developed to analyze the unsteady lubrication film thickness, pressure stress and friction stress in the work zone in strip rolling. The distribution of pressure stress and friction stress in the work zone was obtained. A numerical simulation was made on a 1850 cold rolling mill. The influence of back tension stress and reduction on the distribution of pressure stress and friction stress between the roll gaps was qualitatively analyzed by numerical simulation. The calculated results indicate that the higher the back tension, the lower the pressure stress and the friction stress in the work zone, and the largest friction stresses are obtained at the inlet and outlet edges. The pressure and friction gradients are rather small at high back tension. The pressure-sensitive lubricant viscosity increases exponentially with the increase of pressure. The unsteady lubrication phenomenon in the roll bite is successfully demonstrated.
基金Project supported by the Program A for Science and Technology of Education Bureau of Fujian Province of China (Grant No. JA08210)
文摘In this paper the fabrication technique of amorphous SnO2：（Zn, In） film is presented. The transmittance and gap-states distribution of the film are given. The experimental results of gap-states distribution are compared with the calculated results by using the facts of short range order and lattice vacancy defect of the gap states theory. The distribution of gap state has been proved to be discontinuous due to the short-range order of amorphous structure.
基金supported by the Major State Basic Research Development Program of China(973Program,No.2010CB832902)the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KJCX2-YW-N35)
文摘Amorphous silicon （a-Si）, nanocrystalline silicon （nc-Si） and hydrogenated nanocrys- talline silicon （nc-Si：H） films were fabricated by using chemical vapor deposition （CVD） system. The a-Si and nc-Si thin films were irradiated with 94 MeV Xe-ions at fluences of 1.0 × 10^11 ions/cm2, 1.0 × 10^12 ions/cm^2 and 1.0 × 10^13 ions/era2 at room temperature （RT）. The nc-Si：H films were irradiated with 9 MeV Xe-ions at 1.0 ×10^12 Xe/cm^2, 1.0 × 10^13 Xe/cm2 and 1.0×10^14 Xe/cm2 at RT. For comparison, mono-crystalline silicon （c-Si） samples were also irradiated at RT with 94 MeV Xe-ions. All samples were analyzed by using an UV/VIS/NIR spectrometer and an X-ray powder diffractometer. Variations of the optical band-gap （Eg） and grain size （D） versus the irradiation fluence were investigated systematically. The obtained results showed that the optical band-gaps and grain size of the thin films changed dramatically whereas no observable change was found in c-Si samples after Xe-ion irradiation. Possible mechanism underlying the modification of silicon thin films was briefly discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11574174,11774193 and 11790311the National Basic Research Program of China under Grant No 2015CB921000
文摘We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide.Layer-by-layer growth of CuS_（2 ）films with a preferential orientation of（111）on SrTiO_3（001）and Bi_2Sr_2Ca Cu_2O_（8＋）substrates is achieved by molecular beam epitaxy growth.For ultrathin films on both kinds of substrates,we observe symmetric tunneling gap around the Fermi level that persists up to^15 K.The tunneling gap degrades with either increasing temperature or increasing thickness,suggesting new matter states at the extreme twodimensional limit.
文摘The optical reflectance and transmittance spectra in the wavelength range of 300-2500 nm are used to compute the absorption coefficient of zinc oxide films annealed at different post-annealing temperatures 400, 500 and 600°C.The values of the cross point between the curves of the real and imaginary parts of the optical conductivity ɑ_1 and ɑ_1 with energy axis of films exhibit values that correspond to optical gaps and are about 3.25-3.3 eV. The maxima of peaks in plots dR/dλ and dT/dλ versus wavelength of films exhibit optical gaps at about 3.12-3.25 eV.The values of the fundamental indirect band gap obtained from the Tauc model are at about 3.14-3.2 eV. It can be seen that films annealed at 600°C have the minimum indirect optical band gap at about 3.15 eV. The films annealed at 600°C have Urbach＇s energy minimum of 1.38 eV and hence have minimum disorder. The dispersion energy d of films annealed at 500°C has the minimum value of 43 eV.
基金This work was supported by the National Nalural Science Foundation of China(No.50172051).
文摘Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films have been investigated using optical spectroscopy, band structure analyses and ultraviolet photoelectro n spectroscopy (UPS). ZnO films have direct allowed transition band structure, w hich has been confirmed by the character of the optical absorption coefficient. The apparent band gap has been found directly proportional to N2/3, showing that the effect of Burstein-Moss shift on the band gap variations dominates over the many-body effect. With only standard cleaning protocols, the work function of ZnO: (Al, Mn) and ZnO: Al films have been measured to be 4.26 and 4.21eV, respec tively. The incorporation of Mn element into the matrix of ZnO, as a relatively deep donor, can remove some electrons from the conduction band and deplete the d ensity of occupied states at the Fermi energy, which causes a loss in measured p hotoemission intensity and an increase in the surface work function. Based on th e band gap and work function results, the energy band diagram of the ZnO: (Al, M n) film near its surface is also given.
基金Project supported by the National Natural Science Foundation of China(Grant No.10974077)the Innovation Project of Shandong Graduate Education,China(Grant No.SDYY13093)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2010AL026)
文摘The Ga203/ZnO multilayer films are deposited on quartz substrates by magnetron sputtering, the thickness values of Ga203 layers are in a range of 19 nm-2.5 nm and the thickness of ZnO layer is a constant of 1 nm. Formation of spinel ZnGa204 film is achieved via the annealing of the Ga203/ZnO multilayer film. The influences of original Ga203 sublayer thickness on the optical and structural properties of Ga203/ZnO multilayer films and annealed films are studied. With the decrease of the thickness of Ga203 sublayer, the optical band-gap of Ga203/ZnO multilayer film decreases, the intensity of UV emission diminishes and the intensity of violet emission increases. The annealed film displays the enlarged optical band gap and the quenched violet emission. UV fluorescence bands are observed from Ga203 and ZnGa204.
基金Projects(1090406510674056+5 种基金1077407090606002)supported by the National Natural Science Foundation of ChinaProject(20080441042)supported by China Postdoctoral Science FoundationProject(200926)supported by Tonghua Normal University FoundationProject(2010CB923401)supported by the National Basic Research Program of ChinaProject(BK2008024)supported by the Natural Science Foundation of Jiangsu of Province,China
文摘Cobalt doped ZnO film assembled by the nanoparticles was prepared by low energy cluster beam deposition.The microstructure,phase structure and optical properties were investigated for the nanostructured films.The results show that the nanostructured film was assembled by monodisperse spherical nanoparticles with average diameter of about 29.3 nm which are distributed uniformly and compactly.The results of X-ray diffraction(XRD)show that cobalt doped ZnO nanostructured film is indexed to a wurtzite structure of ZnO,and no Co-phase structure and other phases are observed.The UV-visible absorption spectra show that the optical band-gap of the film is broadened after doping.
文摘Optical absorption properties of electron beam evaporated a-Si films(a-Si_(1-x)Gd_x films)are studied for various composition x.It is shown from the experimental results that variation of chemical composition in this kind of materials will lead to a change in near infrared absorption.For 0.1 at%<x<1.0 at%,the changes of op- tical absorption in the films are more sensitive.The optical band gap narrows with increasing content x from 1.52 to 1.36 eV.Doping Gd element properly will be able to compensate the dangling bonds in a-Si films to improve thermal stability and mechanical properties of a-Si films.
