The initial stage of Ni-TiO2 composite system electrodeposition on glassy carbon electrode from an acidic solution of nickel sulfate was investigated using cyclic voltammetry （CV）, chronoamperometry （CA） and elect...The initial stage of Ni-TiO2 composite system electrodeposition on glassy carbon electrode from an acidic solution of nickel sulfate was investigated using cyclic voltammetry （CV）, chronoamperometry （CA） and electrochemical impedance spectroscopy （EIS）. Analysis of current density-time transients was performed using the nonlinear fitting procedure and electrochemical impedance spectroscopy was simulated by Z-view software. Besides, the surface morphology of Ni-TiO2 co-deposition at the initial stage was observed by scanning electron microscopy （SEM）. The results show that, in the case of low overpotential （-790 mV vs SCE）, the presence of TiO2 particles in the plating bath makes the nucleation relaxation time tm^x decreased clearly. Meanwhile, the electro-crystallization of Ni-TiO2 system follows a Scharifker-Hills （SH） progressive nucleation/growth mechanism. While in the case of higher overpotential, the presence of the TiO2 particles in solution makes the nucleation relaxation time tmax increased. At -850 mV （vs SCE）, the co-deposition of Ni-TiO2 system meets SH instantaneous nucleation/growth mechanism. The results of impedance spectra show that the appearance of the characteristic inductive loops represents the nucleation/growth of nickel and the presence of TiO2 particles reduces the charge transfer resistance of solution. The SEM observation confirms that TiO2 particles can be considered as favorable sites for nickel nucleating.展开更多
Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5...Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5SiO4 was studied. The final sample was identified as Li2Fe0.5Mn0.5SiO4 with a Pmn21 monoclinic structure by X-ray diffraction analysis. The crystal phases components and crystal phase structure of the Li2Fe0.5Mn0.4SiO4 material were improved as the increase of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+). Field-emission scanning electron microscopy verified that the Li2Fe0.5Mn0.5SiO4 particles are agglomerates of Li2Fe0.5Mn0.5SiO4 primary particles with a geometric mean diameter of 220 nm. The Li2Fe0.5Mn0.5SiO4 sample was used as an electrode material for rechargeable lithium ion batteries, and the electrochemical measurements were carried out at room temperature. The Li2Fe0.5Mn0.5SiO4 electrode delivered a first discharge capacity of 230.1 mAh/g at the current density of 10 mA/g in first cycle and about 162 mAh/g after 20 cycles at the current density of 20 mA/g.展开更多
A mode II crack in single-crystal silicon was investigated experimentally using high-resolution transmission electron microscopy.Geometric phase analysis and numerical moiré method were employed to map the deform...A mode II crack in single-crystal silicon was investigated experimentally using high-resolution transmission electron microscopy.Geometric phase analysis and numerical moiré method were employed to map the deformation fields of the crack-tip area.The normal strain field maps of the crack-tip area indeed showed the deformation occurs primarily in the vicinity of the dislocations and the normal strains are near zero in the crack-tip area.The shear strain field map shows that the relatively large shear strain is in the crack-tip area.The experimental results were compared with the predictions of linear elastic fracture mechanics.The comparison shows that measured strain distribution ahead of the crack-tip agrees with the predictions of linear elastic fracture mechanics up to 1 nm from the crack-tip.展开更多
The bio-limited forming technology, a new technology organically integrating microbiology, manufacturing science and materials science, is used in the manufacturing of magnetic or conductive microstructures of differe...The bio-limited forming technology, a new technology organically integrating microbiology, manufacturing science and materials science, is used in the manufacturing of magnetic or conductive microstructures of different standard shapes. This paper explores the feasibility of magnetizing microorganism with thermal decomposition method. The principle of thermal decomposition of iron pentacarbonyl has been adopted to investigate the cells of Spirulina (a type of nature micro-helical microorganism) coated with pure iron. Further analysis have been conducted on the observations results of hollow micro-helical magnetic particles form, components and the phase structure obtained by using various tools including optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX), transmission electron microscopy (TEM), and X-ray diffraction analysis (XRD). Results showed that Spirulina cells could be coated with iron particles after the completion of thermal decomposition process, with well-kept shape of natural helixes and consistent components of different sampling points on the surface layer and thickness of layer. After the heat treatment at 700°C, the type of the surface iron layer formed was α-Fe. The paper also investigates the kinetics of the cell magnetization technology by thermal decomposition.展开更多
Formation and preservation of greigite can indicate the physicochemical characteristics of sedimentary environment. Presence of greigite can be diagnosed in the late Pleistocene fluvio-lacustrine sedimentary layers of...Formation and preservation of greigite can indicate the physicochemical characteristics of sedimentary environment. Presence of greigite can be diagnosed in the late Pleistocene fluvio-lacustrine sedimentary layers of 29.4–29.7 and 26.1–27.1 m in core ZK30 of the Yellow River delta, based on analysis of particle size, magnetic properties, scanning electron microscope(SEM) and X-ray diffraction(XRD) measurements. These layers are the transition zones from shallow marine facies to fluvio- lacustrine facies, and from fluvio-lacustrine facies to salt marsh facies in an ascending order, respectively. They are characterized by higher SIRM and SIRM/χ(>30 kA m-1) values than those of other layers, suggesting the possible existence of greigite. Both SEM and XRD analyses confirm its presence. However, sediment layer of 29.4–29.7 m are coarser, and greigite coexists with pyrite, but sediment layer of 26.1–27.1 m are finer and the occurrence of greigite is not accompanied by pyrite. The different occurrence of greigite in the two layers suggests that different climate condition and sedimentary environment control its formation and preservation.展开更多
基金Project(MKPT-04-106) supported by the Project of National Defense of China
文摘The initial stage of Ni-TiO2 composite system electrodeposition on glassy carbon electrode from an acidic solution of nickel sulfate was investigated using cyclic voltammetry （CV）, chronoamperometry （CA） and electrochemical impedance spectroscopy （EIS）. Analysis of current density-time transients was performed using the nonlinear fitting procedure and electrochemical impedance spectroscopy was simulated by Z-view software. Besides, the surface morphology of Ni-TiO2 co-deposition at the initial stage was observed by scanning electron microscopy （SEM）. The results show that, in the case of low overpotential （-790 mV vs SCE）, the presence of TiO2 particles in the plating bath makes the nucleation relaxation time tm^x decreased clearly. Meanwhile, the electro-crystallization of Ni-TiO2 system follows a Scharifker-Hills （SH） progressive nucleation/growth mechanism. While in the case of higher overpotential, the presence of the TiO2 particles in solution makes the nucleation relaxation time tmax increased. At -850 mV （vs SCE）, the co-deposition of Ni-TiO2 system meets SH instantaneous nucleation/growth mechanism. The results of impedance spectra show that the appearance of the characteristic inductive loops represents the nucleation/growth of nickel and the presence of TiO2 particles reduces the charge transfer resistance of solution. The SEM observation confirms that TiO2 particles can be considered as favorable sites for nickel nucleating.
基金Projects(13A047,10B054)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProjects(2011GK2002,2011FJ3160)supported by the Planned Science and Technology Project of Hunan Province,China
文摘Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5SiO4 was studied. The final sample was identified as Li2Fe0.5Mn0.5SiO4 with a Pmn21 monoclinic structure by X-ray diffraction analysis. The crystal phases components and crystal phase structure of the Li2Fe0.5Mn0.4SiO4 material were improved as the increase of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+). Field-emission scanning electron microscopy verified that the Li2Fe0.5Mn0.5SiO4 particles are agglomerates of Li2Fe0.5Mn0.5SiO4 primary particles with a geometric mean diameter of 220 nm. The Li2Fe0.5Mn0.5SiO4 sample was used as an electrode material for rechargeable lithium ion batteries, and the electrochemical measurements were carried out at room temperature. The Li2Fe0.5Mn0.5SiO4 electrode delivered a first discharge capacity of 230.1 mAh/g at the current density of 10 mA/g in first cycle and about 162 mAh/g after 20 cycles at the current density of 20 mA/g.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10862002 and 11062008)the Program for New Century Excellent Talents in University (Grant No. NCET-10-0909)the Natural Science Foundation of Inner Mongolia (Grant No. 2010BS0106)
文摘A mode II crack in single-crystal silicon was investigated experimentally using high-resolution transmission electron microscopy.Geometric phase analysis and numerical moiré method were employed to map the deformation fields of the crack-tip area.The normal strain field maps of the crack-tip area indeed showed the deformation occurs primarily in the vicinity of the dislocations and the normal strains are near zero in the crack-tip area.The shear strain field map shows that the relatively large shear strain is in the crack-tip area.The experimental results were compared with the predictions of linear elastic fracture mechanics.The comparison shows that measured strain distribution ahead of the crack-tip agrees with the predictions of linear elastic fracture mechanics up to 1 nm from the crack-tip.
基金supported by the Foundation for the Author of National Excellent Doctoral Dissertation of PR China (Grant No. 2007B32)the National High Technology Research and Development Program of China (Grant No. 2009AA043804)
文摘The bio-limited forming technology, a new technology organically integrating microbiology, manufacturing science and materials science, is used in the manufacturing of magnetic or conductive microstructures of different standard shapes. This paper explores the feasibility of magnetizing microorganism with thermal decomposition method. The principle of thermal decomposition of iron pentacarbonyl has been adopted to investigate the cells of Spirulina (a type of nature micro-helical microorganism) coated with pure iron. Further analysis have been conducted on the observations results of hollow micro-helical magnetic particles form, components and the phase structure obtained by using various tools including optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX), transmission electron microscopy (TEM), and X-ray diffraction analysis (XRD). Results showed that Spirulina cells could be coated with iron particles after the completion of thermal decomposition process, with well-kept shape of natural helixes and consistent components of different sampling points on the surface layer and thickness of layer. After the heat treatment at 700°C, the type of the surface iron layer formed was α-Fe. The paper also investigates the kinetics of the cell magnetization technology by thermal decomposition.
基金supported by the National Natural Science Foundation of China(Grant Nos.41030856,41176039,41376054 and 41030856)the Natural Science Foundation of Shandong Province(Grant No.2011ZRE29040)
文摘Formation and preservation of greigite can indicate the physicochemical characteristics of sedimentary environment. Presence of greigite can be diagnosed in the late Pleistocene fluvio-lacustrine sedimentary layers of 29.4–29.7 and 26.1–27.1 m in core ZK30 of the Yellow River delta, based on analysis of particle size, magnetic properties, scanning electron microscope(SEM) and X-ray diffraction(XRD) measurements. These layers are the transition zones from shallow marine facies to fluvio- lacustrine facies, and from fluvio-lacustrine facies to salt marsh facies in an ascending order, respectively. They are characterized by higher SIRM and SIRM/χ(>30 kA m-1) values than those of other layers, suggesting the possible existence of greigite. Both SEM and XRD analyses confirm its presence. However, sediment layer of 29.4–29.7 m are coarser, and greigite coexists with pyrite, but sediment layer of 26.1–27.1 m are finer and the occurrence of greigite is not accompanied by pyrite. The different occurrence of greigite in the two layers suggests that different climate condition and sedimentary environment control its formation and preservation.
