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Xin H.-Q.,Lanzhou University of Technology | Hou X.-G.,Lanzhou University of Technology | Hou X.-G.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals | Han X.-X.,CAS Lanzhou Institute of Chemical Physics
Faguang Xuebao/Chinese Journal of Luminescence | Year: 2015

By using liquid exfoliation method with sonication in appropriate stripping solvent, ultrasonic time, ultrasonic power, MoS2 hybrid-nanosheets suspension with different lateral dimension and uniform dispersion nanosheets were obtained. Under 360 nm excitation, the suspension shows both the luminescence properties of monolayer MoS2 and small MoS2 nanoparticles. The strongest peak of the sample is centered at 512 nm, and shows obvious blue-shifted compared with that of monolayers MoS2 exfoliated by the micromechanically cleavage method. The blue-shifted luminescence is mainly caused by the strong quantum confinement effect of the MoS2 hybrid nanosheets which produced in horizontal dimension as well. ©, 2015, Chines Academy of Sciences. All right reserved. Source

Li Y.M.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals | Huo X.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals
Advanced Materials Research | Year: 2014

Electroless silver plating on the surface of fly ash cenospheres was prepared by slowly adding the solution of AgNO3 into the mixed solution of D-glucose solution and alkaline solution after thermo-alkaline treatment. The morphology and composition of the silver-coated fly ash cenospheres composite powders were observed and analyzed by using SEM, EDS and XRD, and the influence of pH, loading quantity on silver plating was invested. The results revealed that, with the pH value of plating solution increasing, the precipitation of silver is improved, but led to self-accelerating decomposition if too high, and the influence of loading quantity on silver relative content and electro-conductivity of composite powders is very great. The silver shell of composite particles is even and compact when the pH value is 12.57 and the loading quantity is 4g/L, which resistivity can reach to 0.05Ω•cm. © (2014) Trans Tech Publications, Switzerland. Source

Zhang Q.,Lanzhou University of Technology | Zhang Q.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals | Mei J.,Lanzhou University of Technology | Wang X.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals | And 3 more authors.
Electrochimica Acta | Year: 2014

A new facile approach to the surface modification of LiNi0.5Mn1.5O4 by lithium polyacrylate coating is demonstrated. This strategy is based on mild polymer electrolyte coating from aqueous lithium polyacrylate solution. The LiNi0.5Mn1.5O4 (LNM) and 1% PAALi coated LNM (LNM@1%PAALi) are characterized by XRD, SEM, TEM, ICP-OES, galvanostatic charge-discharge tests and electrochemical impedance spectra (EIS). XRD and SEM results indicate that there are no clear difference between LNM and LNM@1%PAALi. HRTEM results indicate PAALi is uniformly coated on LiNi0.5Mn1.5O4. ICP-OES results indicate that PAALi coating can effectively prevent the Ni ions and roughly prevent Mn ions dissolving from LiNi0.5Mn1.5O4 cathode materials. Galvanostatic charge-discharge tests show that the discharge capacity of LNM@1%PAALi reaches up to 131.5 mAh g-1 at 0.2 C and the value is still as high as 101.5 mAh g-1 at 12 C. In addition, LNM@1%PAALi shows high coulombic efficiency and retains 90.0% of its initial discharge capacity after 200 cycles. EIS proves that LNM@1%PAALi cells has distinct lower ohmic resistance of the electrolyte. SEM of the cycled electrodes implies that PAALi can promote the formation of valid SEI film, being favor of the compatibility between LNM and electrolyte. © 2014 Elsevier Ltd. All rights reserved. Source

Zhang Q.,Lanzhou University of Technology | Mei J.,Lanzhou University of Technology | Wang X.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals | Guo J.,Lanzhou University of Technology | And 2 more authors.
Journal of Alloys and Compounds | Year: 2014

Spherical LiMn2O4 nanoparticles were successfully prepared via solution combustion synthesis by controlling calcinating temperature. XRD results indicate that high purity LiMn2O4 can be fabricated by calcinating the precursor above 600 °C. SEM results reflect that LiMn2O4 calcinated lower than 600 °C are composed of nanoparticles about 100 nm. Therefore, LiMn2O4 calcinated at 600 °C possess high purity and nanoparticles, which ensure the most excellent electrochemical performance among the precursor as well as LiMn2O4 calcinated at 500 °C, 600 °C and 700 °C. LiMn2O4 calcinated at 600 °C even can deliver a capacity of 103.8 mA h g-1 at 10 C, which is the 83.6% of the capacity at 0.2 C. It also displays excellent capacity retention ratio of 95.1% for 100 cycles at constant current rate of 1 C. © 2014 Elsevier B.V. All rights reserved. Source

Wang X.,Lanzhou University of Technology | Fan D.,Lanzhou University of Technology | Fan D.,State Key Laboratory of Advanced Processing and Recycling of Non ferrous Metals | Huang J.,Lanzhou University of Technology | And 3 more authors.
Journal of Physics D: Applied Physics | Year: 2014

A three-dimensional model containing tungsten electrodes, arc plasma and a weld pool is presented for double electrodes tungsten inert gas welding. The model is validated by available experimental data. The distributions of temperature, velocity and pressure of the coupled arc plasma are investigated. The current density, heat flux and shear stress over the weld pool are highlighted. The weld pool dynamic is described by taking into account buoyance, Lorentz force, surface tension and plasma drag force. The turbulent effect in the weld pool is also considered. It is found that the temperature and velocity distributions of the coupled arc are not rotationally symmetrical. A similar property is also shown by the arc pressure, current density and heat flux at the anode surface. The surface tension gradient is much larger than the plasma drag force and dominates the convective pattern in the weld pool, thus determining the weld penetration. The anodic heat flux and plasma drag force, as well as the surface tension gradient over the weld pool, determine the weld shape and size. In addition, provided the welding current through one electrode increases and that through the other decreases, keeping the total current unchanged, the coupled arc behaviour and weld pool dynamic change significantly, while the weld shape and size show little change. The results demonstrate the necessity of a unified model in the study of the arc plasma and weld pool. © 2014 IOP Publishing Ltd. Source

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