توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Oxidation of Copper on the Electrodeposited Co–Ni Alloy Layers in the Co–Ni\Cu Multilayer
نویسنده(ها): ، ، ،
اطلاعات انتشار: دهمین کنگره ملی خوردگی ایران، سال
تعداد صفحات: ۱۱
In recent years, more attention has been paid on producing ferromagnetic muhilayer by electro deposition (ECD). In this process, metallic muhilayers could be fabricated with acceptable quality and price for magnetic systems such as giant magneto resistance (GMR). It was noticeable that a large amount of oxidation and segregation could be
created due to the difference in the interfacial tension between metallic layers. In the present study. copper surface discharge and oxidation was investigated in the electrodeposited Co–NilCu bilayer system using X–ray photoelectron spectroscopy (XPS). secondary ion mass spectroscopy (SIMS) and atomic force microscopy (AFM). The results indicated the existence of a few monolayers of copper oxide on the sud3ce. attributed to discharge and accumulation of copper atoms on the surface during electrodeposition. This phenomenon was explained by lower interfacial tension of the Cu in comparison with the Co and Ni species. Our results also showed that the surface segregation in electrodeposits was increased due to interface charging and. higher sur:tBce diffusion at applied overpotential The effect of inter:tBce charging on the interfacial tension was confirmed by Lippman model Also. the effect of air exposure on the amount of oxidized copper was related to selective oxidation in the Co–NilCu systems with a higher tendency of copper to surface oxidation. These resuhs confirm that the Cu oxidation is a key parameter in the accumulation during deposition and also during air exposure.<\div>

۲Comparison of Trap–State Distribution and Carrier Transport in TiO2 Nanotubular and Nanoparticular Electrodes of Dye Sensitized Solar Cells
نویسنده(ها): ، ، ،
اطلاعات انتشار: سومین کنفرانس نانوساختارها، سال
تعداد صفحات: ۴
In this paper we have studied the performance of dye–sensitized solar cells (DSCs) based on nanotube arrays of TiO2 with different lengths and compared them to nanoparticular films. By measuring electron transport time and lifetime using transient photocurrent and photovoltage techniques we found out the electron transport is quit comparable in these two morphologies however the electron lifetime is much longer in nanotubular structure so we have much larger electron diffusion length and charge collection efficiencies in nanotubular electrodes. By measuring extracted charges at open circuit condition we found that nanotubular structure have higher density of traps in deeper levels that make it difficult for electrons to transport through these one–dimensional ordered nanostructures, so in spite of high degree of order we have quit comparable transport time similar to nanoparticulate electrodes.<\div>

۳Synthesis of TiO2 nanofibers using electrospinning for photocatalytic application
نویسنده(ها): ، ، ،
اطلاعات انتشار: سومین کنفرانس نانوساختارها، سال
تعداد صفحات: ۴
In this article we introduce electrospinning as a method for preparation carbon doped TiO2 nanofibers. For fiber formation polyvinylpyrrolidone (PVP), titanium isopropoxide (TITP), ethanol and acetic acid were used to prepare a viscous solution and was electrospun under 20 kV applied voltage. Annealing the fibers in air and oxygen removed polymer and TiO2 remained in the shape of nanofibers. XPS results from the annealed samples in air revealed carbon in TiC chemical state. Since optical band gap and crystal structure of TiO2 influence on photocatalytic properties, diffuse reflectance and XRD experiments were performed. We observed a reduction about 0.2 eV in the band gap and mixture of two rutile and anatase phases. Annealing in flowing oxygen environment results more anatase phase and highest photocatalytic activity.<\div>

۴Palladium nanoparticle dispersion over the nanocrystalline WO3 through the reduction of PdCl2 by H2: characterization and gasochromic properties
نویسنده(ها): ، ، ،
اطلاعات انتشار: سومین کنفرانس نانوساختارها، سال
تعداد صفحات: ۴
In this study dispersed Pd nanoparticles (NP) over the sol–gel derived WO3 thin films were produced from the H2–reduction of deposited PdCl2 The surface chemistry of samples was studied by X–ray Photoelectron Spectroscopy (XPS). For example, after the completeness of reduction the Cl atoms are completely eliminated and a PdO\Pd° layer is produced at surface. From Scanning Electron Microscope (SEM) and X–Ray Diffraction (XRD) observations, the PdCl2 layer is crystalline consisting of ~ 50 nm Pd NPs or fractal–like structures embedded in a PdCl2 matrix. They are shrinking in the reduction process and consequently a dispersion of Pd NPs is produced at the surface. The gasochromic properties in the H2\O environment for different PdCl2 amounts revealed that the rate and saturated level of colouring increases with PdCl2 amounts.<\div>

۵Hydrogen Sensitivity of Pure and MWNTs\WO3 hybrid films
نویسنده(ها): ،
اطلاعات انتشار: سومین کنفرانس نانوساختارها، سال
تعداد صفحات: ۴
WO3\MWNTs hybrid gas sensitive films were fabricated on alumina substrate by spin–coating method.Structure, morphology and chemical composition of the functionalized MWNTs, as–prepared WO3 nanoparticles and WO3\MWNTs hybrid films were studied by SEM, TEM, XRD and XPS techniques. MWNTs were initially functionalized (f–MWNTs) to enhance dispersion and reaction with WO3 nanoparticles. Our results show that WO3 nanoparticles were nucleated on oxygenated group of f–MWNTs surface in hybrid suspension. After coating and annealing the films at 350 ºC, the conductance measurement of the hybrid WO3\MWNTs films indicates rather linear gas sensitivity as a function of hydrogen concentrations from 0.0024 to 1.14% at 320 oC. Gas sensitivity behaviour has discussed according to increase in surface area as well as development of two types of depletion layers, one at the n–WO3\ p–MWNTs hetero junction and the other at WO3 grain boundaries.<\div>
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