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2001

Materials Science and Engineering

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Articles 61 - 77 of 77

Full-Text Articles in Physical Sciences and Mathematics

The Applications Of Confocal Raman Micro-Spectroscopy For Study Of Practical Electrode Materials, Yang Y, Chu W, Nan J M, Chen X G, Lin Z G Feb 2001

The Applications Of Confocal Raman Micro-Spectroscopy For Study Of Practical Electrode Materials, Yang Y, Chu W, Nan J M, Chen X G, Lin Z G

Journal of Electrochemistry

Some recent research work about applications of confocal Raman micro spectroscopy for study of practical electrode materials carried out in our lab has been briefly introduced. The examples include study of electrochemical Li + intercalation process, characterization of surface oxide film on AB 5 type electrodes and passive film and pitting corrosion of Rebar electrodes.

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Synthesis Of Limn_2o_(4-Δ) Cl_Δ Cathode Material By Like-Sol-Gel Methode, Zhao Yong Chen, Yi He, Xing Quan Liu, Zhi-Jie Li, Zuo-Long Yu Feb 2001

Synthesis Of Limn_2o_(4-Δ) Cl_Δ Cathode Material By Like-Sol-Gel Methode, Zhao Yong Chen, Yi He, Xing Quan Liu, Zhi-Jie Li, Zuo-Long Yu

Journal of Electrochemistry

LiMn 2O 4 δ Cl δ was synthesized by like sol gel methode, with calculated LiOH.H 2O, Mn(No 3) 2.6H 2O and LiCl.H 2O, and made electrochemical test with these compounds as positive materials. Result demostrated that LiMn 2O 4 δ Cl δ cathode material has exellent stability and nearly no capacity loss after reaching stability.

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How Can Direct Mthanol Fuel Cell Benefit From Carbonate Media, Lin Zhuang, Yang Wang, Jun Tao Lu Feb 2001

How Can Direct Mthanol Fuel Cell Benefit From Carbonate Media, Lin Zhuang, Yang Wang, Jun Tao Lu

Journal of Electrochemistry

The kinetics of methanol oxidation and oxygen reduction in 0.5 mol/L K 2CO 3 were compared with those in 0.5 mol/L H 2SO 4. Experiments revealed that carbonate media could be more beneficial to direct methanol fuel cell(DMFC).Firstly, both electrode reactions show better performance in the carbonate than in the acid; secondly, materials other than noble metals become possible to be used as the anodic and cathodic catalysts;thirdly, the potential dectease caused by methanol crossover could be depressed by using metal oxide catalysts not stable in acid, such as MnO 2.

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Two-Dimensional Surface Raman Imaging Of A Roughened Iron Electrode In Saline Water, Pei-Gen Cao, Jian Lin Yao, Jun Wei Zheng, Bin Ren, Ren-Ao Gu, Zhong Qun Tian Feb 2001

Two-Dimensional Surface Raman Imaging Of A Roughened Iron Electrode In Saline Water, Pei-Gen Cao, Jian Lin Yao, Jun Wei Zheng, Bin Ren, Ren-Ao Gu, Zhong Qun Tian

Journal of Electrochemistry

The analysis of the composite and distribution of iron oxide due to pit corrosion in saline solutions (3.4% NaCl) is of great importance. Many electrochemical methods, XPS, and other photoelectronic techniques have been applied to this domain. Surface?enhanced Raman scattering (SERS) spectroscopy can provide the vibrational information of surface species with high sensitivity and is very useful in the study of surface chemistry of iron. Notwithstanding, the application of SERS in iron corrosion is hampered for its SERS?inactivity. Efforts have been devoted to extend the use of SERS to the study of iron. Approaches include the deposition of particles or …

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A Study On The Performance Of Matrix Prepared By Tape Cast And Its Molten Carbonate Fuel Cells (Mcfcs), Hua-Xin Lin, Bao Lian Yi, Li Zhou, Chang-Qing He, Lian Ying Kong, En Jun Zhang Feb 2001

A Study On The Performance Of Matrix Prepared By Tape Cast And Its Molten Carbonate Fuel Cells (Mcfcs), Hua-Xin Lin, Bao Lian Yi, Li Zhou, Chang-Qing He, Lian Ying Kong, En Jun Zhang

Journal of Electrochemistry

The matrix prepared with γ LiAlO 2 powder and by tape cast displayed higher ability of preventing from gas cross over and lower ohmic polarization. The voltages of the stack (three cells,122 cm 2) stacked with the matrix were 2.02 and 1.78 V at 200 and 246 mA/cm 2, respectively, and the output power reached 53.4 W. The cell(28 cm 2) voltages were 0.85 and 0.75 V at 200 and 300 mA/cm 2, respectively,and the output power was about 6.6 W. Compensating the shrinkage of matrix in stacking cells promoted the enhancement of the MCFC performance.

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Catalytic Effect Of Cl~- On Electrodeposition Of Binary Zinc Alloys With Iron Group Metals, Ren-He Yin, Zheng Hua Fang, Wei Min Cao, A.Zakaria A.Zakaria, Rong-Ming Zhou Feb 2001

Catalytic Effect Of Cl~- On Electrodeposition Of Binary Zinc Alloys With Iron Group Metals, Ren-He Yin, Zheng Hua Fang, Wei Min Cao, A.Zakaria A.Zakaria, Rong-Ming Zhou

Journal of Electrochemistry

Zinc iron group metal alloys were deposited under coulostatic (10C.cm -2 ) at 40 ℃ chloride baths. The deposited alloys were quantitatively analyzed by Atomic Absorption Spectrometry. The current efficiency, percent content and partial polarization curves were obtained by the results. The morphology of the deposits was observed by means of Scanning Electron Microscopy(SEM). We observe that the electrodeposition of zinc iron group metal alloys is one of the best known examples of anomalous codeposition. We found the catalytic effect of Cl - on the electrodeposition behavior of iron group metal. Overpotential of iron group metal droped abruptly at high …

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Adsorption And Oxidation Of Ethanol On Nm-Pt/Gc Electrode Ii. Eqcm And In-Situ Ftir Spectroscopic Studies In Acid Media, Guo Liang Chen Feb 2001

Adsorption And Oxidation Of Ethanol On Nm-Pt/Gc Electrode Ii. Eqcm And In-Situ Ftir Spectroscopic Studies In Acid Media, Guo Liang Chen

Journal of Electrochemistry

The adsorption and oxidation of ethanol on nm?Pt/GC electrode in acid solutions containing 0.1 mol·L -1 H 2SO 4 +0.1 mol·L -1 CH 3CH 2OH was investigated by using cyclic voltammetry , EQCM and in?situ FTIR spectroscopy. The experimental results demonstrated that the oxidation of CH 3CH 2OH is closely relaed to solution acidity and oxygen species on electrode surface; CH 3CH 2OH was oxidized on nm?Pt/GC electrode in acidic media via a dual path reaction mechanism, i.e . CH 3CH 2OH may be oxidized into CO 2 through the dissociative adsorbate (CO) and the reactive intermediates that were determined …

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The Photoelectrochemistry Of Tio_2-Polyaniline Composite Film, Huai Guo Huang, Zhi Xin Zheng, Jin Luo, Hong-Ping Zhang, Ling-Ling Wu, Zhong-Hua Lin Feb 2001

The Photoelectrochemistry Of Tio_2-Polyaniline Composite Film, Huai Guo Huang, Zhi Xin Zheng, Jin Luo, Hong-Ping Zhang, Ling-Ling Wu, Zhong-Hua Lin

Journal of Electrochemistry

A TiO 2 and polyaniline (PANI) composite film was obtained by electrochemical methods. The SEM image of the composite film showed that the PANI film is almost completely covered with TiO 2. The spectra of photocurrent for the TiO 2 PANI composite film , which overlaps the TiO 2 film and PANI film, showed that the composite film is able to have higher conversion efficiency. The spectra of photocurrent for the TiO 2 PANI composite film were different from these of TiO 2 film photosensitized by PANI. The bandgap energy of TiO 2 film on partially oxidized PANI film was …

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Adsorption Behavior Of Co At The Ultrathin Rh And Pt Film Electrodes, Yong Xie, Xiao Qin Li, Bin Ren, Zhong-Qun Tian Feb 2001

Adsorption Behavior Of Co At The Ultrathin Rh And Pt Film Electrodes, Yong Xie, Xiao Qin Li, Bin Ren, Zhong-Qun Tian

Journal of Electrochemistry

Pt group metals have been widely used in catalysis such as hydrogenation of organic compounds and the oxidation of carbon monoxide. The information about CO adsorption on the Pt group surfaces and the influence of other surface species, such as hydrogen and CO 2, will be greatly helpful to elucidate the adsorption behavior of CO on Pt group metal surfaces and get a deeper understanding of catalytic mechanisms of Pt group metals. Surface enhanced Raman spectroscopy (SERS) has been becoming an increasingly important means to characterize the electrochemical metal solution interface over the past two decades. Our laboratory has successfully …

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In Situ Raman Spectroelectrochemical Characterization Of The Prussian Blue/Platinum Modified Electrode, Xiao-Wei Cao, Rong Wang, Gui Hua Wang, Zong Rang Zhang Feb 2001

In Situ Raman Spectroelectrochemical Characterization Of The Prussian Blue/Platinum Modified Electrode, Xiao-Wei Cao, Rong Wang, Gui Hua Wang, Zong Rang Zhang

Journal of Electrochemistry

Prussian Blue is known to be deposited electrochemically on the electrode surface, producing a dense redox active layer. Since the Prussian Blue modified electrode was first reported by Neff in 1978 [1] , different in situ spectroelectrochemical techniques have been widely used to investigate its electrochemical mechanism [2～4] . But no research work related to the in situ Raman spectroscopic studies on it has been reported. In this paper we try to characterize the nature of thin Prussian Blue films on platinum substrates with in situ Raman spectroelectrochemical technique. A Super LABRAM confocal microscopic Raman spectrometer (Dilor) with a He?Ne …

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Unbiased Density Functional Solutions Of Freezing In Binary Mixtures Of Hard Or Soft Spheres, M. Valera, R. F. Bielby, F. J. Pinksi, Duane D. Johnson Jan 2001

Unbiased Density Functional Solutions Of Freezing In Binary Mixtures Of Hard Or Soft Spheres, M. Valera, R. F. Bielby, F. J. Pinksi, Duane D. Johnson

Duane D. Johnson

various size ratios, σ2/σ1, using density functional theory. The Grand Potential is minimized using an unbiased, discrete, real-space mesh that does not constrain the shape of the density, and, in many cases, leads to solutions qualitatively different from those using Gaussians and plane-waves. Besides the usual face-centered-cubic solid-solution phase for σ2/σ1≈1.0, we find a sublattice-melt phase for σ2/σ1=0.85–0.5 (where the small-sphere density is nonlocalized and multi-peaked) and the NaCl phase for σ2/σ1=0.45–0.35 (when the small-sphere density again sharpens). For a range of size ratios of soft sphere mixtures, we could not find stable nonuniform solutions. Preliminary calculations within a Modified-Weighted …

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Experimental Investigation Of Steel Corrosion In Lead Bismuth Eutectic (Lbe): Characterization, Species Identification, And Chemical Reactions, John Farley, Dale L. Perry Jan 2001

Experimental Investigation Of Steel Corrosion In Lead Bismuth Eutectic (Lbe): Characterization, Species Identification, And Chemical Reactions, John Farley, Dale L. Perry

Transmutation Sciences Materials (TRP)

The goal of the present research is to achieve a basic understanding of corrosion of steels by Lead Bismuth Eutectic (LBE). Liquid LBE is under consideration in the transmuter as both a coolant and a target material. There have been studies of LBE, especially by the Russians, but a fundamental understanding and verification of its role in the corrosion of steels is still very 2 incomplete. Post-experiment testing and analysis will be performed on steel samples that have been in intimate contact with LBE. Chemical alterations and resulting chemical species will be measured at the steel surface. Techniques to be …

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Dynamics Of Poly(Vinyl Acetate)-D₃ On Silica, Robert D. O'Connor, Frank D. Blum, Gu Xu Jan 2001

Dynamics Of Poly(Vinyl Acetate)-D₃ On Silica, Robert D. O'Connor, Frank D. Blum, Gu Xu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Poly(vinyl acetate) (PVAc) is an important polymer in applications because of both its bulk and surface characteristics. Its chain architecture gives it a low Tg and, generally, good qualities for processing and applications, which include paints, adhesives, thin films and surface coatings. In this study, we investigate the surface dynamics of PVAc absorbed onto silica with deuterium nuclear magnetic resonance (2H NMR). For dynamics studies, 2H NMR is an excellent technique because it uses an innocuous probe that can report on correlation times (τc) from approximately 10-8 s to 10 s. We report the use of two-dimensional exchange NMR (2D-X) …

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Dynamics Of Polyacrylates In Concentrated Chloroform Solutions, Frank D. Blum, Raj B. Durairaj Jan 2001

Dynamics Of Polyacrylates In Concentrated Chloroform Solutions, Frank D. Blum, Raj B. Durairaj

Chemistry Faculty Research & Creative Works

The dynamics of polymers in polymer solutions have not been probed in great enough detail to provide a coherent picture of the behavior of these polymers, especially in more concentrated solutions. To help understand this behavior further, we have prepared a series of backbone-labeled polymers including poly(n-butyl acrylate)-d1 (PNBA). These provide a basis for comparison of the behavior among a group of related polymers. The dynamics have been probed by using deuterium relaxation times. Since the relaxation times are relatively fast and the quadrupolar relaxation mechanism is well understood, data from this technique provide a convenient means for comparison of …

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Glass Transition Behavior Of Pmma Thin Films, Moses T. Kabomo, Frank D. Blum Jan 2001

Glass Transition Behavior Of Pmma Thin Films, Moses T. Kabomo, Frank D. Blum

Chemistry Faculty Research & Creative Works

In the last decade there has been an increased interest in the study of the properties of supported thin polymer films. This has been prompted by the incorporation of thin films into device applications and many other technologies. Although not without controversy, a large body of experimental work indicates departures from bulk behavior by thin films. Strong evidence from both theoretical and experimental work shows that the interaction of polymer with a substrate alters the polymer conformation and mobility. A variety of techniques has been employed to probe the mobility of thin supported polymer films. Some of these techniques indirectly …

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Graduated Segmental Mobility In Polymer Layers On Silica, Frank D. Blum, Crystal E. Porter, Wuu-Yung Lin Jan 2001

Graduated Segmental Mobility In Polymer Layers On Silica, Frank D. Blum, Crystal E. Porter, Wuu-Yung Lin

Chemistry Faculty Research & Creative Works

The behavior of thin polymer layers on oxide substrates has gotten a great deal of attention as the size of materials, and hence polymer films, has gotten smaller. Indeed, the properties of adsorbed polymers are such that they can be different from those of bulk polymers, especially when the films are very thin. A wide variety of studies have been made on adsorbed polymers and sometimes the results seem contradictory. One of the properties often measured in thin films is the apparent glasstransition temperature, Tg. In principle, many techniques are sensitive to phenomenological changes occurring around Tg and, therefore, can …

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Thermal Analysis Of Ultrathin Ps-R-Pmma Copolymer Films On Silica, Bing Zhang, Frank D. Blum Jan 2001

Thermal Analysis Of Ultrathin Ps-R-Pmma Copolymer Films On Silica, Bing Zhang, Frank D. Blum

Chemistry Faculty Research & Creative Works

Composite materials represent a major part of man-made materials that are used in many applications. The interaction of polymers with surfaces plays a crucial role in the final properties of these materials and, by understanding the surface processes and adsorption mechanisms, better systems can be designed. Therefore, the behavior of polymer molecules at interfaces has been the topic of many studies in recent years and a rough picture has been obtained. Keddie et al. Obtained experimental results showing the dependence of the glass transition temperature (Tg) on the thickness of supported polystyrene films using ellipsometry. Later, they also investigated supported …

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