bluuebunny/crossref_metadata_2025 huggingface dataset:
AC Impedance Monitoring of Activated Carbon Filter Contamination
Authors: Smiechowski Matthew F. , Feaver William B.
Published: May 2012

Adsorptive activated carbon is a porous, conductive media whose structure is dependent on its production process. As materials adsorb into the pores and onto the surface of the carbon, its resistive and capacitive properties will change. Electrochemical impedance spectroscopy of ASZM-TEDA carbon filter beds separately exposed to NO2 and SO2 in humid air was used to analyze changes in the electrochemical properties of the carbon bed and relate them to physical and chemical adsorption of these contaminant gases. The influences of the electrode configuration, applied dc potential, and relative humidity on the impedance results were investigated. Analysis and modeling of time-dependant data, combined with independent measurements of entrance and exit gas concentrations and off-line analytical methods, were used to develop an electrochemical model for further analysis of the experimental results. Results of this study show that impedance spectroscopy measurements can be correlated to the degree of contamination.
Cold Temperature Optimization of Supercapacitors
Authors: Cameron Colin G.
Published: May 2012

Despite its important contribution to the overall series resistance of a supercapacitor, little attention has been directed towards improving the performance of the separator. The present research examines the use of a number of commercially available materials as separators, and characterizes their performance under temperature conditions ranging from room temperature to a simulated Arctic environment.
A Study of Methanol Oxidation by Dynamic Electrochemical Impedance Spectroscopy
Authors: Dahlstro̸m Per K. , Harrington D. A. , Seland F.
Published: May 2012

Methanol oxidation on a smooth polycrystalline platinum electrode is studied by dynamic electrochemical impedance spectroscopy at elevated temperatures employing an autoclave setup. By utilizing custom written software, impedance spectra for all applied electrode potentials are calculated. By increasing the temperature and/or sweep rate, it is shown that the region with three adsorbed species disappears, which is interpreted as less contribution of the parallel pathway at higher temperatures.
LiCoPO4 as Li-Ion Cathode
Authors: Allen Jan L. , Jow T. R. , Wolfenstine Jeff
Published: May 2012

Fe-substituted LiCoPO4 exhibits greatly improved cycle life relative to LiCoPO4. Whereas, pure LiCoPO4 loses more than half of its discharge capacity at the 10th cycle, the Fe-substituted LiCoPO4 retains about 100% of its discharge capacity at the 10th cycle and about 80% of its capacity at the 500th cycle. It is suggested that improved cycle life results from Fe3+ substitution on the Li and Co sites. The partial substitution of Li+ by Fe3+ and Co2+ by Fe2+ and Fe3+ was evidenced from Rietveld analysis of X-ray powder diffraction data, infrared spectroscopy, X-ray photoelectron spectroscopy and Mössbauer spectroscopy. The majority of the Fe3+ substitutes at the Co2+ site. The composition of Fe-substituted LiCoPO4 is Li0.92Co0.8Fe2+0.12Fe3+0.08PO4 for a sample of starting composition LiCo0.8Fe0.2PO4.
Synthesis and Electrochemistry of Nanocrystalline Iron and Manganese Oxide Materials
Authors: Yau Shali Z. , Farley Katie E. , Marschilok Amy C. , Takeuchi Esther S. , Takeuchi Kenneth J.
Published: May 2012

Identification of viable energy storage materials based on inexpensive, earth abundant metal centers is one of the most pressing issues for development of future battery technologies. In addition, low temperature, scalable methodologies are needed for active material synthesis. Preparation, characterization, and electrochemical evaluation of three promising battery materials are described herein. This work will contribute to materials advances in the development of environmentally sustainable materials for new battery technologies.
Response of Electrochemical Impedance Spectroscopy to Evolving Coating Systems
Authors: Hinderliter Brian
Published: May 2012

Electrochemical Impedance Spectroscopy (EIS) is often used to characterize the quality of barrier coating systems with the entire spectrum from 100 kHz to 10mHz taking an hour or more to complete, during which time the coating is often changing if for no other reason than the diffusion of the electrolyte solution into the coating. When the saturated water volume fraction of the coating, the diffusion rate and the electrical response are all low, the EIS response is stable and Kramers-Kronig consistency checks are met. Higher rates of diffusion, water volume fraction, and electrical impedance response to the composite system can impact the resonance frequency and thus the relative impact on the real and imaginary components of the coating impedance. The impact on the impedance for several representative coating systems due to water uptake is compared, along with the Kramers-Kronig consistency.
Investigating the Failure Mechanisms for an Expoxy-Polyamide Coating in a Seawater Environment
Authors: Policastro Steven A. , Eppard Sarah , Lawrence Steven H. , Strom Matthew J. , Rayne Roy J. , Hansen Douglas C. , Martin Farrel J.
Published: May 2012

The objective of this study is to develop a coatings behavior model for epoxy-polyamide coatings in a seawater environment. The model is to account for the loss of coating barrier properties due to ingress of offensive species from seawater, the influence of coatings thickness on maintaining barrier properties, and the influence of surface contamination on initiation of corrosion failure beneath the coating To that end, 60 hot-rolled 4"x4" steel panels were coated and subjected to an aggressive alternate immersion cycle for a 12 months. Prior to being coated, half of the panels were sprayed for 3 seconds with a 0.1M solution of NaCl in order to contaminate a portion of the metal surface with chloride. All of the samples were then coated with one, two, or three layers of MIL P-24441 Formula F150, Type 3 epoxy-polyamide coating. The samples were suspended in an alternate immersion, flowing seawater tank. The immersion/drying cycle was 12 hours long - six hours immersed, 6 hours in air. Half of the samples were cathodically protected with a zinc anode, while the other half were left unpolarized.Electrochemical impedance spectroscopy (EIS) and Scanning Kelvin Probe measurements were made of the coatings on all of the samples after ~90, 120, and 360 days of alternate immersion cycles
Study on a Titanate Film and its Photocathodic Protection Effect for 403 Stainless Steel
Authors: Zhu Yan-Feng , Zhang Juan , Du Rong-Gui , Qi Hai-Qing , Xu Lu , Lin Chang-Jian
Published: May 2012

TiO2 and titanate semiconductor nanomaterials have attracted tremendous interest due to their exceptional electronic and mechanical properties. In the present work, a titanate nanowire network film was prepared by a combined sol-gel and hydrothermal method. The morphology, chemical composition and photoelectrochemical behavior of the film were characterized by scanning electron microscopy, X-ray diffraction, and electrochemical techniques, respectively. The results showed that the titanate film exhibited a special three-dimensional porous structure composed of titanate nanowires. When the 403 stainless steel in a 0.5 M NaCl solution was coupled to the titanate film as a photoanode in a 1.0 M NaOH solution under illumination, its potential decreased by about 570 mV, indicating the film produced a good photocathodic protection effect for the steel. EIS measurements revealed that the charge transfer resistance of the electrochemical reaction process for the steel coupled to the titanate film decreased considerably.
Liquid Tin Anode Solid Oxide Fuel Cell for Direct Biomass Conversion
Authors: Tao Thomas T. , Koslowske Mark , Bentley Jeff , Brodie Jonathan
Published: May 2012

This paper presents preliminary results of various non-food biomass conversions to electricity in a Liquid Tin Anode Solid Oxide Fuel Cell (LTA-SOFC). A major finding favoring direct biomass conversion was that biomass fuel utilization approached near 100%, 99% and 95% for biochar, poplar, and switch grass respectively. Another key finding with positive implications was that biomass ash formed in the LTA-SOFC environment did not readily fuse or form molten slag. SEM evaluation clearly showed that the cellular structure of corncob, poplar and switch grass was intact following operation in the LTA-SOFC, indicating that no melting has occurred. Another important finding was that there was no observed cell degradation during the short term biomass operation. The initial IV curves and total runtime data appeared normal for LTA-SOFC cells running on a fixed charge of biomass. Long term stability of LTA-SOFC operating on biomass yet has to be studied. Finally, the initial power density of the LTA-SOFC test cells operating on biomass fuels was approximately 70-80 mW/cm2.
Characteristics of Molten Metals as Anodes for Direct Carbon Solid Oxide Fuel Cells
Authors: Jayakumar Abhimanyu , Javadekar Ashay , Küngas Rainer , Buttrey Douglas J. , Vohs John , Gorte Raymond
Published: May 2012

Sn, Bi, In, Pb and Sb were examined as molten anodes for solid oxide fuel cells with yttria-stabilized zirconia (YSZ) electrolytes. Cells were operated to characterize the electrochemical oxidation of these metals at the YSZ interface. For Sn and In, which form high-melting oxides, the performance of the cell drops due to formation of a thin solid oxide film on the YSZ interface, which prevents further oxidation. For Bi, such a drop is not observed because its oxide is O2- conductive. For Pb, above the melting point of PbO, the oxide no longer hampers cell performance. For Sb, which forms low melting Sb2O3 (m.p. 929 K), the anode impedance remains low, making efficient fuel cells possible as Sb2O3 is also readily reduced by most types of solid fuels at 973 K. Finally, a high power direct carbon fuel cell (DCFC) is demonstrated with the Sb anode using sugar char fuel.
An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors
Authors: Piquette Alan P. , Hannah Mark E. , Mishra Kailash C.
Published: May 2012

Many light emitting diode (LED) phosphors have overlapping emission and absorption bands, such as Ce3+-doped garnets and Eu2+-doped silicates, nitrides, and oxynitrides. These overlapping bands inevitably lead to self-absorption effects through either non-radiative energy transfer mediated via electron-electron correlation process or actual emission and radiative energy transfer which involves emission and absorption of a photon due to spectral overlap. The first process has been often discussed in the literature. The second process has been investigated in this work through a semi-quantitative formalism. Spectral shift, changes in emission peak shape, photoluminescent conversion efficiency, and phosphor characterization are discussed in light of self-absorption. The simulated results are compared to experimental data and shown to correlate well with observed data.
Structure and Photoluminescence of Eu2+ Activated SrScSi4(O,N)7 Green Phosphors
Authors: Porob Digamber , Karkada Nagaveni , Kumar Nammalwar Prasanth , Setlur Anant
Published: May 2012

In this paper, we discuss synthesis, structure and luminescence properties of Eu2+ activated SrScSi4(O,N)7. The crystal structure was refined from the X-ray powder diffraction pattern using the Rietveld refinement method. The strontium scandium oxynitride composition is isostructural with the family of compounds MYSi4N7 (M = Ca,Sr,Ba) with hexagonal crystal system and space group P63mc. The refined unit cell parameters, a=5.9133(4)Aå, c=9.6338(7)Aå suggests lattice contraction with cell volume 291.73(5) Aå3 compared to SrYSi4N7 (306.83(1)Aå3). The Eu2+ activated material shows efficient green emission peaking around ~520nm under UV excitation with an excitation band at ~350 nm. The blue shift of emission peak position compared to SrYSi4N7:Eu2+ and its correlation to crystal structure will be discussed. We also investigate the nature of the emission and excitation bands in this Eu2+ doped material at low and high temperatures.
Exciton Luminescence in 10B-doped ZnO:Ga Phosphor and Its Application to Neutron Scintillator
Authors: Nanto Hidehito , Kumakura Takenori , Takei Yoshinori , Nakamura Tatsuya , Katagiri Masaki
Published: May 2012

ZnO family phosphors as novel phosphor materials for neutron detector have prepared using Spark Plasma Sintering method. The optical properties of ZnO phosphor prepared are investigated. The following results were obtained. Two dominant PL emission peaks at 395 nm and 495 nm were observed. The lifetime of the PL emission peak at 395 nm (UV emission band) is about 20 ns, which is suitable for neutron detection. The Ga (30mol%)-doped ZnO phosphor exhibited an intense UV emission band without the visible emission band. The Ga-doped ZnO phosphor can be prepared at the atmospheric pressure of about 8 Pa using SPS method. It was found that the PL intensity of UV emission band is increased with improving the crystallinity of the ZnO phosphor. It was confirmed that the exciton emission intensity of the ZnO:Ga doped with B2O3, in which neutron ray is converted to α-ray under(n, α) reaction, was not changed by doping of B2O3 converter.
Monitoring the State of Charge of Operating Vanadium Redox Flow Batteries
Authors: Tang Zhijiang , Aaron Douglas S. , Papandrew Alexander B. , Zawodzinski Thomas A.
Published: May 2012

We describe methods for assessment of the state of charge (SOC) of vanadium redox flow batteries during operation using UV-vis spectrophotometry and full cell OCV measurements. The absorbance of the negative electrolyte solution at 433 nm, 600 nm and 750 nm is linear in SOC for SOC > 0.2. The absorbance of the positive electrolyte does not display a linear relationship with SOC, which we attribute to the formation of a strongly absorbing third species. An analysis of the excess absorbance of the positive electrolyte suggests that a complex with 1:1 stoichiometry is formed by VO2+ and VO2+. Full-cell OCV measurements were found to be an inaccurate gauge of the state of charge of the battery.
Electron Spin Resonance Investigation of the Effects of Vanadium Ions in Ion Exchange Membranes for Uses in Vanadium Redox Flow Batteries
Authors: Lawton Jamie S. , Aaron Douglas S. , Tang Zhijiang , Zawodzinski Thomas A.
Published: May 2012

Electron Spin Resonance (ESR) was used to characterize the effects of the vanadyl ion in Nafion 117. The ESR signal of a tempone spin probe was used as a qualitative standard to compare the signal intensity of the spin probe imbibed in the membrane with the intensity of the vanadium signal in the membrane. Initial measurements of vanadium crossover were recorded by monitoring vanadyl ion concentration increase in a blank solution flowed on one side of the battery apparatus as vanadyl ion solution was flowed simultaneously on the opposite side.
Reduction of Greenhouse Gas Emissions by Metal Interconnect Etch Process Optimization
Authors: Frankwicz Peter , Gardner Les , Moutinho Thomas
Published: May 2012

Fluorine containing dry etch processes have been a cornerstone of semiconductor manufacturing since inception of the industry. Greenhouse gases (GHG) commonly used in device fabrication are CF4, C2F6, SF6, CHF3 and NF3. Texas Instruments Incorporated has been voluntarily pursuing GHG priorities aligned with ISO14001:2004, World Semiconductor Council and United States Environmental Protection Agency (1,2). This paper details manufacturing and unit process optimization to eliminate CHF3 in metal interconnect dry etch of an aluminum - copper analog 180nm technology node process flow in 200mm wafer volume production.
Evaluation of Optical Waveguide by Solid Phase Epitaxial Growth of Amorphous Silicon
Authors: Shin Joonghan , Kim Ki-Chul , Kuh Bongjin , Yang SangRyol , Cho Choong-Rae , Kim JeongMeung , Choi HanMei , Yoo Wonseok , Kim Young Hee , Kim Seung-Gu , Na KyungWon , Lee Eunha , Won JeongYeon , Han HyoukSoo
Published: May 2012

This study reports the evaluation of an optical waveguide fabricated on a bulk-Si platform by using an epitaxially grown Si layer. The epitaxial growth of Si is obtained by the solid phase epitaxy (SPE) using a hot furnace annealing method. It is observed that an optical propagation loss of the waveguide decreases with increasing the epitaxially grown area in the waveguide. In this study, an epitaxial growth rate is greatly enhanced by an (100) growth orientation due to the lower atomic close packing density along the (100) orientation. The optical propagation loss is also improved with the (100) growth orientation because of the higher crystalline quality and full epitaxial growth of Si.
Oxidation of Single Crystal Silicon Nanowires
Authors: Mertens Robert G. , Sundaram Kalpathy B.
Published: May 2012

Silicon nanowires (SiNWs) grown by electroless etching technique using HF/AgNO3 solution were subsequently oxidized. SiNWs grown by this method do not oxidize in the same manner as planar Si. The exposed areas for oxidation, being vertically-align SiNWs, cycle between (100) and (110) orientations, going around the SiNW. A result of this is that, since (100) and (110) oriented Silicon (Si) oxidize at different rates, the oxide growth will produce a "squarish" structure.
Passive Film Observations on Interstitially Hardened 316L Stainless Steel with Nitrogen for Improved Corrosion Resistance
Authors: Tailleart Nicole R. , Martin Farrel J. , Rayne Roy J. , Kahn Hal , Heuer Arthur H. , Natishan Paul M.
Published: May 2012

A low temperature (420 ºC and below), plasma-based interstitial hardening (IH) with nitrogen process on 316L austenitic stainless steels (UNS S31603) was investigated. The IH-treatment significantly improved the hardness and wear resistance for all treatment temperatures. The pitting and crevice corrosion resistance of IH-N samples treated at 370 and 395 ºC in 0.6 M NaCl solutions was improved compared to untreated samples. XPS analysis after crevice corrosion experiments indicated that no chloride was incorporated into the passive film and a TOF-SIMS experiment showed that the IH-N surface are less reactive to oxygen than untreated 316 stainless steel.
Key Parameters to Determine Wall Thinning Due to Flow Accelerated Corrosion
Authors: Uchida Shunuske , Naitoh Masanori , Okada Hidetoshi , Suzuki Hiroaki , Koikari Souji , Koshizuka Seiichi , Lister Derek
Published: May 2012

In order to predict occurrence of flow accelerated corrosion (FAC) and to estimate wall thinning rate due to FAC, six step calculation procedures have been proposed. In the procedures, FAC is determined by six parameters, i.e., the flow dynamics parameter, chromium content in materials, temperature, pH, oxygen concentration, and ferrous ion concentration ([Fe2+]) in bulk water. The high FAC risk zones were evaluated by the maximum wall thinning rates, which were determined by a function of 1D FAC parameters. At the indicated high FAC risk zone, 3D distributions of mass transfer coefficients were obtained and then wall thinning rates were calculated with the coupled model of static electrochemical analysis and dynamic oxide layer growth analysis. In the paper, the effects of all parameters except that related to [Fe2+] on FAC occurrence have been discussed and then the effects of [Fe2+] on wall thinning are discussed.
Effect of the Thermomechanical History on the Corrosion Behavior of 6101 Aluminum-Magnesium-Silicon-Iron Alloy in NaCl Solutions
Authors: Laurino Adrien , Andrieu Eric , Harouard Jean-Paul , Odemer Grégory , Blanc Christine
Published: May 2012

The effect of cold-working, i.e. cold drawing, and aging treatment on the corrosion behavior of a 6101 aluminum alloy was investigated in NaCl solutions. The 6101 T4 aluminum alloy was found to be susceptible to only pitting corrosion with filaments growing from the pits and propagating into the matrix. A 185°C-10 hours aging treatment led to a shift of the corrosion potential of the 6101 alloy towards more cathodic values and promoted intergranular corrosion. When the 6101 alloy was both cold-drawn and aged, modification of the corrosion potential was still observed and intergranular corrosion was not observed for the cold-drawn samples.
On the Self-Passivation Tendency of Mg-Al-Zn (AZ) Alloys in Aqueous Solutions
Authors: Phillips Ryan C , Kish Joseph R.
Published: May 2012

The composition and structure of the surface film formed on Mg Mg alloy AZ80 exposed at the corrosion potential in high purity water at room temperature for 48 h was investigated by STEM-EDS using FIB-prepared cross-sections. A methodology was developed to construct compositional depth profiles from the EDS element maps due to the difficulties encountered when attempting to use a spot analysis approach. The surface film formed is confirmed to be duplex in nature, consisting of a thinner, less-porous nano-crystalline MgO rich inner layer, and a thicker, more-porous Mg(OH)2 rich outer layer. Aspects of the role played by the alloyed Al content and the stability of the surface film below the breakdown potential are discussed.
Intergranular Corrosion Penetration in AA5083 (UNS # A95083) as a Function of Electrochemical and Metallurgical Conditions
Authors: Lim Mary Lyn , Jain Swati , Kelly Robert G. , Scully John R.
Published: May 2012

A coordinated experimental and modeling study of selected factors influencing intergranular corrosion (IGC) penetration depth into AA5083 is presented. Potentiostatic tests at -0.73 VSCE in 0.6 M NaCl solution were conducted on LT, ST, and LS surfaces of sensitized AA5083. The IGC penetration rate was found to depend on applied potential, degree of sensitization (DoS), exposure time, and propagation direction relative to the rolling direction. Depths of IGC penetration were characterized through metallographic techniques, microscopy, and image analyses. The results were analyzed to describe the IGC depth distributions and to serve as input data for a set of descriptive models that can estimate IGC damage progression for AA5083 during exposure to 0.6 M NaCl at pH 8.3. This set of descriptive models was validated with 94% accuracy for 100oC sensitization. Extension of this combined experimental and modeling approach to 80oC sensitization demonstrated that sensitization temperature is another significant factor.
Localized Corrosion of Friction Stir Spot Welds in Magnesium AZ31 Alloy
Authors: James Andre , North Thomas H. , Thorpe Steven J.
Published: May 2012

A scanning reference electrode technique (SRET) apparatus has been designed and commissioned to investigate the corrosion of friction stir spot welds (FSSW) made in AZ31 magnesium alloys. The operational parameters of the apparatus have been calibrated to give adequate spatial resolution. By combining the SRET data with material flow data and immersion test data it was found that the FSSW process causes the formation of distinct noble and active regimes within the weld area. The noble region is aligned with the stir zone (SZ) and is caused by a dynamically recrystallized grain structure which are void of dislocations/twins, and β Mg17Al12 . Localized corrosion attack was observed in both SRET and immersion testing along the thermo-mechanically affected zone (TMAZ). The same effect was consistently observed with a flat versus concave shoulder tool, and dwell times of 1s and 4s.
In Situ Observation for the Reaction of Hydrogen Peroxide in High Temperature Water Utilizing Electrochemical Impedance Spectroscopy
Authors: Satoh Tomonori , Kato Chiaki , Yamamoto Masahiro , Nakano Jun-ichi , Tsukada Takashi
Published: May 2012

In this study, observation of the reaction of H2O2 at the surface of stainless steel utilizing electrochemical impedance spectroscopy (EIS) directly in the high purity water at 288oC was performed to determine the corrosive condition and the corrosion behavior of the stainless steel in high temperature and high purity water containing H2O2. Obtained results were summarized as follows; 1) The EIS data were measured directly in high temperature water without electrolyte injection. 2) The conductivity of the high temperature water at 288oC calculated by Rsol was 8.3x10-6S/cm. 3) The Rp was 9.0x103ohm•cm2 for 100ppb of H2O2, and the estimated corrosion rate was about 30μm/year. 4) The reciprocal of the polarization resistance had a linear relationship to the H2O2 concentration. It indicated that the corrosion current would be determined by the cathodic reaction of H2O2. 5) The estimated DH2O2 was 1.5x10-4cm2/s.
Local Electrochemical Impedance Spectroscopy Investigation of Corrosion Inhibitor Films on Copper
Authors: Souto Ricardo M. , Santana Juan José , Marques A G. , Simões Alda M.
Published: May 2012

In this work, the applicability of localized electrochemical impedance spectroscopy (LEIS) to characterize metal-corrosion inhibitor systems has been investigated. Copper corrosion inhibition by benzotriazole (BTA) and 2-mercaptobenzimidazole (MBI) has been studied, and compared to the electrochemical behaviour of the non inhibited metal. A rather wide frequency range of the AC potential signal was employed, namely 50 mHz ≤ f ≤ 65 kHz. The measurements were conducted for different probe-substrate distances in order to explore the effect of the different component of the localized impedance. Nyquist diagrams exhibit inductive loops in the high frequency range, and capacitive semicircles at intermediate and low frequencies for all the systems investigated, though they were affected in a different extent by the variation of the probe-substrate distance depending on the surface condition of the metal samples, this effect being more notorious for distances smaller than the dimensions of the bi-electrode probe.
Development of a New Microelectrochemical Measurement System for In Situ Optical Microscopic Observation of Pit Initiation Processes
Authors: Chiba Aya , Muto Izumi , Sugawara Yu , Hara Nobuyoshi
Published: May 2012

The previous microelectrochemical measurement system based on the micro-electrode technique with a glass capillary dramatically advanced our understanding of pitting corrosion over the past ten years. However, by using this system, it was impossible to take in-situ and real-time observations of dissolving surfaces. Here we developed a measurement system for in-situ and real-time observations (lateral resolution: ca. 350 nm, time resolution: 30 images/s) of the initiation processes of pitting corrosion on stainless steel by combining an optical microscope with a microelectrochemical cell. The results of the observations on pit initiation at the manganese sulfide (MnS) inclusions clearly indicated marked differences in the initiation processes of metastable and stable pits. The experimental technique developed here is applicable to a wide range of the local electrochemical analysis of electrode surfaces.
Reliable Methods for the Prediction of the Electrochemical Properties of Substituted Pentacenes
Authors: Hodgson Jennifer , Miller Glen P.
Published: May 2012

An assessment of density functional theory methods was used to examine the utility of relatively (computationally) cheap methods in the prediction of the electrochemical properties of substituted pentacenes. Time-dependent B3LYP calculations in solvent, with a triple-zeta basis set, performed on either gas-phase PM3 or B3LYP/6-31G(d) optimized geometries (TD-B3LYP/6-311+G(d,p)//PM3 or TD-B3LYP/6-311+G(d,p)//B3LYP /6-31G(d)) were shown to be reliable methods to accurately predict HOMO energies and HOMO-LUMO gaps. Using these methods, values were calculated which agree with experimentally determined data generally to within 0.04 eV (0.9 kcal/mol) for HOMO energies and to within 0.07 eV (1.6 kcal/mol) for HOMO-LUMO gaps. This study shows that relatively cheap DFT methods are useful in the prediction of the electrochemical properties of substituted acenes. It is therefore now possible to use these methods to provide a basis of study for larger substituted acenes and more complex acene-based systems.
Processing and Properties of High-Entropy Alloys and Micro- and Nano-Wires
Authors: Zhang Yong , Zuo T.T. , Liao W.B. , Liaw P.K.
Published: May 2012

Amorphous and solid-solution phases are both with high entropy; the former is mainly with topological disorder while the later is mainly with chemical disorder. The amorphous phase forms at lower temperatures usually below the eutectic temperature, while the solid-solution phase forms at higher temperatures. Mechanical-alloying results have verified that amorphous and solid-solution phases are the two terminal phases by enough long time of milling of the component elements. The phase formation regions, e.g., amorphous, intermetallic compound, and solid-solution, were summarized from the literature and experimental data, with the parameter of the atomic-size differences, δ, and the parameter of Ω. Recently, the definition of high-entropy alloys (HEAs) was also extended to four components and one of the element may exceed 35%. Wires with diameters at micro- and nanoscale were prepared by the melt-extracted method and thermal-plastic forming method. The dynamic mechanical properties of the wires were evaluated.
Ambient Atmospheric Stability of Organic Thin Films on Metal Alloys
Authors: Mahapatro Anil , Bhure Rahul , Abdel-Fattah Tarek M.
Published: May 2012

Organic thin films on biometallic alloys could serve as a precursor layer for subsequent tailored modification. In this report we demonstrate the preliminary ambient atmospheric stability of phosphonic acid organic thins films on Co-Cr alloy. X-ray photoelectron spectroscopy (XPS) determined the surface atomic composition after film deposition and for the time duration (14 days) of atmospheric stability. The constant presence of XPS phosphorous 'P' peak after deposition and through 14 days indicated the presence and stability of the organic films over the time course of study at ambient conditions. Similarly, atomic force microscopy (AFM) images showed presence of consistent islands of film coating over period of 14 days indicating stability of the films over 14 days.
The Modeling, Fabrication, and Optical Characterization of Silicon and Polymer-Based Photonic Crystals for Biosensing Applications
Authors: Hamza Bashar M. , Kadiyala Anand , Hornak Lawrence A. , Carroll R. Lloyd , Liu Yuxin , Dawson Jeremy M.
Published: May 2012

Two-dimensional, nano-scale photonic crystals (PhCs) in silicon and biocompatible polymer materials, such as: Polydimethylsiloxane (PDMS) and epoxy, are potential core structures in ultra-sensitive biosensors enhancing fluorescence emission in the near IR and visible range. A triangular PhC lattice (r/a = 0.33) of silicon pillars suspended in toluene was designed to enhance emission in the near-IR range. We present here a 27-fold enhancement of PbS-Quantum-Dot emission at 1100 nm. Moving to more biocompatible materials, we also present frequency-domain modeling results demonstrating partial photonic bandgaps for triangular PhC lattices in PDMS and epoxy. The existence of these bandgaps suggests that PhCs in polymer materials could potentially enhance visible-range fluorescence emission and become co-integrated with other on-chip components, such as microfluidic channels and optical waveguides, to produce cost-effective biosensors.
HEV Lithium-Ion Battery Testing and Driving Cycle Analysis in a Heavy-Duty Truck Field Study
Authors: Svens Pontus I. , Lindström Johan , Behm Maårten , Lindbergh Göran
Published: May 2012

This paper presents early results from ongoing field test of HEV batteries on heavy-duty trucks. The presented results focus on the parameters that can affect ageing, such as SOC and power. The goal with this study is to correlate battery ageing to battery usage. Commercial LMO/LTO lithium-ion battery cells were tested onboard four Scania trucks. The test equipment was designed for this type of HEV-battery testing on conventional vehicles by emulating an HEV environment. This concept allows unobtrusive, low cost testing of battery cells under realistic conditions. Each truck is equipped with test equipment containing one cycled battery cell and one calendar aged cell. The hybrid strategy used in this test allows battery power and SOC to vary depending on drive pattern within certain limits. Battery capacity and resistance is measured periodically and this makes it possible to receive information about battery ageing without bringing the cells to the lab.
Gold Metallization of Silicon by Galvanic Displacement
Authors: Raygani Anahit , Magagnin Luca
Published: May 2012

There are several microelectronic processes which are based on gold due to its unique physical and chemical properties. Adhesion of gold films which are deposited by galvanic displacement is investigated by microindentation measurements. For investigation, load-displacement tests are performed on gold nanostructures which are deposited onto mono (100) and polycrystalline silicon in sulfite solutions. Composite hardness model for soft film on hard substrate is used to analyze the results. Gold films growth and composite Vickers microhardness are influenced by the adhesion of the gold film to silicon, as a function of different electrolytes and silicon substrates. The higher composite hardness and more extended deformation zone at the film/substrate lead to stronger adhesion. For the same film thickness, the composite hardness of films which are deposited onto mono silicon is higher than films on poly silicon. The effect of cysteine as additive on adhesion and microhardness measurements is emphasized.
Mechanism Study of Ag Catalyzed Directional Etch of Silicon for Nanowire Formation
Authors: Shao Ingrid , Gignac Lynne
Published: May 2012

Vertically aligned silicon nanowires (Si NWs) on a wafer-scale single crystalline silicon substrate can be formed by dipping a silicon wafer into an appropriate HF/AgNO3 solution. During the catalyzed etch of silicon in this HF/AgNO3 solution, Ag particles on the bottom of the NWs catalyze the silicon dissolution, and Ag dendrites form and stay on top of the Si NWs. It is not understood why the Ag dendrites in contact with Si NWs do not attack/dissolve the Si NWs. In this paper, we will demonstrate the existence of a protection/passivation layer surrounding the Si NWs by investigating aqua regia or nitric acid cleaning effect. Direct observation using the transmission electron microscope (TEM) also showed the existence of the protection layer. In addition, we found the conductivity of the Si substrate did not have significant impact on the NWs formation rate. The transport of electrons from the bottom of the NWs (where Si dissolves) is identified to be through the hydrogen bubbles. The surface protection model together with the hydrogen transport phenomenon explains the key aspects of the silicon nanowire formation mechanism.
Sol Gel Dip Coated Aluminum Doped Zinc Oxide Films and Their Properties
Authors: Murali K. R. , Kalaivanan A. , Sivaramamurthy K. , Perumal S.
Published: May 2012

Aluminium doped ZnO films were deposited by the sol gel dip coating method. The crystalline quality decreased with increase of Al doping. The band gap varies from 3.32 eV to 3.56 eV with increase of Al doping. This blue shift behavior or broadening in the band gap is mainly due to the Moss-Burstein band ﬁlling effect. The films exhibited 60 - 70 % transmission in the visible region. The grain size and surface roughness varied from 45 nm to 15 nm and 3.5 nm to 1.3 nm respectively. The intensity of the Raman peaks at 331, 385, 438 and 582 cm-1 modes decreased with increasing the Al concentration.
Porous Silicon/Iron Oxide Nanocomposites with Deposition Dependent Magnetic Properties
Authors: Granitzer Petra , Rumpf Klemens , Reissner Michael , Morales M. Puerto , Poelt Peter , Uusimäki Toni , Albu Mihaela
Published: May 2012

The combination of porous silicon (PS) with iron oxide nanoparticles results in a nanocomposite system offering a magnetic behavior which is influenced by the properties of the nanosized particles but also by the morphology of the matrix. Mesoporous silicon, fabricated by anodization of a highly n-doped silicon wafer offers oriented pores with average diameters of 50 nm and 90 nm, respectively. Fe3O4 nanoparticles of different size (3.8, 5 and 8 nm) have been used to deposit into the pores of these matrices. The resulting composite exhibits a desired transition temperature between superparamagnetic (SPM) behaviour and blocked state which can be modified by the size of the deposited particles, the distance between the particles and by the variation of the used porous silicon morphology, respectively. Beside scanning electron microscopy (SEM) a sophisticated method for TEM-investigations has been employed to figure out the various characteristics of the system.
Electrodeposition of Functional Ni-Re Alloys for Hydrogen Evolution
Authors: Zabinski Piotr , Franczak Agnieszka , Kowalik Remigiusz
Published: May 2012

The aim of this work was to obtain Ni - Re binary alloy by a simple method of electrodeposition. Nickel - rhenium alloys have been deposited from nickel sulfamate and ammonium perrhenate electrolyte with citrate-anion additives. The effects of bath temperature, current density, bath composition and influence of magnetic field were studied. The impacts of these parameters on hydrogen evolution process for obtained Ni - Re alloys were examined. The deposited layers were determined by optical and scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF).
The Stress Engendered by Oxygen Bubble Formation in the Electrolyte of Solid Oxide Electrolysis Cells
Authors: Comets Olivier , Voorhees Peter W.
Published: May 2012

It has been reported that running a Solid Oxide Electrolysis Cell above a critical current degrades the cell very quickly. This degradation has been linked to oxygen bubble formation in the electrolyte near the oxygen electrode. The applied current in the presence of charge transfer resistances is responsible for a high oxygen potential under the oxygen electrode which translates into a large driving force for the formation of oxygen gas in the electrolyte and can lead to the nucleation of oxygen gas bubbles. When such a bubble nucleates, local equilibrium at the interface between the bubble and oxide leads to an extremely high pressure inside it introducing, in return, significant stresses in the oxide. In this paper, the stress field surrounding the oxygen bubbles in the electrolyte is treated and the resulting elastic energy is determined.
Electrochemical Analysis of Sulphur-Poisoning in Anode-Supported SOFCs under Reformate Operation
Authors: Kromp Alexander , Dierickx Sebastian , Leonide André , Weber André , Ivers-Tiffée Ellen
Published: May 2012

The impact of sulphur-poisoning on the electrochemistry of anode-supported solid oxide fuel cells has been analyzed via electrochemical impedance spectroscopy. Therefore, single cells manufactured by Forschungszentrum Jülich (FZJ) were operated with a reformate fuel. During operation, contents of H2S (0.1 and 0.5 ppm) were added to the fuel. A detailed analysis of impedance spectra by the distribution of relaxation times (DRT) and a subsequent Complex Nonlinear Least Squares (CLNS) fit enabled a separated treatment of the resulting degradation of anodic and cathodic polarization processes. During the exposure to 0.5 ppm H2S, the polarization resistance increased by 200 %, levelling off after 24 h. This strong increase has mainly been attributed to the decreased reaction rate of the electrochemical fuel oxidation. Additionally, a strongly decreased conversion rate of the water-gas shift reaction was determined from the impedance measurements. This implies a dramatically lowered utilization of the CO within the fuel.
Study of Alkaline Water Electrolysis
Authors: Manabe Akiyoshi , Hashimoto Terumi , Kashiwase Masaharu
Published: May 2012

SPE type pure water electrolysis shows good performance for hydrogen generation. However, considering future hydrogen society, SPE electrolysis would face real difficulty to meet a large demand. Chlorine Engineers Corp., Ltd. (CEC) is one of the major electrolyzer manufacturers in the chlor-alkali industry and has great experience in cell design and cell technology. Zero gap system was applied for cell evaluation based on CEC technology. A special electric collector for cathode was used to create zero gap without damaging the separator. Cell voltage was 1.76V at 40A/dm2, 80 deg C without any problems. Raney Ni alloy coating had advantage for oxygen over-voltage. (100mV - 200mV saving against Ni metal) Thermal decomposition coating of cathode showed low hydrogen over-voltage. (around 100mV) Ion exchange membrane N117 and F8020 showed high cell voltage (over 2.2V) but low O2 impurity in H2 gas (over 99.95%). Porous polyolefin film showed 1.76V cell voltage but no durability.
Rechargeable Batteries for the 300-Mile Electric Vehicle and Beyond
Authors: Abraham K. M.
Published: May 2012

The energy density required for rechargeable batteries to power 300-mile range electric vehicles on a single charge is about 600 Wh/kg. Li-ion batteries are unable to meet this need in the foreseeable future. The prospects for advanced rechargeable batteries for the 300-mile EV are presented with brief discussions on the status of Li-air and Li-S batteries
LiNi0.4Mn1.6O4 / Electrolyte and Carbon Black / Electrolyte High Voltage Interfaces: To Evidence the Chemical and Electronic Contributions of the Solvent on the Cathode- Electrolyte Interface Formation
Authors: Demeaux Julien , Caillon-Caravanier Magaly , Galiano Hervé , Lemordant Daniel , Claude-Montigny Bénédicte
Published: May 2012

Solvent and lithium salt decomposition products on LiNixMnyO4-type electrodes are known to be ROM, ROCO2M (M= Li, Ni, Mn), LiF, LixPFyOz, polycarbonates and polyethers. These compounds are chemically formed due to the high nucleophilic character of spinel oxide and LiPF6 decomposition. The high potentials (> 4.7 V vs. Li/Li+) may cause EC and PC polymerization, while DMC forms oligomers. The use of carbon black-based electrodes highlights electronic and, surprisingly, chemical contributions to the cathode-electrolyte interface. A comparison between EC/DMC (1:1 in weight) 1 M LiPF6 and PC/DMC (1:1 in weight) 1 M LiPF6 electrolytes for Li/carbon black-PVdF cells demonstrated a superior ability of the EC/DMC solution to form a well-covering passivation film via faradaic reactions thanks to a higher stability toward oxidation. Electrochemical cycling in Li/LiNi0.4Mn1.6O4 cells confirms this EC/DMC superiority when it comes to forming passivation films, in turn leading to reduced capacity losses and a higher Columbic efficiency.
Fuel Cell Performances of Bio-Membranes Made of Chitosan-Polyelectrolyte Thin Films and Nanowires into Anodic Alumina Membranes
Authors: Bocchetta Patrizia , Conciauro Francesca , Santamaria Monica , Di Quarto Francesco
Published: May 2012

Chitosan (CS) / Phosphotungstic acid (PTA) polyelectrolytes in the shape of thin films and nanowires supported by Anodic Alumina Membranes (AAM) have been fabricated through solution cast and filtration techniques, respectively. Their ability to function in a H2/O2 fuel cell under mild conditions (room temperature, low humidity and low Pt loading) is proved for the first time. The fabricated membrane electrode assemblies produce power peaks of ~20 mW cm-2 for both films and nanowires. The CS/PTA films (20-40 μm thick) are able to produce a quite constant power density of ~10 mW cm-2 recorded for at least 7 h. The gradual decrease of the power output with time observed for CS/PTA nanowires in AAM supports (50 μm thick) is accompanied by a durability of about 6 h, which represents an improvement with respect to previous results obtained in AAM-based fuel cell.
Phosphazene Based Additives for Improvement of Safety and Battery Lifetimes in Lithium-Ion Batteries
Authors: Harrup Mason K. , Gering Kevin L. , Rollins Harry W. , Sazhin Sergiy V. , Benson Michael T. , Jamison David K. , Michelbacher Christopher J. , Luther Thomas A.
Published: May 2012

There needs to be significant improvements made in lithium-ion battery technology principally in the areas of safety and useful lifetimes to truly enable widespread adoption of large format batteries for the electrification of the light transportation fleet. In order to effect the transition to lithium ion technology in a timely fashion, one promising next step is through improvements to the electrolyte in the form of novel additives that simultaneously improve safety and useful lifetimes without impairing performance characteristics over wide temperature and cycle duty ranges. Recent efforts in our laboratory have been focused on the development of such additives. This paper presents the results of the study of a series of structurally similar phosphazenes that exhibit promise for use as electrolyte additives. This series, termed the SM series, employs cyclic phosphazene trimers with six pendant groups each composed of short chain linear ethers.
The Safety Evaluation Test of Lithium-Ion Batteries in Vehicles - Investigation of Overcharge Test Method -
Authors: Takahashi Masashi , Komatsu Kazunori , Maeda Kiyotaka
Published: May 2012

We conducted overcharge tests on various types of lithium-ion batteries as single cells and battery modules and compared the test results. In single cell tests, test results differed depending on the presence or absence of restraining plates, the restraining plate material, and the presence or absence of heat insulators. Furthermore, when heat dissipation was inhibitory, test results were similar to those for a battery module. A battery module is composed of stacked single cells and has more inhibitory heat dissipation than an independent single cell. Therefore, when conducting an overcharge test on a single cell, it is necessary to select the restraining plate material and restraining plate form considering the heat dissipation of an assembled battery, such as a battery module or pack, in order to simulate the restricted state in a battery module and avoid large differences in the test results for a battery module or pack.
In Situ CCVD Grown Bilayer Graphene Transistor
Authors: Wessely Pia Juliane , Wessely Frank , Birinci Emrah , Schwalke Udo
Published: May 2012

In this paper we report on a novel method to fabricate graphene transistors directly on oxidized silicon wafers without the need to transfer graphene. By means of catalytic chemical vapor deposition (CCVD) the in-situ grown monolayer graphene field-effect transistors (MoLGFETs) and bilayer graphene field-effect transistors (BiLGFETs) are realized directly on oxidized silicon substrate. In-situ CCVD grown MoLGFETs exhibit the expected Dirac point together with the typical low on/off-current ratios of 16. In addition, however, in-situ CCVD grown BiLGFETs possess unipolar p-type device characteristics with an extremely high on/off-current ratio up to 1x107 exceeding previously reported values by several orders of magnitude. With this novel fabrication method hundreds of large scale in-situ CCVD grown graphene FETs are realized simultaneously on one 2' wafer. Besides the excellent device characteristics, the complete CCVD fabrication process is silicon CMOS compatible. This will allow a simple and low-cost integration of graphene devices for nanoelectronic applications in a hybrid silicon CMOS environment.
Electrode Characteristics of Individual, MnO2 Coated Carbon Nanotubes
Authors: Corso Brad L. , Perez Israel , Collins Philip G.
Published: May 2012

We investigate interfacial charge transfer between a manganese oxide (MnO2) pseudocapacitor material and graphitic carbon supports in the limit where the graphitic carbon is defect free. We achieve this limit experimentally by fabricating model electrodes comprising MnO2 deposited on single, pristine, isolated single-walled carbon nanotubes. Li ion cyclic voltammetry of the composites gives a specific capacitance in accord with MnO2 storage capacities, but with kinetics limited by the poor electron transfer properties of defect free carbon. By fitting the data to an equivalent circuit model, we determine the charge transfer resistivity of MnO2-carbon interfaces to be 9 x 107 Ohm-cm when defects are absent, a limiting value for high power cathodes.