bluuebunny/crossref_metadata_2025 huggingface dataset:
Precipitation of Antimony Implanted into Silicon
Authors: Koffel Stephane , Pichler Peter , Reading Michael A. , Van den Berg Jakob , Kheyrandish Hamid , Hamm Silke , Lerch Wilfried , Pakfar Ardechir , Tavernier Clement
Published: May 2012

Antimony was implanted into silicon, followed by a rapid thermal annealing step to recrystallize the substrate. Post-activation annealings were made at 800 and 900 °C with increasing time, to study the deactivation of antimony using a combination of SIMS, MEIS and TEM analyses. It was found that the antimony profile does not broaden for moderate thermal budgets. However, during thermal treatments, antimony atoms continuously move towards the surface. There, they pile-up in non-substitutional positions and form precipitates. It was also confirmed that this phenomenon happens after solid phase epitaxy. Possible explanations are discussed.
Thermoelectric Characteristics of Annealed N-Type BiTe Thin Film
Authors: Hsu H. H. , Cheng Chun-Hu , Chen P.C. , Yeh C. H. , Chen Y. R. , Chou Y. W. , Lin Y. L. , Yang C. C.
Published: May 2012

The thermoelectric n-type Bi-Te based thin films with and without oxygen annealing were investigated and the related thermoelectric properties were well defined and characterized in this study. We found that the Seebeck coefficient, electrical resistivity and power factor for thin-film BiTe were potentially comparable with those of bulk materials if an appropriate annealed treatment could be realized. In addition, the formation of TeO with higher resistivity in thin-film BiTe might bring out the contribution on the enhanced Seebeck coefficient, which showed the potential to the application of thin-film thermoelectric device.
Photoluminescence Characterization of the Interface Properties of Si Nanolayers and Nanowires
Authors: Sakurai Yoko , Ohmori Kenji , Yamada Keisaku , Shiraishi Kenji , Kakushima Kuniyuki , Iwai Hiroshi , Nomura Shintaro
Published: May 2012

We present results of the photoluminescence (PL) measurements of silicon nanowires (NWs) and silicon nanolayers for device characterization.
(Invited)Localized Dissolution Kinetics From Fast In Situ Radiography of Propagating Pits in Stainless Steel and Implications for Modeling Pitting Corrosion over Long Time-Scales
Authors: Laycock Nicholas J. , Krouse Donal P. , Ghahari S.M. , Davenport Alison J. , Rayment Trevor , Padovani Cristiano
Published: May 2012

In-situ synchrotron radiography has been used to observe propagating 2D pits in a thin foil of 304 stainless steel sandwiched between glass slides. Key kinetic parameters have been extracted from these radiographs such that they can be used as input parameters for numerical simulations of pitting corrosion. Simulation results are presented for pits growing under potentiostatic control, with a focus on propagation stability in the concentrated (> 1M) chloride solutions that cause atmospheric pitting corrosion of 304 stainless steel.
Factors Controlling the Location of Crevice Attack in Austenitic Stainless Steels
Authors: Lee Jason S. , Kelly Robert G.
Published: May 2012

Microfabrication techniques and computational modeling were employed to examine the factors controlling the spatial distribution of crevice corrosion of 316L stainless steel in ferric chloride environments. Crevice fabrication consisted of a structural material surrounding a sacrificial material, the latter of which was selectively etched to form a rigorously defined hollow structure over the 316L substrate. For crevice gaps below 3 microns, the site of greatest attack down the crevice length was independent of gap size. A multivariable surface was used to model the variations in the electrochemical boundary condition as a function of chloride concentration. Modeling results predicted the location of greatest attack and that neither ohmic drop nor chemistry change models are suitable for austenitic stainless in acidic chloride environments. Instead, results showed that a chemistry dependent potential-current behavior is the factor that controls the spatial distribution of crevice corrosion attack in this system.
The Modeling and Measurement of Boundary Conditions for Pit Size on Stainless Steels under Atmospheric Exposure Conditions
Authors: Shedd Mara E. , Kelly Robert G.
Published: May 2012

Literature values prove the existence of maximum pit size. Values from exposures to natural environments exist for a range of materials in which exposure times of 10 y or more clearly show a plateau in the size of the largest pits. A recently published model uses the conditions that result from atmospheric exposures to place a bound on the size to which a pit can grow. Although this approach has been shown to compare well to data collected from exposures of stainless steels over long times (> 25 y) at coastal locations, laboratory validation is required in which salt loading density, RH and temperature can be rigorously controlled. After three months, the laboratory exposures of four stainless steel alloys, with 240 and 600 μg/cm2 of NaCl and 90 and 95% RH, were found to have little pit damage, and all pit sizes were correctly bounded by predicted model values.
Computer Simulation of Crevice Corrosion of Stainless Steels: Influence of Alloying Elements and Film Depassivation
Authors: Malki Brahim , Souier Tewfik , Peguet Lionel , Baroux Bernard
Published: May 2012

Crevice corrosion kinetics of AISI 430 and AISI 304 stainless steels (SS) are investigated using both electrochemical transients measurements and finite element method calculations. The experimental results lead to a quantitative picture of the well-known corrosion resistance difference between austenic and ferritic SS. A rational explanation of this behavior is provided by the modeling approach. The results lead to the formulation of critical conditions for crevice propagation in terms of dissolution current (IG) and depassivation pHd. In particular, the model estimates correctly the evolution of the corroded surface and fairly predicts the better crevice corrosion resistance of the austenitic grade, which is attributed to the slow dissolution rates in active conditions and to low pHd.
Characterization of Passive Films Formed on Manganese Nickel-Free Stainless Steel Exposed to Simulated Concrete Pore Environment
Authors: Veleva Lucien P. , Tsaneva Boryana
Published: May 2012

Manganese is a key component in low-cost SS formulations when nickel is replaced by Mn. Passive layers grown on Cr18Mn12 free-nickel SS samples immersed in saturated Ca(OH)2 and Portland cement extract, were studied. The corrosion behavior of the grown passive films was monitored at open circuit potential. In the presence of chloride ions the passivation process is perturbed and competes with the dissolution one. The surface becomes irregular, rough and Mn was found enriched in areas of non metallic inclusions in the passive layer, while the Fe/Mn and Fe/Cr ratios tend to decrease. The formed film is N-richer at the metal-oxide interface, as a consequence of its anodic segregation during dissolution-passivation process. Surface protuberances in the morphology of the SS could be explained in terms of unattacked oxide inclusions that still remain in the formed passive film or due to manganese insoluble compounds, which aid the corrosion resistance of the studied steel.
Use of Scanning Kelvin Probe Force Microscopy to Investigate the Effects of Surface Preparation on Intermetallic Particles in AA7xxx Aluminum Alloys
Authors: Zhang Weilong , Yu Xiaomei , Kryzman Michael , Garosshen Thomas J. , Piech Marcin , Jaworowski Mark R. , Zafiris George S.
Published: May 2012

Scanning Kelvin probe force microscopy (SKPFM) was used to quantitatively measure the surface potentials (also referred to as Volta potential) on different intermetallic particles relative to the matrix in AA7xxx aluminum alloys, in combination with scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). Both Cu and Fe-rich intermetallics showed rather high, positive Volta potential differences (~ +400 mV), while Mg/Si-rich one exhibited a negative potential (~ -250 mV) relative to the matrix for the Al alloys investigated. Large variations in the measured Volta potential, which appeared to be independent of particle size, were observed for these Cu and Fe-rich (Al7Cu2Fe) and Mg/Zn rich (Mg2Zn) particles in the custom Al-Zn-Mg-Cu alloy. The effects of different surface preparation on the Volta potentials of Cu/Fe-rich and Mg/Si-rich intermetallic particles were investigated. The results indicate that the influence of surface preparation is complex, but largely depends on the type of intermetallic particles, and whether there is any particle dissolution during the surface preparation.
Pit Propagation in Pure Aluminum Investigated via the 1D Artificial Pit Technique: Growth Regimes, Surface Morphology and Implications for Stability Criteria
Authors: Cook Anthony B. , Engelberg Dirk L. , Stevens Nicholas P. , Laycock Nicholas J. , White Stephen , Ghahari Majid , Monir Medhi , Holroyd Henry J. , Newman Roger C.
Published: May 2012

The growth kinetics of various diameter 1D aluminum artificial pits were investigated under potential control in 1 mol dm-3 HCl. Pits of diameter ≥ 50 μm display mass transport control at high potentials, Ohmic growth at intermediate values with a transition to a further region of potential-independent dissolution at ca. 100 mV prior to repassivation. Optical and x-ray computed tomography observations of pit cross-sections suggest Ohmic propagation is associated with non-uniform dissolution over the pit surface. By contrast narrow diameter pits (25 μm) show no evidence of dissolution below their limiting current density and appear to grow without surface roughening until 10 - 20 mV before repassivation. Investigation of the nature of pit growth prior to this point via potential perturbation techniques confirmed that dissolution occurs under mass transport control. These observations support the hypothesis that sustained pit propagation requires a high degree of saturation, close to 100%, in AlCl3.
Correlating Pit Initiation in Aluminum with Passive Oxide Defect Structure
Authors: Zavadil Kevin R.
Published: May 2012

Microelectrochemical methods are combined with scanning electron microscopy to explore passive oxide breakdown and pit initiation on Al(111) thin films. Anodic galvanostatic polarization is conducted in a microcapillary cell to limit the available current and to restrict the analysis area for subsequent microscopic evaluation. An ability to drive a single pit initiation event is demonstrated using this approach. Subsequent microscopy shows that pore cluster formation on the off-(111) axis facets that are emergent from the grain boundaries is responsible for pit initiation. Early stage, fully formed pits possess oxide membranes that contain pore clusters. Pores evolve from voids that form at the oxide-Al interface, establishing a link between these interfacial voids and pit initiation. Localized oxygen vacancy saturation and the anion-cation vacancy annihilation reaction during anodic polarization drive void growth, the void-to-pore transition, and pit initiation at off-(111) axis facets in this system.
Activation Energy for the Corrosion of Aluminum Powders in Water
Authors: Skrovan John
Published: May 2012

The self passivation of aluminum in water generally prevents the generation of hydrogen from an aluminum-water reaction in conditions preferred for portable systems. However the potential for corroding aluminum to produce quantities of hydrogen at a lower total system mass compared to compressed storage tanks is spurring research into accelerating aluminum corrosion by ball milling and mixing with other powders. This allows commercially useful amounts of hydrogen to be generated at moderate temperatures and neutral pH regions. To further study the mechanism behind the increased rate the activation energies were calculated for hydrogen evolution from pure aluminum, aluminum that had been ball milled, and aluminum mixed with alumina powder. Overall, aluminum that is in contact with higher amounts of aluminum hydroxide, either grown or added, showed a drop in activation energy from approximately 80 kJ/mole down to 24 kJ/mole.
Experimental Evaluation and Modeling of Galvanic Interactions between Aluminum Alloy 7075-T6 and Noble Materials
Authors: Shi Yijing , Kelly Robert G.
Published: May 2012

Galvanic interactions between aluminum alloys and noble materials in corrosive environments can cause structural problems in the use of military and commercial assets. The aim of the current work is to determine the conditions that lead to significant localized corrosion by galvanic coupling and to understand its controlling mechanism. The cathodic kinetics of noble materials (silver, nickel and carbon-fiber reinforced bismaleimide (BMI)) and the dissolution kinetics of aluminum alloy AA7075-T6 were quantitatively investigated and used as boundary conditions for a numerical study. Finite element analyses were used to study the galvanic interactions of AA7075-T6 and noble materials in a geometry modeled on a two fastened plates as a function of solution pH and chloride concentration [Cl-]. The results in the paper indicated that both initiation and propagation of localized corrosion were influenced by the galvanic interactions, and these were evaluated as a function of geometry, noble material, and solution composition.
ZnO-based Transparent Electrodes for LCD TVs
Authors: Yamamoto Naoki , Makino Hisao , Morisawa Kirihiko , Yamamoto Tetsuya
Published: May 2012

20-in. liquid crystal display (LCD) TVs were successfully fabricated with Ga-doped ZnO (GZO) transparent electrodes on the RGB color filter and conventional indium tin oxide transparent electrodes on the thin film transistor pixel array. The high optical transmittance of the GZO film is beneficial for the color representation characteristics of LCD TVs. A technique for the formation of GZO fine patterns was also developed using wet-chemical etching and the pH values of chemicals used for the photolithography and etching processes were optimized. Line/space patterns widths of 2 um/2 um were accomplished using the optimized patterning technique.
A pH Sensor Based on Surface-Enhanced Raman Scattering
Authors: Li Ming , Wu Nianqiang
Published: May 2012

Surface-Enhanced Raman scattering sensor is being developed for facile applications in biological and environmental fields. Its advantages including portable spectrometer and ability of point-of-care detection will benefit the real-time analysis. We investigated the SERS response to the pH value in solutions. It was found that in acidic solution, the hydrogen bond interaction will bring AuNPs together, resulting in the aggregation of AuNPs. After aggregation of AuNPs, the solution became purple from wine-red. This color response inspired the present system to be colorimetric sensor for the rough detection of pH values. Furthermore, the intensity of Raman peak increases with the pH value change from alkalinity to acidity. It was concluded that Raman signal of p-MBA adsorbed onto AuNPs can be used to indicate the pH value in solutions.
Improvement of Cycleability for Li-Si Alloy Anodes Using Si Thin Flakes for Li-Ion Batteries
Authors: Yamada Tomoyuki , Saito Morihiro , Yodoya Chihiro , Kamei Akika , Hirota Masato , Takenaka Toshio , Tasaka Akimasa , Inaba Minoru
Published: May 2012

Pure Si thin flakes (Si Leaf Powder® (Si-LP)) of different thicknesses (50, 100, 200, 300 and 400 nm) were prepared, and their charge/discharge properties were investigated as anode materials for lithium ion batteries (LIBs). Thickness of the thin Si-LP (100 nm) changed reversibly during charging and discharging, while the expanded thickness upon charging was kept after fully discharged for the thick one (300 nm), indicating insufficient Li de-alloying at C/6 rate. The slower kinetics for the thicker Si-LPs was also confirmed by examination of the open circuit potential (OCP) and the rate capability. These suggested that Li atoms diffused easily within the thinner Si-LPs and the uniform Li distribution suppressed the physical stress due to the Li alloying and de-alloying, resulting a good cycleability. In addition, addition of vinylene carbonate (VC) in electrolyte reduced charge transfer resistance of the Li alloying/de-alloying reaction and much more improved the cycleability of Si-LPs.
New Developments in CMP Pad Conditioner Technology
Authors: Singh Rakesh K. , Smith Joseph , Galpin Andrew , Wargo Christopher R.
Published: May 2012

This paper focuses on the challenges and new developments in chemical mechanical planarization (CMP) pad conditioner technology for the next-generation applications, with a special emphasis on the comparative performance characterization of pad conditioners. Empirical data from a number of case studies are presented. Different design 4" disk pad conditioners were evaluated using a benchtop polisher, a benchtop tribometer, and a 300 mm wafer polisher/tribometer to determine pad cut-rate, pad surface roughness, coefficient of friction (COF), and Cu polishing behavior. Results are presented for the effect of pad conditioner design parameters, including abrasive/feature size and distribution, on the pad cut-rate and pad surface roughness. Such information may be helpful in reducing the fab selection and optimization time for pad conditioners in advanced technology node applications. Present study demonstrates the usefulness of pad conditioner laboratory scale characterization.
Preparation of Magnesium Hydroxide Film by Electrochemical Reaction
Authors: Ishizaki Hiroki , Ito Seishiro
Published: May 2012

Mg(OH)2 films with hexagonal structure were grown on a conductive substrate by electrochemical deposition from a 0.1mol/L magnesium nitrate aqueous solution kept at 323K. The crystal structure of these films corresponded to the hexagonal structure with the space group of P3m1 as determined by using Rietveld analysis, regardless of the cathodic potential. The resistivity of Mg(OH)2 films decreased with an increase in the cathodic potential. In particular, at the cathodic potential of -0.9V, Mg(OH)2 films had the resistivity as low as 1.1Ωcm. This film was composed of aggregates of triangular grains and had no defects such as pores and cracks.
Nucleation and Growth of Copper on Ru-Based Substrates: I. The Effect of the Inorganic Components
Authors: Nagar Magi , Vereecken Philippe M. , Strubbe Katrien , Radisic Aleksandar
Published: May 2012

The effect of the inorganic components, namely copper sulfate (CuSO4), sulfuric acid (H2SO4) and hydrochloric acid (HCl) on the nucleation and growth of copper on Ru-based substrate is reported in the absence and the presence of a suppressor molecule, polyethylene glycol (PEG). In the absence of PEG it was that found the island density, Np was the highest when CuSO4 and HCl concentrations were low while H2SO4 concentration was high. The effect of each component remained similar when all components were mixed together. In the presence of PEG, the effect of CuSO4 and H2SO4 remained similar. However, for the HCl, an optimal concentration was found where Np reached a maximum value. The study illustrates the importance of an optimal bath composition toward faster coalescence of the Cu islands into a continuous Cu film for direct plating applications.
Nucleation and Growth of Copper on Ru-Based Substrates: II. The Effect of the Suppressor Additive
Authors: Nagar Magi , Radisic Aleksandar , Strubbe Katrien , Vereecken Philippe M.
Published: May 2012

The effect of the molecular mass (Mm) of polyethylene glycol (PEG) and its derivatives on the copper island density (Np) on ruthenium-tantalum (RuTa) alloy was investigated by utilizing scanning electron microscopy (SEM) and galvanostatic methods. The experimental results show that the island density is affected by the strength of suppression which can be modified by using different suppressor molecules. Furthermore, we use galvanostatic measurements to evaluate the suppression strength and show that potential-time transients recorded during galvanostatic deposition of Cu can be used to estimate the island density.
Electrochemical Deposition of Ni into Mesoporous Silicon
Authors: Dolgyi Alexey , Bandarenka Hanna , Prischepa Serghej , Yanushkevich Kazimir , Nenzi Paolo , Balucani Marco , Bondarenko Vitaly
Published: May 2012

Nickel nanowires have been formed by the stationary electrochemical deposition of nickel into mesoporous silicon from the modified Watts bath. The polycrystalline nature of the Ni deposit has been established as well as expansion of its lattice parameter in comparison with bulk nickel. Control of the potential of porous silicon during electrochemical deposition allows to determine the moment of complete filling of pore space with Ni. The maximum achieved filling factor was 67% of the pores. The pore dimensions have been found to define the length and the diameter of the Ni nanowires that have equaled to 10 um and 100-120 nm, respectively.
(Invited) Electrochemical Routes towards Sustainable Hydrocarbon Fuels
Authors: Mogensen Mogens
Published: May 2012

The potential of renewable energy and possible solution to the intermittency problem of renewable energy sources like sun and wind are explained. The densest storage of energy is in the form of hydrocarbons. The most suitable method of conversion and storage within a foreseeable future is electrolysis followed by conversion into synthetic hydrocarbons, alcohols or ethers. Several types of electrolysers exist. The various types are listed together with a short description of principle and status. It is argued that electrolysis will at least become part of large sustainable energy systems in the future. In spite of this, it is important to research and develop as many viable sustainable energy technologies as economical possible.
Fuel Synthesis with CO2 Captured from Atmosphere: Thermodynamic Analysis
Authors: Wang Tao
Published: May 2012

Synthetic hydrocarbon fuel, derived from renewable energy and captured carbon dioxide from flue gas and/or ambient air, can close its carbon cycle and is an important approach to sustainable energy. In this study, the thermodynamic performance of a co-electrolysis process for producing hydrogen and carbon monoxide from water and captured CO2 is investigated, based on current carbon capture and high-temperature electrolysis technologies. The exergy analysis is useful because it can reveal the energy losses due to irreversibilities and indicate possibilities for improvement of a process. Fuel synthesis systems integrated with or separated from different carbon capture technologies were evaluated and the analysis results have indicated that compared to the energy/exergy consumed by electrolysis, the energy/exergy penalty from CO2 capture is insignificant. The thermodynamic efficiency of fuel synthesis could be increased by developing fuel generation technologies with lower electricity requirements, especially when using solar and nuclear energy.
(Invited) Efficient Generation of High Energy Density Fuel from Water
Authors: Ayers Katherine E. , Dalton Luke T. , Anderson Everett B.
Published: May 2012

Carbon-free energy generation is a necessity to meet rising global energy needs while minimizing environmental impact. Hydrogen has the potential to be a cost competitive and scalable solution to replace fossil fuels, and water electrolysis is an attractive concept for producing hydrogen with zero carbon footprint when integrated with a renewable energy source. Proton Energy Systems is a world leader in hydrogen generation from PEM electrolysis and has demonstrated the commercial viability of this technology in the industrial gas market, with pathways defined to reach targets in the energy markets. Recent catalyst research at Proton has demonstrated efficiency improvements while maintaining stability. Ongoing collaboration with 3M has also shown feasibility to reduce the catalyst loading by over an order of magnitude vs. current commercial loadings. This paper will discuss Proton's fueling efforts, particularly at high pressure, and advancements in efficiency which enable localized generation of hydrogen where it is needed.
Effects of the Electrolyte on Electrochemical Reduction of CO2 on Sn Electrode
Authors: Wu Jingjie , Risalvato Frank , Zhou Xiao-Dong
Published: May 2012

This paper discusses the effects of the electrolyte on the selectivity and activity of electrochemical reduction of CO2 on Sn electrode including changes in cation, anion and concentration. The production of formate was quantitatively monitored by 1H NMR spectroscopy. Both the anion SO42- and the cation Na+ favor higher faradaic efficiency and energy efficiency while HCO3- and Cs+ enable high rate production of formate. The faradaic efficiency is as high as 69-76% for 0.5 M Na2SO4 in the potential range from -1.5 to -1.7 V vs. SCE. 0.5 M KHCO3 is an optimal electrolyte for high production rate of formate which could reach over 3.8 μmol min-1 cm-2 at potentials of -2.0 V vs. SCE while keeping faradaic efficiency of ~63%.
Electrochemical Reduction of CO2 at Temperatures Below 300 oC
Authors: Hallinder Jonathan , Holtappels Peter , Mogensen Mogens
Published: May 2012

Reduction of CO2 at intermediate temperatures (T< 300 oC) is a tempting way to produce hydrocarbons. One benefit of performing CO2 reduction below 300 oC is that it would possibly allow a single process for production of hydrocarbons. CsH2PO4, BaHPO4 and a composite thereof have been investigated as electrolyte materials both with respect to thermal stability and to conductivity. BaHPO4 showed an improved thermal stability compared to CsH2PO4, but it did at the same time exhibit a low conductivity (1⋅10-6 S cm-1 at 304 oC). CsH2PO4 started to dehydrate at 249 oC, but this dehydration was shown to be reversible. Its conductivity was measured to be 2⋅10-2 S cm-1 at 240 oC. Full cells with copper as the CO2 reduction catalyst have been manufactured and tested in CO2 containing atmospheres. Initial performance of 34 mA cm-2 at 245 oC has been achieved.
Performance and Durability of Solid Oxide Electrolysis Cells for Syngas Production
Authors: Sun Xiufu , Chen Ming , Hjalmarsson Per , Ebbesen Sune Dalgaard , Jensen So̸ren Ho̸jgaard , Mogensen Mogens , Hendriksen Peter Vang
Published: May 2012

Performance and durability of Ni/YSZ based solid oxide electrolysis cells (SOECs) for co-electrolysis of H2O and CO2 at high current density were investigated. The cells consist of a Ni/YSZ support, a Ni/YSZ fuel electrode, a YSZ electrolyte, and a LSM-YSZ oxygen electrode. The cell durability was examined at 800°C and electrolysis current density of -1 or -1.5 A/cm2 with 60% reactant (H2O+CO2) utilization. The cell voltage degradation showed a strong dependence on the electrolysis current density, with an overall cell voltage degradation rate of 0.24 mV/h at -1 A/cm2 and of 0.82 mV/h at -1.5 A/cm2. Electrochemical characterization of the cells showed that the degradation was mainly related to the LSM/YSZ electrode when operated at -1 A/cm2, whereas at increased current density (-1.5 A/cm2), both the Ni/YSZ and LSM/YSZ electrodes showed degradation.
Impedance Studies on LSCM/GDC Composite Cathode for High Temperature CO2 Electrolysis
Authors: Yue Xiangling , T.S. Irvine John
Published: May 2012

The cathode performance of LSCM/GDC composite for high temperature CO2 electrolysis has been studied by electrochemical impedance spectroscopy (EIS) measurements in a three-electrode electrolysis cell. The main feature in the impedance of LSCM/GDC is that it showed a Gerischer like impedance dispersion at 900oC in all CO2-CO mixtures investigated here. The Rs of LSCM/GDC changes little with the variations in CO2/CO ratio and operating voltage, however, the Rp of LSCM/GDC composite reduces with increasing CO concentration and operation potential. The activation energy for area specific resistance and for cathode polarization resistance is ~58 and 72 kJ mol-1 in CO2/CO 70/30 fuel, respectively. The surface adsorption/desorption equilibration and/or surface diffusion processes play a dominant role in the electrochemical reduction of CO2 by SOEC.
Degradation of Solid Oxide Electrolyser Cells with Different Anodes
Authors: Xu Cheng , Wang Yin , Jin Le , Ding Junfeng , Ma Xiao , Wang Wei Guo
Published: May 2012

Solid oxide electrolyser cells (SOECs) have been considered effective to produce hydrogen at a high conversion efficiency through high temperature electrolysis (HTE) process and has a potential to scale up to a large-scale economy hydrogen source. The crucial issue for the SOEC moving into practical applications is stability. In this paper, investigation was conducted with the focus on the anode degradation using SOEC cells with strontium doped lanthanum manganite (LSM) anode and strontium doped lanthanum ferro-cobaltites (LSCF) anode. The results showed a more stable performance in LSM cells than LSCF cells when testing at 750ºC anode degradation and anode delamination contributed most of performance drop. The LSM cell is thus more suitable for HTE than the LSCF cell due to its better bonding between the electrolyte and anode.
Electrochemical Studies on Anode Supported Solid Oxide Electrolyzer Cells
Authors: Njodzefon Jean-Claude , Klotz Dino , Leonide André , Kromp Alexander , Weber André , Ivers-Tiffée Ellen
Published: May 2012

A zero-dimensional and isothermal stationary model demonstrably predicting the current-voltage (C/V) characteristics of anode supported Solid Oxide Fuel Cells is proven to accurately reproduce these C/V characteristics in reverse (Electrolyzer) operation mode as well. The asymmetry observed in the C/V curves of both modes is totally reproduced and also explicitly explained.
Effect Of Current Switching on LSM-YSZ Composite Electrode Durability
Authors: Yakal-Kremski Kyle , Hughes Gareth A. , Call Ann V. , Barnett Scott A.
Published: May 2012

A method for durability testing of solid oxide cell electrodes in current-switching operation is presented. The method provides both electrochemical and microstructural information by using multiple symmetrical cells connected in series. Electrochemical impedance spectroscopy measurements were done periodically during life tests of (La0.8Sr0.2)0.98MnO3-Zr0.84Y0.16O2 (LSM-YSZ) symmetrical cells at 800°C in air with a current of 0.5 or 1.5Acm-2 switched every 30 minutes. By periodically removing cells from the circuit during the life test, microstructural changes due to current were observed at different stages. Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) tomographic measurements of electrode microstructure were done on cells with different times at current. Silver, from current collectors used in the tests, was found to migrate into the electrodes near the YSZ electrolyte during fuel cell operation. The silver content increased with time at current and presumably explained the observed steady increase in polarization resistance.
Development of a Predictive Thermo-Chemical Expansion and Stress Model in (Pr,Ce)O2-δ
Authors: Bishop Sean R. , Tuller Harry L.
Published: May 2012

The non-stoichiometry induced stress developed in the potential cathode material, Pr0.1Ce0.9O2-d (PCO), upon cooling from high temperature is modeled. Stresses can develop in such mixed ionic electronic materials due to changes in oxygen stoichiometry, resulting in defect induced dilation, or chemical expansion. In this example, a simulated bulk sample of PCO is cooled from 1400 C in air and O2 at different rates and the resulting diffusion limited concentration gradient is predicted and converted into a stress distribution using the chemical coefficient of expansion. Maximum tensile stresses of ~500 MPa are predicted at the sample surface, which can be reduced by cooling in more oxidizing atmospheres and/or at slower rates.
(Invited) Solid Oxide Membrane Process for the Reduction of Uranium Oxide Surrogate in Spent Nuclear Fuel
Authors: Jiang Yihong , Zink Peter A. , Pal Uday B.
Published: May 2012

Solid oxide membrane (SOM) electrolysis was employed to reduce ytterbium oxide (Yb2O3) which was identified as a possible surrogate for uranium oxide in spent nuclear fuel treatment. In this research, an yttria-stabilized zirconia (YSZ) tube was used as the SOM membrane in a LiF-YbF3-Yb2O3 salt to reduce ytterbium (Yb) metal on an inert cathode. The melting point of the supporting electrolyte (LiF-YbF3) was analyzed as a function of Yb2O3 concentration. The stability of YSZ tubes at the electrolysis operating temperature in the chosen flux was characterized. Yb metal deposited on the cathode during the SOM electrolysis process was analyzed.
(Invited) Solar Thermal Electrochemical Production of Energetic Molecules: Efficient STEP Solar Water Splitting, Carbon Capture, and Solar Metals, Fuel and Bleach Production
Authors: Licht Stuart , Wu Hongjun , Lau Jason , Wang Baohui , Hettige Chaminda , Bergmann Harry , Asercion Joseph
Published: May 2012

The Solar Thermal Electrochemical Production of energetic molecules converts solar energy at high efficiency. Rather than electricity, a variety of useful chemicals, including solar fuels and iron without CO2 emission, are produced by this STEP process. A synergy of solar thermal and solar-electric and other renewable energy electronic charge transfer, forms an alternative higher efficiency solar energy conversion process. For example, STEP can split CO2 with >50% solar efficiency. Previously, we demonstrated STEP carbon capture, STEP fuels and STEP iron. Here we expand the STEP process portfolio to include the solar production of magnesium and bleach.
Pressurized Solid Oxide Fuel Cells with Reformate as Fuel
Authors: Willich Caroline , Westner Christina , Henke Moritz , Leucht Florian , Kallo Josef , Maier Uwe , Friedrich K. Andreas
Published: May 2012

In this contribution the influence of pressure on an SOFC is studied with steam-reformed methane as a fuel. Experiments were performed with a reformate containing 58.4% H2, 20% H2O, 12.2% CO, 5.5% CO2 and 3.9% CH4 and another mixture containing 18% H2, 34% H2O, 2% CO, 27% CO2 and 19% CH4 as well as a hydrogen/nitrogen mixture. The influence of pressure on OCV, power density at constant voltage and constant current as well as on gas composition was examined for the different fuels. Power density increases of up to 70% were found.
Nano Facilitated Charge Transfer for an 11 Electron Redox Couple for Anodic Charge Storage: VB2
Authors: Licht Stuart , Lau Jason , Hettige Chaminda , Wu Hongjun , Wang Baohui , Asercion Joseph , Cubeta Ulyana , Stuart Jessica
Published: May 2012

The storage of multiple electrons per molecule provides opportunities to greatly enhance electrochemical energy capacity. VB2 releases, via electrochemical oxidation, 11 electrons per molecule at a favorable, electrochemical potential. Nanochemical improvements of VB2 are probed to facilitate charge transfer and discharge voltage. Mechanochemical synthesized VB2 exhibit higher voltage, sustain higher rate, and depth of discharge than macroscopic VB2. Recently, we introduced a synthetic pathway to nanorod VB2. In addition, here a straightforward synthetic route to nano-VB2 particles, via planetary ball milling of elemental vanadium and boride in a 1:2 equivalent ratio is presented. Variation of the mechanochemical synthesis milling speed and milling time is used to optimize this nano-VB2 for use as a high capacity anode material with enhanced charge transfer and increase voltage. Coupled with an air cathode, this 4060 mAh/g intrinsic capacity anode has energy capacity greater than that of gasoline.
Magnesium Recycling of Partially Oxidized, Mixed Magnesium-Aluminum Scrap through Combined Refining and Solid Oxide Membrane Electrolysis Processes
Authors: Guan Xiaofei , Zink Peter A. , Pal Uday B. , Powell Adam C.
Published: May 2012

Pure magnesium (Mg) is recycled from 19g of partially oxidized 50.5wt.% Mg-Aluminum (Al) alloy. During the refining process, potentiodynamic scans (PDS) were performed to determine the electrorefining potential for magnesium. The PDS show that the electrorefining potential increases over time as the magnesium content inside the Mg-Al scrap decreases. Up to 100% percent of magnesium is refined from the Mg-Al scrap by a novel refining process of dissolving magnesium and its oxide into a flux followed by vapor phase removal of dissolved magnesium and subsequently condensing the magnesium vapor. The solid oxide membrane (SOM) electrolysis process is employed in the refining system to enable additional recycling of magnesium from magnesium oxide (MgO) in the partially oxidized Mg-Al scrap. The combination of the refining and SOM processes yields 7.4g of pure magnesium.
Very Low Impedance Battery Architecture for Electrified Vehicles
Authors: Kaun Thomas D. , Sandahl Joel
Published: May 2012

Rolled-Ribbon is design and manufacturing method for battery cells that incorporates features of very short path length to bring current flow as well as heat from the cell and battery. Disc-shaped cells can be stacked to form a dense and efficient battery architecture for electrified vehicles. Relative to competing architectures, Rolled-Ribbon combines the low-cost winding and dimensional stability of the cylindrical format with fully-tabbed, very short electrodes of a prismatic (that is replicated by winding). The very short electrode of the cells and the quasi-bipolar arrangement approximately lower cell structural impedance (ACIR) by 50% and DC-pulse impedance by 25% for Li-ion battery. As such, Rolled-Ribbon overcomes the power/energy tradeoffs faced by competing architectures. Specific energy is increased with larger cells and high power is maintained.
Influence of Impurities in TiO2 Coatings on Electrode Potential of Photocatalytic Anode Assembling to Marine Microbial Fuel Cell
Authors: Motoda Shin-ichi , Uematsu Susumu , Shinohara Tadashi
Published: May 2012

The electrochemical measurement and surface morphology analysis of TiO2 coatings were conducted to improve the performance of microbial fuel cell (MFC) in natural seawater. From the experimental results, the 95.2% TiO2 purity electrode caused the noble shift of electrode potential which resulted from suppression of the photocatalytic effect. This phenomenon did not occur in 99.9% purity coatings, so the influence of impurities such as Si or Zr contained in the coatings was considered. Furthermore, the localized potential at the segregation of Si or Zr was higher than that of the rest, so the electrode potential of TiO2 coated anode was considered to be affected by the localized corrosion which had occurred beneath the deteriorated TiO2 coatings.
Failure Investigation of LiFePO4 Cells under Overcharge Conditions
Authors: Xu Fan , He Hao , Dun Clif , Liu YaDong , Wang Mei-xian , Liu Qi , Ren Yang , Xie Jian
Published: May 2012

The failure mechanism of commercial A123 18650 LiFePO4 battery in the overcharge failure process at 1C and 110% SOC has been studied. It was found that, during the normal cycle, the anode and cathode voltages were from -0.25 V to 0.25 V and 2.60 V to 4.50 V respectively, while in the 10% overcharge process, the anode voltage was between -0.4V to 0.22V (vs. Li/Li+) and the cathode voltage changed from 2.20 V to 4.86 V (vs. Li/Li+). The overcharge failure was studied using SEM and EDX. It was found that coding spots appeared in the anode side. Fe, Ni and Ge were found only in the coding spots by performing EDX, indicating the micro shorting by metal dendrite is the main reason of the failure of battery during the 10% overcharge process. It could be concluded from the results of High Energy Synchrotron X-ray Diffraction (HESXRD) that Fe was not from the decomposition of LiFePO4. The potential of Fe/Fe2+ oxidation/reduction pair in the LiPF6/EC-EMC electrolyte system was found to be 2.2 V/2.7 V. It was concluded that Fe cations could not only be reduced on the surface of graphite, but also at the cathode side during the overcharge process. Compared with normal cycle, under the overcharge process, the impurities containing iron in the raw material was more conducted to dendrite formation leading to micro-shorting because of the wider reduction voltage range in the overcharge process.
Effects of Single Walled Carbon Nanotubes on Arabidopsis Mesophyll Cells
Authors: Cui Daxiang , Ruan Hengguang , Zhang Xueqing , Hu Shanglian , Huang Peng , Song Hua , Wang Kang , Ruan Jing
Published: May 2012

Herein we reported the effects of single-walled carbon nanotubes (SWCNTs) on Arabidopsis mesophyll cells. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 hours, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' apoptosis. In conclusion, SWCNTs maybe a good transporter in the plant world, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts.
The Regularities of Electrolytic Dissociation of 1,2-Cyclobutanedicarboxylic Acids
Authors: Kvaratskhelia Elene , Kvaratskhelia Ramaz
Published: May 2012

The dissociation parameters for the dilute (0.0001-0.01M) solutions of cis and trans-1,2-cyclobutanedicarboxylic acids were calculated with the aid of the new original method for analysis the regularities of electrolytic dissociation of weak multibasic organic acids with the effect of "overlapping" equilibria. The equations for determination the regions of predominance of various charged and uncharged forms of these acids were also described.
Electronic Absorption and Voltammetric Analysis of Ni(II) Coordination in the Room Temperature Ionic Liquid: 1-Ethyl-3-Methylimidizolium Chloride/Aluminum Chloride
Authors: Parker Joseph F. , Cheek Graham T. , Roeper Donald F. , O'Grady William E.
Published: May 2012

The coordination chemistry of Ni(II) in the ionic liquid aluminum chloride : 1-ethyl-3-methyl imidazolium chloride (EMIC) has been determined using visible absorption spectrophotometry. By dissolving nickel chloride (NiCl2) in Lewis acidic and basic ionic liquids and observing the resultant spectra and voltammetric information, one can determine the coordination and electron-transfer properties of Ni(II) at the various acidities. The optical data indicate the formation of tetrahedral NiCl42- in the ionic liquid with excess EMIC (basic melt, NAlCl3 < 0.5) with absorption maxima at 659 and 707 nm. In acidic melts (NAlCl3 > 0.5), the wavelength of maximum absorbance shifts to 462 nm. This dramatic change in the visible spectrum is indicative of a change in the coordination of Ni(II) from tetrahedral (basic) to octahedral (acidic) geometry, changes which are mirrored in the cyclic voltammetry data of the same samples. Studies in the neutral melt are also presented here.
Evaluation of Grain Size Distributions of Cu Interconnects with Less Than 100nm Width by X-ray Diffraction Method
Authors: Inami Takashi , Onuki Jin
Published: May 2012

Grain size distributions of less than 100nm wide Cu interconnects made by DC electroplating have been evaluated by a rapid and nondestructive method using X-ray diffraction. The influence of the depth and width in the trench and the thickness of electroplated Cu film on the grain size distribution in narrow Cu interconnect. It was found that the mean grain size of annealed narrow Cu interconnect depends linearly on the product of the ratio of excess Cu film thickness to trench depth and trench width.
(Invited) Resistivity Reduction in Very Narrow Cu Wiring
Authors: Onuki Jin , Sasajima Yasushi , Tamahashi Kunihiro , YiQing Ke , Terada Shouhei , Hidaka Kishio
Published: May 2012

Low resistivity 60nm wide Cu wires were realized by the combination of lessening impurities through additive-less plating and high-heating rate annealing. Resistivities of Cu wires made with the new method were about 20% lower than those made by conventional plating with additives and annealing at the same temperature. Low resistivity Cu wires were formed even at temperatures 100k lower than conventional annealing temperatures due to substantial grain growth by high-heating rate annealing in the Cu wires made with additive-less plating.
(Invited) High Speed Copper Electrodeposition for Through Silicon Via(TSV)
Authors: Hayashi Taro , Kondo Kazuo , Takeuchi Minoru , Suzuki Yushi , Saito Takeyasu , Okamoto Naoki , Marunaka Masao , Tsuchiya Takayuki , Bunya Masaru
Published: May 2012

High-speed copper electrodeposition is needed to optimize the TSV process with a high throughput. To inhibit electrodeposition on the top surface of the TSV, the ODT was microcontact-printed on the top surface. The ODT microcontact-printing effectively inhibits the copper electrodepositon on the top surface. With 1.0 ppm SDDACC, V-shapes were formed in the via cross sections and these shapes lead to bottom-up via filling [1]. Without micro-contact-printing, and with 1.5 ppm SDDACC, V-shapes were again formed in the via cross sections and these shapes lead to bottom-up via filling. We succeeded in filling 10 μm diameter and 70 μm deep vias within 35 minutes without micro- contact-printing. This was achieved by optimizing the SDDACC concentration with CVS measurements. The inhibition layer of the micro-contact-printing does not speed up the TSV electrodeposition. The most important factor to speed up the TSV electrodeposition is optimization of the additives.
The Bottom-Up Copper Fill of Ø5µm × 40µm Vias Using 2-Component Model Chemistry
Authors: Radisic Aleksandar , Yang Liu , Drijbooms Christel , Bender Hugo
Published: May 2012

We have explored the possibility to fabricate Cu interconnects for 3D Stacked-Integrated-Circuit (3D-SIC) applications using electrochemical deposition from the Cu bath with model organic additives. The Cu bath used was a two-component bath, with bis(3-sulfopropyl) disulfide (SPS) as the accelerator, and poly-ethylene glycol (PEG) as the suppressor additive. In this paper, we present the results of extensive tests performed to identify deposition parameters and bath composition leading to bottom-up Cu fill of Ø5µm × 40µm vias.
Laser Induced Forward Transfer of Interconnects for 3D Integration
Authors: Oosterhuis Gerrit , Prenen An , Huis in't Veld A.J.
Published: May 2012

Interconnects are an important cost driver in advanced 3D chip packaging. This holds for Through Silicon Vias (TSV) for chip stacking, but also for other interconnect steps like re-distribution layers and solder bumps. Especially in applications with a low number (<100 mm-2) of relatively large features (10-100 µm diameter) with high aspect ratio (up to 1:10), conventional plating processes are slow and become cumbersome with increasing aspect ratio, thus becoming cost ineffective. Hence, industrially feasible, alternative direct-write processes are of interest for advanced interconnects. Laser Induced Forward Transfer (LIFT) is a direct write process with high potential to become a cost effective alternative for conventional patterned metallization schemes. Different process alternatives will be discussed and compared.
Design and Verification of Benzocyclobutene (BCB) Templates for Chip-to-Wafer Alignment in 3D Integration
Authors: Zhang Dingyou , Lu Jian-Qiang
Published: May 2012

We report on designs of Benzocyclobutene (BCB) templates for chip-to-wafer (C2W) alignment in 3D integration, in order to effectively reduce the wafer bow and improve the alignment accuracy and wafer-level uniformity. The BCB template enables well-controlled alignment, few thermal cycles and high throughput of 3D system fabrication. In this paper, we evaluated the changes of wafer bow during the C2W 3D fabrication processes and proposed several solutions to reduce the wafer bow, including partial etch of backside oxide, use of a thinner BCB template, use of a partial cure of BCB, or removal of the template corner. Among these options, removing BCB template corner can release the wafer level stress, while improving the alignment accuracy and BCB etch uniformity.