bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi-Stacked Flip Chips with Copper Plated Through Silicon Vias and Re-distribution for 3D System-in-Package Integration
Authors: Lee Shi-Wei Ricky , Hon Ronald 
Published: April 2011

ABSTRACTThe study is a prototype design and fabrication of multi-stacked flip chip three dimensional packaging (3DP) with TSVs for interconnection. Three chips are stacked together to make a 3DP with solder bumped flip chips. TSVs are fabricated and distributed along the periphery of the middle chip. The TSVs are formed by dry etching, deep reactive ions etching (DRIE), with dimensions of 150 × 100 microns. The TSVs are plugged by copper plating. The filled TSVs are connected to the solder pads by extended pad patterns surrounding the top and the bottom of TSVs on both sides of the wafer for the middle chip. After pad patterning passivation and solder bumping, the wafer is sawed into chips for subsequent 3D stacked die assembly. Because the TSVs are located at the periphery of the middle chips and stretch across the saw street between adjacent chips, they will be sawed through their center to form two open TSVs (with half of the original size) for electrical interconnection between the front side and the back side of the middle chip. The top chip is made by the conventional solder bumped flip chip processes and the bottom chip is a carrier with some routing patterns. The three middle chips and top chip are stacked by a flip chip bonder and the solder balls are reflowed to form the 3DP structure. Lead-free soldering and wafer thinning are also implemented in this prototype. In addition to the conceptual design, all wafer level fabrication processes are described and the subsequent die stacking assembly is also presented.
Through-Silicon-Via Copper Deposition for Vertical Chip Integration
Authors: Kim Bioh 
Published: April 2011

ABSTRACTConsumers are demanding smaller, lighter electronic devices with higher performance and more features. The continuous pressure to reduce size, weight, and cost, while increasing the functionality of portable products, has created innovative, cost-effective 3D packaging concepts. Among all kinds of 3D packaging techniques, through-silicon-via (TSV) electrodes can provide vertical connections that are the shortest and most plentiful with several benefits (1). Connection lengths can be as short as the thickness of a chip. High density, high aspect ratio connections are available. TSV interconnections also overcome the RC delays and reduce power consumption by bringing out-of-plane logic blocks much closer electrically.The technologies engaged with TSV chip connection include TSV formation, insulator/barrier/seed deposition, via filling, surface copper removal, wafer thinning, bonding/stacking, inspection, test, etc. Process robustness and speed of copper deposition are among the most important technologies to realize TSV chip integration. There are generally three types of via filling processes; lining along the sidewall of vias, full filling within vias, and full filling with stud formation above the via. Here, the stud works as a mini-bump for solder bonding. Two methodologies have been generally adopted for via filling process; (a) via-first approach : blind-via filling with 3-dimensional seed layer, followed by wafer thinning and (b) thinning-first approach : through-via filling with 2-dimensional seed layer at the wafer bottom after wafer thinning. Currently, the first approach is more popular than the second approach due to difficulty in handling and plating thinned wafers (2).We examined the impact of varying deposition conditions on the overall filling capability within high aspect ratio, deep, blind vias. We tested the impacts of seed layer conformality, surface wettablity, bath composition (organic and inorganic components), waveform (direct current, pulse current, and pulse reverse current), current density, flow conditions, etc. Most deposition conditions affected the filling capability and profile to some extent. We found that reducing current crowding at the via mouth and mass transfer limitation at the via bottom is critical in achieving a super-conformal filling profile. This condition can be only achieved with a proper combination of aforementioned process conditions. With optimized conditions, we can repeatedly achieve void-free, bottom-up filling with various via sizes (5-40μm in width and 25-150μm in depth).
Research on Computer Optimization of Low-Cost Hydrogen Storage Alloy Containing Boron Prepared by Strip Casting and its Microstructure and Performance
Authors: Guo Hong , Weiping Han , Ximin Zhang , Likai Shi 
Published: April 2011

ABSTRACTA kind of low-cost hydrogen storage alloy containing B has been prepared by near rapid solidification strip casting. And computer optimization has been carried out with MASTER software through mode identification and neuro-network. The alloy microstructure, the alloy performance and the battery performance have been evaluated through optical microscope, TEM and X-ray diffraction. The results indicate that the alloy microstructure is fine columnar crystal and there exists the second phase of CeCo4B on the crystal interface, which increases the diffusion channels for hydrogen atoms and improves the alloy activation. The MmNi3.9Co0.37Mn0.4Al0.3B alloy has excellent performance at room, high and low temperatures prepared by strip casting.
Role of Annealing for Improving Hydrogen Storage Properties of Ti-Cr-V Alloy
Authors: Munekata Yasuhiro , Washio Kota , Suda Takanori , Hashimoto Naoyuki , Ohnuki Somei , Arashima Hironobu , Ito Hideaki 
Published: April 2011

ABSTRACTOne of impotent materials issues of Ti-Cr-V based hydrogen storage alloys is to improve cyclic degradation of storage capacity, which has been assumed to be the effect of internal stress. We focused on the sub-micron structure of this material, which can be accumulated during cyclic use. We used 24Ti-36Cr-40V alloy for the specimens, after FZ melting. Powered samples were fabricated by mechanical grinding under Ar environment. Vacuum annealing was carried out for reducing residual stress and lattice defects. PCT properties were tested at 293 K under 4.5 MPa. XRD and TEM were carried out for important samples. In the first cycle, the annealing resulted in the increasing of storage capacity, but in the second cycle the improving was disappeared. Comparing microstructures with and without annealing, complex dislocation structures were observed after cyclic hydrogenation. It is notable that dislocation free structure was some time observed in the fine grains of less than 0.1 micron, which suggests the possibility of fine structure without defect accumulation.
Proton Diffusion in Hydrated Acceptor-Doped Barium Zirconate
Authors: Wilmer Dirk , Seydel Tilo , Kreuer Klaus-Dieter 
Published: April 2011

AbstractQuasielastic neutron scattering experiments have been performed on proton-conducting hydrated Y-doped BaZrO3at temperatures between 473 K and 673 K. Quasielastic broadening is observed at all temperatures, but only at the higher ones the scattering exhibits the characteristics of the proton transport process. Attempts to interpret our data in the framework of the two-state model yield unconvincing results. A simpler approach using the isotropic Chudley-Elliott model yields reasonable values for the proton self-diffusivities but also unusually high values for the jump distance which are close to the mean distance between dopants.
Cell Performance Stability of HMFC using Ba(Ce1-xZrx)0.8Y0.2O3 Perovskite Type Proton Conductor as Electrolyte
Authors: Iijima Masahiko , Ito Naoki , Matsumoto Shinichi , Iguchi Satoshi 
Published: April 2011

AbstractWe have developed a new type of FC which shows high performance at intermediate temperatures to solve the disadvantage of using hydrocarbon as fuel to FC system. This new FC is an ultra-thin proton conductor electrolyte supported by a metal hydrogen membrane. We have named itHydrogenMembraneFuelCellThe HMFC using BaCe0.8Y0.2O3 (BCY) as the electrolyte and pure Palladium as the substrate exhibits a high cell performance of 2.7 A/cm2 @0.5V, 873K and 1.8 A/cm2 @0.5V, 673K. But the BCY cell performance drops rapidly during several hours. It was inferred that this phenomenon is caused by BCY electrolyte dissolved by hydrothermal reaction with H2O vapor which was generated by the fuel cell reaction.We studied the possibility as HMFC electrolyte of Ba(Ce0.5Zr0.5)0.8YO3 (BCZY) and BaZr0.8Y0.2O3 (BZY) which are exchanged the B site of BCY perovskite ceramic from Ce to Zr to improve the resistance against the hydrothermal dissolution. BCZY and BZY confirmed the resistance against the hydrothermal dissolution improved compared with BCY by analyzing after the hydrothermal treatment. The BCZY cell shows the same level of the performance as the BCY cell and the performance stability has improved over the BCY cell.
Mixed-Conducting Membranes for Hydrogen Production and Separation
Authors: Balachandran U. , Ma Beihai , Lee Tae H , Song Sun-Ju , Chen Ling , Dorris Stephen E 
Published: April 2011

AbstractMixed-conducting oxides, possessing both ionic and electronic charge carriers, have found wide application in recent years in solid-state electrochemical devices that operate at high temperatures, e.g., solid-oxide fuel cells, batteries, and sensors. These materials also hold promise as dense ceramic membranes that separate gases such as oxygen and hydrogen from mixed-gas streams. We are developing Sr-Fe-Co oxide (SFC) as a membrane that selectively transports oxygen during partial oxidation of methane to syngas (mixture of CO and H2) because of SFC's high combined electronic and ionic conductivities. We have evaluated extruded tubes of SFC for conversion of methane to syngas in a reactor that was operated at ≈900°C. Methane conversion efficiencies were >90%, and some of the reactor tubes were operated for >1000 h. We are also developing dense proton-conducting oxides to separate pure hydrogen from product streams that are generated during methane reforming and coal gasification. Hydrogen selectivity in these membranes is nearly 100%, because they are free of interconnected porosity. Although most studies of hydrogen separation membranes have focused on proton-conducting oxides by themselves, we have developed cermet (i.e., ceramic-metal composite) membranes in which metal powder is mixed with these oxides in order to increase their hydrogen permeability. Using several feed gas mixtures, we measured the nongalvanic hydrogen permeation rate, or flux, for the cermet membranes in the temperature range of 500-900°C. This rate varied linearly with the inverse of membrane thickness. The highest rate, ≈32 cm3(STP)/min-cm2, was measured at 900°C for an ≈15-μm-thick membrane on a porous support structure when 100% H2 at ambient pressure was used as the feed gas.
Synthesis and Densification of Nanometric Ce0.8Sm0.2O1.9-δ
Authors: Esposito Vincenzo , Fronzi Marco , Traversa Enrico 
Published: April 2011

AbstractNanometric 20% molar Sm-doped ceria (SDC20) powders were synthesized by tetrametylethylen ammine (TMDA) co-precipitation method. SDC20 was sintered in several conditions to control the final microstructure. Fast firing and conventional sintering were performed. LiNO3was used as an additive to promote liquid phase sintering of ceria at low temperatures (900-1200°C). Powders and dense pellets were analysed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) measurements were performed on dense pellets in air to estimate the contribution of grain boundary and bulk to the electrical conductivity. Liquid phase sintering produced the densest samples with the highest conductivity.
Design of Anodes for IT SOFC: Effect of Complex Oxide Promoters and Pd on Activity and Stability in Methane Steam Reforming of Ni/YSZ (ScSZ) Cermets
Authors: Sadykov Vladislav A , Mezentseva Natalia V , Bunina Rimma v , Alikina Galina M , Lukashevich Anton I , Rogov Vladimir A , Moroz Ella M , Zaikovskii Vladimir I , Ishchenko Arcady , Bobrenok Oleg F , Smirnova Alevtina , Irvine John , Vasylyev Oleksandr 
Published: April 2011

AbstractEffect of fluorite-like or perovskite-like complex oxide promoters and Pd on the performance of Ni/YSZ and Ni/ScSZ cermets in methane steam reforming or selective oxidation by O2 into syngas at short contact times was studied. Spatial uniformity of dopants distribution in composites was controlled by TEM combined with EDX, while the lattice oxygen mobility and reactivity was elucidated by CH4 and H2 TPR. Oxide promoters allow to operate even at stoichiometric H2O/CH4 ratio by suppressing coke deposition through modification of Ni surface, while doping by Pd ensures reasonable performance at moderate (∼550 °C) temperatures required for Intermediate–Temperature Solid Oxide Fuel Cells (IT SOFC).
Sintering Behavior and Phase Characterisation of Composite Perovskite/Fluorite Ceramics for Intermediate Temperature SOFCs and Oxygen Separation Membranes
Authors: Tangtrakam Natee , Swanson Matthew , Moran Peter , Kuebler Jakob , Kapat Jayanta , Orlovskaya Nina 
Published: April 2011

AbstractThe sintering behavior and structural changes of fluorite Gd0.2Ce0.8O2-δ(GDC) with one of three perovskites: LaMnO3 (LMO), (La0.7Sr0.3)0.98MnO3 (LSM) and La0.6Sr0.4Fe0.8Co0.2O3 (LSFC) composite ceramics were studied. Sintering was carried out for two hours at five different temperatures: 1100°C, 1200°C, 1300°C, 1400°C, and 1500°C. The highest sinterability has been found in LSFC + GDC. LSM + GDC appear to undergo two-step sintering mechanisms. Of all types of ceramics, only sintered LMO experiences a phase change, from rhombohedral R C to orthorhombic Pnma structure, with respect to its powder phase at sintering temperatures ≥1200 °C. The transition is notably suppressed when LMO is part of an LMO + GDC composite. GDC in a fluorite and/perovskite composite, when sintered, undergoes a temperature-dependent expansion in its unit cell that is not observed in pure GDC ceramics. This structural change will impact the function of composite ceramics as a fuel cell cathode, or oxygen separation membranes.
Electrochemical Properties of Nanocrystalline Y2-xPrxRu2O7 Pyrochlore for Electrodic Application in IT-SOFCS
Authors: Abate Chiara , Duncan Keith , Traversa Enrico , Wachsman Eric 
Published: April 2011

AbstractNanocrystalline powders of Y2-xPrxRu2O7 were prepared by a co-precipitation method, and were tested as electrode on ESB and GDC electrolytes by electrochemical impedance spectroscopy in the 300-750°C temperatures range. The electrode polarization was studied as a function of the amount of praseodymium in the cathode material. Both systems, Y2-xPrxRu2O7/ESB and Y2-xPrxRu2O7/GDC, showed a similar variation of the electrode area specific resistance (ASR). Y1.5Pr0.5Ru2O7 cathode material presented the best performance, with ASR value of 0.19 Ωcm2 on ESB and 4.23 Ωcm2 on GDC at 700°C. Furthermore, the change in ASR with the oxygen partial pressure suggested that the rate limiting step is the surface diffusion of the adsorbed oxygen at the electrode surface to the triple-phase boundary. Thus, the low value of resistivity of the Y1.5Pr0.5Ru2O7 in contact with ESB results from a much lower charge transfer resistance compared to the Y2-xPrxRu2O7/GDC system, and a partial solid diffusion at the interface electrode/electrolyte that increases the effective triple phase boundary length. This suggests that Y2-xPrxRu2O7 is a promising material for cathode application in ESB-based electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs).
Ab Initio Study of Oxygen-Vacancy Ordering in Oxygen Conducting Ba2In2O5
Authors: Lee Yueh-Lin , Morgan Dane 
Published: April 2011

AbstractThe thermodynamic properties of Ba2In2O5 are studied using Monte Carlo simulation of an ab initio based cluster expansion. The simulations predict a first-order orthorhombic to tetragonal phase transition, followed by a second-order tetragonal to cubic phase transition, which is in good agreement with experiments. It is predicted that the orthorhombic to tetragonal transition is associated with major disordering in the O(3) plane as well as some introduction of vacancies in the O(2) plane.
Nanosized Amorphous Materials as Anodes for Lithium Batteries
Authors: Fan Quan , Whittingham M. Stanley 
Published: April 2011

AbstractThe carbon anode presently used in commercial lithium ion batteries has a relatively low capacity and may pose safety problems particularly under fast charging. Nanosized amorphous materials have excellent electrochemical behavior when applied as anodes for lithium ion batteries; especially they have advantages over bulk materials on capacity retention and rate capability. The initial studies on some amorphous compounds are promising. A commercialized tin-cobalt-carbon amorphous material, which is composed of ∼5nm nanoparticles, shows a capacity retention of >350 mAh/g for 50+ cycles. Manganese oxide nanofibers were synthesized by polymer templated electrospinning followed by calcinations. The fibers have 200-500 nm diameter and the main composition is Mn3O4. The capacity remains 400 mAh/g for at least 50 cycles.
Room-Temperature Synthesis and Electrical Properties of La, Nd and Gd Apatite-type Silicates
Authors: Fuentes Antonio F. , Martinez-Gonzalez Luis G. , Moreno Karla J. , Rodriguez-Reyna Evelyn , Amador Ulises 
Published: April 2011

AbstractWe show in this paper the possibility of using mechanical milling to prepare apatite-type La, Nd and Gd silicates starting from stoichiometric mixtures of the constituent oxides. XRD patterns collected after grinding the starting mixtures for 9 hours contain only the characteristic reflections of the target materials with no other phase apparently present. Electrical conductivity data were successfully fitted to a Jonscher-type empirical expression with fractional exponent n included in the 0.35-0.75 range. Activation energies for oxygen migration were found to decrease as the size of the rare-earth cation increases. Therefore, the highest conductivity values were found for the apatite-type lanthanum silicate.
Characterization of the Carbon-Coating of LiFePO4 by Transmission Electron Microscopy and Raman Spectroscopy
Authors: Massot Michel , Zaghib Karim , Mauger Alain , Gendron François , Julien Christian M 
Published: April 2011

AbstractWe present the properties of the carbon layer deposited at the surface of the LiFePO4 particles. Characterizations include scanning electron microscopy, high-resolution transmission electron microscopy, and Raman scattering spectroscopy. Analuysis of Raman spectra reveals that the carbon deposit is hydrogenated with very small hydrogen/carbon ratio, so that it belongs to the family of the amorphous graphitic carbon. It is expected to have the same properties (small hardness, high electronic conductivity) that favor both the Li diffusion from the LiFePO4 bulk and the charge-discharge rate of the cell.
Perspectives on an Advanced Hydrogen Storage System: Platinum-Carbon Nanotube Nanocomposite Materials
Authors: Zacharia Renju , Rather Sami-ullah , Hwang Sang Woon , Manuel Stephan Arul , Nahm Kee Suk 
Published: April 2011

ABSTRACTTransition-metal functionalized-carbon nanotubes (CNTs) represent an important genre of hydrogen storage systems that exhibit superior storage capacity and improved storage kinetics when compared with the pristine CNTs. Here, we compare the reversible gravimetric hydrogen storage capacity of platinum-functionalized CNTs with that of pristine tubes, both measured at 300 K and an equilibrium hydrogen pressure of 1.67 MPa. The maximum reversible hydrogen storage capacity exhibited by the nano-composite material is found to be 3.2 ± 0.1 wt%, which is a nearly 50 % enhancement when compared with that of the pristine tubes. The enhanced hydrogen storage capacity of functionalized CNTs is attributed to the spill-over phenomena as suggested by the estimated storage capacity of Pt phase. The hydrogen storage in Pt nanoparticles modeled using the atomic magic number calculation and Pt hydride stoichiometry of PtH4 also suggests that nearly 15 closed shells of Pt atoms reversibly adsorb and spill hydrogen on to CNT binding sites.
Structural, Magnetic and Electrochemical Properties of the Spinel LiMn2-yCoyO4 Nanosized Powders
Authors: Amdouni Nourredine , Gendron François , Mauger Alain , Julien Christian M 
Published: April 2011

ABSTRACTWe present the synthesis, structure, magnetic properties and electrode behaviour of LiMn2-yCoyO4 (0≤y≤0) spinel oxides prepared by the wet-chemitry via the carboxylic acid route. LiMn2-yCoyO4 samples crystallise with the cubic spinel-like structure (Fd3m S.G.). Optical spectra indicate that the vibrational mode frequencies and relative intensities of the bands are sensitive to the covalency of the (Co,Mn)-O bonds. Magnetic susceptibility and electron spin resonance measurements show the compositional dependence of the magnetic parameters, i.e. Curie temperature, Curie-Weiss constant and Néel temperature, when Mn is substituted by Co. The overall electrochemical capacity of LiMn2-yCoyO4 oxides have been reduced due to the 3d6 metal substitution, however, a more stable charge-discharge cycling performances have been observed when electrodes are charged up to 4.3 V as compared to the performance of the native oxide.
Solid Oxide Fuel Cells in Unmanned Undersea Vehicle Applications
Authors: Carreiro Louis George , Burke A. Alan 
Published: April 2011

ABSTRACTThe Navy is currently investigating solid oxide fuel cells (SOFCs) for the propulsion of unmanned undersea vehicles (UUVs). SOFCs are being targeted because of their potential to carry out extended missions, which are not possible using current battery technology. In addition, they offer the advantages of being able to utilize energy-dense hydrocarbon fuels and are self-sustaining while supplying heat to reforming processes.The SOFC system evaluated in this study consisted of a Ni-YSZ-based, 6-cell stack with anode supported cells close-coupled with a micro-channel steam reformer. Various reformate gas compositions, steam to carbon ratios and flow rates were tested to gather a range of data under the expected operating conditions of UUVs. The system was operated for more than 70 hours consuming approximately 0.5 to 0.7 ml/min of fuel and producing about 100 to 230 watts of power. The integrated stack and reformer displayed stable performance with a fuel utilization of 80% and an efficiency of 50% at maximum power output.
Semi-Transparent Amorphous Silicon Solar Cells on Inexpensive Plastic Substrates
Authors: Matulionis Ilvydas , Hu Jian , Stavrides Alex , Call Nathan , Kunrath Augusto , Madan Arun 
Published: April 2011

ABSTRACTWe report a monolithic series connected semi-transparent (transmission > 40%) amorphous silicon (a-Si:H) solar cell panel (substrate area 30cm × 40cm), which has an i-layer thickness <2000Å and an active area efficiency, η ∼ 3%. We also report on all laser scribed, series connected mini-modules with an aperture area η > 3% constructed on inexpensive plastic substrates.
Activated Carbons for High Power Energy Storage: Below the Surface of Non-Faradaic Reactions
Authors: Barpanda Prabeer , Amatucci Glenn G 
Published: April 2011

ABSTRACTThe effect of iodine doping on the electrochemical performance of activated carbons for non-aqueous symmetric and asymmetric hybrid supercapacitors was investigated. The incorporation of iodine via high energy mechanical milling techniques significantly modified the physical and electrochemical properties of activated carbon precursors. The increasing amount of iodine into carbons leads to a unique combination of lower surface area coupled with higher volumetric and gravimetric electrochemical capacitance. Iodine modification of the carbon resulted in a 100% increase in volumetric capacitance. This improvement was a result of improved non-faradaic capacitance and the development of faradaic capacity.