bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Transition of LiMn2O4Spinel and its Application for Lithium Ion Secondary Battery
Authors: Tabuchi Junji , Numata Tatsuji , Shimakawa Yuichi , Shirakata Masato 
Published: April 2011

ABSTRACTLiMn2O4has a phase transition at room temperature, which is caused by Jahn-Teller distortion. DC resistivity of LiMn2O4shows an anomaly at the transition temperature, while no such anomaly is observed in samples with excess lithium. X-ray diffraction patterns of LiMn2O4reveal that the crystal structure changes from cubic at higher temperature to orthorombic, as a first approximation, at lower temperature. However, no differences in initial charge-discharge curve are observed, which means that the Jahn-Teller distortion has no effect on electrochemical characteristics. The authors have succeeded in mass-producing lithium ion secondary batteries with a manganese spinel cathode.
Application of potentially biodegradable polyamide and polyester containing disulfide bonds to positive active materials for lithium secondary batteries
Authors: Tsutsumi H. , Okada S. , Toda K. , Onimura K. , Oishi T. 
Published: April 2011

ABSTRACTPotentially biodegradable polyamide (poly(imino-3, 3'-dithiodipropionylimmo-2, 2'-dithiodiethyl), -(NHCOCH2CH2-S-S-CH2CH2CO-NHCH2CH2-S-S-CH2CH2)n-, PIDI) and polyester (crosslinked poly(oxy-3, 3'-dithiodipropionyloxymethylene-l,4-phenylenemethylene,-(ICOCH2CH2-S-S-CH2CH2COO-CH2-C6H5-CH2)n-c-PODOM)) were prepared by interfacial polymerization between 3,3'-dithiodipropionic acid and cystamine, or 1, 4-benzenedimethanol. PIDI and c-PODOM showed the electrochemical responses based on reduction of the disulfide bonds in the polymer chains and re-oxidation of the produced thiolate anions. Degradation of PIDI and PODOM was investigated in various pH buffer solution. The apparent rate constant of c-PODOM at 25 °C was 1.3 × 103% day−1at pH 7 and that of PIDI at 37 °C was 3.5 × 103% day−1at pH 7. Estimated period for 90 % degradation of the polymers at pH 7 is about 1800 days (c-PODOM, 25 °C) and 630 days (PIDI, 37 °C).
Preparation and Battery Applications of Micron Sized Li4Ti5O2
Authors: Peramunage D. , Abraham K. M. 
Published: April 2011

ABSTRACTThe objective of this study was to highlight the usefulness of micron-sized Li4Ti5O12 in three distinctive areas: a) cathode of a low-voltage Li battery, b) insertion type auxiliary electrode to investigate the electrochemistry of oxide cathode materials, and c) anode of a Li-ion cell in conjunction with LiMn2O4 cubic spinel cathode. Li cells with Li4Ti5O12 exhibited an open circuit voltage of ∼1.6V, >90% utilization (in terms of the theoretical capacity) at ∼C/10 rate, ∼40% utilization 5C rate, and extended full-depth charge/discharge cycling at ≥ 1C rates with virtually no capacity fade. LiMn2O4 cathodes, evaluated in Li(4+xTi5O12 (x = ∼1.2)/LiMn2O4 cells, exhibited extended full-depth cycling capability with a small capacity fade rate of <0.1% which appeared to slow down with cycling. At a 1C discharge rate, over 190 cycles were demonstrated corresponding to an end utilization of ∼90 mAh/g or ∼0.6 mole Li per LiMn204. Balanced Li4Ti5O12//solid polymer electrolyte//LiMn2O4 full cells of slightly cathode-limited configuration had an open-circuit voltage of ∼3.0V and a mid-discharge voltage of ∼2.5V showing full-depth extended cycling capability at a utilization of ∼90 mAh/g or ∼0.6 mole Li per LiMn204 at the 1C and ∼0.45 mole Li per LiMn2O4 at the 7.5C discharge rate.
Structural Phase Transformations in V2O5 Thin Film Cathode Material for Li Rechargeable Batteries
Authors: McGraw J. M. , Perkins J. D. , Zhang J.-G. , Parilla P. A. , Ciszek T. F. , Fu M. L. , Trickett D. M. , Turner J. A. , Ginley D. S. 
Published: April 2011

ABSTRACTWe report on investigations of V2O5 thin film cathodes prepared by pulsed laser deposition and the phase transformations which occur during electrochemical cycling. Our experimental results on PLD-grown, textured V2O5 crystalline films concur with reports in the literature that there is a voltage threshold above which, cycling appears to be completely reversible and below which, cycling appears to be irreversible. Crystalline films discharged beyond the threshold to 2.0 V vs. Li exhibited an immediate and continuous fade in capacity as well as a ∼90% decrease in XRD peak intensity and a similar decrease in Raman signal intensity in as few as 10 cycles. We have made co-phase material by both electrochemically discharging virgin, crystalline V2O5 and by further discharging previously cycled films which showed irreversible structural changes.
Effects of Aluminum Doping on The Phase Stability and Electrochemical Properties of LiCoO2 and LiMnO2
Authors: Jang Y.-I. , Huang B. , Wang H. , Chiang Y.-M. , Sadoway D. R. 
Published: April 2011

ABSTRACTAluminum is of interest as a constituent for Li battery electrodes due to its low cost and low mass, and because ab initio calculations indicate that solid solution of LiAlO2 with LiMO2 (M = transition metal) in the α-NaFeO2 structure can increase intercalation voltage [1]. In this study, we investigated the effect of Al doping on LiCoO2 and LiMnO2. Single phase LiAlyCo1-yO2 has been synthesized up to y = 0.5 by firing homogenous hydroxide precursors. A systematic increase in the open circuit voltage is observed with Al content. In LiAlyMn1-yO2, the addition of LiAlO2 stabilizes LiMnO2 in the α-NaFeO2 structure under conditions where neither endmember is stable in the structure. High reversible capacity was obtained over both a 4 V and 3 V plateau, indicating that the compound transforms to a spinel-related structure during cycling, but that the cooperative Jahn-Teller distortion is suppressed.
Effect of HF in LiPF6 Based Electrolytes on the Properties of Surface Passivation Films Formed on Graphite Electrodes in Li Secondary Batteries
Authors: Sato T. , Deschamps M. , Suzuki H. , Ota H. , Asahina H. , Mori S. 
Published: April 2011

ABSTRACTThe effect of hydrofluoric acid (HF) concentration in conventional LiPF6/EC+DEC electrolyte on the properties of solid electrolyte interphase (SEI) films formed on synthetic graphite electrode and the electrochemical performance were studied using x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), elemental analysis and electrochemical measurement. The morphology and composition of SEI are affected by a small amount of HF in the electrolyte. Higher F content in the SEI was observed when high HF electrolyte were used, although the irreversible capacities used for formation of SEI were nearly the same value. The cycleability of the synthetic graphite electrode was greatly improved when surface film contains larger amount of LiF.
Growth and Electrochemical Characterization of Single Phase MoxN Films for the Fabrication of Hybrid Double Layer Capacitors
Authors: Roberson S. L. , Evans D. , Finello D. , Davis R. F. 
Published: April 2011

ABSTRACTThe electrochemical stability and capacitance in H2SO4, KOH, and propylene carbonate of single phase polycrystalline γ-Mo2N and δMoN thin film electrodes deposited at 350 and 700° C, respectively, at a rate of 0.5 μm/min on Ti substrates have been determined. The films were prepared by chemical vapor deposition at 100 torr using Mo(CO)6 and NH3 flowing at 1.5 standard liters per minute (slm). Cyclic voltammetry referenced to a standard Ag/AgCl electrode indicated that both phases possessed a more positive voltage stability limit in H2SO4 than KOH. Films of γ-Mo2N had voltage stability ranges of -0.3 to 0.6 V and -1.3 to - 0.3 V in 4.4 M H2SO4 and 7.6 M KOH, respectively. Films of δ-MoN possessed voltage stability ranges of -0.3 to 0.7 V and -1.3 to -0.3 V in the same respective electrolytes. Both phases had a voltage stability of approximately one volt in the propylene carbonate electrolyte. These results were used to design and fabricate a hybrid capacitor composed of a Ta/Ta2O5 anode and a δ-MoN cathode contained in an electrolyte of 4.4M H2SO4. The hybrid device had an operating voltage range between 0 and 50 V, a temperature range of -55 to + 90°C, a capacitance of ≈ 5.0 mF and an energy density of ≈ 1.32 J/cm3. This device is now in pre-production at Evans Capacitor Corporation.
Anodic Oxidation of Nitrogen-Added Al-Based Alloys for Thin-Film Transistors
Authors: Arai Toshiaki , Iiyori Hideo 
Published: April 2011

ABSTRACTNovel anodized films of nitrogen-added aluminum-based alloys were proposed for use in the fabrication of gate insulators for thin-film transistors, and the effect of nitrogen addition on the anodized aluminum-based alloys was investigated. Gadolinium and neodymium were employed as alternative alloy components. The film thickness, the dielectric constant, and the roughness average of the anodized films decreased as the nitrogen content increased, and the nitrogen content was required to be lower than 20 at.%. The most improved values of the breakdown electric fields of anodized aluminum-gadolinium and aluminum-neodymium alloy were 10.1 MV/cm with 6.0 at.% nitrogen content and 9.9 MV/cm with 4.0 at.% nitrogen content, respectively. The leakage currents of the anodized films under a negative bias, which could not be suppressed by high-temperature annealing, were adequately suppressed by nitrogen addition, especially in anodized aluminum-gadolinium alloy. The current leakage of the anodized aluminum-gadolinium alloy with 6.0 at.% nitrogen content became -8E-13 A at -10 V and 150°C. This value is nearly equal to that of chemical-vapor-deposited (CVD) films.
Computer Simulation of ZnO Varistors Failures
Authors: Bartkowiak M. , Mahan G. D. , Comber M. G. , Alim M. A. 
Published: April 2011

ABSTRACTA simple thermo-mechanical model is applied to evaluate the influence of the nonuni-formity of ZnO varistor disks used in surge arresters on their energy handling capability. By solving heat transfer equations for a varistor disk with nonuniform electrical properties, we compute the time dependence of the temperature profile and the distribution of thermal stresses. The model can identify the energy handling limitations of ZnO varistors imposed by three different failure modes: puncture, thermal runaway, and cracking. It conforms to the available failure data, and explains the observation that energy handling improves at high current densities.
A Novel Approach to Semiconductor Electrical Properties - The Advanced Method of Transient Microwave Photoconductivity (AMTMP)
Authors: Grabtchak S. , Cocivera M. 
Published: April 2011

ABSTRACTThe advanced method of transient microwave photoconductivity (AMTMP) represents a new method based on cavity perturbation theory, microwave photoconductivity and harmonic oscillator model analysis. AMTMP provides a direct observation of changes to the complex dielectric constant, and free and trapped electron decays can be studied separately. The results obtained for polycrystalline CdSe thin films clearly indicate that a multiple trapping model developed for amorphous materials does not provide a satisfactory description. For SI GaAs the harmonic oscillator model provides a quantitative interpretation. The limitations are discussed for the application of this method to porous Si.
Evaluation of Gap States in Hydrogen-Terminated Silicon Surfaces and Ultrathin SiO2/Si Interfaces by using Photoelectron Yield Spectroscopy
Authors: Miyazaki S. , Tamura T. , Maruyama T. , Murakami H. , Kohno A. , Hirose M. 
Published: April 2011

ABSTRACTThe energy distributions of gap state densities for H-terminated Si surfaces and thermally-grown SiO2/c-Si interfaces have been evaluated by total photoelectron yield spectroscopy (PYS) with a dynamic range of eight orders of magnitude which is sufficient to detect the density of states as low as 1010cm−2eV−1. It is confirmed from the threshold energies for direct and indirect photo-excitations that, for monohydride-terminated Si(111) surfaces prepared by an NH4F treatment, no significant band-bending is observable. For H-terminated n-type sample, the gap state densities of the order of 1011cm−2eV−1 were estimated in the region within 0.4 eV from the valence band edge, which may be attributable to a very little oxidation in the sample preparation. It is also found that, for as-grown 2.5nm-thick SiO2/n+ Si, there exist interface states around midgap with densities as high as ∼1012cm−2eV−1.
The Influence of Ionic Activity on the Electrical Properties of PECVD (TEOS) Silicon Dioxide
Authors: Romanelli Cardoso A. , Pereira Da Silva M. L. , Santiago-Aviles J. J. 
Published: April 2011

ABSTRACTA Plasma enhanced CVD system was modified to place a potential screen between a plasma and a silicon wafer. Silicon dioxide from an organometallic precursor (TEOS) was deposited onto silicon wafers. In this way, any alteration of the screen potential resulted in a modified ion speed, or the removal of the ion flux incident on the wafer. The oxides films produced in this manner were analyzed by Raman spectroscopy, and both C-V and I-V techniques. The characterization results suggest an important role for Oxygen ion bombardment on the TEOS oxidation process, such as the removal of carbon compounds from the film as TEOS oxidizes. We have evidence that ion bombardment decreases the dielectric constant and increases the hysteresis of the SiOx films. A qualitative model to explain the experimental results was developed.
Silicon Rapid Thermal Processing with Ripple Pyrometry
Authors: Fiory A. T. 
Published: April 2011

ABSTRACTThermal processing in silicon integrated circuit fabrication steps for dopant activation, metal silicides, annealing, and oxidation commonly uses single-wafer furnaces that rapidly heat wafers with incandescent infrared lamps. Radiation pyrometers and thermocouple probes are the principle methods of measuring wafer temperature for closed-loop control of rapid thermal processes. The challenge with thermocouples is in dealing with heat from the lamps and non-ideal thermally resistive wafer contact. The challenge with pyrometry is in compensating for the variable emissivity of wafer surfaces and suppressing interference from the lamps. Typical deposited or grown layers of silicon nitride, silicon dioxide, and polycrystalline silicon can produce dramatic changes in emissivity. Layer thicknesses and composition are generally not known with sufficient accuracy, so a method for real time in situ emissivity compensation is required. Accufiber introduced a “ripple technique” to address this issue. The idea is to use two probes, separately sensing radiation from the wafer and the lamps, and extracting AC and quasi-DC parts from each. The AC signals provide a measure of the reflectivity of the wafer, and thence emissivity, as well as the fraction of reflected lamp radiation present in the DC signals. Lucent Technologies introduced a method of using AC lamp ripple to measure wafer temperatures with two radiation probes at a wall in the furnace. One probe views radiation emanating from the wafer through a gap in the lamp array. The other probe has a wide field of view to include lamp radiation. The accuracy of Lucent devices, determined from process results on wafers with various emissivities, is typically in the range of 12°C to 18°C at three standard deviations.
Monitoring and Control in Vapor phase Epitaxy
Authors: Pearsall T. P. 
Published: April 2011

ABSTRACTMonitoring and control in epitaxy based on chemical vapor deposition is a challenge created by growth conditions that often preclude more common sensors like thermocouples and mass spectrometry. We report results of experiments to measure and control temperature and flux by non-invasive optical sensing. We have developed a temperature control system with precision and accuracy better that 5°C. Satisfactory control of flux poses difficulties that will require innovative solutions before a useful control system can be developed.
Polycapillary Optics for in Situ Diagnostics
Authors: Hofmann F. A. , Gao N. , Owens S. M. , Gibson W. M. , Macdonald C. A. , Lee S. M. 
Published: April 2011

ABSTRACTPolycapillary optics, shaped arrays consisting of hundreds of thousands of hollow glass capillary tubes, are used to redirect, collimate, or focus x-ray beams from conventional laboratory-based sources. Focused spot sizes as small as 20μm have been measured, with flux densities two orders of magnitude larger than that produced by pinhole or crossed slit collimation. Such flux increases have made possible faster and more sensitive x-ray fluorescence (XRF) and diffraction measurements to the extent that in situ measurements become possible. XRF data taken with a 12 W source were comparable to data taken with a 1.5 kW source. Ex situ diffraction and texture measurements on thin multilayered films and single crystal silicon demonstrate the tremendous experimental and analytical improvements made possible by polycapillary optics.With 0.5° and 2° focusing polycapillary x-ray optics, diffraction intensity gains of more than two orders of magnitude were measured on small Lysozyme protein crystals with exposure times an order of magnitude less than required by traditional measurement techniquesIn addition, the optics greatly reduce the background high energy Bremsstrahlung, permitting more accurate analysis of thin complex multilayer diffraction peaks. Rapid measurement times resulting from the application of these polycapillary optics, indicate tremendous possibilities for in situ process monitoring
In-Situ Fourier Transform Infrared Spectroscopy for Real-Time Diagnostics of Thin Film Processes
Authors: Solomon P. R. , Charpenay S. , Zhang W. , Bonanno A. S. , Rosenthal P. A. , Cosgrove J. E. , Kinsella K. K , Kung P. J. 
Published: April 2011

ABSTRACTInfrared spectroscopy is a versatile tool that is well adapted to in-situ diagnostics of many thin film properties and processes. In this paper, we will describe the application of infrared instrumentation for real-time in-situ measurements of film temperature, emissivity, thickness, free carriers, and optical constants using model based spectral analysis. We will illustrate the use of Fourier transform infrared (FT-IR) emission and reflection spectroscopy to monitor the fabrication of stacks of ferroelectric and conductive oxides on silicon substrates during pulsed laser deposition. The ability to measure the infrared optical constants of dielectrics such as silicon dioxide, including the detailed spectral dependence of the vibrational absorption bands at high temperatures, will be presented. The suitability of the technique for real-time sensing during rapid thermal processing will be illustrated using the example of carrier activation during a shallow-junction rapid thermal anneal.
Microanalysis of Soot Particulates using Stem
Authors: Bell David C. , Rainey Lenore C. , Palotás ÁrpÁd B. , Vandersande John B. 
Published: April 2011

ABSTRACTScanning transmission electron microscopy (STEM) coupled with energy dispersive x-ray analysis (EDX) and electron energy-loss spectroscopy (EELS) has been used to characterize the elemental composition and oxidation conditions of various soot samples. The STEM employed in this investigation was the Vacuum Generators HB603, with a microanalytical resolution approaching 1 rnm, that allowed the analysis of individual soot particles and aggregates. The aim of this research is quantification of the EDX spectra which is possible after background and absorption corrections. This information can then be used for comparative studies of different fuels and combustion processes. EELS has been employed to determine the amount of graphitic carbon in a soot particulate, and the detection of trace elements of low atomic number. It has been shown in soot that for Carbon the energy-loss of the p shell electrons increases with the amount of oxidation at high temperatures. Analysis and characterization of gas turbine soot, collected from an engine exhaust duct of a 737-300 aircraft showed an abundance of different elements. Some of these elements originated from the fuel and combustion processes, while other elements were components of the engine itself that combined with the soot particulates during the combustion process. The study showed that soot impurities were found in all discrete sections of aggregates, and that only one or two small soot particulates were necessary to obtain a chemical fingerprint. Other investigations include; coal soot, diesel soot at different engine operating conditions and soot produced from wood burning. The richness of the spectra obtained and the ability to quantify results represents an opportunity to accomplish source identification in a novel, powerful way.
SPA Monitoring of GaN Movpe Surface
Authors: Kobayashi Naoki , Kobayashi Yasuyuki 
Published: April 2011

ABSTRACTFor the purpose of clarifying the growth mechanism of GaN metal-organic vapor phase epitaxy (MOVPE), the GaN surface during the growth on the (0001) sapphire substrate were in-situ monitored by surface photo-absorption (SPA) method. Ga-rich and N-rich surfaces can be distinguished by their reflectivities. It is found that the surface stoichiometry changes with the substrate temperature and with the carrier gas. In the nitrogen carrier gas, a N-rich GaN surface is stably formed at temperatures up to about 1000°C under NH3 flow. In contrast, the surface in H2 carrier gas is N-rich below 720°C, but becomes Ga-rich above 850°C. The desorption kinetics indicates that H2 enhances the N desorption.
Indentation Creep Analysis of Amorphous Nitrogen-Containing Carbon Films
Authors: Tanaka Daisuke , Ohshio Shigeo , Saitoh Hidetoshi 
Published: April 2011

ABSTRACTAn indentation creep analysis has been performed to investigate micro-mechanical properties of amorphous nitrogen-containing carbon films. Using results of the slope of the time-displacement relation of creep procedure, the strain rate sensitivity exponent m is obtained. The m value of 0.004 was obtained for diamond-like carbon film without nitrogen. In contrast, those were found to be in the range between 0.009 and 0.101 for nitrogen-containing carbon films. These slightly increased with increasing the nitrogen content of the films. We present results that indicate that the nano-indentation creep technique enables clarification of the nano-structure of nitrogen-containing carbon films.
Stress-Strain Curves by Tensile Testing of Thin Metallic Films On Thin Polyimide Foils: Al, AlCu, CuNi(Mn)
Authors: Macionczyk F. , Brückner W. , Reiss G. 
Published: April 2011

ABSTRACTFor better understanding the mechanical properties of thin films it is helpful to use the same experimental methods as for bulk material, like tensile tests, thereby being able to directly compare the results. However, tensile tests of free-standing metallic thin films are often difficult to perform for reasons of preparation, handling, and stresses in the films. By leaving the metallic film on an elastic substrate tensile tests were performed in a rather simple and precise manner, using a commercial tensile testing machine. Stress-strain curves were determined by separating the force working on the substrate from that working on the film-substrate compound. Those measurements were done at room temperature for Al, AlCu(0. 5 wt %) and Cuo0.57Ni0.42Mn0.01 thin (200–2000 nm) films prepared by magnetron sputtering on 8 μm and 13 μm thick polyimide (Kapton) foils. The film microstructure was characterized by scanning and transmission electron microscopy and X-ray diffraction. The tensile strength of the fine grained films was found to be up to one order of magnitude higher than for the corresponding coarse grained bulk material. Al and AlCu films showed little, CuNi(Mn) films showed no plastical behavior. Crack formation started between 0.3 % and 2 % strain depending on the material, the thermal history, and the grain size.