2006 Physics and Advanced Technologies In the News (open access)

2006 Physics and Advanced Technologies In the News

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Date: March 28, 2007
Creator: Hazi, A. U.
Object Type: Report
System: The UNT Digital Library
3C454.3 Revelas the Structure and Physics of its 'Blazar Zone' (open access)

3C454.3 Revelas the Structure and Physics of its 'Blazar Zone'

Recent multi-wavelength observations of 3C454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the 'blazar zone', its dissipative nature, and high energy radiation mechanisms. As the optical, X-ray, and millimeter light-curves indicate, significant fraction of the jet energy must be released in the vicinity of the millimeter-photosphere, i.e. at distances where, due to the lateral expansion, the jet becomes transparent at millimeter wavelengths. We conclude that this region is located at {approx} 10 parsecs, the distance coinciding with the location of the hot dust region. This location is consistent with the high amplitude variations observed on {approx} 10 day time scale, provided the Lorentz factor of a jet is {Gamma}{sub j} {approx} 20. We argue that dissipation is driven by reconfinement shock and demonstrate that X-rays and {gamma}-rays are likely to be produced via inverse Compton scattering of near/mid IR photons emitted by the hot dust. We also infer that the largest gamma-to-synchrotron luminosity ratio ever recorded in this object - having taken place during its lowest luminosity states - can be simply due to weaker magnetic fields carried by a less powerful jet.
Date: November 28, 2007
Creator: Sikora, M.; Moderski, R. & Madejski, G.M.
Object Type: Article
System: The UNT Digital Library
ABSTRACT: The Community Environmental Monitoring Program: Reducing Public Perception of Risk Through Stakeholder Involvement (open access)

ABSTRACT: The Community Environmental Monitoring Program: Reducing Public Perception of Risk Through Stakeholder Involvement

Between 1951 and 1992, 928 nuclear tests were conducted at the Nevada Test Site (NTS), including 100 atmospheric and 828 underground tests. Initial public reaction to the tests was largely supportive, but by the late 1950s this began to change, largely as a result of fear of the potential for adverse health effects to be caused by exposure to ionizing radiation resulting from the tests. The nuclear power plant accident at Three Mile Island in 1979 served to heighten these fears, as well as foster a general distrust of the federal agencies involved and low public confidence in monitoring results. Modeled after a similar program that involved the public in monitoring activities around the Three Mile Island nuclear power plant, the Community Environmental Monitoring Program (CEMP) has promoted stakeholder involvement, awareness, and understanding of radiological surveillance in communities surrounding the NTS since 1981. It involves stakeholders in the operation, data collection, and dissemination of information obtained from a network of 29 stations across a wide area of Nevada, Utah, and California. It is sponsored by the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO) and administered by the Desert Research Institute (DRI) of the Nevada System …
Date: February 28, 2007
Creator: Hartwell, T.
Object Type: Article
System: The UNT Digital Library
Accounting for false negatives in hotspot detection (open access)

Accounting for false negatives in hotspot detection

Hotspot sampling designs are used in environmental sampling to identify the location of one (or more) contiguous regions of elevated contamination. These regions are known as hotspots. The problem of how to calculate the probability of detecting an elliptical hotspot using a rectangular or triangular grid of sampling points was addressed by Singer and Wickman in 1969. This approach presumed that any sample which coincided with a hotspot would detect the hotspot without error. However, for many sampling methodologies, there is a chance that the hotspot will not be detected even though it has been sampled directly--a false negative. We present a mathematical solution and a numerical algorithm which account for false negatives when calculating the probability of detecting hotspots that are circular in shape.
Date: August 28, 2007
Creator: Sego, Landon H. & Wilson, John E.
Object Type: Report
System: The UNT Digital Library
ACCUMULATION OF RADIOCESIUM BY MUSHROOMS IN THE ENVIRONMENT: A LITERATURE REVIEW (open access)

ACCUMULATION OF RADIOCESIUM BY MUSHROOMS IN THE ENVIRONMENT: A LITERATURE REVIEW

During the last 50 years, a large amount of information on radionuclide accumulators or ''sentinel-type'' organisms in the environment has been published. Much of this work focused on the risks of food-chain transfer of radionuclides to higher organisms such as reindeer and man. However, until the 1980's and 1990's, there has been little published data on the radiocesium ({sup 134}Cs and {sup 137}Cs) accumulation by mushrooms. This presentation will consist of a review of the published data for {sup 134,137}Cs accumulation by mushrooms in nature. This review will discuss the aspects that promote {sup 134,137}Cs uptake by mushrooms and focus on mushrooms that demonstrate a large propensity for use in the environmental biomonitoring of radiocesium contamination. It will also provide descriptions of habitats for many of these mushrooms and discuss on how growth media and other conditions relate to Cs accumulation.
Date: May 28, 2007
Creator: Duff, M
Object Type: Article
System: The UNT Digital Library
ACRF Ingest Software Status: New, Current, and Future - February 2007 (open access)

ACRF Ingest Software Status: New, Current, and Future - February 2007

The purpose of this report is to provide status of the ingest software used to process instrument data for the Atmospheric Radiation Measurement Program Climate Research Facility (ACRF). The report is divided into 4 sections: (1) for news about ingests currently under development, (2) for current production ingests, (3) for future ingest development plans, and (4) for information on retired ingests.
Date: February 28, 2007
Creator: Koontz, A. S.; Choudhury, S.; Ermold, B. D. & Gaustad, K. L.
Object Type: Report
System: The UNT Digital Library
Advanced Amine Solvent Formulations and Process Integration for Near-Term CO2 Capture Success (open access)

Advanced Amine Solvent Formulations and Process Integration for Near-Term CO2 Capture Success

This Phase I SBIR project investigated the economic and technical feasibility of advanced amine scrubbing systems for post-combustion CO2 capture at coal-fired power plants. Numerous combinations of advanced solvent formulations and process configurations were screened for energy requirements, and three cases were selected for detailed analysis: a monoethanolamine (MEA) base case and two “advanced” cases: an MEA/Piperazine (PZ) case, and a methyldiethanolamine (MDEA) / PZ case. The MEA/PZ and MDEA/PZ cases employed an advanced “double matrix” stripper configuration. The basis for calculations was a model plant with a gross capacity of 500 MWe. Results indicated that CO2 capture increased the base cost of electricity from 5 cents/kWh to 10.7 c/kWh for the MEA base case, 10.1 c/kWh for the MEA / PZ double matrix, and 9.7 c/kWh for the MDEA / PZ double matrix. The corresponding cost per metric tonne CO2 avoided was 67.20 $/tonne CO2, 60.19 $/tonne CO2, and 55.05 $/tonne CO2, respectively. Derated capacities, including base plant auxiliary load of 29 MWe, were 339 MWe for the base case, 356 MWe for the MEA/PZ double matrix, and 378 MWe for the MDEA / PZ double matrix. When compared to the base case, systems employing advanced solvent formulations and …
Date: June 28, 2007
Creator: Fisher, Kevin S.; Searcy, Katherine; Rochelle, Gary T.; Ziaii, Sepideh & Schubert, Craig
Object Type: Report
System: The UNT Digital Library
ALSNews 2007 (open access)

ALSNews 2007

Compilation of Advanced Light Source newsletter, ALSNews, for 2007, Volumes 272-282.
Date: November 28, 2007
Creator: McCullough (Ed.), Julie & Tamura (Ed.), Lori
Object Type: Report
System: The UNT Digital Library
Analysis of stress sensitivity and its influence on oil productionfrom tight reservoirs (open access)

Analysis of stress sensitivity and its influence on oil productionfrom tight reservoirs

This paper presents a study of the relationship betweenpermeability and effective stress in tight petroleum reservoirformations. Specifically, a quantitative method is developed to describethe correlation between permeability and effective stress, a method basedon the original in situ reservoir effective stress rather than ondecreased effective stress during development. The experimental resultsshow that the relationship between intrinsic permeability and effectivestress in reservoirs in general follows a quadratic polynomial functionalform, found to best capture how effective stress influences formationpermeability. In addition, this experimental study reveals that changesin formation permeability, caused by both elastic and plasticdeformation, are permanent and irreversible. Related pore-deformationtests using electronic microscope scanning and constant-rate mercuryinjection techniques show that while stress variation generally has smallimpact onrock porosity, the size and shape of pore throats have asignificant impact on permeability-stress sensitivity. Based on the testresults and theoretical analyses, we believe that there exists a cone ofpressure depression in the area near production within suchstress-sensitive tight reservoirs, leading to a low-permeability zone,and that well production will decrease under the influence of stresssensitivity.
Date: August 28, 2007
Creator: Lei, Qun; Xiong, Wei; Yuan, Cui & Wu, Yu-Shu
Object Type: Article
System: The UNT Digital Library
ANALYSIS OF TANK 28F SALTCAKE CORE SAMPLES FTF-456 - 467 (open access)

ANALYSIS OF TANK 28F SALTCAKE CORE SAMPLES FTF-456 - 467

Twelve LM-75 core samplers from Tank 28F sampling were received by SRNL for saltcake characterization. Of these, nine samplers contained mixtures of free liquid and saltcake, two contained only liquid, and one was empty. The saltcake contents generally appeared wet. A summary of the major tasks performed in this work are as follows: (1) Individual saltcake segments were extruded from the samplers and separated into saltcake and free liquid portions. (2) Free liquids were analyzed to estimate the amount of traced drill-string fluid contained in the samples. (3) The saltcake from each individual segment was homogenized, followed by analysis in duplicate. The analysis used more cost-effective and bounding radiochemical analyses rather than using the full Saltstone WAC suite. (4) A composite was created using an approximately equal percentage of each segment's saltcake contents. Supernatant liquid formed upon creation of the composite was decanted prior to use of the composite, but the composite was not drained. (5) A dissolution test was performed on the sample by contacting the composite with water at a 4:1 mass ratio of water to salt. The resulting soluble and insoluble fractions were analyzed. Analysis focused on a large subset of the Saltstone WAC constituents.
Date: February 28, 2007
Creator: Martino, C; Daniel McCabe, D; Tommy Edwards, T & Ralph Nichols, R
Object Type: Report
System: The UNT Digital Library
Analysis of Turbulent Mixing Jets in Large Scale Tank (open access)

Analysis of Turbulent Mixing Jets in Large Scale Tank

Flow evolution models were developed to evaluate the performance of the new advanced design mixer pump for sludge mixing and removal operations with high-velocity liquid jets in one of the large-scale Savannah River Site waste tanks, Tank 18. This paper describes the computational model, the flow measurements used to provide validation data in the region far from the jet nozzle, the extension of the computational results to real tank conditions through the use of existing sludge suspension data, and finally, the sludge removal results from actual Tank 18 operations. A computational fluid dynamics approach was used to simulate the sludge removal operations. The models employed a three-dimensional representation of the tank with a two-equation turbulence model. Both the computational approach and the models were validated with onsite test data reported here and literature data. The model was then extended to actual conditions in Tank 18 through a velocity criterion to predict the ability of the new pump design to suspend settled sludge. A qualitative comparison with sludge removal operations in Tank 18 showed a reasonably good comparison with final results subject to significant uncertainties in actual sludge properties.
Date: March 28, 2007
Creator: Lee, S.; Richard Dimenna, R.; Robert Leishear, R. & David Stefanko, D.
Object Type: Article
System: The UNT Digital Library
Appliances, Lighting, Electronics, and Miscellaneous EquipmentElectricity Use in New Homes (open access)

Appliances, Lighting, Electronics, and Miscellaneous EquipmentElectricity Use in New Homes

The "Other" end-uses (appliances, lighting, electronics, andmiscellaneous equipment) continue to grow. This is particularly true innew homes, where increasing floor area and amenities are leading tohigher saturation of these types of devices. This paper combines thefindings of several field studies to assess the current state ofknowledge about the "Other" end-uses in new homes. The field studiesinclude sub-metered measurements of occupied houses in Arizona, Florida,and Colorado, as well as device-level surveys and power measurements inunoccupied new homes. We find that appliances, lighting, electronics, andmiscellaneous equipment can consume from 46 percent to 88 percent ofwhole-house electricity use in current low-energy homes. Moreover, theannual consumption for the "Other" end-uses is not significantly lower innew homes (even those designed for low energy use) compared to existinghomes. The device-level surveys show that builder-installed equipment isa significant contributor to annual electricity consumption, and certaindevices that are becoming more common in new homes, such as structuredwiring systems, contribute significantly to this power consumption. Thesefindings suggest that energy consumption by these "Other" end uses isstill too large to allow cost-effective zero-energy homes.
Date: February 28, 2007
Creator: Brown, Richard E.; Rittelman, William; Parker, Danny & Homan,Gregory
Object Type: Article
System: The UNT Digital Library
Arroyo Mocho Boulder Removal Project: Lawrence Livermore National Laboratory Hetch Hetchy Pump Station (open access)

Arroyo Mocho Boulder Removal Project: Lawrence Livermore National Laboratory Hetch Hetchy Pump Station

The purpose of this biological assessment is to review the proposed Arroyo Mocho Boulder Removal Project in sufficient detail to determine to what extent the proposed action may affect any of the threatened, endangered, proposed, or sensitive species and designated or proposed critical habitats listed below. In addition, the following information is provided to comply with statutory requirements to use the best scientific and commercial information available when assessing the risks posed to listed and/or proposed species and designated and/or proposed critical habitat by proposed federal actions. This biological assessment is prepared in accordance with legal requirements set forth under regulations implementing Section 7 of the Endangered Species Act (50 CFR 402; 16 U.S.C 1536 (c)). It is our desire for the Arroyo Mocho Boulder Removal Project to receive incidental take coverage for listed species and critical habitat within the greater project area by means of amending the previous formal Section 7 consultation (1-1-04-F-0086) conducted a few hundred meters downstream by Lawrence Livermore National Laboratory (LLNL) in 2002. All conservation measures, terms and conditions, and reporting requirements from the previous Biological Opinion (1-1-04-F-0086) have been adopted for this Biological Assessment and/or amendment.
Date: June 28, 2007
Creator: Burkholder, L; Kato, T & Van Hattem, M
Object Type: Report
System: The UNT Digital Library
An Assessment of the 3D Geometric Surrogacy of Shock Timing Diagnostic Techniques for Tuning Experiments on the NIF (open access)

An Assessment of the 3D Geometric Surrogacy of Shock Timing Diagnostic Techniques for Tuning Experiments on the NIF

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Date: August 28, 2007
Creator: Robey, H. F.; Muncro, D. H.; Spears, B. K.; Marinak, M. M.; Jones, O. S.; Patel, M. V. et al.
Object Type: Article
System: The UNT Digital Library
Asynchronous Event-Driven Particle Algorithms (open access)

Asynchronous Event-Driven Particle Algorithms

We present in a unifying way the main components of three examples of asynchronous event-driven algorithms for simulating physical systems of interacting particles. The first example, hard-particle molecular dynamics (MD), is well-known. We also present a recently-developed diffusion kinetic Monte Carlo (DKMC) algorithm, as well as a novel event-driven algorithm for Direct Simulation Monte Carlo (DSMC). Finally, we describe how to combine MD with DSMC in an event-driven framework, and discuss some promises and challenges for event-driven simulation of realistic physical systems.
Date: February 28, 2007
Creator: Donev, A
Object Type: Article
System: The UNT Digital Library
Beta-Phosphinoethylboranes as Ambiphilic Ligands in Nickel-Methyl Complexes (open access)

Beta-Phosphinoethylboranes as Ambiphilic Ligands in Nickel-Methyl Complexes

The ambiphilic {beta}-phosphinoethylboranes Ph{sub 2}PCH{sub 2}CH{sub 2}BR{sub 2} (BR{sub 2} = BCy{sub 2} (1a), BBN (1b)), which feature a ethano spacer CH{sub 2}CH{sub 2} between the Lewis acidic boryl and Lewis basic phosphino groups, were synthesized in nearly quantitative yields via the hydroboration of vinyldiphenylphosphine. Compounds 1a and 1b were fully characterized by elemental analysis, and by NMR and IR spectroscopy. X-ray crystallographic studies of compound 1b revealed infinite helical chains of the molecules connected through P{hor_ellipsis}B donor-acceptor interactions. The ability of these ambiphilic ligands to concurrently act as donors and acceptors was highlighted by their reactions with (dmpe)NiMe{sub 2}. Zwitterionic complexes (dmpe)NiMe(Ph{sub 2}PCH{sub 2}CH{sub 2}BCy{sub 2}Me) (2a) and (dmpe)NiMe(Ph{sub 2}PCH{sub 2}CH{sub 2}[BBN]Me) (2b) were generated via the abstraction of one of the methyl groups, forming a borate, and intramolecular coordination of the phosphine moiety to the resulting cationic metal center. Compound 2b was characterized by X-ray crystallography. Furthermore, B(C{sub 6}F{sub 5}){sub 3} abstracts the methyl group of a coordinated borate ligand to generate a free, 3-coordinate borane center in [(dmpe)NiMe(1a)]{sup +}[MeB(C{sub 6}F{sub 5}){sub 3}]{sup -} (3).
Date: October 28, 2007
Creator: Fischbach, Andreas; Bazinet, Patrick R.; Waterman, Rory & Tilley, T. Don
Object Type: Article
System: The UNT Digital Library
Borehole Summary Report for C4997 Rotary Drilling, WTP Seismic Boreholes Project, CY 2006 (open access)

Borehole Summary Report for C4997 Rotary Drilling, WTP Seismic Boreholes Project, CY 2006

The following Final Geologic Borehole Report briefly describes the drilling of a single borehole at the Waste Treatment Plant (WTP) on the Hanford, Washington, U.S. Department of Energy (DOE) reservation. The location of the WTP is illustrated in Figure 1-1. The borehole was designated as “C4997”, and was drilled to obtain seismic and lithologic data for the Pretreatment Facility and High-Level Waste Vitrification Plant in the WTP. Borehole C4997 was drilled and logged to a total depth of 1428 ft below ground surface (bgs) on October 8, 2006, and was located approximately 150 ft from a recently cored borehole, designated as “C4998”. Pacific Northwest National Laboratory (PNNL) determined the locations for C4997, C4998, and other boreholes at the WTP in cooperation with the U.S. Army Corps of Engineers (USACE) Review Panel, and the Defense Nuclear Facilities Safety Board (DNFSB). The total depth of Borehole C4997 was also determined by PNNL.
Date: February 28, 2007
Creator: Difebbo, Thomas J.
Object Type: Report
System: The UNT Digital Library
Borehole Summary Report for Waste Treatment Plant Seismic Borehole C4993 (open access)

Borehole Summary Report for Waste Treatment Plant Seismic Borehole C4993

A core hole (C4998) and three boreholes (C4993, C4996, and C4997) were drilled to acquire stratigraphic and downhole seismic data to model potential seismic impacts and to refine design specifications and seismic criteria for the Waste Treatment Plant (WTP) under construction on the Hanford Site. Borehole C4993 was completed through the Saddle Mountains Basalt, the upper portion of the Wanapum Basalt, and associated sedimentary interbeds, to provide a continuous record of the rock penetrated by all four holes and to provide access to the subsurface for geophysical measure¬ment. Presented and compiled in this report are field-generated records for the deep mud rotary borehole C4993 at the WTP site. Material for C4993 includes borehole logs, lithologic summary, and record of rock chip samples collected during drilling through the months of August through early October. The borehole summary report also includes documentation of the mud rotary drilling, borehole logging, and sample collection.
Date: February 28, 2007
Creator: Rust, Colleen F.; Barnett, D. BRENT; Bowles, Nathan A. & Horner, Jake A.
Object Type: Report
System: The UNT Digital Library
Borehole Summary Report for Waste Treatment Plant Seismic Borehole C4996 (open access)

Borehole Summary Report for Waste Treatment Plant Seismic Borehole C4996

This report presents the field-generated borehole log, lithologic summary, and the record of samples collected during the recent drilling and sampling of the basalt interval of borehole C4996 at the Waste Treatment Plant (WTP) on the Hanford Site. Borehole C4996 was one of four exploratory borings, one core hole and three boreholes, drilled to investigate and acquire detailed stratigraphic and down-hole seismic data. This data will be used to define potential seismic impacts and refine design specifications for the Hanford Site WTP.
Date: January 28, 2007
Creator: Adams , S. C.; Ahlquist, Stephen T.; Fetters, Jeffree R.; Garcia, Ben & Rust, Colleen F.
Object Type: Report
System: The UNT Digital Library
Branching Fraction and P-violation Charge Asymmetry Measurements for B-meson Decays to eta K+-, eta pi+-, eta'K, eta' pi+-, omega K, and omega pi+- (open access)

Branching Fraction and P-violation Charge Asymmetry Measurements for B-meson Decays to eta K+-, eta pi+-, eta'K, eta' pi+-, omega K, and omega pi+-

The authors present measurements of the branching fractions for B{sup 0} meson decays to {eta}{prime}K{sup 0} and {omega}K{sup 0}, and of the branching fractions and CP-violation charge asymmetries for B{sup +} meson decays to {eta}{pi}{sup +}, {eta}K{sup +}, {eta}{prime}{pi}{sup +}, {eta}{prime}K{sup +}, {omega}{pi}{sup +}, and {omega}K{sup +}. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 383 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation. The measurements agree with previous results; they find no evidence for direct CP violation.
Date: June 28, 2007
Creator: Aubert, B.
Object Type: Article
System: The UNT Digital Library
Bunch Length Measurements in SPEAR3 (open access)

Bunch Length Measurements in SPEAR3

A series of bunch length measurements were made in SPEAR3 for two different machine optics. In the achromatic optics the bunch length increases from the low-current value of 16.6ps rms to about 30ps at 25ma/bunch yielding an inductive impedance of -0.17{Omega}. Reducing the momentum compaction factor by a factor of {approx}60 [1] yields a low-current bunch length of {approx}4ps rms. In this paper we review the experimental setup and results.
Date: November 28, 2007
Creator: Corbett, W.J.; Fisher, A.; Huang, X.; Safranek, J.; Sebek, J.; /SLAC et al.
Object Type: Article
System: The UNT Digital Library
Cell shape regulates global histone acetylation in human mammary epithelial cells (open access)

Cell shape regulates global histone acetylation in human mammary epithelial cells

Extracellular matrix (ECM) regulates cell morphology and gene expression in vivo; these relationships are maintained in three-dimensional (3D) cultures of mammary epithelial cells. In the presence of laminin-rich ECM (lrECM), mammary epithelial cells round up and undergo global histone deacetylation, a process critical for their functional differentiation. However, it remains unclear whether lrECM-dependent cell rounding and global histone deacetylation are indeed part of a common physical-biochemical pathway. Using 3D cultures as well as nonadhesive and micropatterned substrata, here we showed that the cell 'rounding' caused by lrECM was sufficient to induce deacetylation of histones H3 and H4 in the absence of biochemical cues. Microarray and confocal analysis demonstrated that this deacetylation in 3D culture is associated with a global increase in chromatin condensation and a reduction in gene expression. Whereas cells cultured on plastic substrata formed prominent stress fibers, cells grown in 3D lrECM or on micropatterns lacked these structures. Disruption of the actin cytoskeleton with cytochalasin D phenocopied the lrECM-induced cell rounding and histone deacetylation. These results reveal a novel link between ECM-controlled cell shape and chromatin structure, and suggest that this link is mediated by changes in the actin cytoskeleton.
Date: February 28, 2007
Creator: Le Beyec, Johanne; Xu, Ren; Lee, Sun-Young; Nelson, Celeste M.; Rizki, Aylin; Alcaraz, Jordi et al.
Object Type: Article
System: The UNT Digital Library
Certification of Completion of Item 2 of ASC FY07 Level-2 Milestone ID #2380 (open access)

Certification of Completion of Item 2 of ASC FY07 Level-2 Milestone ID #2380

This report documents the completion of Item 2 of the three milestone deliverables that comprise Milestone ID 2380: Deploy selected Tri-Lab resource manager at LLNL and develop support model. Specifically: LLNL will integrate and support a commercial resource manager software product at LLNL to be used across the tri-lab HPC facilities.
Date: March 28, 2007
Creator: Lipari, D A
Object Type: Report
System: The UNT Digital Library
Characterization and Electrochemical Performance of SubstitutedLiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) Cathode Materials (open access)

Characterization and Electrochemical Performance of SubstitutedLiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) Cathode Materials

A complete series of LiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) materials have been synthesized and investigated as cathode materials for lithium ion batteries. When cycled between 2.0 and 4.3 V vs. Li/Li+ at a current density of 0.1 mA/cm2, stable capacities of ~;;160 mAh/g for y=0 to ~;;110 mAh/g for y=0.2 are achieved. Upon increasing the current density, it is found that all materials containing aluminum show reduced polarization and improved rate performance. The optimal performance at all current densities was found for the compound with y=0.05. The effect of aluminumsubstitution on the crystal structure of the host is discussed.
Date: November 28, 2007
Creator: Wilcox, James D. & Doeff, Marca M.
Object Type: Article
System: The UNT Digital Library