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New cubic phase of lithium nitride to 200 GPa

Description: We present a new cubic ({gamma}) Li{sub 3}N phase discovered above 40({+-}5) GPa. Structure and electronic bands are examined at high pressure with synchrotron x-ray diffraction and inelastic x-ray scattering in a diamond anvil cell, and also with first-principles calculations. We observe a dramatic band-gap widening and volume collapse at the phase transition. {gamma}-Li{sub 3}N remains extremely stable and ionic to 200 GPa, with predicted metallization near 8 TPa. The high structural stabilit… more
Date: July 19, 2005
Creator: Lazicki, A.; Maddox, B.; Evans, W.; Yoo, C. S.; McMahan, A. K.; Pickett, W. E. et al.
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Partner: UNT Libraries Government Documents Department
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A Beamline for High Pressure Studies at the Advanced Light Source With a Superconducting Bending Magnet as the Source

Description: A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of… more
Date: April 21, 2005
Creator: Kunz, M.; MacDowell, A. A.; Caldwell, W. A.; Cambie, D.; Celestre, R. S.; Domning, E. E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A System for Measuring Defect Induced Beam Modulation on Inertial Confinement Fusion-class Laser Optics

Description: A multi-wavelength laser based system has been constructed to measure defect induced beam modulation (diffraction) from ICF class laser optics. The Nd:YLF-based modulation measurement system (MMS) uses simple beam collimation and imaging to capture diffraction patterns from optical defects onto an 8-bit digital camera at 1053, 527 and 351 nm. The imaging system has a field of view of 4.5 x 2.8 mm{sup 2} and is capable of imaging any plane from 0 to 30 cm downstream from the defect. The system i… more
Date: October 18, 2005
Creator: Runkel, M.; Hawley-Fedder, R.; Widmayer, C.; Williams, W.; Weinzapfel, C. & Roberts, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effect of Wavefront Error on 10^-7 Contrast Measurements

Description: We have measured a contrast of 6.5 {center_dot} 10{sup -8} from 10-25{lambda}/D in visible light on the Extreme Adaptive Optics testbed using a shaped pupil for diffraction suppression. The testbed was designed with a minimal number of high-quality optics to ensure low wavefront error and uses a phase shifting diffraction interferometer for metrology. This level of contrast is within the regime needed for imaging young Jupiter-like planets, a primary application of high-contrast imaging. We hav… more
Date: October 6, 2005
Creator: Evans, J. W.; Sommargren, G.; Macintosh, B.; Severson, S. & Dillon, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Strain mapping on gold thin film buckling and siliconblistering

Description: Stress/Strain fields associated with thin film buckling induced by compressive stresses or blistering due to the presence of gas bubbles underneath single crystal surfaces are difficult to measure owing to the microscale dimensions of these structures. In this work, we show that micro Scanning X-ray diffraction is a well suited technique for mapping the strain/stress tensor of these damaged structures.
Date: September 1, 2005
Creator: Goudeau, P.; Tamura, N.; Parry, G.; Colin, J.; Coupeau, C.; Cleymand, F. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Advanced polychromator systems for remote chemical sensing (LDRD project 52575).

Description: The objective of this LDRD project was to develop a programmable diffraction grating fabricated in SUMMiT V{trademark}. Two types of grating elements (vertical and rotational) were designed and demonstrated. The vertical grating element utilized compound leveraged bending and the rotational grating element used vertical comb drive actuation. This work resulted in two technical advances and one patent application. Also a new optical configuration of the Polychromator was demonstrated. The new op… more
Date: January 1, 2005
Creator: Sinclair, Michael B.; Pfeifer, Kent Bryant & Allen, James Joe
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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In-situ Studies of the Martensitic Transformation in Ti Thin Films using the Dynamic Transmission Microscope (DTEM)

Description: The {alpha} to {beta} transition in pure Ti occurs mainly by a 'martensitic type' phase transformation. In such transformations, growth rates and interface velocities tend to be very large, on the order of 10{sup 3} m/s, making it difficult to observe the transformation experimentally. With thin films, it becomes even more difficult to observe, since the large surface augments the nucleation and transformation rates to levels that require nanosecond temporal resolution for experimental observat… more
Date: November 21, 2005
Creator: LaGrange, T. B.; Campbell, G. H.; Colvin, J. D.; King, W. E.; Browning, N. D.; Armstrong, M. R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High Pressure Structure of Half-Metallic CrO2

Description: Evidence for a structural phase transition from rutile {alpha}-CrO{sub 2} phase I (P4{sub 2}/mnm) to orthorhombic {beta}-CrO{sub 2} phase II (CaCl{sub 2}-like, Pnnm) is presented using angle-resolved synchrotron x-ray diffraction and high sensitivity confocal Raman spectroscopy. The transition to the CaCl{sub 2} structure, which appears to be second-order, occurs at 12 {+-} 3 GPa without any measurable discontinuity in volume, but is accompanied by an apparent increase in compressibility. Raman… more
Date: September 7, 2005
Creator: Maddox, B.; Yoo, C. S.; Kasinathan, D.; Pickett, W. E. & Scalettar, R. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Development of an efficient large-aperture high damage-threshold sol-gel diffraction grating.

Description: In order to develop the next generation of high peak intensity lasers, new grating technology providing higher damage thresholds and large apertures is required. The current assumption is that this technical innovation will be multilayer dielectric gratings, wherein the uppermost layer of a thin film mirror is etched to create the desired binary phase grating. A variant of this is explored with the upper grating layer being a lower density gelatin-based volume phase grating in either sol-gel or… more
Date: March 1, 2005
Creator: Ashley, Carol S.; Rambo, Patrick K.; Schwarz, Jens; Dunphy, Darren Robert; Branson, Eric D.; Smith, Ian Craig et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Material dynamics under extreme conditions of pressure and strain rate

Description: Solid state experiments at extreme pressures (10-100 GPa) and strain rates ({approx}10{sup 6}-10{sup 8}s{sup -1}) are being developed on high-energy laser facilities, and offer the possibility for exploring new regimes of materials science. These extreme solid-state conditions can be accessed with either shock loading or with a quasi-isentropic ramped pressure drive. Velocity interferometer measurements establish the high pressure conditions. Constitutive models for solid-state strength under t… more
Date: September 6, 2005
Creator: Remington, Bruce A.; Allen, Patrick; Bringa, Eduaro; Hawreliak, Jim; Ho, Darwin; Lorenz, K. Thomas et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Laser System for Photoelectron and X-Ray Production in the PLEIADES Compton Light Source

Description: The PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility provides tunable short x-ray pulses with energies of 30-140 keV and pulse durations of 0.3-5 ps by scattering an intense, ultrashort laser pulse off a 35-75 MeV electron beam. Synchronization of the laser and electron beam is obtained by using a photoinjector gun, and using the same laser system to generate the electrons and the scattering laser. The Ti Ti:Sapphire, chirped pulse amplification… more
Date: April 21, 2005
Creator: Gibson, D J; Barty, C J; Betts, S M; Crane, J K & Jovanovic, I
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Facile Synthesis of a Crystalline, High-Surface Area SnO2 Aerogel

Description: We report the preparation of a novel monolithic SnO{sub 2} aerogel using a straightforward sol-gel technique. TEM and XRD analysis show that the as-prepared material is comprised of interconnected, randomly oriented crystalline (rutile) SnO{sub 2} nanoparticles {approx}3-5 nm in size. As a result, the low-density SnO{sub 2} monolith ({approx}97% porous) exhibits a very high surface area of 383 m{sup 2}/g. /XANES spectroscopy at the Sn M{sub 4,5} edge reveals that the electronic structure of the… more
Date: January 3, 2005
Creator: Baumann, T. F.; Kucheyev, S. O.; Gash, A. E. & Satcher, J. H. Jr.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Defining Electron Backscatter Diffraction Resolution

Description: Automated electron backscatter diffraction (EBSD) mapping systems have existed for more than 10 years [1,2], and due to their versatility in characterizing multiple aspects of microstructure, they have become an important tool in microscale crystallographic studies. Their increasingly widespread use however raises questions about their accuracy in both determining crystallographic orientations, as well as ensuring that the orientation information is spatially correct. The issue of orientation a… more
Date: February 7, 2005
Creator: El-Dasher, B S & Rollett, A D
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Solid-Solid Phase Transition Kinetics of FOX-7

Description: Since it was developed in the late 1990s, 1,1-diamino-2,2-dinitroethene (FOX-7), with lower sensitivity and comparable performance to RDX, has received increasing interest. This paper will present our results for the phase changes of FOX-7 using DSC and HFC (Heat Flow Calorimetry). DSC thermal curves recorded at linear heating rates of 0.10, 0.35 and 1.0 C min{sup -1} show two endothermic peaks and two exothermic peaks. The two endothermic peaks represent solid-solid phase transitions, which ha… more
Date: July 12, 2005
Creator: Burnham, A K; Weese, R K; Wang, R; Kwok, Q M & Jones, D G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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PERMEABILITY, SOLUBILITY AND DIFFUSIVITY OF HYDROGEN ISOTOPES IN STAINLESS STEELS AT HIGH GAS PRESSURES

Description: The Defense Waste Processing Facility (DWPF) is about to process High Level Waste (HLW) Sludge Batch 4 (SB4). This sludge batch is high in alumina and nepheline can crystallize readily depending on the glass composition. Large concentrations of crystallized nepheline can have an adverse effect on HLW glass durability. Several studies have been performed to study the potential for nepheline formation in SB4. The Phase 3 Nepheline Formation study of SB4 glasses examined sixteen different glasses … more
Date: September 12, 2005
Creator: Subramanian, K & Michael Morgan, M
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A Beamline for High-Pressure Studies at the Advanced Light Sourcewith a Superconducting Bending Magnet as the Source

Description: A new facility for high-pressure diffraction and spectroscopy using diamond anvil high-pressure cells has been built at the Advanced Light Source on Beamline 12.2.2. This beamline benefits from the hard X-radiation generated by a 6 Tesla superconducting bending magnet (superbend). Useful x-ray flux is available between 5 keV and 35 keV. The radiation is transferred from the superbend to the experimental enclosure by the brightness preserving optics of the beamline. These optics are comprised of… more
Date: June 30, 2005
Creator: Kunz, Martin; MacDowell, Alastair A.; Caldwell, Wendel A.; Cambie, Daniella; Celestre, Richard S.; Domning, Edward E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Effect of Solution Annealing on the Microstructural Behavior of Alloy 22 Welds

Description: Multi-pass gas tungsten arc welds of Alloy 22 were subjected to solution annealing durations of 20 minutes, 24 hours, 72 hours and 1 week at temperatures of 1075, 1121, 1200, and 1300 C. The specimens were studied in cross section by secondary electron microscopy to determine the effect of solution annealing on tetrahedrally close packed (TCP) precipitate stability. Electron backscatter diffraction mapping was also performed on all of the specimens to determine the recrystallization behavior of… more
Date: May 6, 2005
Creator: El-Dasher, B S; Edgecumbe, T S & Torres, S G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Characterization of Host Phases for Actinides in Simulated Metallic Waste Forms by Transmission Electron Microscopy.

Description: Argonne National Laboratory has developed an electrometallurgical process for conditioning spent sodium-bonded metallic reactor fuel prior to disposal. A waste stream from this process consists of stainless steel cladding hulls that contain undissolved metal fission products such as Tc, Ru, Rh, Pd, and Ag; a small amount of undissolved actinides (U, Np, Pu) also remains with the hulls. These wastes will be immobilized in a waste form whose baseline composition is stainless steel alloyed with 15… more
Date: November 21, 2005
Creator: Janney, D. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Gratings for High-Energy Petawatt Lasers

Description: To enable high-energy petawatt laser operation we have developed the processing methods and tooling that produced both the world's largest multilayer dielectric reflection grating and the world's highest laser damage resistant gratings. We have successfully delivered the first ever 80 cm aperture multilayer dielectric grating to LLNL's Titan Intense Short Pulse Laser Facility. We report on the design, fabrication and characterization of multilayer dielectric diffraction gratings.
Date: November 8, 2005
Creator: Nguyen, H T; Britten, J. A.; Carlson, T. C.; Nissen, J. D.; Summers, L. J.; Hoaglan, C. R. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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X-ray Scattering Techniques for Characterization of Nanosystems in Lifescience

Description: The intent of this chapter is to provide the basics of using x-ray diffraction techniques in order to obtain information on the structure and morphology of the nanosystems, and also to point out some of its strengths and weaknesses when compare to other characterization techniques. X-ray scattering examines over a wide range of density domains from a tenth to a thousandth angstrom. Essentially, this covers a whole range of condensed matter, including the structure and morphology of nanosystems,… more
Date: April 11, 2005
Creator: Saw, C K
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Up-to-date p-p Interaction Modeling and Secondary gamma, e+/- and Neutrino Spectra in Astronomical Environment

Description: We have calculated spectra of stable secondary particles ({gamma}, e{sup {+-}}, {nu}{sub e}, {bar {nu}}{sub e}, {nu}{sub {mu}}{bar {nu}}{sub {mu}}) produced in high energy p-p interactions in astrophysical environment. The calculation has incorporated the up-to-date rising inelastic cross-sections, the diffraction dissociation process, and the Feynman scaling violation for the first time. We then found that the diffractive process makes secondary particle spectra harder than that of the inciden… more
Date: June 28, 2005
Creator: Abe, T.; Kamae, T.; Karlsson, N.; Koi, T. & Mizuno, T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Diffraction grating eigenvector for translational and rotational motion

Description: Future energy scaling of high-energy chirped-pulse amplification systems will benefit from the capability to coherently tile diffraction gratings into larger apertures. Design and operation of a novel, accurate alignment diagnostics for coherently tiled diffraction gratings is required for successful implementation of this technique. An invariant diffraction direction and phase for special moves of a diffraction grating is discussed, allowing simplification in the design of the coherently tiled… more
Date: July 28, 2005
Creator: Rushford, M C; Molander, W A; Nissen, J D; Jovanovic, I; Britten, J A & Barty, C J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Effect of Solution Annealing Temperatures on the Crevice Corrosion Mode of Alloy 22

Description: The effect of solution annealing temperature on the observed corrosion attack mode in Alloy 22 welds was assessed. Three types of specimens were examined, including the as-welded state, solution annealed for 20 minutes at 1121 C, and solution annealed for 20 minutes at 1200 C. The microstructures of the specimens were first mapped using electron backscatter diffraction to determine the grain structure evolution due to solution annealing. The specimens were then subjected to electrochemical test… more
Date: October 31, 2005
Creator: El-Dasher, B S; Etien, R & Torres, S G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Calibration of Parameters in Beta-Delta HMX Phase Transformation Kinetics Using Computer Simulations

Description: The kinetics of the beta-delta solid-solid phase transformation of HMX (nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) were modeled in ALE2D using four similar equilibrium-inhibited nucleation-growth models: a reversible set of Arrhenius kinetics following a LANL model, and three sets of kinetics derived based on an autocatalytic model using the bidirectional reaction formalism. The parameters for the bidirectional kinetics models were calibrated using simulations of two experiment… more
Date: November 17, 2005
Creator: Wemhoff, A. P. & Burnham, A. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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