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Pressure Induced Phase Transformation of Pb(Zr(0.95)Ti(0.05))O(3) Based Ceramics: Grain Size Dependence

Description: A substantial decrease in hydrostatic ferroelectric (FE) to antiferroelectric (AFE) transformation pressure was measured for Pb(Zr{sub 0.949}Ti{sub 0.051}){sub 0.989}Nb{sub 0.0182}O{sub 3} ceramics with decreasing grain size. The 150 MPa decrease in hydrostatic FE to AFE transformation pressure over the grain size range of 8.5 {micro}m to 0.7{micro}m was shown to be consistent with enhanced internal stress with decreasing grain size. Further, the Curie Point decreased and the dielectric constan… more
Date: December 21, 1999
Creator: Tuttle, Bruce A.; Voigt, James A.; Scofield, Timothy W.; Aselage, Terrence L.; Rodriguez, Mark A.; Yang, Pin et al.
Partner: UNT Libraries Government Documents Department
open access

Monte Carlo Simulations of Phosphate Polyhedron Connectivity in Glasses

Description: Monte Carlo simulations of phosphate tetrahedron connectivity distributions in alkali and alkaline earth phosphate glasses are reported. By utilizing a discrete bond model, the distribution of next-nearest neighbor connectivities between phosphate polyhedron for random, alternating and clustering bonding scenarios was evaluated as a function of the relative bond energy difference. The simulated distributions are compared to experimentally observed connectivities reported for solid-state two-dim… more
Date: December 21, 1999
Creator: ALAM,TODD M.
Partner: UNT Libraries Government Documents Department
open access

New result on K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} from BNL E787

Description: E787 at BNL has reported evidence for the rare decay K{sup +} {r_arrow} {pi}{sup +}{nu}{bar {nu}}, based on the observation of one candidate event. In this paper, we present the result of analyzing a new dataset of comparable sensitivity to the published result.
Date: June 21, 1999
Creator: REDLINGER,G.
Partner: UNT Libraries Government Documents Department
open access

Improved MCFC performance with Li/Na/Ba/Ca carbonate electrolyte.

Description: Earlier electrolyte segregation tests of Li/Na carbonate used chemical analysis such as inductively coupled plasma/atomic emission spectroscopy (ICP/AES) of matrix strips wetted with carbonate and exposed to 5- to 20-V potential gradients. A segregation factor was correlated to the Li/Na carbonate composition. While fairly substantial segregation occurs at the eutectic composition of 52% Li, it is minimal at 60% to 75% Li. Such lithium-rich Li/Na carbonates may not be practical because the melt… more
Date: July 21, 1999
Creator: Centeno, C.-J.; Kaun, T. D.; Krumpelt, M. & Schoeler, A.
Partner: UNT Libraries Government Documents Department
open access

Perturbative and non-perturbative corrections to B {r_arrow}D(*) l nu*

Description: It is shown that certain double ratios introduced for computing semileptonic form factors are accurate to order 1/m{sub Q}{sup 2}, even when the action and current are accurate to order 1/m{sub Q}.
Date: September 21, 1999
Creator: Kronfeld, Andreas S.
Partner: UNT Libraries Government Documents Department
open access

X-ray reflectivity study of formation of multilayer porous anodic oxides of silicon.

Description: The paper reports data on the kinetics of anodic oxide films growth on silicon in aqueous solutions of phosphoric acids as well as a study of the morphology of the oxides grown in a special regime of the oscillating anodic potential. X-ray reflectivity measurements were performed on the samples of anodic oxides using an intense synchrotron radiation source. They have a multilayer structure as revealed by theoretical fitting of the reflectivity data. The oscillations of the anodic potential are … more
Date: July 21, 1999
Creator: Chu, Y.; Fenollosa, R.; Parkhutik, V. & You, H.
Partner: UNT Libraries Government Documents Department
open access

Development and application of NDE methods for monolithic and continuous fiber ceramic matrix composites.

Description: Monolithic structural ceramics and continuous fiber ceramic matrix composites (CMCs) are being developed for application in many thermally and chemically aggressive environments where structural reliability is paramount. We have recently developed advanced nondestructive evaluation (NDE) methods that can detect distributed ''defects'' such as density gradients and machining-induced damage in monolithic materials, as well as delamination, porosity, and throughwall cracks, in CMC materials. These… more
Date: May 21, 1999
Creator: Ellingson, W. A.
Partner: UNT Libraries Government Documents Department
open access

HIGH PT PHYSICS WITH THE STAR EXPERIMENT AT RHIC.

Description: The STAR experiment at RHIC is a TPC-based, general purpose detector designed to obtain charged particle spectra, with an emphasis on hadrons over a large phase space. An electromagnetic calorimeter provides measurement of e's, {gamma}'s, {pi}{sup 0}'s and jets. Data-taking with Au + Au collisions at {radical}5 = 200 GeV/c{sup 2} begins in Fall 1999. The STAR experiment's investigation of techniques and signals using hard probes to study the high energy-density matter at RHIC and to search for … more
Date: March 21, 1999
Creator: TURNER,K. FOR THE STAR COLLABORATION
Partner: UNT Libraries Government Documents Department
open access

New developments in the application of synchrotron radiation to material science.

Description: Recent developments in the application of synchrotrons radiation to materials science are discussed, using techniques which exploit the high brilliance of the newer synchrotrons sources, such as microbeam techniques and correlation spectroscopy. These include studies of environmental systems, residual stress, slow dynamics of condensed matter systems and studies of liquid surfaces and thin magnetic films.
Date: April 21, 1999
Creator: Sinha, S. K.
Partner: UNT Libraries Government Documents Department
open access

Diamond Anvils With Integrated Diamond-Encapsulated Microprobes for High-Pressure Electrical Transport Experiments

Description: We have fabricated diamond anvils specially designed for use in ultra-high pressure electrical transport experiments. These anvils, which we refer to as ''designer anvils'', feature thin-film metal microprobes which are encased in a layer of high-quality, epitaxial, chemically vapor deposited (CVD) diamond. The synthetic diamond film ensures that the microprobes are survivable to Mbar pressures, and also serves to electrically insulate the microprobes from the high-pressure gasket. High-pressur… more
Date: July 21, 1999
Creator: Akella, J.; Catledge, S. A.; Vohra, Y. K. & Weir, S. T.
Partner: UNT Libraries Government Documents Department
open access

Synchrotron x-ray reflectivity study of oxidation/passivation of copper and silicon.

Description: Synchrotron x-ray-scattering technique studies of copper and silicon electrochemical interfaces are reported. These two examples illustrate the application of synchrotron x-ray techniques for oxidation, passivation, and dissolution of metals and semiconductors.
Date: July 21, 1999
Creator: Chu, Y.; Nagy, Z.; Parkhutik, V. & You, H.
Partner: UNT Libraries Government Documents Department
open access

The effects of neutron irradiation on fracture toughness of austenitic stainless steels.

Description: Austenitic stainless steels are used extensively as structural alloys in reactor pressure vessel internal components because of their superior fracture toughness properties. However, exposure to high levels of neutron irradiation for extended periods leads to significant reduction in the fracture resistance of these steels. This paper presents results of fracture toughness J-R curve tests on four heats of Type 304 stainless steel that were irradiated to fluence levels of {approx}0.3 and 0.9 x 1… more
Date: May 21, 1999
Creator: Chopra, O. K.; Gruber, E. E. & Shack, W. J.
Partner: UNT Libraries Government Documents Department
open access

A novel thin film solid oxide fuel cell for microscale energy conversion

Description: A novel approach for the fabrication and assembly of a solid oxide fuel cell system is described which enables effective scaling of the fuel delivery, manifold, and fuel cell stack components for applications in miniature and microscale energy conversion. Electrode materials for solid oxide fuel cells are developed using sputter deposition techniques. A thin film anode is formed by co-deposition of nickel and yttria-stabilized zirconia (YSZ). This approach provides a mixed conducting inter-faci… more
Date: July 21, 1999
Creator: Jankowski, Alan F. & Morse, Jeffrey D.
Partner: UNT Libraries Government Documents Department
open access

Development of NDE methods for hot gas filters.

Description: Ceramic hot gas candle filters are currently under development for hot gas particulate cleanup in advanced coal-based power systems. The ceramic materials for these filters include nonoxide monolithic, nonoxide-fiber-reinforced composites, and nonoxide reticulated foam. A concern is the lack of reliable data on which to base decisions for reusing or replacing hot gas filters during plant shutdowns. The work in this project is aimed at developing nondestructive evaluation (FIDE) technology to al… more
Date: July 21, 1999
Creator: Deemer, C.; Ellingson, W. A.; Koehl, E. R.; Lee, H.; Spohnholtz, T. & Sun, J. G.
Partner: UNT Libraries Government Documents Department
open access

Allocating resources and building confidence in public-safety decisions for nuclear waste sites

Description: There are three basic ways to protect the public from the hazards of exposure to radionuclides in nuclear waste: completely contain the waste; limit the rate at which radionuclides are released; and, once radionuclides are released, minimize their impact by reducing concentrations and retarding transport. A geologic repository system that implements all three provides maximum protection for the public: if one element fails, the others serve to protect. This is ''defense-in-depth.'' Demonstratin… more
Date: May 21, 1999
Creator: Lew, K L & Wilder, D G
Partner: UNT Libraries Government Documents Department
open access

Historical Background on the Performance Assessment for the Waste Isolation Pilot Plant

Description: In 1979, six years after selecting the Delaware Basin as a potential disposal area, Congress authorized the U.S. Department of Energy to build the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico, as a Research and development facility for the safe management storage, and disposal of waste contaminated with transuranic radioisotopes. In 1998, 19 years after authorization and after site selection, the U.S. Environmental Protection Agency (EPA) certified that the WIPP disposal system … more
Date: October 21, 1999
Creator: RECHARD,ROBERT P.
Partner: UNT Libraries Government Documents Department
open access

High-Resolution Transmission Electron Microscopy Calibration of Critical Dimension (CD) Reference Materials

Description: NIST and Sandia have developed a procedure for producing and calibrating critical dimension (CD), or linewidth, reference materials. These reference materials will be used to calibrate metrology instruments used in semiconductor manufacturing. The artifacts, with widths down to 100 nm, are produced in monocrystalline silicon with all feature edges aligned to specific crystal planes. A two-part calibration of these linewidths is used: the primary calibration, with accuracy to within a few lattic… more
Date: September 21, 1999
Creator: Allen, Richard A.; Cresswell, Michael W.; Everist, Sarah C.; Ghoshtagore, Rathindra N.; Headley, Thomas J. & Linholm, Loren W.
Partner: UNT Libraries Government Documents Department
open access

Roles and Delegation of Authority (R/DA) System

Description: The processes of defining managerial roles and providing for delegation of authority are essential to any enterprise. At most large organizations, these processes are defined in policy manuals and through sets of standard operating procedures for many, if not all, business and administrative functions. Many of these staff-initiated, administrative functions require the routing of documents for approval to one or more levels of management. These employee-oriented, back office types of workflows … more
Date: October 21, 1999
Creator: Abbott, John P.; Hutchins, James C. & Schoch, David G.
Partner: UNT Libraries Government Documents Department
open access

Modeling Solute Diffusion in the Presence of Pore-Scale Heterogeneity

Description: A range of pore diffusivities, D{sub p}, is implied by the high degree of pore-scale heterogeneity observed in core samples of the Culebra (dolomite) Member of the Rustler formation, NM. Earlier tracer tests in the culebra at the field-scale have confirmed significant heterogeneity in diffusion rate coefficients (the combination of D{sub p} and matrix block size). In this study, expressions for solute diffusion in the presence of multiple simultaneous matrix diffusivities are presented and used… more
Date: October 21, 1999
Creator: FLEMING,SEAN W. & HAGGERTY,ROY
Partner: UNT Libraries Government Documents Department
open access

Geotechnical Issues in Total System Performance Assessments of Yucca Mountain

Description: A Total System Performance Assessment (TSPA) of Yucca Mountain consists of integrated sub-models and analyses of natural and engineered systems. Examples of subsystem models include unsaturated-zone flow and transport, seepage into drifts, coupled thermal hydrologic processes, transport through the engineered barrier system, and saturated-zone flow and transport. The TSPA evaluates the interaction of important processes among these subsystems, and it determines the impact of these processes on … more
Date: December 21, 1999
Creator: HO,CLIFFORD K.; HOUSEWORTH,JIM & WILSON,MICHAEL L.
Partner: UNT Libraries Government Documents Department
open access

EXPECTED TRIGGER RATES OF HIGH PT JETS AND DIRECT PHOTONS IN THE STAR EMC.

Description: The STAR experiment at RHIC is a large acceptance detector. The electromagnetic calorimeter (EMC) will provide a sensitive trigger to study high p{sub t} jets and hard photons in AuAu, pp, and pAu collisions. The capability for the EMC to trigger on jets and direct photons was studied for trigger level 0. Trigger efficiencies and expected process rates were obtained for pp reactions. Results from pp interactions will be essential to the interpretation of AuAu results as well as for the spin phy… more
Date: March 21, 1999
Creator: BELT-TONJES,M. FOR THE STAR COLLABORATION
Partner: UNT Libraries Government Documents Department
open access

Simulation of edge-plasma profiles and turbulence related to L-H transitions in tokamaks

Description: Understanding plasma profile evolution and plasma turbulence are two important aspects of developing a predictive model for edge-plasma in tokamaks and other fusion-related devices. Here they describe results relevant to the L-H transition phenomena observed in tokamaks obtained from two simulations codes which emphasize the two aspects of the problem. UEDGE solves for the two-dimensional (2-D) profiles of a multi-species plasma and neutrals given some anomalous cross-field diffusion coefficien… more
Date: September 21, 1999
Creator: Cohen, R H; Rognlien, T D & Xu, X Q
Partner: UNT Libraries Government Documents Department
open access

THE YEAR-ONE PHYSICS CAPABILITIES OF STAR.

Description: When the Relativistic Heavy Ion Collider (RHIC) at BNL begins operation in the Fall of 1999, heavy ions will be accelerated in collider mode for the first time, and a new energy regime will be entered for Heavy Ion Physics. The Solenoidal Tracker At RHIC (STAR) detector has a near 4{pi} coverage and is dedicated to taking hadronic measurements. A large volume Time Projection Chamber placed in a solenoidal magnet at 0.5T is used to track and identify the many thousands of produced particles. STA… more
Date: March 21, 1999
Creator: CAINES,H. FOR THE STAR COLLABORATION
Partner: UNT Libraries Government Documents Department
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