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Displaying 1151 - 1175 of 1323

Arsenic Clustering and Precipitation Analysis in Ion-Implanted Si Wafers by X-Ray Absorption Spectroscopy and SIMS

September 1, 2000

Author(s)

M A. Sahiner, S W. Novak, Joseph Woicik, J Liu, V Krishnamoorty

EXAFS and SIMS have been used to obtain clustering and precipitation information in As (arsenic) implanted Si wavers. CZ (001) Siwafers were first implanted by As + at 100 keV to a dose of 1x10 15/cm 2 followed by a second As + implantation at 20-30 keV

Model for Cyclic Fatigue of Quasi-Plastic Ceramics in Contact with Spheres

September 1, 2000

Author(s)

K -. Lee, Yeon-Gil G. Jung, I M. Peterson, Brian R. Lawn, D H. Kim, S K. Lee

A model of contact damage accumulation from cyclic loading with spheres and ensuing strength degradation in relatively tough, heterogeneous ceramics is developed. The damage takes the form of a quasiplastic zone beneath the contact, consisting of an array

Polydispersity During the Formation and Growth of the Stober Silica Particles from Small-Angle X-Ray Scattering Measurements

September 1, 2000

Author(s)

H Boukari, Gabrielle G. Long, M T. Harris

The early stages of formation of Stober silica particles have been investigated in situ during the hydrolysis and condensation of tetraethylorthosilicate under base-ammonia conditions in different alcoholic solvents. Time=resolved ultra small-angle X-ray

Processing and Mechanical Properties of A1203/Ni3AI Composites with Interpenetrating Network

September 1, 2000

Author(s)

S Skirl, Ralph Krause, Sheldon M. Wiederhorn, J Rodel

Composites with microstructures of interpenetrating networks were manufactured by gas pressure infiltration of the Ni 3Al into porous preforms of aluminum oxide. Composites with contents of Ni 3Al contents of between 15% and 30% by volume were made and

Structural Study of Ba 11 Fe 8 Ti 9 O 41 by X-Ray Diffraction

September 1, 2000

Author(s)

T Siegrist, C Svensson, Terrell A. Vanderah, Robert S. Roth

The crystal structure of Ba 11Fe 8Ti 9O 41 was determined using single-crystal and powder X-ray diffraction nethods. This new phase crystallizes in the hexagonal space group P6 3/mmc (No 194) (a=5.7506(3) , c=61.413(2) ; Z=2; Pcalc=5.75 g/cm 3) and

Use of Instrumented Indentation to Determine Mechanical Properties of Thin Films, Coatings and Functionally Graded Materials

August 10, 2000

Author(s)

Douglas T. Smith

Instrumented indentation testing is an effective local probe of the elastic and plastic properties of a material, and is particularly useful in the study of films and coatings, where traditional bulk tension or compression tests typically cannot be used

Assessment of Moisture Measurement Techniques for Ceramic Processing

August 1, 2000

Author(s)

P S. Wang

This report presents an assessment of moisture measurement tests by techniques currently available for ceramic processing applications. The techniques tested include near infrared, microwave, proton nuclear magnetic resonance, magnetic resonance imaging

Comparative of Texture Analysis Techniques for Highly Oriented a-Al 2 O 3

August 1, 2000

Author(s)

M M. Seabugh, Mark D. Vaudin, James Cline, G L. Messing

Texture measurements were performed on liquid phase sintered alumina textured by a templated grain growth process. Texture distributions were measured using four techniques (x-ray pole figure, rocking curve, and Rietveld refinement and stereological

Cracking of Brittle Coatings Adhesively Bonded to Substrates of Unlike Modulus

August 1, 2000

Author(s)

K -. Lee, Y W. Rhee, Douglas H. Blackburn, Brian R. Lawn, H Chai

The role of elastic mismatch in determining critical conditions for indentation fracture in brittle coatings on substrates of unlike modulus is investigated. A model transparent trilayer system, consisting of a glass coating layer bonded to a thick

Magnetic Behavior of Atomically Engineered NiO-Co-Cu-based Giant Magnetoresistance Spin Valves Pb as a Surface Modifier

August 1, 2000

Author(s)

H D. Chopra, E J. Repetski, H J. Brown, P J. Chen, L Swartzendruber, William F. Egelhoff Jr.

The present study illustrates the efficacy of using surface modifiers, or simply surfactants, to alter, modify, or control the nature of interfaces and film morphology in order to control physical properties in magnetic multilayers. In particular, the

Molecular Orientation of Single and Two-Armed Monodendron Semifluorinated Chains on Soft and Hard Surfaces Studied Using NEXAFS

August 1, 2000

Author(s)

Jan Genzer, E Sivaniah, E K. Kramer, J G. Wang, M Xiang, K Char, Christopher K. Ober, Robert A. Bubeck, Daniel A. Fischer, M Graupe, R Colorado, O E. Shmakova, T R. Lee

Near-edge absorption fine structure (NEXAFS) measurements are used to probe the molecular orientation of semifluorinated (SF) mesogens, -(CH 2)x(CF 2)yF, which are attached to I) the isoprene backbone of polyisoprene or a styrene-isoprene diblock copolymer

Phonons and Static Dielectric Constant in CaTiO 3 From First Principles

August 1, 2000

Author(s)

Eric J. Cockayne, Benjamin P. Burton

CaTiO 3 has a static dielectric constant that extrapolates to a value greater than 300 at zero temperature. We investigate the origin of this large dielectric response on a microscopic level, using first-principles plane-wave pseudopotential density

Surface Stability in Liquid-Crystalline Block Copolymers With Semifluorinated Monodendron Side Groups

August 1, 2000

Author(s)

M Xiang, X Li, Christopher K. Ober, K Char, Jan Genzer, E Sivaniah, E K. Kramer, Daniel A. Fischer

Block copolymers with semifluorinated monodendron side groups were synthesized by attachement of a first generation 2-or 3-armed monodendron acid chloride to a hydroxylated poly(styrene-b-1,2/3,4-isoprene). A convergent growth strategy was developed to

Thermal-Conductivity Apparatus for Steady-State, Comparative Measurement of Ceramic Coatings

August 1, 2000

Author(s)

Andrew J. Slifka

An apparatus has been developed to measure the thermal conductivity of thermal barrier coatings. Since the method uses an infrared microscope for temperature measurement, coatings as thin as 20 υm can, in principle, be measured using this technique. The

Vortex Pinning in Microindented Yba 2 Cu 3 O 7-x Single Crystals

August 1, 2000

Author(s)

Marina Turchinskaya, Douglas T. Smith, Alexander L. Roytburd, Debra L. Kaiser

A high resolution magneto-optical technique with a magnetic indicator film was used to study the effect of a regular array of micrometer-sized mechanical indentations on magnetization dynamics at the surface of a twinned single crystal of Yba 2Cu 3O 7-δ as

Certification of Ceramic Particle Size Distribution Reference Materials at NIST

July 17, 2000

Author(s)

James F. Kelly, P Pei

The availability of certified or reference particle size distributions has become increasingly important for the testing and certification of equipment used in size analysis. We describe here the currently available NIST Standard Reference Materials (SRMs)

A Nanocomposite Poly(Methyl-Methacrylate) Bone Cement

July 1, 2000

Author(s)

A H. Gomoll, A Bellare, W Fitz, T S. Thornhill, R D. Scott, P R. Jemian, Gabrielle G. Long

Poly(methyl methacrylate) (PMMA) based orthopaedic bone cements contain 1-3 micro υ size radiopacifier particles. Incomplete dispersion of these particles leads to the presence of 50-200 micro υ size agglomerates. These large defects are sites of high

Abrasive Machining of Glass-Ceramics With a Dental Handpiece

July 1, 2000

Author(s)

X Dong, L Yin, S Jahanmir, L K. Ives, E D. Rekow

Machinable glass ceramics are used to prepare dental restorations with modern dental CAD/CAM systems. Unfortunately, little is understood about the influence of mahining parameters on material removal rates and any damage which could be introduced into the

Effect of Interfacial Layers on Wear Behavior of a Dental Glass-Ceramic

July 1, 2000

Author(s)

A Ravikiran, S Jahanmir

Wear studies on a glass-ceramic dental restorative material were performed under two types of lubrication conditions with distilled water. In one set of experiments, the contact interface was continuously flushed with fresh water to remove the wear debris

Fracture and the Structure of Silica

July 1, 2000

Author(s)

Stephen W. Freiman

Not only because of its historic and widespread use in applications where its strength and brittle nature are significant factors, but also because it is homogeneous in composition and structure, and isotropic in its properties, glass is an ideal medium in

Keys to the Enhanced Performance of Mercuric Iodide Radiation Detectors Provided by Diffraction Imaging

July 1, 2000

Author(s)

B W. Steiner, L van den Berg, U Laor

High resolution monochomatic diffraction imaging is playing a central role in the optimization of novel high energy radiation detectors for superior energy resolution at room temperature. In the early days of the space program, the electronic transport

Microstructure and Chemistry of Non-Stoichiometric (Ba,Sr)TiO 3 Thin Films Deposited by Metalorganic Chemical Vapor Deposition

July 1, 2000

Author(s)

Igor Levin, Richard D. Leapman, Debra L. Kaiser

The microstructure and chemistry of (Ba,Sr)TiO 3 thin films deposited on Pt/SiO 2/Si substrates by metalorganic chemical vapor deposition were studied using high-resolution transmission electron microscopy and quantitative spectrum imaging in electron

Silicon Nitride Boundary Lubrication: Effect of Sulfonate, Phenate, and Salicylate Compounds

July 1, 2000

Author(s)

Richard S. Gates, Stephen M. Hsu

The boundary lubrication characteristics of sulfonates, phenates, and salicylates in a silicon nitride on silicon nitride contact were investigated. The additives were blended at one percent by weight solution in a purified paraffinic base oil and tested

Lattice Metric Singularities and Their Impact on the Indexing of Powder Patterns

June 8, 2000

Author(s)

Alan D. Mighell

A Lattice Metric Singularity occurs when unit cells defining two (or more) lattices yield the identical set of calculated d-spacings. The existence of such singularities, therefore, has a practical impact on the indexing of powder patterns. For example

Chemistry of NO 2 on CeO 2 and MgO: Experimental and Theorectical Studies on the Formation of NO 3

June 1, 2000

Author(s)

J A. Rodriguez, T Jirsak, S Sambasivan, Daniel A. Fischer, A Maiti

In environmental catalysis the destruction or removal of nitrogen oxides (DeNOx process) is receiving a lot of attention. Synchrotron-based x-ray absorption near-edge spectroscopy, high-resolution photoemission, and first-principles density-functional