L. Heatherly

Oak Ridge National Laboratory

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R.E. Clausing

Oak Ridge National Laboratory

A. Goyal

University at Buffalo, State University of New York

L. C. Emerson

Universidade Federal do Amazonas

M. Paranthaman

Oak Ridge National Laboratory

E.P. George

Ruhr University Bochum

C.T. Liu

City University of Hong Kong

Keith J. Leonard

Oak Ridge National Laboratory

E. D. Specht

Oak Ridge National Laboratory

S. Sathyamurthy

American Superconductor (United States)

P.M. Martin

Université de Bordeaux

Cooperative Institutions

Oak Ridge National Laboratory

149

University of Tennessee at Knoxville

Knoxville College

United States Department of Energy

Princeton Plasma Physics Laboratory

Joint European Torus

University of Houston

Forschungszentrum Jülich

General Atomics (United States)

Office of Scientific and Technical Information

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Complementary aes and aem of grain boundary regions in irradiated γ'-strengthened alloys

Journal of Nuclear Materials (1986)

K. Farrell N. Kishimoto R.E. Clausing L. Heatherly G.L. Lehman

Auger electron spectroscopy

10.1016/0022-3115(86)90131-5

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Citations (3)

Electron microscopy of growth features on filament assisted CVD diamond films

R.E. Clausing L. Heatherly Karren L. More G. M. Bègun

Scanning and transmission electron microscopy (SEM and TEM) have been used to examine the topographic and internal features of diamond films grown by the hot filament assisted chemical vapor deposition method. Films were grown under conditions chosen to provide three distinctly different diamond microstructures. This paper relates internal and external growth features to each other, to Raman spectra, and to the growth conditions. The growth features are discussed in terms of growth mechanisms. 10 refs., 8 figs.

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Citations (1)

High-Performance High- T _c Superconducting Wires

Science (2006)

Sang Yull Kang A. Goyal Jia Li A. A. Gapud P.M. Martin

We demonstrated short segments of a superconducting wire that meets or exceeds performance requirements for many large-scale applications of high-temperature superconducting materials, especially those requiring a high supercurrent and/or a high engineering critical current density in applied magnetic fields. The performance requirements for these varied applications were met in 3-micrometer-thick YBa2Cu3O(7-delta) films epitaxially grown via pulsed laser ablation on rolling assisted biaxially textured substrates. Enhancements of the critical current in self-field as well as excellent retention of this current in high applied magnetic fields were achieved in the thick films via incorporation of a periodic array of extended columnar defects, composed of self-aligned nanodots of nonsuperconducting material extending through the entire thickness of the film. These columnar defects are highly effective in pinning the superconducting vortices or flux lines, thereby resulting in the substantially enhanced performance of this wire.

Supercurrent

Nanodot

Pulsed Laser Deposition

10.1126/science.1124872

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Citations (410)

Helium gas release due to grain boundary fracture in neutron-irradiated high-nickel austenitic alloys and a ferritic steel

Journal of Nuclear Materials (1991)

N. Kishimoto R.E. Clausing L. Heatherly K. Farrell

Embrittlement

Brittleness

10.1016/0022-3115(91)90259-a

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Citations (4)

Textures and morphologies of chemical vapor deposited (CVD) diamond

R.E. Clausing L. Heatherly L.L. Horton E. D. Specht G. M. Bègun

The textures, surface morphologies, structural perfection, and properties of diamond films grown by activated chemical vapor deposition (CVD) vary greatly with the growth conditions. The evolution of two commonly observed polycrystalline morphologies, which give rise to textures, will be described as well as the development of four films grown to produce , , and near '' textures with various combinations of growth facets. These films were grown to test models of texture development. Films free of twins, microtwins, and stacking faults are deposited when only (100) facets are permitted to grow. In polycrystalline materials, special conditions must be met to avoid the formation of planar defects at the peripheries of individual crystallites. The planar defects grow from (111) or mixed microfaceted surfaces. Twinning plays an important role in growth of (111) faceted surfaces. The films have been characterized with Raman spectroscopy, x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical methods. 13 refs., 7 figs.

Texture (cosmology)

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Crystalline phase development during vacuum conversion of thin barium fluoride precursor films on metallic substrates

Physica C Superconductivity (2003)

F.A. List E. D. Specht L. Heatherly Keith J. Leonard S. Sathyamurthy

Barium fluoride

Barium

Torr

Reaction rate

Atmospheric temperature range

10.1016/s0921-4534(03)00965-1

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Citations (19)

Versatile UHV sample transfer system

Journal of Vacuum Science and Technology (1979)

R.E. Clausing L. Heatherly L. C. Emerson

A vacuum transfer system has been developed that allows samples to be inserted from air into an Auger analyzer. Following an initial analysis they may then be moved to and from a separate vacuum chamber for other studies. The system is constructed of standard UHV components and can be fabricated to cover any desired transfer distance. All-metal sealed valves isolate the various chambers so that the vacuum integrity of each is maintained. The sample size is limited only by the smallest constriction within the components, which is 2 cm in the system described. The transfer is rapid and is capable of being controlled remotely for use in a hostile environment.

Ultra-high vacuum

Vacuum chamber

Sample (material)

10.1116/1.570063

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Citations (14)

Effects of processing on the microstructure and mechanical behavior of binary Cr–Ta alloys

Materials Science and Engineering A (2002)

Y. H. He Peter K. Liaw Yu‐Lin Lu C.T. Liu L. Heatherly

Directional solidification

Fractography

10.1016/s0921-5093(01)01609-4

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Citations (7)

Textures and morphologies of chemical vapor deposited (CVD) diamond

Diamond and Related Materials (1992)

R.E. Clausing L. Heatherly L.L. Horton E. D. Specht G. M. Bègun

Texture (cosmology)

10.1016/0925-9635(92)90139-f

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Citations (86)

Hydrogen–deuterium changeover experiments in a plasma-wall interaction simulator

Journal of Vacuum Science and Technology (1982)

R.E. Clausing L. Heatherly L. C. Emerson

Hydrogen recycling from walls and limiters of tokamaks constitutes the major source of plasma particles after the initial few milliseconds of a plasma pulse. The physical processes involved in recycling are thus very important to the control of plasma density and composition. Isotope changeover experiments in the laboratory show that thermally activated processes such as recombination and diffusion play significant roles in recycling. These processes are important not only during the plasma pulse but also continue after the plasma pulse ends, thus the length of time between pulses, the wall temperature, and the vacuum pumping rate all influence changeover dynamics. This paper shows that for type 304 stainless steel walls changeover can range from ≳95% to <50% complete in one 200 ms pulse depending upon these parameters. The initial part of changeover during a plasma pulse is very rapid and involves equilibrating the isotopic compositions of the plasma reservoir and the near-surface wall hydrogen reservoir involved in recycling. The rate limiting step then seems to become vacuum pump-out rates. Because one of the steps in gas evolution during and after the pulse is the recombination process, which is dependent on the square of the surface hydrogenic concentration, changeover can be accelerated if the hydrogenic concentration at the surface is kept high by repeated plasma pulses in the new isotope. The old isotope is evolved as HD.

Changeover

Kinetic isotope effect

10.1116/1.571557

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Citations (2)