45 Result(s)

Chapter

Magnetization, Flux Creep and Transport in Tl-Ca-Ba-Cu-O Thin Films

The enormous experimental and theoretical effort on high-temperature copper-oxide-based superconductors began with the La-Ba-Cu-O system [1], shifted to the Y-Ba-Cu-O system [2], and recently has focused on th...

E. L. Venturini, J. F. Kwak, D. S. Ginley… in Science and Technology of Thin Film Superc… (1989)

Chapter

Preparation of Thin and Thick Film Superconductors in the Tl-Ca-Ba-Cu-O System

The advent of high temperature superconductivity in Cu-O based materials has catalyzed a tremendous amount of activity in the synthesis, characterization and application of these materials [1]. The recent disc...

D. S. Ginley, J. F. Kwak, E. L. Venturini… in Science and Technology of Thin Film Superc… (1989)

Article

Chemical Preparation of Powders and Films for High Temperature Superconductors

A precipitation process has been developed to prepare precursor powders which can be calcined and sintered to form high critical temperature superconductors such as YBa₂Cu₃O_7−x. Precursor powders are prepared usi...

B. C. Bunker, J. A. Voigt, D. L. Lamppa, D. H. Doughty… in MRS Online Proceedings Library (1988)

Article

Synthesis and Properties of YBaSrCu₃O_6.9 Prepared from Soluble Precursors

Solution chemistry routes have been used to prepare single-phased superconducting ceramics of YBaSrCu₃O_6.9 (1113). Resistivity measurements on air annealed samples showed a superconducting onset temperature of 85...

Paul J. Nigrey, J. F. Kwak, E. L. Venturini… in MRS Online Proceedings Library (1988)

Article

Improved Magnetization for YBa₂Cu₃O_7-δ Annealed in Oxygen Above 1000°C

Air sintering and subsequent oxygen annealing at high temperatures are integral to the production of ceramic superconducting YBa₂Cu₃O_7-δ. We present results directed toward optimizing the temperature for these tw...

E. L. Venturini, D. S. Ginley, R. J. Baughman, B. Morosin… in MRS Online Proceedings Library (1987)

Article

Origin of Paramagnetic Defect in Single Crystal and Ceramic B₄C

We compare electron spin resonance (ESR) spectra of B₄C samples made by three methods. The samples are 1) two ceramics made by hot-pressing boron and carbon powders, 2) a polycrystal made by carbothermic reductio...

E. L. Venturini, D. Emin, T. L. Aselage in MRS Online Proceedings Library (1987)

Article

Bulk Ceramic and Screen Printed EuBa₂Cu₃O_7-δ

The structural, magnetic and electrical properties of EuBa₂Cu³O_7-δ have been investigated both for bulk ceramics and screen printed thick films. The bulk ceramic reaches zero resistance at 92 K, and has large int...

W. S. Fu, D. S. Ginley, M. A. Mitchell, E. L. Venturini… in MRS Online Proceedings Library (1987)

Article

Freestanding Films of YBa₂cu₃O_6.9

Thick (20–300 /im) freestanding films of ceramic YBa₂Cu₃O_0–9 have been obtained by resintering YBa₂Cu₃O_0–9 powder in air after screen printing onto fused silica substrates. An interfacial reaction occurs between ...

D. S. Ginley, M. A. Mitchell, W. Fu, J. F. Kwak… in MRS Online Proceedings Library (1987)

Article

Bulk Superconductivity in La₂CuO₄

J. E. Schirber, E. L. Venturini, B. Morosin, J. F. Kwak… in MRS Online Proceedings Library (1987)

Article

Reoxygenation of vacuum-annealed YBa₂Cu₃O_6.9

Vacuum-annealed samples of single-phase orthorhombic YBa₂Cu₃O_6.9 have been reoxygenated. The vacuum-annealed material is tetragonal, semiconducting at room temperature, and shows no superconductivity. Upon anneal...

D. S. Ginley, P. J. Nigrey, E. L. Venturini, B. Morosin… in Journal of Materials Research (1987)

Article

Variation of the pressure dependence of the superconducting transition temperature with x in La_1−xSr_x CuO₄

Hydrostatic pressure measurements of the superconducting transition temperature were made as a function of x in La_2−xSr_x CuO₄. A sharp change in the behavior occurs between x = 0.2 and 0.25 in that the pressure d...

J. E. Schirber, E. L. Venturini, J. F. Kwak, D. S. Ginley… in Journal of Materials Research (1987)

Chapter

Grain Decoupling at Low Magnetic Fields in Ceramic YBa₂Cu₃O_7-δ

The ongoing series of discoveries of new materials with ever higher transition temperatures has generated an unprecedented flood of research activity in recent months, particularly on the 90 K superconductors ...

J. F. Kwak, E. L. Venturini, D. S. Ginley, W. Fu in Novel Superconductivity (1987)

Chapter

X-Ray Diffraction Studies of Shock-Synthesized Zinc Ferrite

Mechanically-blended stoichiometric powder mixtures of zinc oxide and ferric oxide have been subjected to high pressure shock wave loading between 7.5 and 27 GPa. By varying the initial packing densities betwe...

B. Morosin, E. L. Venturini, R. A. Graham in Shock Waves in Condensed Matter (1986)

Chapter

Mossbauer Study of Shock-Synthesized Zinc Ferrite

Mössbauer spectroscopy has been used to characterize ZnO-Fe₂O₃ powder mixtures subjected to shock loading at 22 GPa with associated peak shock temperatures ranging from 300°C to 655°C. The ⁵⁷Fe spectra for the sh...

D. L. Williamson, B. Morosin, E. L. Venturini… in Shock Waves in Condensed Matter (1986)

Chapter

Deuteron Magnetic Resonance in a-Zr₂PdD_2.9

Deuteron Magnetic Resonance (DMR) measurements at 30.7 MHz have been performed on an a-Zr₂PdD_2.9 sample between 19 and 460 K. A Bruker CXP 200 spectrometer and a cryogenic probe were used to examine Fourier trans...

V. P. Bork, P. A. Fedders, R. E. Norberg… in Hydrogen in Disordered and Amorphous Solids (1986)

Chapter

Magnetic Properties of Shock-Synthesized and Furnace-Reacted Zinc Ferrite

The static magnetic properties of spinel structure zinc ferrite are compared for products from shock synthesis and conventional isothermal reaction using a stoichiometric mixture of zinc oxide and ferric oxide...

E. L. Venturini, B. Morosin, R. A. Graham in Shock Waves in Condensed Matter (1986)

Chapter

Subthreshold Generation of Free Radicals in Shock-Loaded Organic Solids

A wide variety of chemical reactions have been observed in organic compounds subjected to shock loading [1]. A shock wave in condensed media produces a unique and violent environment which is characterized by ...

Brian W. Dodson, E. L. Venturini, J. W. Rogers Jr. in Shock Waves in Condensed Matter (1986)

Chapter

Chemical Synthesis under High Pressure Shock Loading

Many reports of chemical synthesis under high pressure shock loading have been published over the past thirty years, but little progress has been made in develo** an understanding of the mechanisms responsib...

R. A. Graham, B. Morosin, Y. Horie, E. L. Venturini… in Shock Waves in Condensed Matter (1986)

Chapter

Shock-Induced Modification of Inorganic Powders

Early exploratory work in Japan,^{1, 2} the Soviet Union^{3, 4} and the United States^{5, 6} demonstrated that high pressure shock-wave loading such as produced by the detonation of high explosives or high speed projectil...

R. A. Graham, B. Morosin, E. L. Venturini… in Emergent Process Methods for High-Technolo… (1984)

Chapter

Densification Kinetics of Shock-Activated Nitrides

In 1966, Bergmann and Barrington¹ reported that, for a variety of oxide and carbide powders, improvement in the sintering behavior was obtained when the powders were subjected to explosive shock treatment. They c...

E. K. Beauchamp, R. E. Loehman, R. A. Graham… in Emergent Process Methods for High-Technolo… (1984)