29 Result(s)

Article

Metallic Microwave Conductivity in Shock-Loaded Rutile

Electron spin resonance (ESR) has been used to characterize the paramagnetic defects present in both single crystal and powder rutile (TiO₂) subjected to explosive shock loading and preserved for post-shock study...

E. L. Venturini, R. A. Graham in MRS Online Proceedings Library (1983)

Article

Transmission Electron Microscopy of Shock-Modified and Annealed Rutile

The annealing behavior of shock modified rutile (TiO₂) powder was studied by transmission electron microscopy, x-ray line broadening, and electron spin resonance. Specimens were examined in the as-received and as...

M. J. Carr, R. A. Graham, B. Morosin, E. L. Venturini in MRS Online Proceedings Library (1983)

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)

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

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

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

Freestanding thick films of YBa₂Cu₃O_6.9 by screenprinting techniques

Thick (20–300 μm) freestanding polycrystalline films of ceramic YBa₂Cu₃O_6.9 have been obtained by resintering YBa₂Cu₃O_6.9 powder in air after screen printing onto fused silica substrates. An interfacial reaction ...

D. S. Ginley, M. A. Mitchell, J. F. Kwak, E. L. Venturini… in Journal of Materials Research (1989)

Article

Annealing and Strain Effects on Tl-Ba-Ca-Cu-O Crystals and Ceramics

Superconducting transition temperatures (T_c’S) in the Tl-Ba-Ca-Cu-O system are shown to be a function of processing for both single crystals and bulk ceramics. Crystals with the identical structural phase and nom...

E. L. Venturini, B. Morosin, D. S. Ginley, J. F. Kwak… in MRS Online Proceedings Library (1989)

Article

Cation Disordering in the Tl-2122 Superconductors

We have examined several crystals belonging to the Tl-2122 structure type (Tl₂CaBa₂Cu₂O₈ with c=29Å), and have shown that cation solid solution occurs. Such cation disorder appears to be responsible for the obser...

B. Morosin, D. S. Ginley, E. L. Venturini, R. J. Baughman… in MRS Online Proceedings Library (1989)

Article

Superconductivity and Stoichiometry in Tl₂Ca₂Ba₂Cu₃O_x Single Crystals

Magnetization and resistivity data are presented which show a substantial difference in superconducting transitions for nominal Tl₂Ca₂Ba₂Cu₃O_x plates with identical crystal structures grown from two different “me...

E. L. Venturini, C. P. Tigges, R. J. Baughman… in MRS Online Proceedings Library (1989)

Article

Ion-Irradiation Effects in Tl₂Ca₂Ba₂Cu₃0₁₀ Superconductors

The effects of oxygen and helium ion irradiation on the superconducting properties of Tl₂Ca₂Ba₂Cu₃0₁₀ thin films were investigated. The transition temperature and width were monitored as a function of ion fluence...

J. C. Barbour, J. F. Kwak, E. L. Venturini, D. S. Ginley… in MRS Online Proceedings Library (1989)

Article

Novel Processing of Hts Based Conductors

Conductor development is one of the major long term goals in high temperature superconductor research. In this paper we report on two promising processing technologies that have been utilized to produce superc...

D. S. Ginley, E. L. Venturini, J. F. Kwak, R. J. Baughman… in MRS Online Proceedings Library (1989)

Article

Rapid Thermal Processing Of High Temperature Superconducting Fiber

We report on the rapid thermal processing (RTP) of YBa₂Cu₃O₇ (Y-123) fibers. Unsintered fibers are densified by RTP. We show that fibers which were originally semiconducting and tetragonal before RTP form normal ...

J. W. Halloran, M. J. Neal, D. S. Ginley, E. L. Venturini… in MRS Online Proceedings Library (1990)

Article

Tl-Based Films: A Comparison of Processing Procedures

The structural, electrical and magnetic properties are compared for three superconducting Tl-Ca-Ba-Cu-O thin films prepared by different deposition and sintering protocols. One film containing a mixture of Tl₂Ca₂

B. Morosin, E. L. Venturini, C. P. Tigges, D. S. Ginley… in MRS Online Proceedings Library (1992)

Article

Structural studies on Tl–Ca–Ba–Cu−0 superconducting thin films

The microstructure of mixed phase, c-axis oriented Tl–Ca–Ba–Cu–O thin films, exhibiting excellent superconducting properties, has been examined by transmission electron microscopy and x-ray diffraction. Although ...

Bruno Morosin, Grant M. Norton, Barry C. Carter… in Journal of Materials Research (1993)