29 Result(s)
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Article
E. L. Venturini
Materials Science
Nanotechnology
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Article
Microscopic Study of Metal Hydrides Using Electron Spin Resonance
Electron spin resonance (ESR) of dilute paramagnetic ions in nonmagnetic metallic hydrides provides microscopic information about the hydrogen ions in the immediate vicinity of the impurity. By comparing ESR s...
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Article
Stability of Tl–Ba–Ca–Cu–O superconducting thin films
We report the stability of TlBa2CaCu2O7 and Tl2Ba2CaCu2O8 on LaAlO3(100) epitaxial thin films, under a variety of conditions. All films are stable in acetone and methanol and with repeated thermal cycling to cryo...
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Article
A new hybrid two-zone/crucible furnace process for the growth of epitaxial Tl2Ba2CaCu2O8 superconducting films
Epitaxial Tl2Ba2CaCu2O8 (Tl-2212) films ∼5500 Å thick are grown on LaAlO3(100) substrates using a new hybrid two-zone/crucible furnace process enabling precise control of thallination. This method combines the be...
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Article
Correlation of Intermediate Ion Energy Induced Extended Defect Continuity to Enhanced Pinning Potential in Tl-2212 Films
Lattice defects are introduced into the structure to suppress the motion of magnetic vortices and enhance the critical current density in high temperature superconductors. Point defects are not very effective ...
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Article
Synthesis and properties of Tl–Ba–Ca–Cu–O superconductors
We review the synthesis methods and properties of single crystal, powder, and thin film TlBaCaCuO high-temperature superconducting (Tl-HTS) materials. With transition temperatures ≥ 100 K for several compounds...
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Article
HRTEM of Extended Defects in TL-2212 Thin Films
Many applications of high temperature superconductors, HTS, require the presence of lattice defects in the material structure to suppress the motion of magnetic vortices and enhance the critical current densit...
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Article
Stability of the Tl-1223 phases
The thermodynamic stability of TlBa2Ca2Cu3O9–y (1223) and substitutionally related phases has been studied by performing extended high-temperature anneals in a two-zone furnace. This approach allows for independe...
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Article
Magnetic Properties of Nanosize Iron Clusters
Isolated, monodisperse α-Fe clusters between 1.4 and 15 nm in diameter were prepared inside inverse micelles using an oil-continuous, nonaqueous system. The magnetic properties of these clusters were studied i...
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Article
Two-zone annealing of Tl0.5Pb0.5(Sr0.8Ba0.2)2Ca2Cu3Oy
Stable conditions have been identified for two-zone processing of the superconducting thallium cuprate Tl0.5Pb0.5(Sr0.8Ba0.2)2Ca2Cu3Oy. With P(O2) of 0.8 atm, P(Tl2O) of 4.4 × 10−3 atm, and a sample temperature o...
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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 ...
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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
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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 ...
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Article
Annealing and Strain Effects on Tl-Ba-Ca-Cu-O Crystals and Ceramics
Superconducting transition temperatures (Tc’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...
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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...
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Article
Superconductivity and Stoichiometry in Tl2Ca2Ba2Cu3Ox Single Crystals
Magnetization and resistivity data are presented which show a substantial difference in superconducting transitions for nominal Tl2Ca2Ba2Cu3Ox plates with identical crystal structures grown from two different “me...
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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...
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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...
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Article
Freestanding thick films of YBa2Cu3O6.9 by screenprinting techniques
Thick (20–300 μm) freestanding polycrystalline films of ceramic YBa2Cu3O6.9 have been obtained by resintering YBa2Cu3O6.9 powder in air after screen printing onto fused silica substrates. An interfacial reaction ...
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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 YBa2Cu3O7−x. Precursor powders are prepared usi...
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Article
Synthesis and Properties of YBaSrCu3O6.9 Prepared from Soluble Precursors
Solution chemistry routes have been used to prepare single-phased superconducting ceramics of YBaSrCu3O6.9 (1113). Resistivity measurements on air annealed samples showed a superconducting onset temperature of 85...
