A Process for Producing “Granular Single Crystals” of Ceramics from Polycrystals by Biaxial Alignment, Demonstrated for High-Tc Superconductors

1991 ◽  
Vol 249 ◽  
Author(s):  
Rafael Hidalgo ◽  
Xin-Yu Zhanl ◽  
Sheng-Qi Wang ◽  
Baoshan Zhang ◽  
Jian-Zhong Zhang ◽  
...  
Keyword(s):  
Earth Element ◽  
Cuprate Superconductors ◽  
Weak Links ◽  
High Tc Superconductors ◽  
New Approach ◽  
High Tc ◽  
Step Procedure ◽  
Suitable Combination ◽  
The Moment ◽  
Biaxial Alignment

ABSTRACTA recently developed method for producing triaxial alignment of single crystalline grains may be applicable to ceramics other than the high-Tc cuprate superconductors for which it was designed as a means of reducing the grain boundary weak links due to grain orientational misfit. This technique uses a suitable combination of a mechanical force and a magnetic field acting on the moment of a rare earth element incorporated into the ceramic; a "granular single crystal" is thus formed. A detailed step-by-step procedure is presented here to facilitate use of the new approach.

ENERGY BAND OVERLAPPING IN HIGH-Tc SUPERCONDUCTORS

1996 ◽  
Vol 10 (30) ◽  
pp. 1483-1490 ◽  
Author(s):  
M. MORENO ◽  
R. M. MÉNDEZ-MORENO ◽  
M. A. ORTIZ ◽  
S. OROZCO
Keyword(s):  
Weak Coupling ◽  
Cuprate Superconductors ◽  
Weak Coupling Limit ◽  
Band Model ◽  
Coupling Constant ◽  
High Tc Superconductors ◽  
Energy Bands ◽  
Effective Coupling ◽  
High Tc ◽  
Two Band Model

Multi-band superconductors are analyzed and the relevance of overlapping energy bands to the high-T c of these materials is studied. Within the BCS framework, a two band model with generalized Fermi surface topologies is developed. Values of the overlapped occupancy parameters for typical cuprate superconductors are obtained as a function of the ratio R and the effective coupling constant, λ, in the weak-coupling limit. The overlap scale is of the order or lower than the cutoff (Debye) energy. The typical behavior of the isotope effect is obtained. As these superconductors have transition temperatures above the phonon barrier, the results of this approach are important to the generic understanding of the high-T c superconducting mechanism.

New high-Tc superconductors without rare earth element

1988 ◽  
Vol 153-155 ◽  
pp. 602-607 ◽  
Author(s):  
Hiroshi Maeda ◽  
Yoshiaki Tanaka ◽  
Masao Fukutomi ◽  
Toshihisa Asano ◽  
Kazumasa Togano ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
High Tc Superconductors ◽  
High Tc

THE MULTILAYERED HIGH Tc SUPERCONDUCTORS; THE JOSEPHSON MODEL OF WEAK LINKS

1995 ◽  
Vol 09 (21) ◽  
pp. 2811-2820
Author(s):  
VALERY A. CHERENKOV
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Temperature Superconductors ◽  
Weak Links ◽  
High Tc Superconductors ◽  
Main Attention ◽  
Multilayered Structures ◽  
High Tc ◽  
Stimulation Of

The multilayered (N-S(D)-N)-types structures have been observed: there are the traditional Niobium low-temperature superconductors and new high-temperature superconductors. The main attention had been directed to the anisotropy, defectively and the stimulation of the superconductivity in the multilayered structures.

The interaction of nanostripes and the twin structure in light-rare-earth-element-based 123-type high-Tc superconductors

2011 ◽  
Vol 471 (3-4) ◽  
pp. 66-70 ◽  
Author(s):  
M.R. Koblischka ◽  
A. Koblischka-Veneva ◽  
M. Muralidhar ◽  
Th. Wolf ◽  
N. Hari Babu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Light Rare Earth Element ◽  
Light Rare Earth ◽  
High Tc Superconductors ◽  
Twin Structure ◽  
High Tc

CRITICAL TEMPERATURE OF HIGH-Tc SUPERCONDUCTORS AND BOUNDARY CONDITIONS IN GINZBURG-LANDAU THEORY

2009 ◽  
Vol 23 (20n21) ◽  
pp. 4269-4276 ◽  
Author(s):  
A. LYKOV
Keyword(s):  
Boundary Condition ◽  
Critical Temperature ◽  
Order Parameter ◽  
Cuprate Superconductors ◽  
Landau Theory ◽  
Structural Elements ◽  
High Tc Superconductors ◽  
Ginzburg Landau ◽  
High Tc ◽  
Insulating Properties

New boundary condition for the order parameter in the Ginzburg-Landau theory is applied to the case of CuO 2 planes which are the main structural elements responsible for superconductivity in high-Tc superconductors. It was found that the order parameter in these superconductors is significantly depressed in the CuO 2 planes. As a result, this boundary condition to the GL equations is found to limit the critical temperature of high-Tc superconductors. Thus, in order to increase Tc of cuprate superconductors, the number of CuO 2 planes that are within a short distance of each other in unit cell or insulating properties of the layers located in the vicinity to the CuO 2 planes should be increased.

Biaxial alignment of high-Tc superconductor polycrystals VIII: Phi-circle scan analysis of EuBa2Cu3O7−δ (Eu-123)

1996 ◽  
Vol 11 (5) ◽  
pp. 1108-1113 ◽  
Author(s):  
Sheng-Qi Wang ◽  
Roberta A. Bigelow ◽  
Jian-Zhong Zhang ◽  
Carlos Bonetto ◽  
Bala Maheswaran ◽  
...  
Keyword(s):  
Large Angle ◽  
Weak Links ◽  
Magnetic Field Direction ◽  
New Paradigm ◽  
High Tc ◽  
Axis Alignment ◽  
Biaxial Alignment ◽  
High Degree ◽  
The Magnetic Field

To reduce grain boundary weak links due to large-angle grain orientation mismatch, bulk (thick film) EuBa2Cu3O7−δ high-Tc superconductor specimens were biaxially aligned by a mechanical force such that their [001] axes were perpendicular to the specimen surfaces and by a magnetic force so as to orient their [010] axes to lie parallel to the magnetic field direction in the specimen plane. We describe here the characterization of such EuBa2Cu3O7−δ thick films by φ-circle XRD scans of (013) reflections, demonstrating a high degree (33%) of c-axis alignment with FWHM of <5° and approximately Gaussian distributions of a, b-axis alignment with a FWHM of 47°. The formation of “granular single crystals”, toward which this work is a further advance, can be seen as establishing a new paradigm in ceramics science.

CAN POSITRON 2D–ACAR RESOLVE THE ELECTRONIC STRUCTURE OF HIGH-Tc SUPERCONDUCTORS?

1992 ◽  
Vol 06 (11) ◽  
pp. 617-635 ◽  
Author(s):  
L. P. CHAN ◽  
K. G. LYNN ◽  
D. R. HARSHMAN
Keyword(s):  
Electronic Structures ◽  
Cuprate Superconductors ◽  
Positron Lifetime ◽  
Short Description ◽  
Annihilation Radiation ◽  
High Tc Superconductors ◽  
High Tc ◽  
Theoretical Assumptions ◽  
Surface Measurements ◽  
Fine Structures

We examine the ability of the positron Two-Dimensional Angular Correlation Annihilation Radiation (2D-ACAR) technique to resolve the electronic structures of high-T c cuprate superconductors. Following a short description of the technique, discussions of the theoretical assumptions, data analysis and experimental considerations, in relation to the high-T c superconductors, are given. We briefly review recent 2D-ACAR experiments on YBa 2 Cu 3 O 7−x, Bi 2 Sr 2 CaCuO 8+δ and La 2−x Sr x CuO 4. The 2D-ACAR technique is useful in resolving the band crossings associated with the layers of the superconductors that are preferentially sampled by the positrons. Together with other Fermi surface measurements (namely angle-resolved photoemission), 2D-ACAR can resolve some of the electronic structures of high-T c cuprate superconductors. In addition, 2D-ACAR measurements of YBa 2 Cu 3 O 7−x and Bi 2 Sr 2 CaCuO 8+δ also reveal an interesting temperature dependence in the fine structures, and a change in the positron lifetime in the former.

A new approach for the growth of high-Tc superconductors

1996 ◽  
Vol 4 (4) ◽  
pp. 191-194
Author(s):  
J. Jaklovszky ◽  
G. Aldica ◽  
C. Rusu ◽  
A. Crisan
Keyword(s):  
High Tc Superconductors ◽  
New Approach ◽  
High Tc

A new approach to the design of high-Tc superconductors: Metallised interlayers

1996 ◽  
Vol 105 (5-6) ◽  
pp. 1379-1384 ◽  
Author(s):  
J. L. Tallon ◽  
C. Bernhard ◽  
Ch. Niedermayer ◽  
J. Shimoyama ◽  
S. Hahakura ◽  
...  
Keyword(s):  
High Tc Superconductors ◽  
New Approach ◽  
High Tc

COMMON MAGNETIC ORIGIN OF THE RESONANCE PEAK AND INCOMMENSURATION IN HIGH-Tc SUPERCONDUCTORS

2000 ◽  
Vol 14 (29n31) ◽  
pp. 3334-3341 ◽  
Author(s):  
C. D. BATISTA ◽  
G. ORTIZ ◽  
A. V. BALATSKY
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Cuprate Superconductors ◽  
Resonance Peak ◽  
Low Energy ◽  
Unified Theory ◽  
Superconducting Transition ◽  
High Tc Superconductors ◽  
High Tc ◽  
Magnetic Origin

We present a unified theory for the resonance peak and low-energy incommensurate response observed in high-Tc cuprate superconductors. The origin of both features is purely magnetic and they represent universal features signaling the existence of an incommensurate spin state both below and above the superconducting transition temperature. We argue that the resonance peak is the reflection of commensurate antiferromagnetism. Our theoretical scenario gives an account of the main universal features observed in various families of superconductors and predicts those that have not been observed yet experimentally.

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