Critical current in high Tc grain boundary junctions

1998 ◽  
Vol 84 (7) ◽  
pp. 3972-3979 ◽  
Author(s):  
Jerome A. Luine ◽  
Vladimir Z. Kresin
Keyword(s):  
Grain Boundary ◽  
Critical Current ◽  
High Tc

Grain Boundary Structure and Properties of High-Tc Superconductors

1992 ◽  
Vol 275 ◽  
Author(s):  
K. Jagannadham ◽  
J. Narayan
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Boundary Effects ◽  
Boundary Structure ◽  
Excess Charge ◽  
High Tc Superconductors ◽  
High Tc ◽  
Grain Boundary Structure

ABSTRACTWe have modelled the grain boundaries in high-Tc superconducting oxides and determined the critical current density. The tunneling of superconducting pairs across the coalesced regions is used to determine the boundary effects. The length of the coalesced regions, with continuity of the Cu-O planes maintained by relaxation of the atom positions, is determined by minimization of the energy of the configuration. The depression of the order parameter is evaluated using the continuity conditions at the boundary in the proximity effect formulation. The excess charge distribution at the core of the boundary, determined from the solution to the Poisson's equation, is used to determine the scattering of the superconducting pairs. The width of the boundary, evaluated from modelling, determines the transmission coefficient for tunnelingof superconducting pairs. The critical current density is expressed in terms of these four important factors associated with the grain boundary. All the experimental results are explained by the present modelling of the grain boundary effects.

High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

1988 ◽  
Vol 46 ◽  
pp. 882-883
Author(s):  
H.-J. Ou ◽  
J. M. Cowley
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Grain Boundary ◽  
Strong Field ◽  
Imaging Study ◽  
Structure Defects ◽  
High Tc ◽  
High Tc Superconductor ◽  
Diffraction Patterns ◽  
Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

1996 ◽  
Vol 54 ◽  
pp. 338-339
Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Electromagnetic Properties ◽  
Length Scale ◽  
Density Values ◽  
Current Densities ◽  
Applied Fields ◽  
A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

Grain-boundary links and critical current of tapes

1997 ◽  
Vol 10 (6) ◽  
pp. 444-449 ◽  
Author(s):  
P N Mikheenko ◽  
J Horvat ◽  
Q Y Hu ◽  
M Ionescu ◽  
S X Dou
Keyword(s):  
Grain Boundary ◽  
Critical Current

Preparation of Y-BA-CU Oxide Superconducting Composite Tapes by a Diffusion Process

1987 ◽  
Vol 99 ◽  
Author(s):  
K. Tachikawa ◽  
M. Sugimoto ◽  
N. Sadakata ◽  
O. Kohno
Keyword(s):  
Diffusion Process ◽  
Critical Current ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Oxide Compound ◽  
High Tc ◽  
Powder Metallurgical Process ◽  
Current Densities ◽  
Wire Fabrication ◽  
Made In

Since discovery of the Y-Ba-Cu oxide compound showing superconductivity above liquid nitrogen temperature, intensive study has been under way to clarify nature of the high Tc oxides[l-4]. Much efforts were also made in the field of superconductor applications. A number of studies have been carried out by a powder metallurgical process of Y-Ba-Cu oxide compound wires, although, obtained critical current densities were still low at liquid nitrogen temperature[5–6]. Other techniques for wire fabrication is also being attempted[7–9]. In this study, Y-Ba-Cu oxide superconducting composite tapes were prepared by a diffusion process, which is one of the promising methods to obtain a high critical current density.

Sign in / Sign up

Export Citation Format

Share Document