Correlation between grain and grain-boundary critical current densities in ex situ coated conductors with variable YBa2Cu3O7−δ layer thickness

2006 ◽  
Vol 88 (12) ◽  
pp. 122502 ◽  
Author(s):  
A. Palau ◽  
T. Puig ◽  
X. Obradors ◽  
R. Feenstra ◽  
A. A. Gapud
Keyword(s):  
Grain Boundary ◽  
Critical Current ◽  
Layer Thickness ◽  
Coated Conductors ◽  
Ex Situ ◽  
Current Densities

Evidence for Extensive Grain Boundary Meander and Overgrowth of Substrate Grain Boundaries in High Critical Current Density ex Situ YBa2Cu3O7−x Coated Conductors

2005 ◽  
Vol 20 (8) ◽  
pp. 2012-2020 ◽  
Author(s):  
D.M. Feldmann ◽  
D.C. Larbalestier ◽  
T. Holesinger ◽  
R. Feenstra ◽  
A.A. Gapud ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Film Thickness ◽  
Critical Current ◽  
Current Density ◽  
Thick Films ◽  
Coated Conductors ◽  
Ex Situ ◽  
High Critical Current Density ◽  
Ybco Films

It has been generally accepted that YBa2Cu3O7−x (YBCO) films deposited on deformation textured polycrystalline metal tapes result in YBCO grain boundary (GB) networks that essentially replicate the GBs of the underlying substrate. Here we report that for thicker YBCO films produced by a BaF2 ex situ process, this is not true. Using electron backscatter diffraction combined with ion milling, we have been able to map the evolution of the YBCO grain structure and compare it to the underlying template in several coated conductors. For thin (≤0.5 μm) YBCO films deposited on rolling-assisted biaxially textured substrates (RABiTS), the YBCO GBs nearly directly overlap the substrate GBs. For 0.7–1.4 μm YBCO films, the GBs were found to meander along the substrate GBs and along the sample normal, with displacements several times the film thickness. In very thick films (2.5–2.9 μm), the YBCO grains can completely overgrow substrate grains and GBs, resulting in a substantial disconnection of the YBCO and substrate GB networks. Similar behavior is found for BaF2 ex situ YBCO films on ion-beam-assisted deposition-type templates. The ability of the YBCO to overgrow substrate grains and GBs is believed to be due to liquid-phase mediated laminar grain growth. Although the behavior of the YBCO GB networks changes with YBCO film thickness, the samples maintained high critical current density (Jc) values of >2 MA/cm2 for films up to 1.4 μm thick, and up to0.9 MA/cm2 for 2.5–2.9-μm-thick films.

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.

YBa2Cu3O7-y−coated conductors with high engineering current density

2000 ◽  
Vol 15 (12) ◽  
pp. 2647-2652 ◽  
Author(s):  
M. Paranthaman ◽  
C. Park ◽  
X. Cui ◽  
A. Goyal ◽  
D. F. Lee ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Critical Current ◽  
Current Density ◽  
Ybco Film ◽  
Pulsed Laser ◽  
Coated Conductors ◽  
Laser Deposition ◽  
Ex Situ ◽  
Layer Sequence ◽  
Ybco Coated Conductors

Short segments of YBa2Cu3O7-y (YBCO) coated conductors were fabricated on rolling-assisted biaxially textured substrates (RABiTS) with a layer sequence of CeO2/YSZ/Ni using an ex situ BaF2 precursor process. Pulsed laser deposition (PLD) was used to deposit both YSZ and CeO2 layers. The YBCO films were grown using e-beam coevaporated Y–BaF2–Cu precursors followed by postannealing. An overall engineering current density, JE, of 28,000 A/cm2 and critical current, Ic, of 147 A/cm width at 77 K were achieved for a 1.6-μm-thick YBCO film. This result demonstrates the possibility of using both the ex situ BaF2 precursor approach and the RABiTS process for producing long lengths of high-JE coated conductors.

Orientation dependence of grain-boundary critical current densities in high-Tcbicrystals

1995 ◽  
Vol 51 (10) ◽  
pp. 6792-6795 ◽  
Author(s):  
T. Amrein ◽  
L. Schultz ◽  
B. Kabius ◽  
K. Urban
Keyword(s):  
Grain Boundary ◽  
Critical Current ◽  
Orientation Dependence ◽  
Current Densities

Critical Current Densities of Isolated Grain Boundaries in Coated Conductors

2009 ◽  
Vol 19 (3) ◽  
pp. 3569-3572 ◽  
Author(s):  
M. Weigand ◽  
S. Speller ◽  
N.A. Rutter ◽  
G.M. Hughes ◽  
C. Grovenor ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Critical Current ◽  
Coated Conductors ◽  
Current Densities

Improved critical current densities in ex situ processed MgB2 tapes fabricated with chemically treated powder

2007 ◽  
Vol 22 (5) ◽  
pp. 1281-1285 ◽  
Author(s):  
H. Fujii ◽  
K. Togano ◽  
K. Ozawa
Keyword(s):  
Critical Current Density ◽  
Benzoic Acid ◽  
Acid Solution ◽  
Critical Current ◽  
Benzene Solution ◽  
Ex Situ ◽  
Chemically Treated ◽  
Current Densities ◽  
Powder In Tube ◽  
Mgo Layers

Fe-sheathed MgB2 tapes were fabricated using powder chemically treated through an ex situ process employing a powder-in-tube (PIT) technique. The treatment of MgB2 powder in a benzene solution of benzoic acid caused the pulverization and disappearance of large grains. Compared with the pristine powder without treatment, the tape made from this powder showed a fivefold increase in critical current density (Jc) in 10 T. This was due to the pulverization of grains by the chemical treatment and the removal of surface MgO layers from MgB2 grains by dissolution in the acid solution. The removal of MgO layers was effective in promoting substitution of carbon from the solvent for boron.

TEM Characterization of Grain Boundary Structure in YBCO Coated Conductors

2000 ◽  
Vol 6 (S2) ◽  
pp. 394-395
Author(s):  
H. Kung ◽  
J.P. Hirth ◽  
S.R. Foltyn ◽  
P.N. Arendt ◽  
Q.X. Jia ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Grain Boundaries ◽  
Critical Current ◽  
Current Density ◽  
Lattice Mismatch ◽  
Coupling Effect ◽  
High Temperature Superconductors ◽  
Coated Conductors ◽  
Boundary Structure

Studies of defects, such as grain boundaries, in high temperature superconductors (HTS) are important due to the interaction of the defects with flux-bearing vortices. The benefit of in-plane grain alignment has been documented in YBCO thin film bicrystals, in which the high critical current density (Jc) observed across small angle grain boundaries deteriorates exponentially with grain boundary angles beyond ∼ 7°. In addition to the weak coupling effect, a grain boundary may also influence the transport properties via the grain boundary dislocations (GBDs) serving as pinning centers to increase the critical current density. There have been a number of studies on grain boundary structures in YBCO. Despite many differences in structure among the different types of boundaries, it has been established that the low angle [001] tilt boundary in YBCO consists of aperiodic array of edge type GBDs with [100] type Burgers vector that accommodate the lattice mismatch, and the regions between the GBDs are channels of relatively undisturbed lattices [1].

Sign in / Sign up

Export Citation Format

Share Document