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.

Analysis of Electromagnetic Properties of Bulk Superconductors

2021 ◽  
Vol 21 (9) ◽  
pp. 4941-4943
Author(s):  
Sang Heon Lee
Keyword(s):  
Critical Current Density ◽  
Single Crystal ◽  
Critical Current ◽  
Current Density ◽  
Magnetic Force ◽  
Electromagnetic Properties ◽  
Weak Links ◽  
Metallic Silver ◽  
Bulk Superconductor ◽  
Slow Cooling

In the present study, a YBa2Cu3O7−y bulk superconductor added with 5~10 wt% Ag was fabricated employing Sm123 as a seed to produce a superconductive single crystal. Metallic silver was added to the single crystal of YBa2Cu3O7−y to remove defects such as cracks and pores. Electromagnetic properties of the bulk superconductor at 77 K were analyzed based on relationships of magnetic levitation, trapped magnetic force, and critical current density. The critical current density of the superconductor at 77 K and 0 T was 3.53 × 104 A/cm2. Discontinuous points in the distribution of magnetic field lines were not observed, implying that these two specimens grew well as a single crystal without specific weak links. For the growth of a superconductive nano crystal employing slow cooling at temperature of formation of 123 phase, superconductive nano crystals were aligned in a-b direction, the direction of peak current flow. The peak value of the trapped magnetic force of the YBa2Cu3O7−y superconductor specimen was 3.23 kG. Using the FC method, peak forces of attraction and repulsion were 21.696 N and 70.168 N, respectively.

Strongly coupled critical current density values achieved in Y1Ba2Cu3O7−δ coated conductors with near-single-crystal texture

2003 ◽  
Vol 82 (25) ◽  
pp. 4519-4521 ◽  
Author(s):  
S. R. Foltyn ◽  
P. N. Arendt ◽  
Q. X. Jia ◽  
H. Wang ◽  
J. L. MacManus-Driscoll ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Single Crystal ◽  
Critical Current ◽  
Current Density ◽  
Coated Conductors ◽  
Strongly Coupled ◽  
Crystal Texture ◽  
Density Values

YBCO Bulk Superconductors with Sm Addition

2017 ◽  
Vol 891 ◽  
pp. 483-488 ◽  
Author(s):  
Daniela Volochová ◽  
Vitaliy Antal ◽  
Jozef Kováč ◽  
Pavel Diko
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Properties ◽  
Ybco Bulk ◽  
Pinning Centers ◽  
Bulk Superconductors ◽  
Powder Addition ◽  
Current Densities ◽  
Precursor Powders

The influence of Sm addition on the microstructure and superconducting properties of Y-Ba-Cu-O (YBCO) bulk superconductors has been studied. Precursor powders YBa2Cu3O7-δ (Y-123), Y2O3 and CeO2 were enriched with different amounts of SmBa2Cu3Oy (Sm-123) or Sm2O3 powders with the aim to increase critical current density, Jc,by introducing additional pinning centers. YBCO bulk superconductors with SmBa2Cu3Oy (Y123-Sm) or Sm2O3 (Y123-SmO) powder addition were prepared by the optimized top seeded melt growth process in the form of single grains. Microstructure analysis revealed that Sm2O3 addition leads to a higher amount of smaller Y2BaCuO5 (Y-211) particles, what is related to high critical current densities (Jc ~ 7 x 104 A/cm2) of the YBCO samples with Sm2O3 addition in low magnetic fields. The effect of Sm addition in the form of SmBa2Cu3Oy as well as Sm2O3 powder on Y2BaCuO5 particle size, critical temperature, Tc, and critical current density, Jc, is reported.

Increased grain boundary critical current density Jcgb by Pr-doping in pulsed laser–deposited Y1−xPrxBCO thin films

2011 ◽  
Vol 110 (11) ◽  
pp. 113905 ◽  
Author(s):  
M. Irjala ◽  
H. Huhtinen ◽  
V. P. S. Awana ◽  
M. Falter ◽  
P. Paturi
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Pulsed Laser

Influence of critical current density on magnetic force of HTSC bulk above PMR with 3D-modeling numerical solutions

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542038 ◽  
Author(s):  
Yiyun Lu ◽  
Yujie Qin
Keyword(s):  
Finite Element ◽  
Heat Conduction ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Numerical Solutions ◽  
Bulk Sample ◽  
Electromagnetic Properties ◽  
Finite Element Program ◽  
Hts Bulk

Numerical simulations of thermo-electromagnetic properties of a high temperature superconducting (HTS) bulk levitating over a permanent magnetic guideway (PMG) are performed by resorting to the quasistatic approximation of the H-method coupling with the classical description of the heat conduction equation. The numerical resolving codes are practiced with the help of the finite element program generation system (FEPG) platform using finite element method (FEM). The [Formula: see text]–[Formula: see text] power law is used to describe the electric current nonlinear characteristics of HTS bulk. The simulation results show that the heat conduction and the critical current density are tightly relative to the thermal effects of the HTS bulk over the PMG. The heat intensity which responds to the heat loss of the HTS bulk is mainly distributed at the two bottom-corners of the bulk sample.

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.

Grain boundary microstructure and transport critical current density in YBa2Cu3Ox

1992 ◽  
Author(s):  
Donglu Shi ◽  
Yufei Gao ◽  
A. C. Biondo ◽  
J. G. Chen ◽  
K. L. Merkle ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Transport Critical Current Density ◽  
Boundary Microstructure

The interfacial structure of orthogonally oriented twins in YBa2Cu3O7

1993 ◽  
Vol 51 ◽  
pp. 938-939
Author(s):  
Yimei Zhu ◽  
M. Suenaga ◽  
J. Tafto
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Twin Boundary ◽  
Current Density ◽  
Interfacial Structure ◽  
Hrem Image ◽  
Twin Boundaries ◽  
Wedge Shape

Interfaces such as the twin boundary and grain boundary in YBa2Cu3O7-δ are thought to be important in reconciling the large discrepancy between the low critical-current density observed in bulk polycrystalline. Recently, we studied another type of frequently encountered interface, i.e., the interface between the orthogonally orientated (110) and (-110) twins. In the vicinity of the interface, the crystal has a characteristic geometry because of additional constrains due to the impediment and the local orientational difference. The impinging twins usually have a wedge shape (Fig. la), and when the wedge slope is large, the tip of the twin splits (Fig. lb). A HREM image of a tapered twin is shown in Fig.2. Four twin variants give rise to five boundaries. Boundaries between IV-III, III-IV, IV-II, and II-IV are twin boundaries, while II-III, which has no apparent structure, is the interface of the orthogonal twins. If there is no constrain, the orientation of II and III should be equivalent (Fig.3a and 3b); however, we observed that the lattice in II does not align with that in III.

MAGNETIZATION AND INTRAGRANULAR CRITICAL CURRENT DENSITY IN Yb1Ba2Cu3O7−x HIGH TEMPERATURE SUPERCONDUCTOR

1995 ◽  
Vol 09 (28) ◽  
pp. 3715-3723
Author(s):  
RAANA MAHMOOD ◽  
M. NASIR KHAN ◽  
M. S. ZAFAR ◽  
FARID A. KHWAJA ◽  
A. WAHEED
Keyword(s):  
Electrical Resistivity ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Applied Field ◽  
High Temperature Superconductor ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Current Densities

The Yb 1 Ba 2 Cu 3 O 7−x samples have been prepared by the solid state reaction using the appropriate amount of Yb 2 O 3, BaCO 3, and CuO powders and characterized them using X-ray diffraction and electrical resistivity techniques. The X-ray diffraction pattern of the sample shows an orthorhombic structure refined in the space group Pmmm. The critical current densities are calculated from magnetization measurements over a temperature range 77 K to 86 K, and in magnetic fields up to 2 KOe. The intragrain critical current density is estimated to range from 5.24 × 106 ( A/cm 2) at an applied field of 0.2 KOe to 1.01 × 106 ( A/cm 2) at an applied field of 2 KOe at T = 77 K in this sample.

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