Critical current density and microstructure variations in YBa2Cu3O7−x + BaSnO3 films with different concentrations of BaSnO3

2008 ◽  
Vol 23 (12) ◽  
pp. 3363-3369 ◽  
Author(s):  
C.V. Varanasi ◽  
J. Burke ◽  
L. Brunke ◽  
H. Wang ◽  
J.H. Lee ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Gradual Increase ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
Transmission Electron ◽  
Order Of Magnitude ◽  
High Fields ◽  
Magnitude Increase

Previous work on YBa2Cu3O7−x (YBCO) + BaSnO3 (BSO) films with a single composition showed significant critical current density (Jc) improvements at higher fields but lowered Jc in low fields. A detailed study on BSO concentrations provided here demonstrates that significant Jc enhancement can occur even up to 20 mol% BSO inclusion, where typical particulate inclusions in these concentrations degrade the YBCO performance. YBCO + BSO films were processed on (100) LaAlO3 substrates using premixed targets of YBa2Cu3O7-x (YBCO) with additions of 2, 4, 10, and 20 mol% BSO. The critical transition temperature Tc of the films remained high (>87 K), even with large amounts (20 mol%) of BSO. YBCO + BSO films showed a gradual increase in Jc at high fields as the amount of BSO was increased. More than an order of magnitude increase in Jc was measured in YBCO + BSO samples as compared to regular YBCO at 4 T. YBCO + 10 mol% BSO films showed overall improvement at all the field ranges while YBCO + 20 mol% BSO was better only at high fields. Transmission electron microscopy revealed the presence of ∼7–8-nm-diameter BSO nanocolumns, the density of which increased with increasing BSO content correlating well with the observed improvements in Jc.

Properties and Defects of Type II Superconductors

MRS Bulletin ◽  
1991 ◽  
Vol 16 (12) ◽  
pp. 37-41 ◽  
Author(s):  
Donglu Shi
Keyword(s):  
Crystal Structure ◽  
Transition Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Type Ii ◽  
Critical Transition ◽  
Critical Transition Temperature ◽  
High Degree ◽  
Superconducting Parameters

Three major superconducting parameters can characterize a type II superconductor: critical transition temperature, Tc, upper critical magnetic field, Hc2, and critical current density, Jc. Because of the variety of crystal structures, chemical stoichiometrics, and microstructures of the materials, these superconducting parameters differ greatly from system to system.It has been found that the critical transition temperature is closely related to the crystal structure and stoichiometry. Previous studies have shown that compounds with a high degree of symmetry tend to be more favorable to superconductivity. Compounds with a cubic structure, such as a bcc structure, usually have higher Tc values than compounds with a hexagonal lattice. Among conventional superconductors, the so-called A-15 structure is most favorable for high transition temperatures. It is well known that many high Tc superconductors such as YBa2Cu3Ox and Bi2Sr2CaCu2Ox have an orthorhombic structure with a high degree of symmetry.The upper critical field, Hc2, is more complicated in terms of its relationship to structural characteristics. Experimental results have indicated that Hc2 is more closely related to the chemical stoichiometry and crystal structure than to the microstructure.However, the critical current density, Jc, can vary tremendously in a compound with a given crystal structure. The change in critical current density is associated with the so-called flux pinning that arises from the interaction between the flux lines and crystal defects. Thus, Jc is determined mostly by the microstructure of the materials.

Critical Current Density Enhancement and Moisture Destruction Studies of the Compound Superconductor Y-Ba-Cu-Ag-O

1987 ◽  
Vol 99 ◽  
Author(s):  
Y. D. Yao ◽  
A. Krol ◽  
Y. H. Krol ◽  
C. Walters ◽  
S. Spagna ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Moisture Treatment ◽  
Density Enhancement ◽  
Order Of Magnitude ◽  
High Transition ◽  
Moisture Conditions ◽  
State Resistance

ABSTRACTWe have fabricated a series of samples of YBa2(Cu1−x Agx)3Oy compounds where 0 ≤ × ≤ 1, with the intention to study the changes in critical current density and the effect of moisture treatment on normal state resistance R in these high transition-temperature superconductors. The samples exhibited a decrease of the transition-temperature Tc vs the Ag concentration x. Tc is about 93 K for YBa2Cu3Oy and 20 KCfor YBa2Ag3Oy, but it is almost unaffected by the presence or Ag for × < 0.2. An enhancement of the critical current density Jc by nearly an order of magnitude for the samples with 0 < × ≤ 0.1 has been observed. Both Jc and R are found to be sensitive to the ambient moisture conditions.

Spatial variations in composition in high-critical-current-density Bi-2223 tapes

2000 ◽  
Vol 15 (2) ◽  
pp. 285-295 ◽  
Author(s):  
T. G. Holesinger ◽  
J. F. Bingert ◽  
M. Teplitsky ◽  
Q. Li ◽  
R. Parrella ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Compositional Analysis ◽  
Structural Features ◽  
Spatial Variations ◽  
High Critical Current Density ◽  
Transmission Electron ◽  
Filament Structure ◽  
Considerable Range

A detailed compositional analysis of high-critical-current-density (Jc) (55 and 65 kA/cm2at 77 K) (Bi,Pb)2Sr2Ca2Cu3Oy(Bi-2223) tapes was undertaken by energy dispersive spectroscopy in the transmission electron microscope. Structural features were coupled with characteristic compositions of the Bi-2223 phase. The average of all compositional measurements of the Bi-2223 phase was determined to be Bi1.88Pb0.23Sr1.96Ca1.95Cu2.98Oy. However, spatial variations in the Bi-2223 composition and differing phase equilibria were found throughout the filament structure. In particular, a considerable range of Bi-2223 compositions can be found within a single tape, and the lead content of the Bi-2223 phase is significantly depressed in the vicinity of lead-rich phases. The depletion of lead in the Bi-2223 phase around the 3221 phases may be a current-limiting microstructure in these tapes.

Critical Current Density and Microstructure of Yba2Cu3O7-X Films as a Function of Film Thickness

1989 ◽  
Vol 169 ◽  
Author(s):  
A. Mogro-Campero ◽  
L.G. Turner ◽  
E.L. Hall ◽  
N. Lewis
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Film Plane ◽  
Nominal Composition ◽  
Substrate Plane ◽  
Furnace Annealing ◽  
Cross Sectional ◽  
Continuous Layer ◽  
Transmission Electron

AbstractThin films of nominal composition YBa2Cu3O7‐x (YBCO) were produced on (100) SrTiO3 substrates by coevaporation and furnace annealing. Film thicknesses in the range of 0.2 to 2.4/μm were analyzed. Microstructural investigations by cross sectional transmission electron microscopy (TEM) reveal a continuous layer of about 0.4 μm thickness adjacent to the substrate with c‐axis normal to the substrate plane. In thicker films the remaining top portion has the c‐axis in the film plane. The critical current density (J ) at 77 K decreases with increasing thickness in the thickness range exceeding 0.4 μm, qualitatively consistent with the microstructural observations, but quantitatively inconsistent with a simple model based on the microstructural data.

High-Critical-Current-Density Epitaxial Films of SmBa2Cu3O7-xin High Fields

2005 ◽  
Vol 44 (No. 4) ◽  
pp. L129-L132 ◽  
Author(s):  
Yutaka Yoshida ◽  
Kaname Matsumoto ◽  
Yusuke Ichino ◽  
Masakazu Itoh ◽  
Ataru Ichinose ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Epitaxial Films ◽  
High Critical Current Density ◽  
High Fields

EFFECT OF NANO-Y-ZrO2 ADDITION ON THE MICROSTRUCTURE AND CRITICAL CURRENT DENSITY OF MgB2 SUPERCONDUCTORS

2004 ◽  
Vol 03 (04n05) ◽  
pp. 563-569 ◽  
Author(s):  
Q. W. YAO ◽  
X. L. WANG ◽  
A. H. LI ◽  
S. X. DOU ◽  
P. R. MUNROE
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Magnetic Measurements ◽  
Transmission Electron ◽  
Long Time ◽  
Powder Addition ◽  
Short Time ◽  
Mgb2 Superconductors

Polycrystalline MgB 2 samples with 0, 5, 10, and 20 wt% nano- Y - ZrO 2 (YSZ) powder addition were prepared by short time, as little as several minutes, or long time in-situ reaction process. The phases, microstructures and flux pinning behaviors were characterized using X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and Magnetic Measurements. Results indicated that nano-YSZ particles included in MgB 2 grains. Samples doped with 10wt% YSZ powders showed new record of critical current density Jc as high as 1×106 and 4×106 A/cm 2 in low magnetic fields at 30 and 20K, respectively. However, the Jc drops faster compared to that made by long time sintering samples. It is proposed that the improved Jc in low fields was due to the enhanced density of the sample, which was caused by the YSZ nano-particle inclusion.

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