EFFECTS OF Gd DOPING IN YBa2Cu3O7-delta ON THE CRITICAL CURRENT DENSITY

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3216-3219 ◽  
Author(s):  
S. XU ◽  
X. S. WU ◽  
G. B. MA ◽  
M. LIU
Keyword(s):  
Critical Temperature ◽  
Solid State ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Solid State Reaction ◽  
Applied Field ◽  
Unit Cell ◽  
Rietveld Refinements ◽  
Resistivity Measurements

Gd is successfully embedded into YBa 2 Cu 3 O 7-δ by the solid state reaction. Rietveld refinements show that Gd replaces Cu in the unit cell. By magnetization and resistivity measurements, the effects of Gd -doping in YBCO on the critical current density J c and the critical temperature T c in YBa 2 Cu 3 O 7-δ( YBCO ) have been investigated. J c varies with the applied field and the content of Gd and has a maximum at x = 0.03. The characteristic behavior of J c with varying the Gd content can be explained in terms of the competition between two different effects caused by Gd -doping in YBCO: the inhomogeneity of grains distribution in nano-scale and the variation of superconductivity.

scholarly journals Effect of Heat Treatments under High Isostatic Pressure on the Transport Critical Current Density at 4.2 K and 20 K in Doped and Undoped MgB2 Wires

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5152
Author(s):  
Daniel Gajda ◽  
Andrzej J. Zaleski ◽  
Andrzej J. Morawski ◽  
Malgorzata Małecka ◽  
Konstantin Nenkov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Solid State ◽  
Thermal Treatment ◽  
Magnetic Fields ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Solid State Reaction ◽  
Transport Critical Current Density ◽  
Mgb2 Wires

Annealing undoped MgB2 wires under high isostatic pressure (HIP) increases transport critical current density (Jtc) by 10% at 4.2 K in range magnetic fields from 4 T to 12 T and significantly increases Jtc by 25% in range magnetic fields from 2 T to 4 T and does not increase Jtc above 4 T at 20 K. Further research shows that a large amount of 10% SiC admixture and thermal treatment under a high isostatic pressure of 1 GPa significantly increases the Jtc by 40% at 4.2 K in magnetic fields above 6 T and reduces Jtc by one order at 20 K in MgB2 wires. Additionally, our research showed that heat treatment under high isostatic pressure is more evident in wires with smaller diameters, as it greatly increases the density of MgB2 material and the number of connections between grains compared to MgB2 wires with larger diameters, but only during the Mg solid-state reaction. In addition, our study indicates that smaller wire diameters and high isostatic pressure do not lead to a higher density of MgB2 material and more connections between grains during the liquid-state Mg reaction.

scholarly journals Influence of Carbon Content on Superconductivity of Bi2Sr2CaCu2Ox

2017 ◽  
Vol 5 (1) ◽  
pp. 77
Author(s):  
Deawha Soh ◽  
Zhanguo Fan ◽  
N. Korobova
Keyword(s):  
Solid State ◽  
Grain Boundary ◽  
Critical Current Density ◽  
Carbon Content ◽  
Critical Current ◽  
Conventional Method ◽  
Current Density ◽  
Solid State Reaction ◽  
Sintering Process ◽  
Shs Method

<p>Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>X</sub> was prepared by the conventional method of solid state reaction and SHS method. The samples were annealed in different atmosphere in order to examine the influence of atmospheres on the carbon contents in the Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>X</sub> compound. The lowest carbon content in Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>X</sub> could be attended when the sample was annealed in O<sub>2</sub> at 800 °C for 100 hours. The CO<sub>2</sub> in air pollute the samples and increase the carbon content in the sintering process. The critical current density of the Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>X</sub> samples will decrease with the increasing carbon contents in the samples. The impurity carbon will deposit in the grain boundary, which makes critical current density lower.</p>

scholarly journals Distinct doping dependence of critical temperature and critical current density in Ba1−xKxFe2As2 superconductor

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Dongjoon Song ◽  
Shigeyuki Ishida ◽  
Akira Iyo ◽  
Masamichi Nakajima ◽  
Jun-ichi Shimoyama ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Doping Dependence

Porosity Effect on Superconducting Properties of YBa2Cu3Oδ and YCaBa4Cu6Oδ

2015 ◽  
Vol 1107 ◽  
pp. 601-605
Author(s):  
S.A. Senawi ◽  
H. Azhan ◽  
W.N.F.W. Zainal ◽  
W.A.W. Razali ◽  
A. Nazree ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Critical Current Density ◽  
Porous Structure ◽  
Critical Current ◽  
Current Density ◽  
Resistivity Measurement ◽  
Effective Cross Section ◽  
Ceramic Materials ◽  
Solid State Reaction Method ◽  
Superconducting Properties

This paper reports on the properties of YBa2Cu3Od (Y123) and YCaBa4Cu6Oy (Y146) with non-porous and porous structures. The relationship between calcium doping and critical temperature (Tc) was studied to determine the optimal superconducting properties. A series of heating and grinding via solid state reaction method was used to fabricate the ceramic materials. The electrical properties were investigated via critical temperature, TC and critical current density, JC using the resistivity measurement system (RMS). Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) were used to analyze the material morphology and structure, respectively. The orthorhombicity increased due to less porosity of the samples. The calcium presence partially replaced larger Ba(II) site and degraded orthorhombicity. The highest critical current density (JC) was porous YCaBa2Cu3Oy which was 2.32 A/cm2 compared to 0.75 A/cm2 for porous YCaBa4Cu6Oy at 60 K. The critical temperature for porous structure was less than non porous structure for Ca doped Y146 system which was 69.9 K and 67.9 K. SEM micrograph unveiled that the Jc was induced significantly by continuity of grain formation via grain size. Pores homogenized the grains surface quality and connectivity due to strain release thus increasing effective cross section of the sample for current density (Jc) over the vast areas.

Critical current density and resistivity measurements for long patterned lines in Tl2Ba2CaCu2O8thin films

1993 ◽  
Vol 74 (2) ◽  
pp. 1426-1430 ◽  
Author(s):  
W. L. Holstein ◽  
C. Wilker ◽  
D. B. Laubacher ◽  
D. W. Face ◽  
P. Pang ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Resistivity Measurements

Irradiation Defect Structures In YBa2Cu3O7-xand their Correlation with Superconducting Properties

1990 ◽  
Vol 209 ◽  
Author(s):  
Marquis A. Kirk
Keyword(s):  
Critical Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Neutron Irradiation ◽  
Current Density ◽  
Amorphous Material ◽  
Amorphous Structure ◽  
Fast Neutrons ◽  
High Fluences ◽  
Defect Microstructures

ABSTRACTWe review our work on irradiation effects in single crystal YBa2Cu3O7-x. Transmission electron microscopy has been employed to study the defect microstructures produced by irradiations with fast neutrons, MeV ions (Kr, Ne and p), and electrons. The atomic structure within defect cascades was investigated using 50 keV Kr and Xe ion irradiations to low doses. Evidence is shown for an amorphous structure with some incoherent recrystallization within individual cascades. Correlation with enhancements in critical current density produced by neutron irradiations suggest that this cascade structure effectively pins magnetic flux lines.At sufficiently high fluences of fast neutrons or MeV Kr and Ne ions, a cellular microstructure is found. This structure consists of cells or microcrystallites of good crystalline and superconducting material (in the case of neutron irradiation), with cell walls of amorphous material. Full amorphization proceeds with the growth of cell wall volume. The formation of this microstructure coincides with a decrease in critical transport current, but is not observed by magnetization measurements.Increases in critical current density under proton irradiation, comparable to those produced by neutron irradiation, have been reported. The defect structure produced by proton irradiations is examined here and found to differ from that of neutron irradiations. The structure is suggested to be consistent with the clustering of mobile defects (at 300 K) produced by the lower energy recoils which dominate in proton irradiations. In both the proton and fast neutron irradiations, to fluences producing the maximum enhancements in critical current densities, the degradations in critical temperature are not severe, <10 K.Our most recent measurements of changes in critical temperature and current density, and defect microstructure following electron irradiations will be described

scholarly journals Температурные зависимости критических параметров неоднородных сверхпроводящих пленок

2021 ◽  
Vol 63 (8) ◽  
pp. 1035
Author(s):  
П.И. Безотосный ◽  
К.А. Дмитриева
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
External Magnetic Field ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Superconducting Films ◽  
Critical Magnetic Field ◽  
Temperature Dependences ◽  
Comparison Of The Results

The results of calculating the temperature dependences of the critical current density and critical magnetic field of thin inhomogeneous superconducting films are presented. Comparison of the results obtained for inhomogeneous films with the results of calculations for homogeneous ones showed that in both cases, the decrease in the critical magnetic field occurs according to the root law, and the critical current density changes according to a power law with a degree of 3/2 when approaching the critical temperature. Quantitatively, the critical current density for inhomogeneous films in the absence of an external magnetic field is lower than for homogeneous ones. In turn, the critical magnetic field of inhomogeneous films is much larger than the critical field of homogeneous films.

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