Silsbee rule in YBa2Cu3O7 ceramic superconductors

1989 ◽  
Vol 67 (6) ◽  
pp. 614-616 ◽  
Author(s):  
E. G. Zwartz ◽  
B. A. Judd ◽  
E. Batalla ◽  
L. S. Wright ◽  
W. D. MacDonald
Keyword(s):  
Magnetic Fields ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Ac Susceptibility ◽  
Meissner Effect ◽  
Transport Critical Current Density ◽  
Ceramic Superconductors ◽  
Ceramic Samples ◽  
Alternating Magnetic Fields

The transport critical current density, Jc, and the ac susceptibility have been measured for 28 YBa2Cu3O7, ceramic samples. It is observed that a Silsbee-like rule relates Jc to the alternating magnetic fields at which the ceramics begin to show a reduced Meissner effect.

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.

Effect of Nano-Sized Nickel Ferrite Addition on Superconducting Properties of (Tl0.85Cr0.15)Sr2CaCu2O7-δ Superconductors

2019 ◽  
Vol 290 ◽  
pp. 227-232
Author(s):  
Wei Kong ◽  
Ing Kong ◽  
Nur Akasyah Jaafar ◽  
M. Aizat Kamarudin ◽  
Nurul Raihan Suib ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Nickel Ferrite ◽  
Ac Susceptibility ◽  
High Temperature Superconductors ◽  
Diffraction Method ◽  
Solid State Reaction Method ◽  
Transport Critical Current Density

The effect of nanosized nickel ferrite (NiFe2O4) addition on (Tl0.85Cr0.15)Sr2CaCu2O7-δ superconductors has been investigated. (Tl0.85Cr0.15)Sr2CaCu2O7-δ high temperature superconductors was prepared via solid-state reaction method using high purity oxide powders. Nanosized NiFe2O4 was added to the compound at composition x = 0 - 0.003 wt.%. Samples were studied using scanning electron microscopy (SEM), X-ray diffraction method (XRD), electrical resistance versus temperature, transport critical current density Jc and AC susceptibility measurements. SEM micrographs showed close-packed microstructure with low porosity. XRD patterns showed a dominant phase of Tl-1212 with a minor phase of Tl-1201 for all samples. All of the samples displayed metallic normal state behavior before the onset transition temperature (Tc-onset) which was between 102 and 104 K. The transition temperature (Tcχ’) from AC susceptibility measurement also showed the similar results between 101 and 103 K. Tc-zero was slightly suppressed with the addition of nanosized NiFe2O4. The peak temperature Tp from the imaginary part of the susceptibility χ” was found between 77 - 91 K for all samples. The highest transport critical current density (Jc) at 77 K was shown by sample x = 0.001 wt.% at 2213 mAcm-2. Nanosized NiFe2O4 has significantly enhanced the Jc of (Tl0.85Cr0.15)Sr2CaCu2O7-δ superconductor.

ANOMALOUS INCREASE OF THE TRANSPORT AND INDUCTIVE CRITICAL CURRENT DENSITY DUE TO LOW DC-FIELD COOLING IN SINTERED RBa2Cu3O7−x HIGH Tc SUPERCONDUCTORS

1991 ◽  
Vol 05 (26) ◽  
pp. 1727-1733
Author(s):  
T. PUIG ◽  
M. PONT ◽  
J.S. MUÑOZ
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Ac Susceptibility ◽  
Transport Critical Current Density ◽  
Zero Field ◽  
High Tc ◽  
Current Densities ◽  
Magnetic Flux Pinning ◽  
Intergranular Critical Current Density

The transport critical current density of bulk sintered samples of RBa2Cu3O7−x with R=Y, Gd, Ho, and Er has been determined at 77 K from I–V curves at different applied dc-magnetic fields (0≤H≤20 Oe), also the ac-susceptibility as a function of ac-field amplitude has been measured with a superimposed dc-magnetic field from 0 to 30 Oe at 77 K. The transport and magnetic (inductive) critical current densities, are clearly larger in field cooled samples than in zero field cooled samples. Likewise, the degree of shielding as determined from the ac-susceptibility measurements is larger for field cooled samples than for zero field cooled. This anomalous behaviour can be explained in terms of the magnetic flux pinning present in the grains when the sample is field cooled, which leads to a decrease in the magnetic induction of the intergrain region and therefore to a higher intergranular critical current density compared to a zero field cooled sample.

INTERGRANULAR PROPERTIES OF (Y1-x-yZrxCay)Ba2Cu3O7-δ COMPOUNDS

1999 ◽  
Vol 13 (13) ◽  
pp. 1645-1654 ◽  
Author(s):  
I. GR. DEAC ◽  
E. BURZO ◽  
A. V. POP ◽  
V. POP ◽  
R. TETEAN ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Ac Susceptibility ◽  
Temperature Dependent ◽  
Susceptibility Data ◽  
Dc Magnetic Field ◽  
Complex Susceptibility ◽  
Granular Superconductors ◽  
Intergranular Critical Current Density

The intergranular properties of ( Y 1-x-y Zr x Ca y) Ba 2 Cu 3 O 7-δ ceramics were studies by using temperature-dependent ac susceptibility measurements at zero dc magnetic field. The intergranular critical current density was determined from ac susceptibility data by varying the field amplitude H ac . From the imaginary part of the complex susceptibility, χ″(T), we have determined the temperature dependence of the critical current density by using the Bean's model. The ac field dependencies of the intergrain χ″-peak temperatures T p are linear and agree with Müller critical state model. The results were analyzed in terms of superconductor-insulator-superconductor (SIS)-and superconductor-normal-superconductor (SNS)-type models for granular superconductors.

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