On the critical fields and current densities of YBa2Cu3O7and La1.85Sr0.15CuO4superconductors

1988 ◽  
Vol 63 (8) ◽  
pp. 4176-4178 ◽  
Author(s):  
S. Senoussi ◽  
M. Oussena ◽  
S. Hadjoudj
Keyword(s):  
Critical Fields ◽  
Current Densities

Structure and Functional Properties of Bulk MgB2 Superconductors Synthesized and Sintered under Pressure

2014 ◽  
Vol 792 ◽  
pp. 21-26 ◽  
Author(s):  
Tatiana Prikhna ◽  
Michael Eisterer ◽  
Wolfgang Gawalek ◽  
Athanasios G. Mamalis ◽  
Artem Kozyrev ◽  
...  
Keyword(s):  
Critical Current ◽  
Material Structure ◽  
Bulk Materials ◽  
Critical Fields ◽  
Current Densities ◽  
Upper Critical Fields ◽  
Irreversibility Fields ◽  
Grain Boundary Pinning ◽  
Effect Of Oxygen ◽  
Oxygen Impurities

The high pressure (50 MPa - 2 GPa) – high temperature synthesized MgB2 bulk materials are characterized by nearly theoretical density (1-2% porosity), 80-98% connectivity, extremely high critical current densities (e.g. at 20 K, in 0–1 T jc=1.3–1.0 MA·cm-2 (with 10% SiC) and jc= 0.92 – 0.73 MA·cm-2 (without doping)), large irreversibility fields (Birr(18.4 K) =15 T and Birr (0 K) = 32.5 T) and high upper critical fields (Bc2 (22 K) =15 T and Bc2(0 K) ~ 42.1 T). The transformation of grain boundary pinning to point pinning in MgB2-based materials with increasing manufacturing temperature (from 800 to 1050 oC) under pressures from 0.1 to 2 GPa correlates well with an increase in critical current density in low external magnetic fields caused by the redistribution of boron and the oxygen impurities in the material structure. As the manufacturing temperature increases, the discontinuous oxygen enriched layers transform into distinct Mg-B-O inclusions and the size and amount of inclusions of higher magnesium borides MgBX (X>4) are reduced. The effect of oxygen and boron redistribution can be enhanced by Ti or SiC additions.

MICROWAVE ABSORPTION STUDIES ON V-B GROUP METAL OXIDES DOPED Bi(Pb)-2223 CERAMIC SUPERCONDUCTOR

1996 ◽  
Vol 10 (03n05) ◽  
pp. 133-143
Author(s):  
P. SUBHASH ◽  
G. NARSINGA RAO ◽  
D. SURESH BABU
Keyword(s):  
Josephson Junction ◽  
Microwave Absorption ◽  
Phase Variation ◽  
Signal Amplitude ◽  
Temperature Dependent ◽  
Critical Fields ◽  
Low Field ◽  
Josephson Medium ◽  
Absorption Studies ◽  
Current Densities

Microwave absorption studies have been carried out on samples Bi 1.6 Pb 0.3 V 0.1 Sr 2· Ca 2 Cu 3 O y, Bi 1.6 Pb 0.3 Nb 0.1 Sr 2 Ca 2 Cu 3 O y, and Bi 1.6 Pb 0.3 Ta 0.1 Sr 2 Ca 2 Cu 3 O y. DC Microwave absorption studies of all the samples showed the presence of single 2223 phase. Variation of Low Field Microwave Absorption (LFMA) signal amplitude of these samples showed definite peaks at 95 K, 83 K and 90 K respectively. The temperature dependent average Josephson loop diameter was estimated for all these samples. The experimental data was analyzed on the basis of Josephson Medium Model. From this model, the temperature dependent junction penetration depth λ j , Josephson junction upper and lower critical fields H C1j and H C2j and Josephson junction critical current densities J Cj were estimated.

CRITICAL FIELDS AND CURRENT DENSITIES IN YBa2Cu3O7-δ

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-2099-C8-2103
Author(s):  
S. Senoussi ◽  
M. Oussena ◽  
C. Aguillon ◽  
P. Tremblay
Keyword(s):  
Critical Fields ◽  
Current Densities

On the Determination of Intrinsic Properties of Ceramic High-Tc Superconductors by Ac Susceptibility Measurements

1992 ◽  
Vol 275 ◽  
Author(s):  
F. Ludwig
Keyword(s):  
Sample Size ◽  
Critical State ◽  
Ac Susceptibility ◽  
Field Amplitude ◽  
Critical State Model ◽  
State Model ◽  
Critical Fields ◽  
Current Densities ◽  
Ac Field

ABSTRACTVarious models have been proposed to interpret ac susceptibility curves measured on sintered high-To superconductors (HTSC) and to deduce parameters like critical current densities and critical fields. To get more clearness, systematic studies of position and height of the intergranular maximum in χ'' have been performed on several ceramic HTSC samples in dependence of both ac field amplitude and sample size. In the present paper, the data are used to discuss the various models proposed in the literature. It is shown that modifications of the critical state model using incorrect jc(Hi) functions as well as other interpretations of the χ'' peak yield not actually intrinsic but sample size and geometry dependent parameters. The dependence of both position and height of the intergranular maximum in χ '' on ac field amplitude and sample size can be explained in the framework of a modified critical state model using a power law for the jc(Hi) dependence.

Critical fields and current densities of Y-Ba-Cu-O compounds

1988 ◽  
Vol 153-155 ◽  
pp. 1497-1498 ◽  
Author(s):  
W. Boon ◽  
M. d'Halle ◽  
J.-P. Locquet ◽  
M. Bruggeman ◽  
H. Strauven ◽  
...  
Keyword(s):  
Critical Fields ◽  
Current Densities

HIGH-FIELD AND MICROSTRUCTURE STUDIES OF SUPERCONDUCTING nYBa2Cu3Oy:AgO COMPOSITES

1989 ◽  
Vol 03 (06) ◽  
pp. 525-535 ◽  
Author(s):  
C.Y. HUANG ◽  
H.H. TAI ◽  
M.K. WU
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Field ◽  
Polarized Light ◽  
Critical Fields ◽  
Strong Pinning ◽  
Current Densities ◽  
Very High ◽  
Scanning Electron

We have measured the resistance of superconducting n YBa 2 Cu 3 O y: AgO (n=2,3,4, and 5) composites above 77 K for magnetic field up to 20 T. The data reveal that the resistance is zero even at 80 K and 20 T. The temperature dependence of the critical field near T c (91.6 K) is very strong, and critical fields at 0 K are thus expected to be very high. Our results of scanning electron microscopy and polarized light microscopy have shown that the presence of silver results in the growth of very large grains (~0.5 mm) with silver dispersed in the grains, giving rise to strong pinning and, hence, large superconducting critical current densities.

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