AC susceptibility of the sintered Bi1.6Pb0.4Sr2(Ca1-xMx)2Cu3Oδbulk high-Tc superconductors

2001 ◽  
Vol 689 ◽  
Author(s):  
Malik I Adam ◽  
Abdul Halim Shaari ◽  
Zainul A Hassan ◽  
Kaida Khalid
Keyword(s):  
Ac Susceptibility ◽  
Field Amplitude ◽  
Nominal Composition ◽  
Temperature Peak ◽  
High Tc Superconductors ◽  
Reaction Route ◽  
Pinning Mechanism ◽  
High Tc ◽  
Ac Field ◽  
Qualitative Discussion

ABSTRACTAC susceptibility measurements as a function of temperature, frequency and applied ac field amplitude were performed on two rectangular bar shaped samples of nominal composition Bi1.6Pb0.4Sr2(Ca1-xMx)2Cu3Oδ, with M=Pr, Gd, and x=0.01, obtained by the usual solid state reaction route. The incorporation of the rare earth elements at low concentration stage results in an improvement of grain connectivity for the sample doped with Pr. On the other end, the ac field amplitude and frequency dependence of the susceptibility curves disclosed bulk pinning hystersis loss feature. The potential barrier height, activation energy at the grain boundary extracted from the low temperature peak revealed that flux creep is governing the pinning mechanism inside the samples. Qualitative discussion in the framework of the critical state model was highlighted

Field induced transition of the AC susceptibility in high-Tc superconductors

1996 ◽  
Vol 46 (S3) ◽  
pp. 1589-1590 ◽  
Author(s):  
Oliver Waldmann ◽  
Gerald Lichtschlag ◽  
Florian Steinmeyer ◽  
Andrei Talalaevskii ◽  
Paul Müller
Keyword(s):  
Ac Susceptibility ◽  
High Tc Superconductors ◽  
High Tc

Ac Susceptibility Studies of the High Tc Superconductors: Dissipative Effects in La2.xSrxCuO4-Y and YBa2Cu3O7-Y Systems

1989 ◽  
Vol 169 ◽  
Author(s):  
Xinsheng Ling ◽  
M. E. Filipkowski ◽  
E. K. Heller ◽  
J. I. Budnick
Keyword(s):  
Grain Boundaries ◽  
Order Parameter ◽  
Ac Susceptibility ◽  
Similar Process ◽  
Charge Carrier Density ◽  
High Tc Superconductors ◽  
High Tc ◽  
Spatial Fluctuation ◽  
Dissipative Effects ◽  
Ceramic Samples

AbstractWe have studied the variation of dissipative effects with doping in the high Tc superconductors La2-xSrxCuO4-y and YBa2Cu3O7-y by studying the lossy component of ac susceptibility as a function of temperature. We find relatively strong excess losses at low temperature in both systems, which indicate stronger flux creep at grain boundaries, in lower level doped ceramic samples produced by a similar process. This effect is more significant in the La2-xSrxCuO4-y (214) system than in the YBa2Cu3O7-y(123) system. We suggest that the microscopic mechanisms of weakening of the order parameter in the grain boundaries may be different in the two systems. In the 214 system, as the charge carrier density in the CuO2 planes is reduced, the spatial fluctuation of the order parameter in the CuO2 planes is enhanced. In the 123 system, the initial removal of O from the sample, which weakens the coupling between planes and increases the spatial fluctuation of the order parameter between CuO2 planes. The grain boundaries are degraded in both systems. The degradation in the 214 samples is more significant than in the 123 samples.

THE COMPOSITION AND STRUCTURE OF Y-Ba-Cu-O SUPERCONDUCTORS

1987 ◽  
Vol 01 (02) ◽  
pp. 341-349
Author(s):  
Z.Y. Hua ◽  
C.L. Jia ◽  
H.S. Cheng ◽  
Y.M. Cai ◽  
A.R. Jiang
Keyword(s):  
Single Phase ◽  
Nominal Composition ◽  
High Tc Superconductors ◽  
Small Particles ◽  
High Tc ◽  
Third Phase ◽  
Composition And Structure ◽  
The Difference ◽  
Phase Phase ◽  
Superconductive Phase

High Tc superconductors of Y-Ba-Cu-O system with (Y+Ba):Cu=1~2 have been investigated. Results show that any sample in this system with a proportion of Y:Cu between 0.6 and 1.2 is oxygen-deficient and will be superconductive after sintering in an oxygen flow. In this system all superconductors with different nominal composition have a superconductive phase of perovskite-1ike YBa2Cu3O7 (Phase A), and the difference of constituents is shown in another phase (Phase B) which acts as a gettering center. When the composition has an excess of Y, there will be a third phase (Phase C) which has been identified as small particles of Y2O3 . For an exact nominal proportion of Y:Ba:Cu=1:2:3 , single-phase superconductors can be prepared.

THE Ni INFLUENCE ON THE INTERGRANULAR PROPERTIES OF BULK (Bi,Pb):2223 SUPERCONDUCTOR

1999 ◽  
Vol 13 (11) ◽  
pp. 371-378 ◽  
Author(s):  
A. V. POP
Keyword(s):  
Linear Dependence ◽  
Critical State ◽  
Ac Susceptibility ◽  
Field Amplitude ◽  
Critical State Model ◽  
State Model ◽  
Force Density ◽  
Pinning Force ◽  
Ac Field ◽  
Pinning Force Density

The effect of Ni 3+ ions on the intergranular T p temperature of the imaginary peaks of the ac susceptibility has been studied for a (Bi,Pb):2223 superconductor. The linear dependence of T p as a function of ac field amplitude agree with Muller critical state model. The Ni 3+ ions induced an increase of intergranular pinning force density. J cJ (T) dependence near T c agrees with the assumption of SNS intergrain junctions.

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.

Microstructure of a Y2Ba2Cu3O7-Σ superconductor pellet prepared by shock consolidation

1988 ◽  
Vol 46 ◽  
pp. 952-953
Author(s):  
R. F. Antrim ◽  
J. Marti ◽  
Z. Iqbal
Keyword(s):  
Shock Wave ◽  
High Temperature ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Nominal Composition ◽  
High Tc Superconductors ◽  
High Tc ◽  
Shock Compaction ◽  
High Pressure High Temperature

R&D in high Tc superconductors encompasses two broad areas, namely, 1) synthesis and characterization of high Tc superconducting powders and 2) consolidation of the powders into useful parts. In the latter area, techniques such as thin film deposition, high temperature sintering of the powders and continuous casting are being pursued by various groups. Another technique which could prove useful in the fabrication of larger pieces is that of shock compaction. In this approach, explosives are used to propel a piston, resulting in a shock wave which leads to high pressure- high temperature consolidation of the powder. In this report we examine the microstructure that results when a superconducting powder was consolidated into a pellet using the shock-loading technique.The nominal composition of the starting powder was Y1Ba2Cu3O7δ (“123”). Explosives were used to create a shock-wave with an estimated peak pressure of 60 GPa and temperatures of about 800°C.

AC susceptibility and local intergranular magnetic field in high-Tc superconductors

1993 ◽  
Vol 214 (1-2) ◽  
pp. 111-118 ◽  
Author(s):  
P. Levy ◽  
H. Ferrari ◽  
V. Bekeris ◽  
C. Acha
Keyword(s):  
Magnetic Field ◽  
Ac Susceptibility ◽  
High Tc Superconductors ◽  
High Tc

The Fe Influence on the Vortex Response to the AC Field in Bulk (Bi, Pb):2223 Superconductor

1998 ◽  
Vol 12 (27) ◽  
pp. 1117-1124 ◽  
Author(s):  
A. V. Pop
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Critical State ◽  
Ac Susceptibility ◽  
Field Amplitude ◽  
Critical State Model ◽  
Pinning Force ◽  
Fast Decrease ◽  
Ac Field

The effect of Fe 3+ ions on the inter- and intragranular Tp and Tg temperatures of the imaginary peaks of the AC susceptibility has been studied for a (Bi, Pb):2223 superconductor. The linear dependencies of Tp and Tg as a function of AC field amplitude agree with Muller critical state model. The Fe 3+ ions induced a fast decrease of inter and intragranular pinning force densities. The intergrain critical current density J cj calculated from χ″(T) curve is lower in x=0.02 Fe doped sample than in x=0.00 sample. J cj (T) dependence near Tc agrees with the assumption of SNS intergrain junctions.

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