Influence of heat-treatment schedules on magnetic critical current density and phase formation in bulk superconducting MgB2

2004 ◽  
Vol 415 (4) ◽  
pp. 158-162 ◽  
Author(s):  
Mohit Bhatia ◽  
M.D. Sumption ◽  
Mike Tomsic ◽  
E.W. Collings
Keyword(s):  
Heat Treatment ◽  
Critical Current Density ◽  
Critical Current ◽  
Phase Formation ◽  
Current Density

Effect of Heat Treatment on Critical Current Density–Magnetic Field Curve for YBa2Cu3O7-δSingle Crystal and Its Microstructure

2000 ◽  
Vol 39 (Part 1, No. 10) ◽  
pp. 5822-5827 ◽  
Author(s):  
Akihiro Oka ◽  
Satoshi Koyama ◽  
Teruo Izumi ◽  
Yuh Shiohara ◽  
Junko Shibata ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Treatment ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density

CORRELATION OF CRITICAL CURRENT DENSITY WITH Cu3+ CONCENTRATION AND DENSITY IN YBa2Cu3O7−x

1989 ◽  
Vol 03 (02) ◽  
pp. 151-155 ◽  
Author(s):  
S.X. DOU ◽  
H.K. LIU ◽  
J.P. ZHOU ◽  
A.J. BOURDILLON ◽  
N. SAVVIDES ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Cold Drawing ◽  
Full Density ◽  
Density Results

Superconducting YBa 2 Cu 3 O 7 wires and tapes were fabricated by cold drawing, rolling and extrusion processes. It was found that the critical current density, after O 2 equilibration, correlates both with density and Cu 3+ concentration. Full density was achieved by using a special heat treatment, but the critical current density was low owing to the low Cu 3+ concentration present in this heavily twinned material. The best critical current density results were obtained for material with density of 92–95% of the theoretical value. The low critical current density of the porous specimens is attributed not only to a poor connectivity between grains but also to a low Cu 3+ concentration due to the instability of Cu 3+ at crystallite surfaces which increase in area with specimen porosity.

Phase Formation and Electrical Transport Properties of Nano-Sized SnO2 Added (Tl0.85Cr0.15)Sr2CaCu2O7-δ Superconductors

2017 ◽  
Vol 268 ◽  
pp. 315-319 ◽  
Author(s):  
Wei Kong ◽  
Ing Kong ◽  
Mohd Mustafa Awang Kechik ◽  
Roslan Abd-Shukor
Keyword(s):  
Critical Current Density ◽  
Transport Properties ◽  
Critical Current ◽  
Phase Formation ◽  
Current Density ◽  
Electrical Transport ◽  
Energy Dispersive ◽  
Transport Critical Current Density ◽  
Electrical Transport Properties ◽  
X Ray

In this work, the effect of nano-sized SnO2 addition on the phase formation and electrical transport properties of (Tl0.85Cr0.15)Sr2CaCu2O7-δ (Tl-1212) superconductor was investigated. Thallium-based high temperature superconductor (HTS) with nominal starting composition (Tl0.85Cr0.15) Sr2CaCu2O7-δ was prepared using high purity oxide powders via solid state reaction method. Nano-sized SnO2 with 0.01 – 0.05 wt.% were added into Tl-1212 superconductors. The characteristic of the samples were determined by powder X-ray diffraction method (XRD), scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), electrical resistance measurements and transport critical current density measurements. Nano-sized SnO2 added (Tl0.85Cr0.15)Sr2CaCu2O7-δ showed Tc-zero between 93 and 95 K. All of the samples indicated a dominant phase of Tl-1212 with a minor phase of Tl-1201. The highest Jc (at 77 K) was shown by sample with 0.03 wt.% at 3260 mA/cm2. SnO2 has significantly enhanced the transport critical current density of Tl-1212 superconductor by acting as flux pinning centers. However, further addition of nano-sized SnO2 in Tl-1212 superconductor caused degradation in Jc. The SEM micrographs with energy dispersive X-Ray analysis (EDX) showed that SnO2 were well distributed in all the samples.

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.

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