On the correlation between order parameter, superconducting volume fraction and critical current density in R: 123 superconductors

2006 ◽  
Vol 139 (3) ◽  
pp. 126-131 ◽  
Author(s):  
A. Sedky ◽  
M.I. Youssif ◽  
S.M. Khalil ◽  
Ayman Sawalha
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Order Parameter ◽  
Volume Fraction ◽  
Superconducting Volume Fraction

The Influence of Sintering Time in High and Low Density Bi-2223 Superconductor

2015 ◽  
Vol 1107 ◽  
pp. 616-621
Author(s):  
M. Robaiah ◽  
H. Azhan ◽  
K. Azman ◽  
I.N. Syuhaida ◽  
C.M.N. Azura ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Volume Fraction ◽  
Solid State Reaction Method ◽  
Zero Magnetic Field ◽  
Low Density ◽  
X Ray Diffraction ◽  
Sintering Time

The effects of sintering time in high and low density Bi-2223 phase formation have been investigated. The samples were prepared by the solid-state reaction method at various sintering times ranging from 24, 48, 72 and 96 hours. Sucrose was added during palletization and after heated at 400°C for two hours the sucrose was removed and hence low density sample was created. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and critical current density. The transition temperature varies between 102 K and 96 K with increasing of sintering times. The optimal sintering time of the samples Bi-2223 system was found at 850°C for 72 hours. The critical current density,JCof high density and low density Bi-2223 was measured to be 7.547 A/cm2and 8.333 A/cm2respectively at 77 K under zero magnetic field. The critical current density,JCand superconductivity transition temperature,TCof low density were found to be higher than the pure samples. The critical transition temperature increased with a short gap betweenTConsetandTC zero. The most intense peak in the XRD pattern of sample at sintering time 72 hours belong to the high-TCphase which also indicates an increase in the volume fraction of the high-TCphase with optimum sintering time.

Superconducting Properties of Bi1.6Pb0.4Sr2Ca2-xDyxCu3Oy Prepared via Co-Precipitation Method

2012 ◽  
Vol 622-623 ◽  
pp. 177-181 ◽  
Author(s):  
H. Azhan ◽  
J.S. Hawa ◽  
K. Azman ◽  
H.N. Hidayah ◽  
S.Y.S. Yusainee
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Volume Fraction ◽  
Resistivity Measurement ◽  
Xrd Analysis ◽  
Precipitation Method ◽  
Electrical Resistivity Measurement ◽  
Nominal Composition ◽  
Co Precipitation

The samples with nominal composition of Bi1.6Pb0.4Sr2Ca2-xDyxCu3Oywhere x = 0.000, 0.025, 0.050, 0.100 and 0.200 were prepared by the co-precipitation (COP) method. The samples were characterized by x-ray diffraction, electrical resistivity measurement and critical current density. The critical current density (JC) and superconductivity transition temperature (TC) of Dy substituted were found to be lower than the Dy-free sample. The TCvalues vary between 100 K and 75 K toward Dy concentration due to a small change of carrier concentration. The highest TC in Dy-doped sample was found at 96 K in x = 0.025. The JCdecreased towards Dy substitution, and it was measured to be 5751.2 mA/cm2 in Dy-free and 3769.8 mA/cm2in x = 0.025 at 77 K. XRD analysis showed the substitutions of Dy reduced the volume fraction of the 2223 phase and increased the volume fraction of the 2212 phase. The proportion of Bi-2223/Bi-2212 (%) were estimated from 76.74/23.26 in Dy free to 18.90/81.10 in x = 0.200.

scholarly journals Self-Propagating High Temperature Synthesis of MgB2 Superconductor in High-Pressure of Argon Condition

2017 ◽  
Vol 19 (2) ◽  
pp. 177 ◽  
Author(s):  
S. Tolendiuly ◽  
S. M. Fomenko ◽  
G. C. Dannangoda ◽  
K. S. Martirosyan
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
High Pressures ◽  
Volume Fraction ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Ar Gas

<p>Magnesium diboride can be synthesized under argon ambient, elevated or high pressures. High-pressure syntheses are promising methods for manufacturing of the bulk MgB<sub>2</sub> superconductor material. We have been used high pressure of Ar gas in order to investigate its effect on properties of MgB<sub>2</sub> superconductor such as critical temperature and current density. Bulk MgB<sub>2</sub> superconductor was synthesized from elemental Mg–B powders in thermal explosion mode of self-propagating high-temperature synthesis (SHS) under argon pressure of 25 atm. XRD pattern of the as-synthesized product indicates an almost complete conversion of the reactants to the MgB<sub>2</sub> single phase. Most of the diffractions peaks are related to the MgB<sub>2</sub> polycrystalline bulk material. The impurity fraction is less than 24.3% in total sample and identified as MgO and MgB<sub>4</sub> secondary phases. The positive effect of pressure of Ar gas during synthesis of MgB2 on critical current density JC has been confirmed. The critical current density of the sample was achieved in high pressure reactor was 3.8×10<sup>6</sup> A/cm<sup>2</sup>. A superconducting volume fraction of 16% under a magnetic field of 10 Oe was obtained at 5 K, indicating that the superconductivity was bulk in nature. The succeeded level of superconductor parameters of the high-pressure synthesized MgB<sub>2</sub> and the possibility to produce a large bulk products make this technology very promising for practical applications.</p>

Influence of Na, Mg and Yb Substitution for Ca in Bi(Pb)-2223 Superconductor

2012 ◽  
Vol 501 ◽  
pp. 289-293 ◽  
Author(s):  
J.S. Hawa ◽  
H. Azhan ◽  
S.Y.S. Yahya ◽  
K. Azman ◽  
H.N. Hidayah ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Volume Fraction ◽  
Resistivity Measurement ◽  
Xrd Analysis ◽  
Electrical Resistivity Measurement ◽  
Ca Substitution ◽  
Na Substitution ◽  
Small Change

The effect of Ca substitution by Na, Mg and Yb on the structural and transport properties of Bi1.6Pb0.4Sr2Ca2-xMxCu3Oy (M = Na, Mg and Yb) (x = 0.0 and 0.2) superconducting samples have been investigated. The samples were prepared by the coprecipitation (COP) method. The samples were characterized by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), electrical resistivity measurement and critical current density. The critical current density (Jc) and transition temperature (Tc zero) of Na, Mg and Yb substituted with x = 0.2 were found to be lower than the pure sample. Tc zero varies between 100 K and 63 K. Mg concentration was found to give the highest Tc zero of 93 K. Tc zero gradually decreased from Mg, Yb to Na corresponding to a small change in the carrier concentration. Jc decreased with Mg, Yb and Na substitution, and it was measured to be 7.4611 A/cm2, 0.0667 A/cm2, 1.4579 A/cm2 and 1.2479 A/cm2 for pure, Na, Mg and Yb substitution, respectively at 60 K. XRD analysis showed that the decrease of the volume fraction for the 2223 phase and increase of the volume fraction for the 2212 phase with substitution of Na, Mg and Yb. The proportion of Bi-2223/Bi-2212 (%) was estimated from 78.13/21.87 for pure to 51.71/48.29 for Na substitution.

Microstructural characterization of YBa2Cu3O7-x thin films formed by metalorganic CVD

1991 ◽  
Vol 49 ◽  
pp. 1080-1081
Author(s):  
P. Lu ◽  
W. Huang ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
J. Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Film Growth ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
Ion Milling ◽  
Conventional Grinding

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.

Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

1996 ◽  
Vol 54 ◽  
pp. 338-339
Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Electromagnetic Properties ◽  
Length Scale ◽  
Density Values ◽  
Current Densities ◽  
Applied Fields ◽  
A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

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