Transverse distribution of critical current density in Ag-sheathed Ba1-xKxFe2As2 tapes

2021 ◽  
Author(s):  
peng yang ◽  
He Huang ◽  
Meng Han ◽  
Wenwen Guo ◽  
Chang Tu ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Reaction Layer ◽  
High Performance ◽  
Ex Situ ◽  
Superconducting Tapes ◽  
Superconducting Properties ◽  
The Core ◽  
Powder In Tube

Abstract The Ag-sheathed Ba1-xKxFe2As2 (Ba-122) monofilamentary tapes were prepared by the ex-situ powder-in-tube (PIT) method. The variation of the microstructure and superconducting properties with the thickness of the superconducting core in the cross-section of sintered tapes is studied. At the same time, the reason is studied in comparison with the unsintered tapes. The research results show that the magnetic Jc of the iron-based superconducting tapes increases continuously with distance from the core-sheath interface, which is the complete opposite of the Bi-based superconductor. The magnetic Jc of central layers for final Ba-122 tapes is about 33% higher than the Jc of the whole tape at 4.2 K and 7 T. We have found that the center of the superconducting core shows higher hardness and better texture. In addition, it is also found that there is a reaction layer at the Ag-superconductor interface. These reasons may result in the reduction of the critical current density near the interface in the tapes. Moreover, we also found the presence of a reaction layer in the hot-pressed (HP) high-performance samples. However, no unevenness was found in the unsintered samples. Therefore, the superconductivity of Ba-122 tapes will be better by reducing the reaction layer and eliminating inhomogeneity at the core-sheath interface of the sintered tapes.

Effect of sintering temperature and cooling rate on microstructure, phase formation, and critical current density of Ag-sheathed Bi1.8Pb0.4Sr2Ca2Cu3Ox superconducting tapes

1998 ◽  
Vol 13 (2) ◽  
pp. 261-268 ◽  
Author(s):  
J. P. Singh ◽  
N. Vasanthamohan
Keyword(s):  
Critical Current Density ◽  
Cooling Rate ◽  
Critical Current ◽  
Current Density ◽  
Sintering Temperature ◽  
Superconducting Tapes ◽  
Temperature Quenching ◽  
Slow Cooling ◽  
Higher Temperature ◽  
Powder In Tube

Silver-sheathed Bi–Pb–Sr–Ca–Cu–O (2223) superconducting tapes (with a starting composition of Bi1.8Pb0.4Sr2Ca1Cu2O8, calcium cuprate, and CuO) were fabricated by the powder-in-tube technique. The tapes were sintered at various temperatures to optimize the formation of Bi1.8Pb0.4Sr2Ca2Cu3O10 phase within the tape. The results show that sintering within the temperature range of 815–825 °C can produce tapes with high critical current density (Jc). The Jc of samples sintered at the higher temperature of 825 °C, where more liquid is present, depended markedly on the rate at which tapes were cooled from the sintering temperature; samples sintered at lower temperatures did not exhibit such a cooling-rate effect. The optimum combination of phase purity and microstructure that yielded an average transport Jc of ≥ 2.5 × 104 A/cm2 was obtained when the tapes were sintered at 825 °C for 150 h and cooled at a rate of 25 °C/h from the sintering temperature. Quenching studies indicate that the Bi-2223 phase becomes unstable below 700 °C during slow cooling. This result may have important implications for processing Bi–Sr–Ca–Cu–O tapes with high Jc. Addition of 15 vol.% Ag flakes to the monolithic core exerted no significant effect on Jc.

Improved critical current densities in MgB2 tapes fabricated through an ex situ process using powders treated in various chemical solutions

2008 ◽  
Vol 23 (2) ◽  
pp. 507-514 ◽  
Author(s):  
H. Fujii ◽  
K. Togano ◽  
K. Ozawa
Keyword(s):  
Critical Current Density ◽  
Benzoic Acid ◽  
Critical Current ◽  
Current Density ◽  
Chemical Treatment ◽  
Benzene Solution ◽  
Ex Situ ◽  
Chemical Solutions ◽  
Current Densities ◽  
Powder In Tube

We have studied grain coupling and critical current density (Jc) in ex situ processed Fe-sheathed MgB2 tapes fabricated by a powder-in-tube (PIT) technique, using MgB2 powder soaked in various chemical solutions. The grain coupling and the Jc are strongly influenced by the chemical solutions. Compared with the chemical treatment in a benzene solution of benzoic acid, the use of a cyclohexane solution of benzoic acid doubles the Jc value. Cyclohexane is less stable and hence effectively removed from the surface of MgB2 grains, bringing about the improved coupling of grains and the Jc enhancement.

Superconducting critical current density enhanced to 285 A cm−2 for Sr2VFeAsO3−δ tapes fabricated by ex situ powder-in-tube process

2019 ◽  
Vol 12 (12) ◽  
pp. 123004
Author(s):  
Suguru Iwasaki ◽  
Ryo Matsumoto ◽  
Shintaro Adachi ◽  
Yoshihiko Takano ◽  
Yoichi Kamihara
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Ex Situ ◽  
Powder In Tube

Effect of ZnO Nano-Oxide Addition on the Superconducting Properties of the (Bi.Pb)2223 Phase

2011 ◽  
Vol 324 ◽  
pp. 241-244 ◽  
Author(s):  
R. Mawassi ◽  
R. Awad ◽  
Mohamad Roumie ◽  
M. Kork ◽  
I. Hassan
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
High Temperature Superconductors ◽  
Weak Links ◽  
Superconducting Properties ◽  
X Ray ◽  
Weight Percentage ◽  
Nano Oxide

The major limitation of Bi-system superconductor applications is the intergrain weak links and weak flux pinning capability producing low critical current density of the Bibased phases. In order to enhance these characteristics and other superconducting properties, effective flux pinning centers are introduced into high temperature superconductors. In this work, different weight percentages of ZnO nano oxide were introduced at the final stage of the Bi1.8Pb0.4Sr2Ca2Cu3O10-y superconductor preparation process. Phase characterization was completed by X-ray diffraction (XRD). Exact constitution of the samples was determined using particle induced X-ray emission (PIXE). Granular and microstructure were investigated using scanning electron microscopy (SEM). Electrical resistivity as function of the temperature was carried to evaluate the relative performance of samples, and finally, E-J characteristic curves were obtained at 77K. Using 0.4 ZnO weight percentage, the electrical and granular properties were greatly enhanced, indicating more efficient pinning mechanisms. A critical current density of 949 A/cm2 was obtained which represents more than twice the value obtained for the pure sample (Jc= 445 A/cm2).

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