Improvement in the critical current density of ex situ powder in tube processed MgB2 tapes by utilizing powder prepared from an in situ processed tape

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.

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Effect of Various C Sources Co-Doping on Transport Critical Current Density and Grains-Connectivity of MgB2/Fe Tapes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.745-746.214 ◽

2013 ◽

Vol 745-746 ◽

pp. 214-218

Author(s):

Xi Feng Pan ◽

Guo Yan ◽

Xiang Hong Liu ◽

Yong Feng ◽

Ping Xiang Zhang ◽

...

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Malic Acid ◽

Flux Pinning ◽

Transport Critical Current Density ◽

Co Doping ◽

The Poor ◽

Powder In Tube

In this paper, we have prepared a series of Fe sheathed MgB2 tapes with SiC, Malic acid and C9H11NO mono-and co-doping by in-situ powder-in-tube (PIT) method, and studied the effects of various C sources co-doping on transport critical current density and flux pinning of MgB2/Fe tapes. The results suggest by various C sources co-doping, the amount of C substitution for boron largely increase, comparing to SiC, Malic acid or C9H11NO mono-doped sample. For MgB2/Fe tapes with 5 mol% SiC+10 wt% Malic acid and 4 wt% C9H11NO+10 wt% Malic acid co-doping, the transport Jc at 4.2 K and 10 T are 14.8 and 13.5 kA/cm2, respectively, which are clearly higher than the Jc of these dopants mono-doped samples. Furthermore, it is found that at the 4 wt.% C9H11NO doped MgB2, the poor in-field Jc should be attributing to the cracks at grains boundary, which results in the bad grains-connectivity.

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

Superconductor Science and Technology ◽

10.1088/1361-6668/ac39ea ◽

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.

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