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https://doi.org/10.3938/NPSM.69.685
Enhancement of Flux Pinning by Artificial Point Defects in K-substituted (Bi, Pb)-2223 Polycrystalline Superconductors
New Phys.: Sae Mulli 2019; 69: 685~689
Published online July 31, 2019;  https://doi.org/10.3938/NPSM.69.685
© 2019 New Physics: Sae Mulli.

Jun Yung OH1, Byeongwon KANG1*, Duc Hai TRAN2, Dong Seok YANG3

1Department of Physics, Chungbuk National University, Cheongju 28644, Korea
2Faculty of Physics, VNU University of Science, Hanoi, Vietnam
3Department of physics Education, Chungbuk National university 28644, Cheongju, Korea
Correspondence to: bwkang@chungbuk.ac.kr
Received April 18, 2019; Revised May 8, 2019; Accepted May 8, 2019.
cc This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
We investigated the influence of K substitution on the superconductivity of polycrystalline Bi$_{1.6}$Pb$_{0.4}$Sr$_{2-x}$K$_x$Ca$_2$Cu$_3$O$_{10+\delta}$ ((Bi, Pb)-2223) superconductors. Polycrystalline samples with a nominal formula of Bi$_{1.6}$Pb$_{0.4}$Sr$_{2-x}$K$_x$Ca$_2$Cu$_3$O$_{10+\delta}$ (x = 0.00, 0.02, 0.04, and 0.06) were prepared by using the conventional solid-state reaction method. Compared to the critical current density ($J_\text{c}$) of pure sample, those for the K-substituted samples showed huge enhancements, as well as a field dependence. According to the analysis of the flux-pinning mechanism based on the Dew-Hughes description, the dominant mechanism changed from normal surface pinning to normal point pinning with increasing K content. Analysis of the extended X-ray absorption fine structure (EXAFS) data indicated that the removal of oxygen near the Sr atom due to lower valence K substitution generated artificial point defects, which serve as effective flux pinning centers, in (Bi, Pb)-2223 superconductors.
PACS numbers: 74.25.-q, 74.62.Dh, 74.25.Op
Keywords: BSCCO, K substitution, Critical current density, Flux pinning mechanism, EXAFS


July 2019, 69 (7)
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