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High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2 wires and bulks

Nature Materials volume 11, pages 682–685 (2012)Cite this article

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Abstract

The K- and Co-doped BaFe2As2 (Ba-122) superconducting compounds are potentially useful for applications because they have upper critical fields (Hc2) of well over 50 T, Hc2 anisotropy γ < 2and thin-film critical current densities Jc exceeding 1 MA cm−2 (refs 1, 2, 3, 4) at 4.2 K. However, thin-film bicrystals of Co-doped Ba-122 clearly exhibit weak link behaviour for [001] tilt misorientations of more than about 5°, suggesting that textured substrates would be needed for applications, as in the cuprates5,6. Here we present a contrary and very much more positive result in which untextured polycrystalline (Ba0.6K0.4)Fe2As2 bulks and round wires with high grain boundary density have transport critical current densities well over 0.1 MA cm−2 (self-field, 4.2 K), more than 10 times higher than that of any other round untextured ferropnictide wire and 4–5 times higher than the best textured flat wire7. The enhanced grain connectivity is ascribed to their much improved phase purity and to the enhanced vortex stiffness of this low-anisotropy compound (γ~1–2) when compared with YBa2Cu3O7−x (γ~5).

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Figure 1: Volumetric magnetic susceptibility as a function of temperature for K-doped Ba-122 wire and bulk.
Figure 2: Upper critical field as a function of temperature.
Figure 3: Microstructures of K-doped Ba-122 bulk investigated by TEM imaging.
Figure 4: Magneto-optical images of a rectangular piece of K-doped Ba-122 bulk material with magnetic fields applied perpendicular to the plane of the sample (thickness = 0.7 mm).
Figure 5: Jctransport and Jcmagnetization as a function of applied magnetic field at 4.2 K for the K-doped wire, compared with other round, untextured, Fe-based superconducting wires.

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References

  1. Putti, M. et al. New Fe-based superconductors: Properties relevant for applications. Supercond. Sci. Technol. 23, 034003 (2010).

    Article  Google Scholar 

  2. Lee, S. et al. Template engineering of Co-doped BaFe2As2 single-crystal thin films. Nature Mater. 9, 397–402 (2010).

    Article  CAS  Google Scholar 

  3. Katase, T. et al. Biaxially textured cobalt-doped BaFe2As2 films with high critical current density over 1 MA/cm2 on MgO-buffered metal-tape flexible substrates. Appl. Phys. Lett. 98, 242510 (2011).

    Article  Google Scholar 

  4. Tarantini, C. et al. Significant enhancement of upper critical fields by doping and strain in iron-based superconductors. Phys. Rev. B 84, 184522 (2011).

    Article  Google Scholar 

  5. Lee, S. et al. Weak-link behavior of grain boundaries in superconducting Ba(Fe1−xCox)2As2 bicrystals. Appl. Phys. Lett. 95, 212505 (2009).

    Article  Google Scholar 

  6. Katase, T. et al. Advantageous grain boundaries in iron pnictide superconductors. Nature Commun. 2, 409 (2011).

    Article  Google Scholar 

  7. Gao, Z. et al. High transport critical current densities in textured Fe-sheathed Sr1−xKxFe2As2+Sn superconducting tapes. Appl. Phys. Lett. 99, 242506 (2011).

    Article  Google Scholar 

  8. Hilgenkamp, H. & Mannhart, J. Grain boundaries in high- Tc superconductors. Rev. Mod. Phys. 74, 485–549 (2002).

    Article  CAS  Google Scholar 

  9. Larbalestier, D. C., Gurevich, A., Feldmann, D. M. & Polyanskii, A. A. High- Tc superconducting materials for electric power applications. Nature 414, 368–377 (2001).

    Article  CAS  Google Scholar 

  10. Durrell, J. H. et al. The behavior of grain boundaries in the Fe-based superconductors. Rep. Prog. Phys. 74, 124511 (2011).

    Article  Google Scholar 

  11. Ma, Y. et al. Fabrication and characterization of iron pnictide wires and bulk materials through the powder-in-tube method. Physica C 469, 651–656 (2009).

    Article  CAS  Google Scholar 

  12. Wang, L. et al. Large transport critical currents of powder-in-tube Sr0.6K0.4Fe2As2/Ag superconducting wires and tapes. Physica C 470, 183–186 (2010).

    Article  CAS  Google Scholar 

  13. Wang, L. et al. Low-temperature synthesis of SmFeAsO0.7F0.3−δ wires with a high transport critical current density. Supercond. Sci. Technol. 23, 075005 (2010).

    Article  Google Scholar 

  14. Gao, Z. et al. Superconducting properties of granular SmFeAsO1−xFx wires with Tc=52 K prepared by the powder-in-tube method. Supercond. Sci. Technol. 21, 112001 (2008).

    Article  Google Scholar 

  15. Yamamoto, A. et al. Evidence for electromagnetic granularity in polycrystalline Sm1111 iron-pnictides with enhanced phase purity. Supercond. Sci. Technol. 24, 045010 (2011).

    Article  Google Scholar 

  16. Kametani, F. et al. Intergrain current flow in a randomly oriented polycrystalline SmFeAsO0.84 oxypnictide. Appl. Phys. Lett. 95, 142502 (2009).

    Article  Google Scholar 

  17. Qi, Y. et al. Transport critical currents in the iron pnictide superconducting wires prepared by the ex situ PIT method. Supercond. Sci. Technol. 23, 055009 (2010).

    Article  Google Scholar 

  18. Fujioka, M. et al. Effective ex-situ fabrication of F-doped SmFeAsO wire for high transport critical current density. Appl. Phys. Express 4, 063102 (2011).

    Article  Google Scholar 

  19. Sun, D., Liu, Y. & Lin, C. Comparative study of upper critical field Hc2 and second magnetization peak Hsp in hole- and electron-doped BaFe2As2 superconductor. Phys. Rev. B 80, 144515 (2009).

    Article  Google Scholar 

  20. Wang, X-L. et al. Very strong intrinsic flux pinning and vortex avalanches in (Ba,K)Fe2As2 superconducting single crystals. Phys. Rev. B 82, 024525 (2010).

    Article  Google Scholar 

  21. Yang, H., Luo, H., Wang, Z. & Wen, H-H. Fishtail effect and the vortex phase diagram of single crystal Ba0.6K0.4Fe2As2 . Appl. Phys. Lett. 93, 142506 (2008).

    Article  Google Scholar 

  22. Scanlan, R. M., Malozemoff, A. P. & Larbalestier, D. C. Superconducting materials for large scale applications. Proc. IEEE 92, 1639–1654 (2004).

    Article  CAS  Google Scholar 

  23. Braccini, V. et al. High-field superconductivity in alloyed MgB2 thin films. Phys. Rev. B 71, 12504 (2005).

    Article  Google Scholar 

  24. Ozaki, T. et al. Fabrication of binary FeSe superconducting wires by novel diffusion process. J. Appl. Phys. (in the press); preprint at http://arxiv.org/abs/1103.3602 (2011).

  25. Togano, K., Matsumoto, A. & Kumakura, H. Critical properties of a dense polycrystalline (Ba,K)Fe2As2 superconductor prepared by a combined process of melting and deformation. Supercond. Sci. Technol. 23, 045009 (2010).

    Article  Google Scholar 

  26. Wang, C. et al. Enhanced critical current properties in Ba0.6K0.4+xFe2As2 superconductor by overdoping of potassium. Appl. Phys. Lett. 98, 042508 (2011).

    Article  Google Scholar 

  27. Durrell, J. et al. Critical current of YBa2Cu3O7−δ low-angle grain boundaries. Phys. Rev. Lett. 90, 247006 (2003).

    Article  CAS  Google Scholar 

  28. Song, X., Daniels, G., Feldmann, D. M., Gurevich, A. & Larbalestier, D. Electromagnetic, atomic structure and chemistry changes induced by Ca-doping of low-angle YBa2Cu3O7−δ grain boundaries. Nature Mater. 4, 470–475 (2005).

    Article  CAS  Google Scholar 

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Acknowledgements

W. Starch, M. Hannion, M. Santos and V. Griffin provided technical support. This work is supported by NSF DMR-1006584, by the National High Magnetic Field Laboratory, which is supported by the National Science Foundation under NSF/DMR-0084173, and by the State of Florida.

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  1. Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA

    J. D. Weiss, C. Tarantini, J. Jiang, F. Kametani, A. A. Polyanskii, D. C. Larbalestier & E. E. Hellstrom

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  1. J. D. Weiss
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  2. C. Tarantini
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  7. E. E. Hellstrom
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Contributions

J.D.W. synthesized all samples, carried out X-ray diffraction, electromagnetic and SEM characterization, and prepared the manuscript. C.T. carried out the high-field resistivity measurements and prepared the manuscript. J.J. carried out electromagnetic characterization and helped design the experiments. F.K. carried out TEM measurements. A.A.P. carried out magneto-optical imaging. D.C.L. and E.E.H. directed the research and contributed to manuscript preparation. All authors discussed the results and implications and commented on the manuscript.

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Correspondence to E. E. Hellstrom.

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The authors declare no competing financial interests.

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Weiss, J., Tarantini, C., Jiang, J. et al. High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2 wires and bulks. Nature Mater 11, 682–685 (2012). https://doi.org/10.1038/nmat3333

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