The formation of defects and their influence on inter-and intra-granular current in sintered polycrystalline 122 phase Fe-based superconductors

Yusuke Shimada, Akiyasu Yamamoto, Yujiro Hayashi, Kohji Kishio, Jun Ichi Shimoyama, Satoshi Hata, Toyohiko J. Konno

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

The evolution of intra-and inter-granular structures in Co-doped BaFe2As2 (Ba-122) has been studied to address key issues associated with limited inter-granular current transport in randomly oriented polycrystalline Fe-based superconducting materials. We found that the following phenomena occur with an increase in reaction temperature: (i) significant grain growth; (ii) formation and evolution of two types of cracks; (iii) enhancement in the intra-granular current loop; (iv) reduction of magnetic shielding volume; and (v) decrease of the inter-granular transport current. A strong correlation between the inverse grain size and the inter-granular current density was observed. These results indicate that the key microstructural feature to achieve high transport current is a small grain size with no inter-granular cracks, and that low temperature synthesis is an effective path to this end. Based on the observed stacking faults and inter-granular amorphous layers, we propose a model for the formation of the two types of cracks in a polycrystalline Ba-122 phase, i.e. intra-and inter-granular cracks.

Original languageEnglish
Article number084003
JournalSuperconductor Science and Technology
Volume32
Issue number8
DOIs
Publication statusPublished - 2019 Jul 1

Keywords

  • Fe-based superconductor
  • electromagnetic properties
  • electron microscopy
  • multi-scale grain structure

ASJC Scopus subject areas

  • Ceramics and Composites
  • Condensed Matter Physics
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry

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