Synthesis of dense MgB2 superconductor via in situ and Ex situ spark plasma sintering method

Joseph Longji Dadiel, Sugali Pavan Kumar Naik, Paweł Pęczkowski, Jun Sugiyama, Hiraku Ogino, Naomichi Sakai, Yokoyama Kazuya, Tymon Warski, Anna Wojcik, Tetsuo Oka, Masato Murakami

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

In this study, high-density magnesium diboride (MgB2) bulk superconductors were synthesized by spark plasma sintering (SPS) under pressure to improve the field dependence of the critical current density (Jc-B) in MgB2 bulk superconductors. We investigated the relationship between sintering conditions (temperature and time) and Jc-B using two methods, ex situ (sintering MgB2 synthesized powder) and in situ (reaction sintering of Mg and B powder), respectively. As a result, we found that higher density with suppressed particle growth and suppression of the formation of coarse particles of MgB4 and MgO were found to be effective in improving the Jc-B characteristics. In the ex situ method, the degradation of MgB2 due to pyrolysis was more severe at temperatures higher than 850C. The sample that underwent SPS treatment for a short time at 850C showed higher density and less impurity phase in the bulk, which improved the Jc-B properties. In addition, the in situ method showed very minimal impurity with a corresponding improvement in density and Jc-B characteristics for the sample optimized at 750C. Microstructural characterization and flux pinning (fP) analysis revealed the possibility of refined MgO inclusions and MgB4 phase as new pinning centers, which greatly contributed to the Jc-B properties. The contributions of the sintering conditions on fP for both synthesis methods were analyzed.

Original languageEnglish
Article number7395
JournalMaterials
Volume14
Issue number23
DOIs
Publication statusPublished - 2021 Dec 1

Keywords

  • Critical current density
  • Flux pinning
  • Grain connectivity
  • MgB
  • Microstructure
  • Spark plasma sintering

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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