Improved Critical Current Densities of Bulk MgB2 Using Carbon-Coated Amorphous Boron

Miryala Muralidhar, Masaki Higuchi, Milos Jirsa, Pavel Diko, Ilkin Kokal, Masato Murakami

Research output: Research - peer-reviewArticle

  • 2 Citations

Abstract

In this study, we report on a further improvement of the critical current density of the sintered bulk MgB2 material utilizing the optimized sintering temperature combined with a varying content of carbon in carbon-encapsulated boron. The MgB2 bulk was prepared from high-purity commercial powder of Mg metal and a carbon-encapsulated boron with 0 wt.%, 2.8 wt.%, 4.5 wt.%, and 7.3 wt.% of carbon, using a single-step solid-state reaction at 805 °C for 3 h in pure argon atmosphere. The magnetization measurements confirmed a sharp superconducting transition with onset T at around 38.5 K, decreasing with increasing carbon content. For 7.3 wt.% of carbon, the bulk MgB2 reached the superconducting transition at around 33 K. Scanning electron microscopy of the fractured bulk MgB2 cross section showed a dispersion of 100-200-nm large grains. Due to the carbon doping and optimized processing, the critical current density (J) in bulk MgB2 samples with the carbon-coated boron was improved both in low and high magnetic fields. The highest J values at 20 K, of 375 and 220 kA/cm2, in the self-field and 1 T, respectively, were achieved in the MgB2 sample with 2.8 wt.% of carbon in the carbon-encapsulated boron. The present results clearly demonstrate that the optimized sintering temperature combined with the appropriate amount of carbon in carbon-coated boron is able to improve the entire J performance of the bulk MgB2 material.

LanguageEnglish
Article number7801872
JournalIEEE Transactions on Applied Superconductivity
Volume27
Issue number4
DOIs
StatePublished - 2017 Jun 1
Externally publishedYes

Fingerprint

critical current
boron
current density
carbon
Boron
Carbon
sintering
temperature
Sintering
Temperature
purity
argon
solid state
atmospheres
magnetization
scanning electron microscopy
cross sections
magnetic fields
metals
Argon

Keywords

  • Carbon-encapsulated boron
  • critical current density
  • flux pinning
  • MgB
  • micro-structure
  • Terms

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

Improved Critical Current Densities of Bulk MgB2 Using Carbon-Coated Amorphous Boron. / Muralidhar, Miryala; Higuchi, Masaki; Jirsa, Milos; Diko, Pavel; Kokal, Ilkin; Murakami, Masato.

In: IEEE Transactions on Applied Superconductivity, Vol. 27, No. 4, 7801872, 01.06.2017.

Research output: Research - peer-reviewArticle

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