Nanoscale grains, high irreversibility field and large critical current density as a function of high-energy ball milling time in C-doped magnesium diboride

B. J. Senkowicz, R. J. Mungall, Ye Zhu, J. Jiang, P. M. Voyles, E. E. Hellstrom, D. C. Larbalestier

Research output: Journal article publicationJournal articleAcademic researchpeer-review

64 Citations (Scopus)

Abstract

Magnesium diboride (MgB2) powder was mechanically alloyed by high-energy ball milling with C to a composition of Mg(B0.95C 0.05)2 and then sintered at 1000 °C in a hot isostatic press. Milling times varied from 1 to 3000min. Full C incorporation required only 30-60min of milling. The grain size of sintered samples decreased with increased milling time to <30nm for 20-50h of milling. Milling had a weak detrimental effect on the connectivity. A strong irreversibility field (H *) increase (from 13.3 to 17.2T at 4.2K) due to increased milling time was observed and correlated linearly with inverse grain size (1/d). As a result, the high-field Jc benefited greatly from lengthy powder milling. Jc (8T, 4.2K) peaked at>80 000Acm-2 with 1200min of milling compared with only ∼26 000Acm-2 for 60min of milling. This non-compositional performance increase is attributed to grain refinement of the unsintered powder by milling, and to the probable suppression of grain growth by milling-induced MgO nanodispersions.
Original languageEnglish
Article number035009
JournalSuperconductor Science and Technology
Volume21
Issue number3
DOIs
Publication statusPublished - 1 Mar 2008
Externally publishedYes

ASJC Scopus subject areas

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

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