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2008/05/28(Wed) 13:54

Large Irreversibility Field of MgB2/Fe Tapes Made by nano-C Doping



We investigated the effect of nanoscale-C doping on the critical current density Jc and irreversibility field Birr of Fe-sheathed MgB2 tapes prepared by the in-situ powder-in-tube method. Higher values of Jc and Birr were seen for 5 at.%C-doped MgB2 tapes at higher sintering temperatures. The C-doped samples sintered at 950°C showed the highest Birr, for example, at 4.2 K, the Birr reached 22.9 T. In particular, at 20 K, Birr for the C-doped tape achieved 9 T, which is comparable to the upper critical field of the commercial NbTi at 4.2 K.

Inst. Elect. Eng., Chinese Academy of Sciences: Y. Ma, X. Zhang, D. Wang
IMR, Tohoku University: S. Awaji, K. Watanabe

Reference: Y. Ma, X. Zhang, S Awaji, D. Wang, Z. Gao, G Nishijima and K Watanabe,
"Large irreversibility field in nanoscale C-doped MgB2/Fe tape conductors",
Supercond. Sci. Technol. 20 (2007) L5-L8

in-situ PIT法によって作製したFeシースMgB2テープにおける臨界電流密度Jcおよび不可逆磁場Biへのナノスケールカーボンの添加効果について調べた.5 at%C添加MgB2では,熱処理温度が高いほど高Jcおよび高Biが見られることが分かった. 950℃で熱処理した試料で最も高いBiが得られ,例えば4.2Kでは22.9Tとなった.同じ試料のBiは20Kでも9Tとなり,市販の実用NbTiの4.2Kにおける上部臨界磁場に匹敵する.

中国科学アカデミー電気工学研究所:Y. Ma, X. Zhang, D. Wang
東北大学金属材料研究所:淡路 智,渡辺和雄