Enhanced critical current properties observed in Na2CO3-doped MgB2
Enhanced critical current properties observed in Na2CO3-doped MgB2
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DOI：
10.1088/0953-2048/17/7/017
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发表时间：
2004-07
影响因子：
3.6
通讯作者：
S. Ueda;J. Shimoyama;A. Yamamoto;S. Horii;K. Kishio
中科院分区：
文献类型：
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作者：
S. Ueda;J. Shimoyama;A. Yamamoto;S. Horii;K. Kishio
碳酸钠掺杂显著改善了MgB_2体材料的临界电流特性。在密封的不锈钢管中通过固态反应制备了一系列Mg 1 − 2xB 2（Na 2CO 3）x（x = 0-0.1）体样品。无论是临界电流密度，Jc，和不可逆场，Hirr，在20 K系统地提高到x = 0.055，并通过过量掺杂单调下降，而它们的Tc不断下降，随着x的增加。x = 0.055的样品的Tc略微降低，为37.6 K，在20 K时记录了最佳的临界电流性能，自电场中的Jc为3.8 × 105 A cm−2，μ 0 Hirr约为6 T。MgO的小颗粒和含碳的局部区域Mg（B，C）2被认为是有效的钉扎中心，导致磁通钉扎力的增强。另外，Na 2CO 3的掺杂显著缩短了MgB 2的相干长度λ，从而使μ 0 Hc 2在x = 0.10的最高掺杂水平下提高到约29 T.
A significant improvement of the critical current properties in MgB2 bulk has been attained by sodium carbonate doping. A series of Mg1−2xB2(Na2CO3)x bulk samples with x = 0–0.1 were prepared by solid-state reaction in sealed stainless tubes. Both the critical current density, Jc, and irreversibility field, Hirr, at 20 K were systematically improved up to x = 0.055 and decreased monotonically by excess doping, while their Tcs were continuously decreased with an increase of x. The sample with x = 0.055, having a slightly decreased Tc of 37.6 K, recorded the best critical current performance at 20 K with Jc of 3.8 × 105 A cm−2 in self-field and μ0Hirr of approximately 6 T. Both small particles of MgO and a carbon-containing local region, Mg(B,C)2, are believed to act as effective pinning centres, resulting in an enhancement of the flux pinning force. In addition, the coherence length ξ of the MgB2 was dramatically shortened by sodium carbonate doping, and consequently the μ0Hc 2 was enhanced to approximately 29 T at the highest doping level of x = 0.10.