Superior high-field current density in slightly Mg-deficient MgB2 tapes
Superior high-field current density in slightly Mg-deficient MgB2 tapes
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DOI：
10.1063/1.2149976
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发表时间：
2005-12
影响因子：
4
通讯作者：
C. Jiang;T. Nakane;H. Kumakura
中科院分区：
文献类型：
--
作者：
C. Jiang;T. Nakane;H. Kumakura
采用原位粉管法制备了一系列x从0.5到1.2的Fe包覆MgxB 2带材。轻微镁缺乏的样品在高磁场中表现出较高的Jc，而与化学计量的镁或镁略有过量的样品表现出更好的Jc在低场区域。x=0.9的样品在所施加的磁场中显示出最好的Jc。MgB 2核心是多孔的Mg-缺乏磁带，但具有较小的晶粒尺寸比样品具有轻微的Mg过量，由于晶粒生长不足。在富硼样品中还观察到一些细小的纳米尺寸的晶粒。由于晶粒尺寸的减小而增强的晶界钉扎可以解释轻微缺Mg的MgB 2带材的优越的上级高场Jc特性。我们的研究结果表明，制备MgB 2样品的Mg稍微过量时，可能不是有利的高场应用开发设备。
A series of Fe-clad MgxB2 tapes with x varying from 0.5 to 1.2 was prepared by the in situ powder-in-tube method. Slightly Mg-deficient samples showed higher Jc in high magnetic fields, whereas samples with stoichiometric Mg or a slight excess of Mg exhibited better Jc in the low-field region. The sample with x=0.9 showed the best Jc in the applied magnetic field. The MgB2 core was porous in Mg-deficient tapes but with smaller grain sizes than the samples with a slight Mg excess due to insufficient grain growth. Some fine nanometer size grains were also observed in the B-rich samples. The enhanced grain boundary pinning due to the smaller grain size may explain the superior high-field Jc property of the slightly Mg-deficient MgB2 tapes. Our results indicate that preparing MgB2 samples with a slight excess of Mg may not be advantageous when developing devices for high-field applications.