A new heat treatment to prepare high-quality polycrystalline and single crystal MgB2 in a single process
A new heat treatment to prepare high-quality polycrystalline and single crystal MgB2 in a single process
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一种在单一工艺中制备高质量多晶和单晶 MgB2 的新热处理方法
DOI：
10.1088/0953-2048/16/6/302
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发表时间：
2002
影响因子：
3.6
通讯作者：
K. Ng
中科院分区：
文献类型：
--
作者：
Mohamed H. Badr;K. Ng
我们报告了一种新的热处理方法，可以在单一工艺中制备致密的多晶和单晶MgB2高质量样品。样品多晶部分的电阻率测量结果为残余电阻率RRR = 16.6，非常低的正常状态电阻率ρ0(40 K) = 0.28µcm。对多晶的SEM和SQUID研究表明，多晶具有高质量、致密性和良好的晶界耦合性。另一方面，高质量的单晶具有独特的形状，类似于六方晶体结构。SQUID测量显示出非常弱的磁通固定特征，这意味着我们的单晶非常干净，即没有磁通捕获中心。在这项研究中，我们得出结论，热处理在确定多晶和单晶MgB2的特性方面起着重要作用。通过x射线、电阻率、直流SQUID和SEM对样品进行了全面表征。
We report here on a new heat treatment to prepare both dense polycrystalline and single crystal MgB2 high quality samples in a single process. Resistivity measurements for the polycrystalline part of the sample gives a residual resistivity ratio RRR = 16.6 and a very low normal state resistivity ρ0(40 K) = 0.28 µcm. Both SEM and SQUID studies on polycrystals reveal the high quality, dense character and good coupling of the grain boundaries. On the other hand, the high-quality single crystals have a unique shape that resembles the hexagonal crystal structure. SQUID measurements reveal a very weak flux pinning character, implying that our single crystals are very clean, i.e. free from flux trapping centres. In this study, we conclude that heat treatment is playing a major role in defining the characteristics of both polycrystalline and single crystal MgB2. Samples are thoroughly characterized by x-ray, resistivity, dc SQUID and SEM.
II型超导体中的德哈斯-范阿尔芬效应理论
DOI：
--
发表时间：
2002
期刊：
Physical Review B 66
影响因子：
--
作者：
K.Yasui;T.Kita
通讯作者：
T.Kita