Pinning behavior of glycine-doped MgB2 bulks with excellent critical current density by Cu-activated low-temperature sintering
Pinning behavior of glycine-doped MgB2 bulks with excellent critical current density by Cu-activated low-temperature sintering
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DOI：
10.1016/j.jallcom.2013.09.136
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发表时间：
2014-02
影响因子：
6.2
通讯作者：
Q. Cai;Yong-chang Liu;Zongqing Ma;Liming Yu;J. Xiong;Huijun Li
中科院分区：
文献类型：
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作者：
Q. Cai;Yong-chang Liu;Zongqing Ma;Liming Yu;J. Xiong;Huijun Li
在600℃下烧结2~5h时，单一添加甘氨酸的Mg-B系由MgO相组成，而不是由MgB2相组成，并进一步在Mg-B-甘氨酸系中引入铜来激活低温烧结效率，在600℃下分别烧结8h、12h和15h后，铜和甘氨酸共掺杂的样品成功地获得了80%以上的MgB2超导相。在3T和20K下，烧结8h的样品表现出非竞争性的临界电流密度(Jc)，这是由于未完全的−_2相和未反应的镁相所致，而15h的样品表现出最佳的临界电流密度(Jc)为1.5T×104A×104A/cm∼_2。系统地研究了MgO(∼_(20)nm)和Mg_(Cu2)(Mg_(Cu2)_2)的钉扎行为，这种钉扎行为是激发载流能力提高的主要原因。通过物相鉴定和显微组织观察，发现沿螺位错生长机制台阶析出的MgB2晶体中的预生氧化镁和析出的MgCu2都可以作为有效的钉扎中心。最后说明了在600℃下烧结15h的样品的整个烧结过程。
Mg–B system with single glycine addition was composed of MgO phase rather than MgB2when sintered at 600 °C for 2 to 5 h. Cu was further introduced into Mg–B–glycine system to active the low-temperature sintering efficiency, and more than 80% MgB2superconducting phase was successfully obtained in Cu and glycine co-doped samples sintered at 600 °C for 8 h, 12 h, and 15 h, respectively. The sample sintered for 8 h showed uncompetitive critical current density (Jc) because of the uncompleted MgB2phase and the unreacted Mg phase, while the 15-h sample showed the bestJcof 1.5 × 104A cm−2at 3 T and 20 K. The pinning behavior of MgO (∼20 nm) and MgCu2(∼10 nm), which should be responsible for the exciting current-carrying capability that theJcperformance was improved over the entire field in contrast with pure MgB2, was systematically investigated. According to the phase identification and the microstructure observation, both the pre-generated MgO involved in the MgB2grains and the MgCu2precipitated along the steps of the screw dislocation growth mechanism could serve as effective pinning centers. Finally, we illustrated the whole sintering process of the sample sintered at 600 °C for 15 h.