面向高场应用的铁基超导材料

Iron-based superconducting materials for high-field applications

铁基超导体的上临界磁场可达100 T以上,并具有较小的各向异性、简单的制备工艺等突出优点,在核磁共振成像(MRI)、核磁共振谱仪(NMR)及高场超导磁体等领域具有重要的应用前景。目前铁基超导材料正处于快速发展的研发阶段,低成本的粉末装管法已广泛应用于铁基超导线带材的制备,临界传输电流密度在4.2 K和10 T下超过10~5A/cm^2;最近世界首根百米量级铁基超导长线的成功研制进一步奠定了铁基超导材料在强电领域的应用基础。本文首先介绍了铁基超导材料的典型结构与基本超导特性,接着以粉末装管工艺流程为主线,从影响铁基线带材临界电流密度的关键因素:相纯度、晶界弱连接以及致密度等方面入手,详细评述了国内外铁基超导线带材制备的最新研究进展。在此基础上,分析当前研究中存在的问题,并提出进一步改善传输性能的可能对策,最后对铁基超导材料的发展趋势进行了展望。

Iron-based superconductors have ultrahigh upper critical fields with He2 values exceeding 100 T and low anisotropy （e.g. 〈 2 for 122 type）, making them potential candidates for high-field applications, such as MRI, NMR and ultra-high field magnets. Conventional powder-in-tube （PIT） method has been the most effective technique for fabricating iron-based superconducting （IBS） wires and tapes. The transport critical current density Jc of IBS wires and tapes has been rapidly increased in the recent years, the highest Jc values have now achieved over 105 A/cm2 （10 T and 4.2 K） in densified and textured 122 tape samples. In August 2016, by a scalable rolling process, the world＇s first 100 meter-class iron-based superconducting wire was fabricated, which demonstrates the great potential in large-scale manufacture. Here we introduce basic properties of iron-based superconductors and review the latest achievements in the fabrication of conductors based on these materials. Finally, the future development and problems to be solved in this area are suggested.