Correlation between microstructure and superconductivity in advanced coated conductors architectures based on technical templates

高温超导体在具有高电流传输能力的电缆或线圈中的应用需要具有强晶体织构的材料，以减少高角度晶界的有害影响。为了实现这些特性，超导层是在高度纹理化的金属基模板上外延生长的。如今，这种纹理模板通常使用不同的方法制作长长度。除了强大的晶体结构外，这种涂层导体还显示出特征的晶界网络，这取决于所使用的模板以及超导体本身的制备路线。无论如何，这一晶界网络对全球电流输运起着决定性的作用。因此，了解超导体的局部晶粒结构与局部电流输运之间的关系对于优化涂层导体的性能至关重要。这些详细的知识最终将使这种导体的制造更具成本效益，从而开辟新的应用前景或取代现有材料，这些材料需要昂贵的氦冷却。因此，这个联合项目的主要目的是将超导体本身的晶界网络的性质与局部电流输运联系起来。为了实现这一目标，将应用先进的高分辨率技术来确定颗粒水平上的电流。这些方法可以确定这些材料的限制区域，从而减少全球电流运输。特别是，计划研究人工二次相的加入以及新型液体辅助沉积方法对这种晶界网络中局部电流输运的影响。与此同时，最近开发的铁基超导体层将被研究，以评估与通常使用的铜材料相比，改进的晶界输运行为是否会导致这种涂层导体结构的优势。最后，确定的微观结构与局部电流之间的相关性将用于模拟这些涂层导体中的全局电流传输，从而进一步优化各自的应用。

The application of high temperature superconductors in cables or coils with a high current transport capability requires materials with a strong crystallographic texture to reduce the detrimental effect of high angle grain boundaries. To realize such properties, the superconducting layers are epitaxially grown on highly textured, metal-based templates. Nowadays, such textured templates are routinely produced in long length using different approaches. Beside the strong crystallographic texture, such coated conductors reveal a characteristic grain boundary network, which depends on the template used as well as on the preparation route of the superconductor itself. In any case, this grain boundary network determines the global current transport in a decisive way. Therefore, it is crucial to understand the correlation between the local grain structure of the superconductor and the local current transport in order to optimize the performance of the coated conductors. The detailed knowledge will finally enable a more cost efficient fabrication of such conductors in order to open new application prospectives or to replace existing materials, which require an expensive Helium cooling.Therefore, the major aim of this joint project is to correlate the properties of the grain boundary network in the superconductor itself with the local current transport. To realize this goal, advanced high-resolution techniques will be applied to determine the current flow on a grain level. These methods allow identifying limiting areas in these materials, which reduce the global current transport. In particular, it is planned to study the influence of incorporating artificial secondary phases as well as the use of novel liquid-assisted deposition methods on the local current transport in such grain boundary networks. Simultaneously, recently developed Fe-based superconductor layers will be investigated in order to evaluate, if the improved transport behavior of their grain boundaries results in advantages for such coated conductor architectures if compared to the typically used cuprate materials. Finally, the identified correlations between the microstructure and the local current flow will be used to model the global current transport in these coated conductors, which enables a further optimization for the respective applications.