The achievement of low-resistance connection in REB2C3O7-z (REBCO, RE = Y, Gd) coated conductors (CCs) has become one of the strategic factors for magnet applications. In this letter, we fabricated low-resistivity (Rsj = 4.9 nΩ·cm2) Ag-diffusion joints of REBCO CC by improving the interface connection of the Ag stabilizer. The effective contact area at the interface between two Ag stabilizers can be increased by polishing the surface of the Ag stabilizers, which can reduce joint resistance (Rj). Compared with a traditional diffusion temperature (400 °C), diffusion bonding of the Ag stabilizers at higher temperatures (800 or 850 °C, typical connection temperatures for superconducting joint) can promote interface connection between two Ag stabilizers. The oxygen content in REBCO will be reduced due to diffusion bonding at higher temperatures. Therefore, we etched some microchannels that serve as the fast oxygen diffusion paths on the surface of the Ag stabilizers to help restore the oxygen content, thereby recovering critical current (Ic) and reducing Rj. The connection mechanism of the interface between two Ag stabilizers was investigated through the cross-sectional analysis and delamination of the joint part. In addition, the REBCO layer can be completely peeled off and almost retain the original Ic by diffusion bonding of the Ag stabilizers at higher temperatures. This fabrication technique is a unique practicable solution to reduce the Rj for the CC with thin Ag stabilizers and improve the peeling quality of the REBCO layer for efficiently fabricating the superconducting joint.

中文翻译：

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改进银稳定剂界面连接实现REBCO涂层导体低电阻率扩散接头


REB2C3O7-z（REBCO，RE = Y，Gd）涂层导体（CC）的低电阻连接的实现已成为磁体应用的战略因素之一。在这封信中，我们通过改进银稳定剂的界面连接，制造了REBCO CC的低电阻率（Rsj = 4.9 nΩ·cm2）银扩散接头。通过对银稳定剂表面进行抛光，可以增加两个银稳定剂界面的有效接触面积，从而降低接头电阻（Rj）。与传统的扩散温度（400℃）相比，银稳定剂在更高温度（800或850℃，超导接头的典型连接温度）下的扩散结合可以促进两个银稳定剂之间的界面连接。 REBCO中的氧含量会因较高温度下的扩散结合而减少。因此，我们在Ag稳定剂表面蚀刻了一些微通道作为氧快速扩散路径，以帮助恢复氧含量，从而恢复临界电流（Ic）并降低Rj。通过截面分析和连接部分的分层研究了两个银稳定剂之间界面的连接机制。此外，通过Ag稳定剂在较高温度下的扩散结合，REBCO层可以完全剥离并几乎保留原始Ic。这种制造技术是一种独特的实用解决方案，可以降低具有薄Ag稳定剂的CC的Rj，并提高REBCO层的剥离质量，从而有效地制造超导接头。