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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. [ABSTRACT FROM AUTHOR]

The YBa2Cu3O7-x (YBCO) coated conductor (CC) is one of the most promising superconducting materials because of their high critical current (Ic) and low dependency of the Ic on the external magnetic field. For superconducting applications, a large number of joints are required to join relatively short YBCO CC tapes. In this paper, we study the electromechanical behavior of lap-jointed YBCO CC tapes fabricated by etching Cu stabilizer at its service temperatures (77 K) under self-field. The effects of etching Cu stabilizer on Ic and joint resistance (Rj) of YBCO CC tapes were discussed. The Rj was reduced and the Ic values of the joints are consistent with the parent CCs tape by etching the Cu stabilizer. Preferable electrical properties under applying axial tension are achieved and proved by the axial tension tests and finite element simulations. This fabrication technique is a unique practicable solution to reduce joint resistance for YBCO CC tapes with thicker metal stabilizing layers and improving electromechanical performance in second generation high temperature superconductor (2G HTS) devices. [ABSTRACT FROM AUTHOR]