Formation of superconducting junctions in MT-YBCO

• Published in: Superconductor science & technology 2005-02, Vol.18 (2), p.S153-S157
• Main Authors: Prikhna, T A, Gawalek, W, Novikov, N V, Moshchil, V E, Sverdun, V B, Sergienko, N V, Surzhenko, A B, Uspenskaya, L S, Viznichenko, R, Kordyuk, A A, Litzkendorf, D, Habisreuther, T, Krachunovska, S, Vlasenko, A V
• Format: Article
• Language: English
• ISSN: 0953-2048; 1361-6668
• DOI: 10.1088/0953-2048/18/2/031

The formation of superconducting junctions between MT-YBCO using TmBa2Cu3O7-delta powder as a solder has been studied. The method proposed excludes the step of a very slow cooling (at a rate of several degrees per hour) during seam formation. The heating and cooling rate for joining parts produced from single-domain material without visible cracks (macrocracks) can be rather high (500-1000 K h-1) and a holding time at the highest temperature (1010 deg C) of several minutes (0.05 h) is enough to form a reliable junction. Reasonable rates of heating and cooling are however around 100 K h-1 if crack propagation is to be avoided in joined blocks used for practical application. Modelling experiments on rings and studies of the ring properties by vibrating sample magnetometer (VSM), field mapping with a Hall probe and magneto-optical microscopy have shown that superconducting properties of the junction were not lower than that of the joined material (jc of about 30 kA cm-2 was observed in zero field at 77 K) and that the proposed process of joining did not adversely affect the properties of the material. The structure of the resulting junction was in good agreement with the structure of MT-YBCO.