Structural and magnetic properties of the ring shaped 40 wt% Y211 added TSMG Y123 bulk superconductors welded by Ag2O added MPMG YBCO solder material

Cakir B., AYDINER A.

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS, vol.28, no.22, pp.17098-17106, 2017 (SCI-Expanded) identifier identifier


In this study, two 40% Y211+Y123 bulk superconductors named Y-1 and Y-2 were fabricated by cold top seeding-melt-growth (TSMG) method by using a Nd123 seed with Y2O3 buffer layer placed to bottom of the pellets. The samples were welded with 17 wt% Ag2O+Y123 bulk sample named Y-Ag using as a solder material with a lower decomposition temperature and is produced by melt-powder-melt-growth process (MPMG) with Y2O3 buffer layer. Small specimens were cut above, below and on welding regions of the welded sample and were named as Y-a, Y-b and Y-ab, respectively. The welded solder material and welded samples were studied with XRD, SEM structural analysis, resistivity and magnetization measurements. The welding region was mechanically durable and supported the critical current density (J (c) ) across the joints. The interface of the parent bulk surface and the epitaxially nucleated interfaces are very clean and no residual liquid phases or defects are observed. The onset (T (c,onset) ) and offset (T (c,offset) ) critical temperatures and upper critical fields (H (c2) ) of the samples were evaluated from the magneto resistivity curves. Below the superconducting onset temperature of around 93 K, all samples exhibit sharp superconducting transition with their T (c) (R ae 0) of around 92 K at the 0 T magnetic field, showing that the welding process had no disruptive effect on T (c) . The H (c2) (0) values were 175, 133 and 91 T for Y-a, Y-ab and Y-b respectively. The calculated J (c) values of Y-a, Y-b and Y-ab were 3.71, 3.38 and 3.08 kA/cm(2), respectively, in 0 T field at 77 K. It was obtained that, the J (c) value of the welding region is the comparable to the welding bulks. As a result, we have succeeded in producing a strongly coupled superconducting YBa2Cu3O7-x joint by combining two bulk superconductors of TSMG Y123 by using a 17 wt% Ag2O added MPMG Y123 solder material.