A buffer bridge process for growing multipleYBa2Cu3O7 − y grains from one top seed

Abstract

This study presents a buffer bridge process that allows growing multipleYBa2Cu3O7 − y (Y123) grains from one top seed. This process uses a buffer bridge pellet (Y2BaCuO5 or Y123) to deliver the Y123 growth from one seed to several Y123 compacts.The top seeded melt growth (TSMG) process combined with the buffer bridgeprocess facilitated the fabrication of several single-grained Y123 superconductorsusing one seed. In addition to achieving the growth of multiple Y123 grains, thisprocess ensured a uniform distribution of superconducting properties of the topsurface because the seed/compact interface area (the number of seeds), which is theroute for the impurities from the seeds, was minimized. Additionally, the impuritycontamination from a seed was considerably suppressed using a buffer pellet. One⟨110⟩ diagonal facet line, as a result of the corner-to-corner growth, developed on the topsurfaces of the prepared Y123 compacts, which is comparable to the x-like facetline of the conventional TSMG processed samples. The trapped magnetic field (H) profilesat 77 K of the prepared Y123 compacts, which were estimated using an Nd–B–Fe permanent magnet, showedthe H contour map of a single-grain mode. The force–distance curves for the field cooledand zero-field cooled Y123 compacts at 77 K showed high and reliable levitationforces with a small deviation among compacts. The buffer bridge processcan be applied to a batch process for the mass production of single-grainREBa2Cu3O7 − y (RE: rare-earth elements) superconductors with uniform top surface properties.