Top seeded melt growth of Gd–Ba–Cu–O single grain superconductors

Abstract

Top seeded melt growth (TSMG) has been used extensively to fabricate large, single grainY–Ba–Cu–O (YBCO) bulk superconductors that can trap large magnetic fields. TheTSMG method is relatively economical and has enabled the development of batch processesfor the fabrication of a large number of bulk single grain superconductors in a singlefurnace. In addition, the technique allows the fabrication of complex-shaped bulk sampleswith controlled and strongly connected grains by using a novel, multi-seeding process. Apractical processing route for processing of LRE–Ba–Cu–O (where LRE represents a lightrare earth element) single grain superconductors (which have superior propertiesto YBCO) has been developed at Cambridge over the past three years, basedon the development of a generic seed of melt textured Mg-doped Nd-123 andsuppression of solid solution phase formation in air by enriching the precursorcomposition with excess Ba. In this paper we report the successful application of apractical TSMG process in the fabrication of high performance Gd–Ba–Cu–O(GdBCO) single grain superconductor. This method has enabled the development of abatch process for GdBCO and we demonstrate for the first time the fabricationof a large number of high performance single grains of this material in a singleprocess. Finally, we report the processing of bulk GdBCO in the form of complexgeometries with controlled grain orientation for bespoke engineering applications.