Field Trapping Properties of $c$-Growth Region in RE123 Melt-Solidified Bulks

We have fabricated Ag-free and Ag-added Dy123 cylindrical melt-solidified bulks with large c -growth region. Samples cut from c-growth region of each bulk exhibited high J _c up to high magnetic fields and excellent field trapping properties. On the contrary, J _c and field trapping properties in the a -growth region were suppressed by subgrain boundaries. Magnetic flux penetration along the subgrain boundaries was confirmed in magneto-optical images of the a -growth region. Both J _c and field trapping properties of Dy123 bulks were improved by Ag-addition due to low level Ag substitution for Cu site in the CuO chain.

I. Introduction

Since the (; ) system exhibits high critical current density up to high fields at 77 K, numerous efforts have been paid for developments of its practical materials, such as coated conductors and melt-solidified bulks. RE123 melt-solidified bulks can trap high magnetic field and hence, they are applicable as strong bulk magnets. The field trapping properties depend on and the size (diameter and height) of the bulks. Therefore, growth of large RE123 melt-solidified bulks [1] and enhancement of have been eagerly attempted thus far [2], [3].