Improved Superconducting Properties of Y123 Melt-solidified Bulks through Controlling Crystal Growth Direction and Cation Stoichiometry

Abstract

Two new approaches to fabricate Y123 melt-solidified bulks with excellent superconducting properties have been developed. One is a new method of crystal growth from a seed crystal with its c-axis parallel to the top surface, and the other is a high-temperature annealing process under a moderately reducing atmosphere after crystal growth. In the present study, the former method increased the area of high-J_c regions, and the latter enhanced J_c, particularly at positions far from the seed crystal at low temperatures through suppression of yttrium substitution for barium. The field-trapping property was also improved through introduction of a reductive annealing process prior to oxygen annealing at low temperatures.