Development of Melt-processed (Nd,Eu,Gd)Ba₂Cu₃O_y Superconductors in Air

(Nd_0.1Eu_0.1Gd_0.8)Ba₂Cu₃O_y "NEG-123"superconductors were synthesized as a function of BaO₂ content with the aim of reducing NEG/Ba substitution and preparing batch production in air. The DTA data were used to schedule the heat treatment profile of the melt growth process. The magnetization measurements indicated that superconducting transition temperature increased with increasing the BaO₂ concentration and a T_c (onset) reached around 95 K for the sample with 24 mol% BaO₂, which is similar to the NEG samples processed in reduced oxygen pressure. Moreover, the superconducting transition temperature decreased when BaO₂ content exceeded 28 mol%. The irreversibility field was increased with increasing the BaO₂ concentration and reached >5 T for the sample with 24 mol% BaO₂ and decreased thereafter. The experimental results suggest that the present approach will contribute to large scale batch production of melt-processed NEG-123 materials in air.