Systematic change of flux pinning in (Dy,RE)123 and (Y,RE)123 melt-solidified bulks with unit cell orthorhombicity

RE-mixing is one of the most effective ways to enhance critical current density J(c) of RE123 melt-solidified bulks; however, the intrinsic effects of RE-mixing on J(c) have not yet been well clarified. Through synthesis and analysis of eight types of melt-solidified bulks containing one or two RE elements, the effects of RE-mixing on J(c)-H characteristics were systematically investigated. It was revealed that RE-mixed bulks show higher J(c) than RE123 bulks accompanied by the secondary peaks of J(c) in a high field region. Analyses on the relationship between J(c) and orthorhombicity suggested that the RE substitution level for Ba sites can be controlled by RE-mixing to enhance J(c) in magnetic fields. Combined with the results of magnetic measurements at 40 and 60 K up to 15 T, RE-mixed bulks originating from Y123 powders were found to be high potential materials for high field generating applications.