Nanoscale Gd₂BaCuO₅ particles in (Sm _0.33Eu_0.33Gd_0.33)Ba₂Cu ₃O_y and magnetic levitation at 90.2 K

The excellent pinning performance, due to ball milled Gd ₂BaCuO₅ 'Gd-211' particles, recently observed in (Nd, Eu, Gd)Ba₂Cu₃O_y, was tested with (Sm, Eu, Gd)Ba₂Cu₃O_y 'SEG-123' and (Nd, Sm, Gd)Ba ₂Cu₃O_y 'NSG-123' bulk superconductors grown by an oxygen-controlled-melt-growth process. In both cases the same effect was present. Microstructure analysis of the SEG-123 sample showed that there are two kinds of secondary phase particle: one between 100 and 200 nm and the other less than 50 nm in size. The former nanoparticles were identified as Gd-211 and Gd-rich SEG-211, the latter were either of LRE-Ba₂CuZrO_y or (LRE, Zr)BaCuO_y. In both SEG-123 and NSG-123 the pinning performance at high temperatures was sufficient for levitation at liquid oxygen temperature (90.2 K).