Magnetic and microstructure study of bulk (Sm0.33Eu0.33Gd0.33)Ba2Cu3Oy with submicron Gd2BaCuO5 second-phase particles

We fabricated melt-processed (Sm 0 . 3 3 Eu 0 . 3 3 Gd 0 . 3 3 )Ba 2 Cu 3 O y superconductors with fine Gd 2 BaCuO 5 (Gd-211) particles and studied microstructure and magnetic properties as a function of the Gd-211 content and the initial particle size. Microstructure observation by scanning electron microscopy and transmission electron microscopy confirmed the presence of submicron secondary-phase particles and nanometer-sized RE 1 + x Ba 2 - x Cu 3 O y (x > 0) clusters. At 77 K, the critical current densities of 107 and 83 kA/cm 2 were achieved at 0 T (self-field) and 2.2 T, respectively (superconducting quantum interference device data).