(Nd0.33Eu0.33Gd0.33)2BaCuO 5 (NEG-211) particles are added to ternary (Nd0.33Eu0.33Gd0.33)Ba2Cu 3Oy (NEG) bulk, melt-processed superconductors. By means of transmission electron and polarized light microscopy, we found that two types of 211 particles are formed; large NEG-211 and submicron-sized particles containing mostly Gd in the rare earth site are formed which can act as effective flux pinning sites. The critical current density at zero field increases monotonously as a function of the NEG-211 concentration, but the secondary peak vanishes above 40 mol % 211 addition. As a result, a critical current density of 68 000 A cm-2 at 77 K and 2.5 T applied field is achieved with at 40 mol % 211 additions.
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