Effect of CeO₂ addition on microstructure and magnetic properties in (Nd,Eu,Gd)-Ba-Cu-O

Morphology of Gd₂BaCuO₅ (Gd-211) secondary phase particles in an oxygen-controlled-melt-growth processed (Nd_0.33Eu_0.33Gd_0.33)Ba₂ Cu₃O_y + 0.5 mol% of Pt (NEG-123) was studied as a function of varying amount (0-3 mol%) of CeO₂. Optical and scanning electron microscopy revealed that sub-micron Gd-211 particles were distributed uniformly throughout the NEG-123 matrix for additions of up to 2 mol% of CeO₂. With increasing CeO₂ content the critical current density, J_c, increased particularly at low magnetic fields. The maximum value of J_c was achieved for 1 mol% CeO₂ and reached 100 kA cm^-2 at zero field and 77 K. The improved low-field critical current density is attributed to the refinement of Gd-211 particles.