Study of superconducting properties of OCMG processed (Nd, Eu, Gd)-Ba-Cu-Owith Pr doping

The superconducting and magnetic properties of oxygen-controlled-melt-grown (Nd, Eu, Gd)Ba2Cu3Oy (NEG-123) superconductors containing Pr in the concen tration range x = 0 to 0.15 are reported. X-ray diffraction results confirm ed the main phase as NEG-123 phase without any significant change in the cr ystal structure. Magnetization measurements revealed a depression of the su perconducting transition temperature, T-c. The transitions are sharp at low Pr concentrations, however, a broad maximum begins to develop when the Pr concentration is x > 0.1. The critical current densities, J(c), and the irr eversibility fields are found to decrease on increasing the Pr content. It is also found that J(c) of the Pr-doped composites for x = 0.12-0.15 is abo ut five orders of magnitude lower than that of the pure NEG-123 composites. The fall in T-c and J(c) on Pr doping is explained in terms of the partial substitution of Pr on the rare earth site and hole localization due to tri valent ions on the Pa site. (C) 1999 Published by Elsevier Science B.V. All rights reserved.