Flux pinning and superconducting properties of ZnO added (Nd,Eu,Gd)Ba2Cu3Oy

The paper provides an experimental basis for preparing large grain (Nd0.33Eu0.27Gd0.39)Ba2Cu3Oy "NEG-123". MgO seeds proved to be efficient in controlling growth orientation when a small quantity of ZnO of around 0.035 wt.% was added to the NEG-123 matrix. A substantial reduction of liquid phase loss was observed for a proper ZnO concentration. A perfect facet line up to the bottom of the sample with c-axis reflection plane was observed after the melt-growth implying high density of the material and practically no liquid loss. The magnetization measurements suggested that the superconducting transition temperatures were not affected up to 0.035 wt.% ZnO addition. Critical current density J(c), measured at 3 T and 77 K (H-a parallel to c-axis), increased with increasing ZnO content up to 0.035 wt.%, where it reached maximum value of 100 kA/cm(2) and decreased thereafter. The scalling analysis of the pinning force density as a function of the reduced field h = H-a/H-irr (H-iir is the irreversibility field) showed a peak at relatively high position as expected for an optimized pinning structure. The present results indicate high potential of ZnO particles for further enhancement of the material performance. (c) 2006 Elsevier B.V. All rights reserved.