Effect of Eu/Gd ratio on flux pinning in (Nd, Eu, Gd)-Ba-Cu-O

Abstract

We have studied the magnetic properties of (Nd0.33EuxGd(0.66-x))Ba2Cu3Oy bulk samples preparedby the oxygen-controlled melt-growth (OCMG) process, in which x ranged from0 to 0.33. The heat treatment profiles for melt processing were determinedaccording to the peritectic decomposition temperatures obtained from thermalanalysis measurements. X-ray diffraction confirmed that the main phase isNEG-123 and the unit cell size decreases monotonously with increasing Gdcontent in the NEG-123 matrix, supporting the presence of a completeNd-Eu-Gd solid solution. The sample with x = 0.08 exhibited a large criticalcurrent density (Jc) of 90 000 A cm-2 at 77 K and 1.7 Tfor H∥ c-axis. The scaling analyses of the volume pinning forceshowed that the peak position in the scaling curve was dependent on the Eu/Gdratio, which indicates that the matrix composition mainly controls theΔTc-pinning mechanism.