3-Dimensional Grain Orientation of RE-Ba-Cu-O Superconductors Using a Modulated Oval Magnetic Field

Tri-axial orientation of twin-free powders of RE₂Ba₄Cu₇O_15-delta (RE247, RE = Y, Dy, Ho, Er) was attempted by modulated rotating magnetic fields. The c -axis orientation was almost completely achieved for all the four RE247 compounds, whereas the degrees of in-plane orientation depended on RE element. Especially for Y247, the degrees of in-plane and c-axis orientation were determined to be ~ 2.5degand < 2deg, respectively, by the phi-scanning and rocking curve measurements. This excellent in-plane orientation is comparable or superior to those for coated conductors ( ~ 4deg) and melt-solidified bulks ( ~ 8deg) of REBa₂Cu₃O_7-delta. Magnetic field dependence of Lotgering factors revealed that the degrees of in-plane orientation were sensitive to the applied magnetic field. The required magnetic field for the tri-axial orientation is determined by the in-plane magnetic anisotropy rather than the magnetic anisotropy between in-plane and out-of-plane directions.