Preparation of melt-textured YBa 2Cu 3O 7− δ bulk with CeO 2 additions and their superconducting properties

Abstract

The c-axis oriented YBa 2Cu 3O 7− δ (Y123) bulk superconductors with up to 2.0 wt.% CeO 2 and 18 mm in diameter were prepared by the so-called MMTG process. The critical current density J C significantly increased with 1.0 or above wt.% CeO 2 additions. The sample with 2.0 wt.% CeO 2 additions exhibited a J C of 330,000 A/cm 2 at 35 K and 0 T, when the field was applied parallel to the c-axis of the sample. The maximum of the trapped magnetic field reached 4.2 T at 30 K at the center of the sample surface, which is more than 10 times larger than conventional Nd–Fe–B permanent magnets. Particles of a Ce–Ba compound, whose existence was identified from the observations using a scanning electron microscope, are not distributed uniformly in the Y123 matrix. This high trapped magnetic field of the sample with 2.0 wt.% CeO 2 additions can be explained in terms of a more homogeneous distribution of fine Y 2BaCuO 5 (Y211) particles in the Y123 matrix compared with the CeO 2-free sample.