Preparation of melt-textured YBa2Cu3O7-delta bulk with CeO2 additions and their superconducting properties

摘要

The c-axis oriented YBa2Cu3O7-delta (Y123) bulk superconductors with up to 2.0 Wt.% CeO2 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.% CeO2 additions. The sample with 2.0 wt.% CeO2 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.% CeO2 additions can be explained in terms of a more homogeneous distribution of fine Y2BaCuO5 (Y211) particles in the Y123 matrix compared with the CeO2-free sample. (C) 2004 Elsevier B.V. All rights reserved.