Pinning mechanism of the high critical current density Sm-Ba-Cu-O superconductors with Sm210/Pd/Pt/CeO2 addition

The superconducting properties and the pinning mechanisms of air-processed melt-textured grown Sm-Ba-Cu-O samples with the addition of small amounts of Pd (0.5wt%), Pt (0.5wt%) and CeO₂ (1.0wt%) were studied. The superconducting properties were enhanced by these additions, especially in co-doped samples. With co-doping of Pd/Pt or Pd/CeO₂, the samples exhibited a high T_c (∼91 K) and a high J_c (0 T,77 K)∼10⁴ A/cm². Pinning forces vs magnetic field studies indicated that these samples have different pinning mechanisms from the un-doped sample. Observations of the microstructures showed that the Pt or CeO₂ addition reduced the sizes of the 211-particles significantly. EPMA results showed that the chemical distributions of these additions are different. Furthermore, TEM/EDS investigations found that the compositional fluctuation of the matrix in the sample co-doped with Pd/Pt is larger than in the sample co-doped with Pd/CeO₂.