Improvement to superconductivity using small amounts of Pd addition in Sm-Ba-Cu-O materials

We have studied the superconducting properties of air-processed melt-textured grown Sm-Ba-Cu-O samples with the addition of small amounts of Pd (0-1.0 wt%). The superconducting properties are enhanced with a small amount (0.1 wt%) of Pd addition, for which T_c is ∼89 K and J_c at 0 T and 77 K is 10⁴ A cm^-2. However, both T_c and J_c deteriorate as the Pd addition is further increased. In addition, J_c of Pd-doped samples exhibits anisotropic J_c(H, T) behaviour. Observation of the microstructures has shown that, as the Pd addition increases, the shape of the Sm₂BaCuO₅ particles (211-particles) tends to become rectangular, and the 211-particle size increases (larger than the control sample). We have observed changes in size and morphology of the 211-particles, dislocations and unidentified nanoscale defects in the Pd-doped samples, which imply that small amounts of Pd additions can affect the microstructure as well as altering the pinning mechanism.