In this paper, we discuss the superconducting properties of air-processed melted-textured-grown (MTG) Sm-Ba-Cu-O samples (single domain) with the addition of small amounts of Pd (0.5 wt%) and Pt (0.5 and 1.0 wt%). When Pd was added, the superconductors showed a high Tconset (∼89 K) and a high Jc (0 T, 77 K) ∼5 × 103 A cm-2. A specimen co-doped with 0.5 wt% Pd and 0.5 wt% Pt displayed excellent superconductivity, with Tconset = 91 K and Jc (0 T, 77 K) ∼1.4 × 104 A cm-2. Transmission electron microscopy (TEM) and scanning electron microscopy observations have shown that, with the addition of Pd, the shapes of Sm2BaCuO5 (Sm211) particles tend to become rectangular and triangular, and the sizes are in the range of 5-30 μm. As for samples co-doped with 0.5 wt% Pt and 0.5 wt% Pd, the proportion of the rectangular Sm211 particles increases, and the size decreases (1-20 μm). According to TEM observations in the interface between SmBa2Cu3O7 (Sm123) and Sm211, we also found that more defects exist at the corner of the rectangular-shaped Sm211 than at that of regular-shaped Sm211. This implies that the addition of Pd can change the shape of Sm211, and then increase the density of defects as well as pinning centres. In addition, the angular dependence of the Jc (H, T) of the Sm-Ba-Cu-O/Pt, Pd sample is slightly different from that of other systems (e.g. Y-Ba-Cu-O/Pt). We have also studied this difference in orientation dependence and the relationship between the distribution of the defects and the peak effect.
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