Synthesis of CdS Nanoparticles by Hydrothermal Method and Their Effects on the Electrical Properties of Bi-based Superconductors

Cadmium sulfide (CdS) nanoparticles were synthesized by hydrothermal process and have been characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDXS) system. The effect of added CdS nanoparticles on the superconducting properties and flux pinning capability in (Bi,Pb)₂Sr₂Ca₂Cu₃O_y system (denoted as (Bi,Pb)-2223) has been reported. Hydrothermal method is an effective route to synthesize CdS nanoparticles with good crystallinity and having average grain size of about 12 nm. Then, small amounts (0–0.4 wt%) of nanosized CdS particles were added to Bi-2233 samples using a solid-state reaction route. The transport critical current densities and the electrical resistivity ρ(T, H) were performed using the four-probe technique. The results show that samples sintered by small amount of CdS nanoparticles (≤ 0.3 wt%) exhibit the higher critical current densities and energy pinning in applied magnetic fields compared to free added sample. Consequently, the addition of CdS could introduce effective pinning centers which account for the improvement in superconducting properties in the Bi-2223 materials.