Lead sulfide effects on electrical properties and AC susceptibility of GdBa2Cu3O7–δ superconductor

The effects of diamagnetic lead sulfide addition on GdBa 2 Cu 3 O 7– δ (Gd123) were investigated. Samples with starting formula GdBa 2 Cu 3 O 7– δ (PbS) x for x = 0, 0.2, 0.3, 0.4 and 0.5 wt.% were prepared using the solid-state reaction method. X-ray diffraction and energy-dispersive X-ray analysis showed that all samples consisted a single Gd123 phase. Scanning electron micrographs showed larger grain size in the non-added sample compared with PbS-added samples. The electrical resistance and AC susceptibility measurements showed that PbS did not affect the transition temperature for x ≤ 0.4 wt.%. However, the peak temperature, T p , of the imaginary part of the susceptibility decreased to lower temperatures with PbS addition. This indicated that PbS weakened the inter-granular coupling and lowered the flux pinning energy. The inter-grain critical current density, J c , of the non-added sample at the peak temperature, T p , of the imaginary part χ″, J c ( T p = 55 K) was 14 A cm –2 .