Lead sulfide effects on electrical properties and AC susceptibility of GdBa_2Cu_3O_(7-δ) superconductor

摘要

The effects of diamagnetic lead sulfide addition on GdBa2Cu3O7_(5 (Gdl23) were investigated. Samples with starting formula GdBa_2Cu_3O_(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 X", J_c (T_p = 55 K) was 14 A cm~(-2).