AC susceptibility and electrical properties of Ag2S added Bi1.6Pb0.4Sr2CaCu2O8 superconductor

Bi_1.6Pb_0.4Sr₂CaCu₂O₈ (Bi-2212) superconductor samples doped with silver sulfide (Ag₂S) in different weight percentages (x = 0, 0.1, 0.2, 0.4, 0.5, and 1.0 wt.%) were synthesized by the solid-state reaction method. X-ray diffraction (XRD) analysis revealed that all the samples contained Bi-2212 as the dominant phase. The electrical resistance versus temperature curves showed metallic normal state behavior for samples with 0 ≤ x ≤ 0.4 while the sample with x = 0.5 wt. % and x = 1.0 wt. % showed a semimetal-like normal state behavior with an onset transition temperature, T_{c onset} between 82 and 96 K and zero transition temperature, T_{c zero} between 65 and 77 K. AC susceptibility curves showed that the susceptibility transition temperature, T_cχ’ was between 76 and 83 K for all samples. The intergrain critical current density, J_c at the peak temperature, T_p of the imaginary part of the susceptibility c” for all samples was between 16 and 19 A⋅cm^− 2. The x = 0.1 wt% sample showed the highest T_p, (65 K), indicating an improvement in the flux pinning strength. The highest maximum intergrain Josephson current, I₀ and Josephson energy, E_j were between 11.12 and 14.41 µA and 23.02–29.60 meV, respectively for x = 0.5 and 1.0 wt% samples. This work demonstrated that a lower amount of Ag₂S improved the flux pinning energy of the Bi-2212 phase while a higher amount of Ag₂S enhanced intergrain coupling.