Structural and magnetic properties of NiS doped Bi-2212 superconductors

Abstract In this work we have studied the effect of NiS doping on the superconducting properties of the Bi-2212 (nominal composition Bi 2.1 Sr 2.1 Ca 0.8 [(CuO) 1− x (NiS) x ] 2 O 8+ δ ), superconductors. Our studies show that NiS doping stabilizes superconductivity in the system but all the NiS doped samples gave a T c lower than the superconducting transition temperature of pure Bi-2212 superconductors. It appears that NiS substitution for CuO planes and modification of the oxygen content due to S substitution on O places jointly produce strong localization of charge carriers and at the same time increase the hole concentration of the system. These combined phenomena occurring in the Bi 2.1 Sr 2.1 Ca 0.8 [(CuO) 1− x (NiS) x ] 2 O 8+ δ system are responsible for the deterioration of superconductivity of NiS doped Bi-2212 superconductors.