Structural and magnetic properties of NiS doped Bi-2212 superconductors

In this work we have studied the effect of NiS doping on the superconductin g properties of the Bi-2212 (nominal composition Bi2.1Sr2.1Ca0.8[(CUO)(1-x) (NiS)(x)](2)O8+delta), superconductors. Our studies show that NiS doping st abilizes superconductivity in the system but all the NiS doped samples gave a T, lower than the superconducting transition temperature of pure Bi-2212 superconductors. It appears that NiS substitution for CuO planes and modif ication of the oxygen content due to S substitution on O places jointly pro duce strong localization of charge carriers and at the same time increase t he hole concentration of the system. These combined phenomena occurring in the Bi2.1Sr2.1Ca0.8[(CuO)(1-x)-(NiS)(x)]O8-delta system are responsible for the deterioration of superconductivity of NiS doped Bi-2212 superconductor s, (C) 2001 Elsevier Science B.V. All rights reserved.