Highly enhanced superconducting properties of Bi-2212 by Y and Pb co-doping

The effects of Y and Pb co-doping on phase evolution, microstructure, electrical and superconducting properties of Bi-2212 have been studied. The results show that Y3+ ions enter into the crystal structure by replacing Ca2+ and/or Sr2+ ions, and hence reduce hole concentration in the electronic structure of the system. Y and Pb co-doping result in the reduction of c-axis resistivity due to strong Josephson coupling between the Cu-O-2 layers at lower Y contents. The T-C and J(C) are significantly enhanced for optimum Y concentration in Pb doped Bi-2212. The variations in the electrical and superconducting properties are due to the structural as well as electronic inhomogeneities and changes in charge carrier concentration due to Pb and Y co-doping. (C) 2009 Elsevier B.V. All rights reserved.