Structural and Transport Properties of the $( \hbox{Bi}_{1.6}\hbox{Pb}_{0.5})(\hbox{Sr}_{2-x}\hbox{Lu}_{x})\hbox{Ca}_{1.1}\hbox{Cu}_{2.1}\hbox{O}_{8 + \delta}$ Superconductor

The effects of Lu-doping on phase evolution, microstructure, electrical, and superconducting properties of Bi-2212 have been studied. The results show that Lu
⁺³
ions enter into the crystal structure in place of Sr
⁺²
ions and, hence, reduce the hole concentration in the electronic structure of the system. Lu-doping results in the reduction of
c
-axis length and increases the Josephson coupling between the Cu-O
₂
layers at lower Lu-contents. The critical temperature
Tc
and the critical current density
Jc
are significantly enhanced for optimum Lu concentration. The variations in the electrical and superconducting properties are due to the structural and electronic inhomogeneities and changes in charge carrier concentration due to Lu-doping in the (Bi, Pb)-2212 superconductor.