Effect of Lithium Doping in the Bi-2212 Superconducting System

Samples with the nominal composition Bi₂Sr₂Ca_1–xLi_xCu₂O_y (x = 0.2,0.4, and 0.6) and Bi₂Sr₂CaCu_2−x L1_xO_z (x = 0.4, 0.6, and 1.0) were prepared by the solid state reaction method. The role of L1 at both Ca and Cu sites in the Bi-2212 composition were studied. From the X-ray diffraction data it was found that the L1-doped at the Ca site increases the c-axis and that doped at the Cu site decreases the c-axis. From the D.C. four-probe resistivity data it was found that Li-doped at the Ca site reduces the T_c and the L1-doped at the Cu site gives T_c(0) above the liquid nitrogen temperature. It was observed that the L1 doping reduces the melting point of Bi-2212 composition. The presence of Lithium was confirmed by inductive the coupled plasma method.