Formation Process of the Li-addition High-Tc Phase in the Bi-Pb-Sr-Ca-Cu-O System

Abstract

Li addition was found to raise T_c up to 116K in the high-T_c phase in the Bi-Pb-Sr-Ca-Cu-O system. But the role and behavior of Li has not yet been clarified. This study has been done for samples with starting compositions of Bi_0.9Pb_0.2Sr_1.0Ca_1.0Cu_1.6Li_xO_y with x=0.03 to 0.10 and heated at 825 to 840°C for 1 to 48h. ICP analysis showed that Li content decreased with increasing sintering time. The lattice constant a decreased at first and then gradually increased. On the other hand, the lattice constant c passed through a maximum around 4h.