Abstract
Supercondudting properties of (Bi, Pb)2(Bi, Sr, Ca)3Cu2O y were studied by electrical resistivity measurements. The oxygen contents of specimens were changed by annealing at different temperatures before rapid quenching. It was revealed that superconducting transition temperatures strongly depended on slight changes of oxygen deficiency which were controlled by changing the annealing temperature, the Ca/Sr ratio, and the Bi and Pb contents. Moreover, the effects of the annealing temperature on the T c differed considerably among specimens with various cationic compositions.