Specimens of M2.2Sr2.0Ca2.0Cu3.zOy [M2.2=Bi1.8Pb0.4-x Inx and Bi1.8Pb0.2M'0.2 (M'=Sn, Sb and Y)] were sintered at 855°C for 40-96hr after decarbonation in air atomosphere and their resistance-temperature curves were compared in order to investigate effects of "inert pair" elements on the formation of the high-Tc phase. In low level of In content (x-value) below 0.18, the stabilization of the high-Tc phase by incorporation of Pb remained almost unaffected. The step wise (shoulder-like) drop in resistance curves due to the coexistence of high and low- Tc phases was observed on specimens of In0.2, Sn0.2 and Sb0.2, showing that lighter inert pair elements have poorer tendency to stabilize the high-Tc phase. The specimen of Y0.2 showed disappearance of the high-Tc phase as well as in specimens of In0.4 without Pb.
