Abstract
Superconducting transition temperature (Tc), hole concentration (nc), and crystal structure for Bi1.7Pb0.3Sr2Ca2Cu3Oy (2223) polycrystals and Bi2Sr2CaCu2Oy (2212) single crystals annealed in different atmospheres have been measured. It is found that the consequence of annealing in O2 is mainly the modification of the oxygen in Cu---O planes, which is different from that in N2 where the change is in the Bi-O planes. The result provides a good explanation for the complicated changes of the Tc with the annealing conditions.