Recently, we discovered some new experimental evidences about the movement and presentation of defects that have strong correlation with the structure and superconductivity in Bi-containing superconductors. The experiments showed that the Bi-containing 2201 phase could be translated into 2212 phase and 2212 into 2223 under unique conditions, respectively. These wanslation can be described as a diffusion-reaction process that is different from normal diffusion process. An unstable plane was found in Bi-containing 2223 phase but not in 2201 and 2212 phases, that means there is a plane with many oxygen vacancies in 2223 phase. Comparing this result with the situation in Y-containing 123 phase, a very interesting result is obtained that ~he sample with unstable plane is of higher Tc than that without it. Annealing the 2223 sample in different atmospheres(N2,O2) , it was discovered that the oxygen went in and out the sample in the different planes, respectively, that was quite different from the situation in Y-containing 123 phase. We sugg,'~! that there are two different planes dominating the superconductivity in Bi-system.
The scientists have done much work to understand the structure and properties of Bi-containing superconductors since this system was discovered [I]. Although many meaningful results have been obtainedI2,3,41, to know this system comprehensively and deeply, much hard work must be done, such as preparation of pure samples, that is one of the main barriers for further studying. Recently, we discovered some experimental evidences about the presentation and movement of defects that have strong correlation with the structure and properties.