Chemical stability of the Bi-2223 phase has been studied for the samples Bi0.9Pb0.2SrCaCu1.6O2 Annealing of the bulk samples below 800°C leads to precipitation of the 3321 phase identified as Sr2.5Bi0.5Pb3Ca2CuOz. The precipitation of the 3321 phase from the 2223 phase decreases the volume fraction of the 2223 phase but Tc (x) remains unchanged. It was found by XRD and SQUID measurements and SEM observation that, through reheating at 850°C after heating at 750°C, the 3321 phase disappeares and the volume fraction of the 2223 phase perfectly recovers.
