STUDY OF THE CRYSTALLIZATION PROCESS IN BI2-XPBXSR2CA2CU3O10-Y GLASS SYSTEMS - OPTICAL POLARIZED-LIGHT MICROSCOPY, ELECTRICAL AND MAGNETIC-PROPERTIES

Synthesis of Bi2-xPbxSr2Ca2Cu3O10-y (x = 0 and x = 0.3) has been perfo rmed using the glass recrystallization route technique. After splat qu enching, the samples were annealed at 820, 850 or 870-degrees-C for 96 or 144 h (with one intermediary grinding). High-resolution polarizati on micrographs and electrical (and magnetic susceptibility) measuremen ts have been taken. Various growth mechanisms can thus be checked, and the physical properties are studied in relation to the microstructure . It is found that the 2223 phase does not crystallize directly from t he amorphous one but results from a dissolution-reprecipitation proces s. The stability of the 2212 phase is emphasized. The 2201 phase preci pitates at high temperature and rapidly reacts with the melt to form t he 2223 phase. The kinetics of the lead-substituted sample seems to be controlled by the Ca2PbO4 phase. which acts as a flux.