Microstructural Development of Superconducting Phases in Pb-BSCCO System Derived from Sol-Gel Technique

摘要

Sol-gel processing technique has been utilized to produce the gel of Pb-BSCCO system (Bi_(2-x)Pb_xSr2Ca2Cu3O_(10±y), where x = 0.2, 0.4, and 0.8, are the mole fraction of Pb substituted against Bi). The gel samples were subsequently heated to 800 °C for 2 h to obtain the powders which were then pressed and sintered at 845 °C for 60 h. The morphologies in the Pb-BSCCO gel, powder and sintered products were observed with scanning electron microscope (SEM) and optical microscope. The plate-like growths of the superconducting phases are evident from the SEM micrographs. The optical micrographs of sintered samples showed that the samples containing 0.2 and 0.8 mole fraction of Pb mainly consisted of dark grey and white regions, while sample having 0.4 mole fraction of Pb comprised of dark grey, light grey, and white regions. The different regions were analyzed by using energy dispersive X-rays (EDX) analyzer attached with SEM. The results revealed that the dark grey regions in all the samples represented the Bi2Sr2CaCu2O_(8±y) (2212) phase whereas, light grey regions in sample (x = 0.4) constituted the Bi2Sr2Ca2Cu3O_(10±y) (2223) phase. The white regions in all samples depicted the presence of CuO. The best result in term of larger fraction of superconducting phase (2223) has been observed in sample containing 0.4 mole fraction of Pb.