RAPID ONE-POWDER PROCESS TO SYNTHESIZE PHASE ASSEMBLAGE COMPOSED OF (BI,PB)(2)SR2CACU2OX, CA2CUO3 AND CUO

Ultrafine (200 nm) BiPbSrCaCuO powder with phase assemblage of (Bi,Pb) (2)Sr2CaCu2Ox, (Bi,Pb)(2)Sr2CaCu2Ox, Ca2CuO3 and CuO is synthesized by our recently developed coprecipitation-based micro-reactor process (C MP) in one-step, based on the study of the effects of atmosphere in ea ch step of CMP on phase assemblages. The phase assemblages are mainly determined by the atmosphere in the ramp step. The O-2-containing atmo sphere leads to the phase assemblages of (Bi,Pb)(2)Sr2CaCu2Ox (2212), Ca2PbO4, Ca2CuO3, CuO and (Bi,Pb)(2)Sr2CuOx(2201) at 800 degrees C. Th e inert (N-2) atmosphere results in the phase assemblages of (Bi,Pb)(2 )Sr2CaCu2Ox, Ca2CuO3 and CuO at 800 degrees C. This variation leads to the quicker formation of (Bi,Pb)(2)Sr2Ca2Cu3Ox at higher temperature in the latter process. The results show that the phase assemblage comp osed of (Bi,Pb)(2)Sr2CaCu2Ox, Ca2CuO3 and CuO is the best candidate fo r the synthesis of highly pure (Bi,Pb)(2)Sr2Ca2Cu3Ox in less than 50 h , The Pb in 2223 phase seems to enter the BiO plane of the 2212 struct ure and thereby stabilizes the parent structure of 2223 phase for furt her insertion of Ca/CuO2 layers. (C) 1998 Elsevier Science B.V. All ri ghts reserved.