Influence of calcining temperature on synthesis of Bi2-xPbxSr2Ca2Cu3O10 superconductor

An extensive and systematic study of heat treatment for the synthesis of th e 2223 phase has been performed, Results of X-ray diffraction (XRD), scanni ng electron microscopy (SEM) and energy dispersive X-ray micro-analysis (ED X) are presented, It is found experimentally that the most efficient heat t reatment temperature to obtain the specimen having a high volume fraction o f 2223 phase is 1133 K, The formation of the 2223 phase begins substantiall y in only one hour after the reaching to 1133 K, In addition, the thermal h ysteresis is essential, Once the specimen is calcined below 1133 K, for exa mple at 1073 K, impurities such as Ca(Sr)-Cu oxides are inevitably included in the final product, even though the firing is made subsequently at 1133 K, The forming of the Ca(Sr)-Cu oxides, which arise from the intermediate s tep in the heat treatment process, influences strongly and prohibits to gro w the 2223 phase. It is stressed that the calcining at 1133 K is important and key technique.