Effects On Superconducting Properties And Microstructure Of BSCCO Material Doped With CeO₂

During a long period of time in which researchers have carried on research continually on the superconductor BSCOO,various adulteration about it has been made in order to improve its superconducting properties.These adulterations mainly included element doing?replacement?and compound doping.In this first mode,different elements caused different consequences for BSCCO.Therefore we can formulate a hypothesis as follows:Suppose all adulterations are made by the same element,can we fide the best condition and quantity if we change the sintering temperature of the working process?must not surpass or under certain temperature?,which means trace of change under a certain amount of condition.Based on this hypothesis,this thesis take“the effect of Sn and Ca of BSCCO respectively under different experiment conditions”as its title.The main points of it can be listed as follows:The investigation of doping effect of x CeO₂?x=0.0-2.0 wt.%?in Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O_?superconductor and all doped samples were prepared by solid-state reaction technique.Some superconducting properties were found to be strongly dependent on CeO₂ content.The nano CeO₂ additive can change the volume fraction of?Bi,Pb?-2223 phase and the T_c?onset?which increased at x=0.2 wt.%doping amount of CeO₂ such as critical temperature,microstructure and the formation of BSCCO phase.At the same time,as shown in the SEM photographs,the microstructure of sample doped with 0.2 wt.%CeO₂ becamedenser,which indicated that appropriate doping amount of CeO₂ can promote crystal nucleation and grain growth.However,for the sample doped with x=2 wt.%CeO₂ additive,the zero resistance were not observed from R-T curves,which suggested that the oxides with excess inrtoduction could destroy the link between neighboring grains and BSCCO phase crystal structure.