The process to obtain high T(110K)phase quickly,the microstructure and properties of Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tapes have been studied.It was found that the formation time of the high T_c phase was ...The process to obtain high T(110K)phase quickly,the microstructure and properties of Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tapes have been studied.It was found that the formation time of the high T_c phase was greatly shortened by the addition of more Ca and Cu to the nominal composition of Bi(Pb):Sr :Ca:Cu=2:2:2:3 and the adoption of appropriate sintering temperature and cooling rate. Superconductor powder with predominant high T,phase was prepared after a 840 C/50 h treatment.The J of the Ag-sheathed tapes and the magnetic field dependence of Jwere obviously improved by repeatedly pres- sing and sintering.The maximum transport current density at 77K in a zero magnetic field was 12,200 A/cm^2. The magnetic dependence of Jwas summarized as follows:6.450 A/cm^(2)(B⊥1.B∥S.0.1T)1,810 A/cm^2 (B⊥1.B∥S,1T),390 A/cm^2(B⊥1.B∥S,2T)(B:magnetic field.1:electric current.S:surface of tapes).The improvement of Jwas attributed to the formation of the plate-like structure with homogeneous composition distribution and the strong c-axis texture.展开更多
文摘The process to obtain high T(110K)phase quickly,the microstructure and properties of Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconductor tapes have been studied.It was found that the formation time of the high T_c phase was greatly shortened by the addition of more Ca and Cu to the nominal composition of Bi(Pb):Sr :Ca:Cu=2:2:2:3 and the adoption of appropriate sintering temperature and cooling rate. Superconductor powder with predominant high T,phase was prepared after a 840 C/50 h treatment.The J of the Ag-sheathed tapes and the magnetic field dependence of Jwere obviously improved by repeatedly pres- sing and sintering.The maximum transport current density at 77K in a zero magnetic field was 12,200 A/cm^2. The magnetic dependence of Jwas summarized as follows:6.450 A/cm^(2)(B⊥1.B∥S.0.1T)1,810 A/cm^2 (B⊥1.B∥S,1T),390 A/cm^2(B⊥1.B∥S,2T)(B:magnetic field.1:electric current.S:surface of tapes).The improvement of Jwas attributed to the formation of the plate-like structure with homogeneous composition distribution and the strong c-axis texture.
