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Ag-sheathed(Bi,Pb)_2Sr_2Ca_2Cu_3O_x tapes were fabricated by a powder-in-tube method.A high criticalcurrent density of 2.8×10~4 A/cm~2 at 77K,0T and 4×10~4 A/cm~2 at 4.2K,5T(H⊥ab),6.3×10~4 A/cm~2 at 4.2K,7T(H∥ab)is obtained.The microstructure of the tapes with high J_c values was in-vestigated by transmission electron microscope(TEM)and X-ray energy dispersive spectrum system(EDS).For comparison,a tape fabricated by a different procedure with a low J_c of about 1×10~4 A/cm~2 at77K,0T was also studied.The relationship between J_c and microstructure of the tapes and the effect of theprocessing on the microstructure and J_c were elucidated. 相似文献
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用振动样品磁强计测量了熔融织构(Sm0.33Eu0.33Gd0.33)Ba2Cu3O7-δ+40mol%(SmEuGd)2BaCuO5超导体从65K到87K的等温磁滞回线,外加磁场平行于样品的c-轴,最高达到8T。所有的临界电流密度曲线都显示出第二峰效应。磁通钉扎力Fp不能由一个单一的函数进行标定,结果表明,有两种不同的钉扎机制在超导体中共同作用,一种是由于RE-Ba和RE-RE交换所引起的△Tc型钉扎中心,它主要在高场时起作用,负责样品的第二峰效应,另一种是其中含有(SmEuGd)211粒子所引起的正常相面和点钉扎,它随着磁场的增加很快降为零。 相似文献
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