MICROSTRUCTURAL AND TRANSPORT-PROPERTIES OF HIGH-JC BI(2223)/AG TAPES

In the Bi(2223)/Ag tapes made by powder-in-tube method, significant effective factors on J(c) were revealed: 1) depth dependence of the orientation; 2) carbon content effect. The orientation degree of (2223) crystals varied throughout the oxide layer. The highest degree of orientation was found just near the interface between the Ag sheath and the (2223) crystals and it degraded towards the center of the oxide layer. This means that supercurrents do not flows near the center of the tape. For the thinner 0.1mm thick tape sample, J(c) of 4.10(4) A/cm2 was obtained at 77K, OT. Carbon originating from CaCO3 and SrCO3 resided on the grain boundaries and interferred with current flow. J(c) was increased 20 times with decreasing carbon content. A large activation energy U empty-set was obtained on the present high J(c) tape.