Enhanced grain-texturing and grain-connectivity in Tl-1223/Ag tapes prepared by using pretreated precursors

Abstract Phase evolution, interface uniformity, microstructure, J c and junctional characteristic of the inter-granular contacts were investigated in Ag-sheathed Tl-1223 tapes prepared using three kinds of reacted precursors, and compared to those in the tape prepared using an unreacted precursor. The precursors were prepared by heat-treating a mixture of Sr–Ba–Ca–Cu–O, Tl 2 O 3 , PbO and Bi 2 O 3 powders at 805 °C (precursor I), 840 °C (precursor II) and 905 °C (precursor III) for 20 min. Tl-1223 phase content, grain size and J c in the tapes appeared to increase in an order of precursors I, II and III. Compared to tapes prepared using an unreacted precursor, the tapes prepared using precursors II and III revealed much reduced pore density and thus much high core density, in addition to enhanced directional-grain-alignment. As results, junctional characteristic of inter-granular contacts appeared to be shifted to a more SNS type. Also the fraction of strong-links were improved. The improved properties are attributed to enhanced grain-connectivity due to the high core density resulting from using the reacted precursors.