Effects of oxygen partial pressure and mechanical deformation on (Tl,Pb)(Ba,Sr)/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ Ag-sheathed tapes

The powder in tube method was used to produce silver sheathed tapes of Tl/sub 0.78/Pb/sub 0.5/Ba/sub 0.4/Sr/sub 1.6/Ca/sub 2/Cu/sub 3/O/sub y/. A precursor powder of Pb/sub 0.5/Ba/sub 0.4/Sr/sub 1.6/Ca/sub 2/Ca/sub 3/O/sub y/ (prepared via the hydroxycarbonate coprecipitation of the metal ions from a stoichiometric nitrate solution) was thallinated and packed into a silver tube and processed into tape. The tape was then heated (in 100% oxygen or air) from 840/spl deg/C by 870/spl deg/C for various anneal times. The effects of different intermediate pressing stresses during tape processing had dramatic effects on both the current-carrying capacity and the tape microstructure. Variation of pO/sub 2/ also led to differences in current-carrying capacity I/sub c/ as did a roll substituted for a press during tape processing.< >