FABRICATION, MICROSTRUCTURE AND CRITICAL-CURRENT DENSITY OF SCREEN-PRINTED AG-(BI,PB)2SR2CA2CU3OX SUPERCONDUCTING TAPES

The influence of the sintering conditions on the microstructure and critical current density J(c) has been studied on screen-printed Ag-(Bi, Pb)2Sr2Ca2Cu3Ox tapes with a ceramics mono-layer core. Three kinds of fabrication Processes, which consist of a combination of cold working (rolling and/or Pressing) and sintering, are applied. Four times repetition of pressing and sintering after the pre-sintering produces the highest c-axis alignment and achieves J(c) = 1.5 X 10(4) A/cm2 (77 K, 0 T). The J(c) versus theta data with an angle theta between B and the c-axis elucidate the relation between the anisotropy ratio gamma = J(c) (B perpendicular-to c)/J(c) (B parallel-to c) and the half-height angular width DELTAtheta of a peak for B perpendicular-to c. This is related to both grain alignment and the J(c) value. An increase in J(c), which comes from an improvement for grain alignment, enhances gamma and narrows DELTAtheta. The J(c) versus theta data are fitted to the expression J(c) (B,theta) = J(c)(B, 90-degrees)/[(gamma - 1)\cos theta\eta+1] by regarding both gamma and eta as adjustable parameters. Fabrication of screen-printed tapes with multi-layers (1 less-than-or-equal-to N less-than-or-equal-to 5) is presented, where the critical current increases from 8.0 A to 30.2 A at 77 K and 0 T as N increases.