Critical current response of BSCCO tapes in tension

Abstract

Uniaxial tension experiments were performed on monofilament Bi_1.9Pb_0.4Sr₂Ca₂Cu₃O_x (BSCCO)-silver and pure silver tapes. Nearly silver-free BSCCO tapes were also tested to study the influence of the silver phase.In situ measurements of the critical current density (J_c) vs applied strain provided evidence for the strength and failure behavior of the superconducting oxide core. Final rolling deformation was used as the primary processing variable. BSCCOAg tapes exhibited strain tolerance of up to 0.4% before the superconducting performance began to degrade. The stress-strain response of a near silver-free core was typical of ceramics with brittle failure occurring after an elastic strain of 0.19%. Although not optimized, the yield strength and J_c improved with greater final rolling deformation. Even greater strain tolerance is postulated by improving the structure and integrity of the oxide core and by increasing the residual compressive stress imposed on the core by the thermal expansion mismatch with the silver sheath.