Small and repetitive axial strain reducing the critical current in BSCCO/Ag superconductors

The critical current in two types of axially deformed BSCCO/Ag tape conductors is investigated. An I/sub c/ reduction is observed for small axial strains (ranging from 0 to 0.3%) with a characteristic slope di/sub c//d/spl epsiv/=-5/spl plusmn/1 (relative I/sub c/, change per relative change in length). In the case of an axial compression there is a more pronounced I/sub c/ reduction. For small axial strains (<0.3%) a certain reversible change in I/sub c/ is observed. This reversible behaviour occurs in combination with an irreversible reduction that increases when the number of strain cycles is increased. The reversible part of the I/sub c/ change remains for a large number of strain cycles (>10000) and has a similar negative slope for both compressive and tensile strains. It is proposed that the reversible I/sub c/ change is correlated to a non-hydrostatic lattice deformation. The I/sub c/ versus strain behaviour is in good agreement with an earlier proposed model.