The origins of high values of the critical current density in the Bi 2Sr 2Ca n−1 Cu nO x system: high- Tc superconducting pathways at low angle tilt boundaries

Abstract

Low angle tilt boundaries in melt processed samples from the Bi 2Sr 2Ca n−1 Cu n O x system exhibit compositionally modulated faceting. Although we see local regions of the low- T c (20 K) (2201) phase at such boundaries which would be highly resistive at liquid nitrogen temperatures, there are also “pathways” crossing the boundary plane made up of the high- T c (2212) and (2223) phases. The characteristics of such low angle tilt grain boundary structures can therefore be modelled to provide a general insight into the correlation between high critical current densities and low texture breadths.