THE ORIGINS OF HIGH VALUES OF THE CRITICAL-CURRENT DENSITY IN THE BI2SR2CAN-1CUNOX SYSTEM - HIGH-T-C SUPERCONDUCTING PATHWAYS AT LOW-ANGLE TILT BOUNDARIES

Low angle tilt boundaries in melt processed samples from the Bi2Sr2Can -1CunOx system exhibit compositionally modulated faceting. Although we see local regions of the low-T-c (20 K) (2201) phase at such boundari es which would be highly resistive at liquid nitrogen temperatures, th ere are also ''pathways'' crossing the boundary plane made up of the h igh-T-c (2212) and (2223) phases. The characteristics of such low angl e tilt grain boundary structures can therefore be modelled to provide a general insight into the correlation between high critical current d ensities and low texture breadths.