ELECTROMAGNETIC AND MICROSTRUCTURAL INVESTIGATIONS OF A NATURALLY GROWN 8-DEGREES [001] TILT BICRYSTAL OF BI2SR2CACU2O8+X

Electromagnetic characterization and high resolution transmission elec tron microscopy have been conducted on the same 8 degrees [001] symmet rical (010) tilt boundary in a naturally grown, bulk-scale bicrystal o f Bi2Sr2CaCu2O8+x (BSCCO-2212). The resistive transition showed excess resistance above and below T-c, suggesting some weak coupling at the boundary, but the inter- and intragranular voltage-current characteris tics, irreversibility fields, and critical current density (J(c)) valu es were very similar and characteristic of strongly coupled grains and grain boundary. The misorientation was accommodated by a set of parti al dislocations with the Frank spacing of 1.9 nm. The dislocation core s appeared to be separated by relatively undistorted regions of crysta l. The J(c) values at 25 K exceeded 10(3) A/cm(2) in fields of several tesla, more than two orders of magnitude larger than that found earli er in [001] twist boundaries of BSCCO-2212. This result is consistent with the view that low angle [001] tilt boundaries play an important r ole for current transport in polycrystalline BSCCO tapes.