Electromagnetic and microstructural investigations of a naturally grown 8° [001] tilt bicrystal of Bi2Sr2CaCu208 + x

Abstract

Electromagnetic characterization and high resolution transmission electron microscopy have been conducted on the same 8° [001] symmetrical (010) tilt boundary in a naturally grown, bulk-scale bicrystal of Bi2Sr2CaCu2O8 + x (BSCCO-2212). The resistive transition showed excess resistance above and below Tc, suggesting some weak coupling at the boundary, but the inter- and intragranular voltage-current characteristics, irreversibility fields, and critical current density (Jc) values were very similar and characteristic of strongly coupled grains and grain boundary. The misorientation was accommodated by a set of partial dislocations with the Frank spacing of 1.9 nm. The dislocation cores appeared to be separated by relatively undistorted regions of crystal. The Jc, values at 25 K exceeded 103 A/cm2 in fields of several tesla, more than two orders of magnitude larger than that found earlier in [001] twist boundaries of BSCCO-2212. This result is consistent with the view that low angle [001] till boundaries play an important role for current transport in polycrystalline BSCCO tapes.