Misorientation angle distributions for large-angle grain boundaries in Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 composite tapes

Abstract

The angular distributions of large-angle grain boundaries were studied by electron microscopy for Bi(2:2:1:2) and Bi(2:2:2:3) composite tapes. For Bi(2:2:2:3) the distributions are random, while for Bi(2:2:1:2), there was a high incidence of special boundary misorientations. The preferred orientations in Bi(2:2:1:2), which were analyzed for [001] and [100] rotations, agreed well with the calculated lattice coincidences based on the constraint Coincidence Site Lattice model, and were attributed to the reorientation of the neighboring grains during its partial melt process.

Structural origin of misorientation-independent superconducting behavior at [001] twist boundaries inBi2Sr2Zhu1, Li2, Tsay3 et al. 1998Phys. Rev. BSelf Cite

“…Thus, the key to verifying the current paths is to determine whether a signifi-cant current can be transported across the ͓001͔ large-angle twist boundaries which represent a large fraction of the boundaries in these tapes. 13 Although there have been extensive studies of grain boundaries in high-T c superconductors, 14 investigations on the relation of structure and property have mainly focused on tilt boundaries in YBCO thin films ͑especially for structural analyses using high-resolution TEM͒. For the Bi-cuprate systems, such studies have been very limited.…”

Grain boundary misorientations and percolative current paths in high-J c powder-in-tube (Bi,Pb)2Sr3Ca3Cu3Ox

“…Such a structure is commonly observed in TEM examinations of Bi-2223 tapes and is referred to as a ''colony'' of subgrains. 20,21 Since EBSPs are formed only by a thin layer ͑10-50 nm͒ on the surface, these subgrains do not contribute to the EBSP. TEM examinations have indicated that in most cases the subgrains are connected by ͓001͔ twist boundaries.…”

“…20,21 Misorientation angle distributions of such boundaries have been carefully analyzed by Zhu et al 21 They find that the distribution is random with no preference for low ⌺ boundaries. 21 Within the confines of the microstructural model proposed here ͑i.e., percolation through low-angle boundaries͒, the presence of a colony structure in the c direction of the grains essentially serves to increase the available percolative options for current flow. Such a model is also consistent with observations of Umezawa et al 8 They find that J c decreases with the presence of 2212 intergrowths at grain boundaries.…”

Bi2Sr2CaCu2O8+δ c-axis bicrystal twist Josephson junctions: the superior phase-sensitive test of order parameter symmetry

“…In commercial Bi2212 tapes, the dominant natural defects are grain boundary junctions twisted a random angle / 0 about the c-axis, which cause no decrease in the critical current of Bi2212 tapes over kilometer distances [8,9]. To study this feature, Li et al made extraordinarily perfect artificial c-axis twist bicrystal junctions [10].…”