Subboundary mesostructures and variable dislocation networks in single domain melt textured YBa_2Cu_3O_7―implications on critical currents

摘要

The microstructure of subboundaries (SBs) occurring in single domain YBa_2Cu_3O_7(Y123) melt textured composites is studied by transmission electron microscopy. The form of SB dislocation networks is controlled by the properties of constituting dislocations. For arbitrary SB configurations, it can be parametrised using the generalised Frank's formula, allowing the calculation of dislocation densities, and an estimation of the SB critical current. Besides the underlying dislocation networks, SBs may develop mesostructures like faceting and stepped interfaces accommodating the deviation from low index planes. Implications of the observed microstructures on the bulk critical currents are addressed.