Grain boundary networks in Y123 coated conductors: Formation, properties and simulation

The grain boundary (GB) network in biaxially textured YBa₂ Cu₃O_x (Y123) coated conductors is the key to their transport properties and determines the upper limit for the critical current density. In this contribution we report on detailed EBSD (electron backscattering diffraction) investigations of the formation of these GB networks in Y123 films deposited on highly biaxially textured metallic substrates and the comparison of the measured critical current density with simulations based on the exact knowledge of the underlying GB network. Highly cube textured Ni-tapes were prepared by rolling and recrystallization and detailed texture maps were determined by EBSD before and after the deposition of Y123 films by thermal evaporation or pulsed laser deposition. This allowed the quantitative evaluation of both the Y123-growth on different oriented Ni-grains and the GB misorientation network which determines the critical current density. This exact texture information was also used to calculate the critical current density based on the well known exponential j_c-dependence across Y123 tilt GBs and is compared to the measured transport j_c across the same substrate area