  We have investigated single grain boundaries (GBs) isolated in coated
conductors produced by Metal-Organic Deposition (MOD). When a magnetic field is
swept in the film plane, an angle-dependent crossover from boundary to grain
limited critical current density Jc is found. In the force-free orientation,
even at fields as high as 8 T, the GBs still limit Jc. We deduce that this
effect is a direct consequence of GB meandering. We have employed these single
GB results to explain the dependence of Jc of polycrystalline tracks on their
width: in-plane measurements become flatter as the tracks are narrowed down.
This result is consistent with the stronger GB limitation at field
configurations close to force-free found from the isolated boundaries. Our
study shows that for certain geometries even at high fields the effect of GBs
cannot be neglected.
