Early in the study of cuprate grain boundary junctions (GBJs) it was observed that the junctions’ characteristic voltage (IcRn) tended to scale, at least approximately, as J 1/2 c . To re-examine the cause of this effect we have measured IcRn as a function of the more complete GBJ oxygenation that can be achieved by ozone annealing and electromigration. While these enhanced oxidation techniques...