Critical current properties and the nature of the electromagnetic coupling in melt-textured YBa2Cu3O6+x bicrystals of general misorientation

Detailed characterization of five (5 degrees, 7 degrees, 11 degrees, 14 degrees, 38 degrees) general misorientation YBa2Cu3O6+x bicrystals produced by the melt-texture, liquid-phase-removal method shows that their field-dependent critical current density characteristic (J(c)(B)) undergoes a progressive, rather than a sharp transition with increasing misorientation. The 5 degrees bicrystal had strongly coupled characteristics, while the 7 degrees, 11 degrees and 14 degrees bicrystals had mixed characteristics, indicative of parallel weakly and strongly coupled paths crossing the grain boundary. This was true even for the 38 degrees bicrystal. We conclude that some strongly coupled channels can remain open in even very high angle, generally misoriented bicrystals. As a whole these bicrystals exhibit a slower fall of J(c)(B) with misorientation angle than do thin film [001] tilt bicrystals. (C) 1997 Elsevier Science B.V.