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, 1 4 degrees, 38 degrees) general misorientation YBa2Cu3O6+x bicrystals p roduced by the melt-texture, liquid-phase-removal method shows that th eir field-dependent critical current density characteristic (J(c)(B)) undergoes a progressive, rather than a sharp transition with increasin g misorientation. The 5 degrees bicrystal had strongly coupled charact eristics, while the 7 degrees, 11 degrees and 14 degrees bicrystals ha d mixed characteristics, indicative of parallel weakly and strongly co upled paths crossing the grain boundary. This was true even for the 38 degrees bicrystal. We conclude that some strongly coupled channels ca n remain open in even very high angle, generally misoriented bicrystal s. As a whole these bicrystals exhibit a slower fall of J(c)(B) with m isorientation angle than do thin film [001] tilt bicrystals. (C) 1997 Elsevier Science B.V.