Controlled growth of bulk bicrystals and the investigation of microstructure-property relations of YBa2Cu3Ox grain boundaries

Abstract

A new method to prepare bicrystals with well defined planar interfaces in YBa₂Cu₃O_x (Y123) has been developed. The bicrystal misorientation is controlled by dual seeding using Nd_1+xBa_2−xCu₃O_y single crystals. The grain boundary plane orientation is influenced by the positioning of the seeds and by control of the temperature gradient. The macro‐, meso‐, and microscopic planarity of the grain boundaries has been established by optical and electron microscopy. In addition, a difference in critical current density between the low (≤10°) and the high (≥20°) misorientation angle regime of nearly two orders of magnitude has been established in a series of [001]‐tilt grain boundaries. Thus, this type of grain boundary may allow a less ambiguous interpretation of the relationship between microstructure and transport properties than is possible from bicrystal thin film boundaries by eliminating the potential variations in properties associated with a varying grain boundary plane.