Large-diameter 5-domain cylindrical pellets were produced by using a seeded melt-texturing process, and transmission electron microscopy and polarized optical microscopy were used to characterize the boundary geometry within pellets. It was found that, in addition to the well-known symmetrical 90º tilt domain boundaries, asymmetrical 90º tilt boundaries made up the faceted boundary segments. Although the faceted boundaries were based upon a basal-plane faced boundary structure which could theoretically lower the super-current density, the twist component which formed in the boundary area could largely benefit current transport.

Geometry of Domain Boundaries in Five-Domain YBa2Cu3Oy Levitators Fabricated by Seeded Melt Processing. X.F.Zhang: Superconductor Science and Technology, 1998, 11[12], 1391-6