Nucleation and growth of single- and multiple-domain YBa/sub 2/Cu/sub 3/O/sub x/ levitators: influence of seed crystallography

Large diameter YBa/sub 2/Cu/sub 3/O/sub x/ levitators have been fabricated using seeded melt processing. Two types of levitators have been produced: single-domain, obtained using flat NdBa/sub 2/Cu/sub 3/O/sub x/ seeds, and five-domain, obtained using cubic NdBa/sub 2/Cu/sub 3/O/sub x/ seeds. The difference in these two types of levitators can be attributed to differences in nucleation and solidification processes. In particular, the nucleation of multiple (five) domain levitators may be related directly to the crystallography of the cubic seeding crystals which also exhibit a multiple-domain structure. Single-domain levitators are produced by seeding with plate-like seed crystals which are composed of a single domain. Subsequent growth of the levitator is dominated by anisotropic solidification. Using these types of seeds, we developed a dual-seeded melt textured growth process for the production of bulk bicrystals which are useful for studies of grain boundary transport behavior.