Employment of Gd-Ba-Cu-O elongated seeds in top-seeded melt-growth processing of Y-Ba-Cu-O superconductors

Top-seeded melt-growth (TSMG) processing of large bulk Y-Ba-Cu-O monodomains was advanced by applying Gd-Ba-Cu-O elongated seeds. The seeds, up to 38 mm in length, were fabricated by cutting Gd-Ba-Cu-O monodomains produced by the TSMG technique. Three types of seeds, differing in their orientation of crystallographic directions, were prepared. Crystal growth of the Y-Ba-Cu-O monodomain depending on crystallographic directions in the seed contact surface was investigated. It was established that every type of seed generates a different growth mode of the initial facet plane. It is shown that elongated seeds make for growth of a dominant crystal without spontaneous nucleation, decrease of processing time, reduction of maximum heating temperature and improvement of manufacturability and reproducibility of the TSMG process. Y-Ba-Cu-O monodomains up to 48 mm in diameter were produced using elongated seeds. They are able to trap magnetic fields up to 1.38 T